Subject: RE: New Lehman on line (almost) From: steve hammond shammon1@............. Date: Sun, 29 Sep 2002 22:21:09 -0700 Looks interesting Jan, nice work. I think it may be under dampened. The standard rule is to pull the boom back a few inches and let it go. The boom should loose 30% of its motion on each swing past center and come to rest in 3 1/2 swings. My standard non dampened period is 12 - 14 seconds with a 40-cm boom and 18 - 20 seconds when dampened. I have pasted some table data below that will help you determine the angle (drop) on your boom and the natural non dampened period. In my system, I also use a 5 lb. mass however, I needed two of the same magnets you are using to get mine to come to rest. They are set in an opposing field design. A 1/4-inch copper plate is attached to the boom and passes between them. I also have another thought and it is about wind currents in the room. What kind of cover are you using? I don't see one in the photo and wanted to be sure you understand, you need to put this unit in an air tight box. As for noise each site is different. Take a look at Larry's site in Redwood City and look at some of the other Lehman style systems. For example, mine in Aptos, CA are AT1 and AT2. I live near a busy road and have to deal with very high noise. Regards, Steve Hammond PSN San Jose - Aptos, CA Boom length in CM. Natural period @ .05 degree Natural Period @ .1 degree Natural Period @ .25 degree Natural Period @ .5 degree Natural Period @ .75 degree Natural Period @ 1 degree Natural Period @ 2 degree 100 67.943 48.043 30.385 21.486 17.543 15.193 10.744 99 67.602 47.802 30.233 21.378 17.455 15.117 10.690 98 67.260 47.560 30.080 21.270 17.367 15.040 10.636 97 66.916 47.317 29.926 21.161 17.278 14.963 10.581 96 66.570 47.072 29.771 21.051 17.189 14.886 10.527 95 66.222 46.826 29.616 20.941 17.099 14.808 10.472 94 65.873 46.579 29.459 20.831 17.009 14.730 10.416 93 65.522 46.331 29.302 20.720 16.918 14.651 10.361 92 65.168 46.081 29.144 20.608 16.827 14.572 10.305 91 64.813 45.830 28.985 20.496 16.735 14.493 10.249 90 64.456 45.577 28.826 20.383 16.643 14.413 10.192 89 64.097 45.323 28.665 20.269 16.550 14.333 10.136 88 63.736 45.068 28.504 20.155 16.457 14.252 10.079 87 63.373 44.811 28.341 20.040 16.363 14.171 10.021 86 63.008 44.553 28.178 19.925 16.269 14.089 9.963 85 62.640 44.293 28.014 19.809 16.174 14.007 9.905 84 62.271 44.032 27.848 19.692 16.078 13.924 9.847 83 61.899 43.769 27.682 19.574 15.982 13.841 9.788 82 61.525 43.505 27.515 19.456 15.886 13.758 9.729 81 61.148 43.239 27.346 19.337 15.789 13.674 9.669 80 60.770 42.971 27.177 19.217 15.691 13.589 9.610 79 60.389 42.701 27.007 19.097 15.593 13.504 9.549 78 60.005 42.430 26.835 18.975 15.494 13.418 9.489 77 59.620 42.157 26.663 18.853 15.394 13.332 9.428 76 59.231 41.883 26.489 18.731 15.294 13.245 9.366 75 58.840 41.606 26.314 18.607 15.193 13.157 9.304 74 58.447 41.328 26.138 18.483 15.091 13.069 9.242 73 58.050 41.048 25.961 18.357 14.989 12.981 9.179 72 57.651 40.766 25.783 18.231 14.886 12.892 9.116 71 57.250 40.482 25.603 18.104 14.782 12.802 9.053 70 56.845 40.195 25.422 17.976 14.678 12.711 8.989 69 56.437 39.907 25.240 17.847 14.572 12.620 8.924 68 56.027 39.617 25.056 17.717 14.466 12.528 8.860 67 55.614 39.325 24.871 17.587 14.360 12.436 8.794 66 55.197 39.030 24.685 17.455 14.252 12.343 8.728 65 54.777 38.733 24.497 17.322 14.144 12.249 8.662 64 54.354 38.434 24.308 17.188 14.034 12.154 8.595 63 53.928 38.133 24.117 17.054 13.924 12.059 8.528 62 53.498 37.829 23.925 16.918 13.813 11.963 8.460 61 53.065 37.523 23.731 16.781 13.702 11.866 8.391 60 52.628 37.214 23.536 16.643 13.589 11.768 8.322 59 52.188 36.902 23.339 16.503 13.475 11.670 8.252 58 51.744 36.588 23.141 16.363 13.360 11.571 8.182 57 51.296 36.272 22.940 16.221 13.245 11.470 8.111 56 50.844 35.952 22.738 16.078 13.128 11.369 8.040 55 50.388 35.629 22.534 15.934 13.010 11.267 7.968 54 49.928 35.304 22.328 15.789 12.891 11.164 7.895 53 49.463 34.976 22.121 15.642 12.771 11.061 7.822 52 48.994 34.644 21.911 15.493 12.650 10.956 7.747 51 48.521 34.309 21.699 15.344 12.528 10.850 7.673 50 48.043 33.971 21.485 15.193 12.405 10.743 7.597 49 47.560 33.630 21.269 15.040 12.280 10.635 7.521 48 47.072 33.285 21.051 14.886 12.154 10.526 7.444 47 46.579 32.936 20.831 14.730 12.027 10.416 7.366 46 46.081 32.584 20.608 14.572 11.898 10.304 7.287 45 45.577 32.228 20.383 14.413 11.768 10.192 7.207 44 45.068 31.868 20.155 14.252 11.637 10.078 7.127 43 44.553 31.504 19.925 14.089 11.504 9.963 7.045 42 44.032 31.135 19.692 13.924 11.369 9.846 6.963 41 43.505 30.762 19.456 13.757 11.233 9.728 6.879 40 42.971 30.385 19.217 13.589 11.095 9.609 6.795 39 42.430 30.003 18.975 13.418 10.956 9.488 6.709 38 41.883 29.616 18.731 13.245 10.814 9.366 6.623 37 41.328 29.223 18.482 13.069 10.671 9.241 6.535 36 40.766 28.826 18.231 12.891 10.526 9.116 6.446 35 40.195 28.423 17.976 12.711 10.379 8.988 6.356 34 39.617 28.014 17.717 12.528 10.229 8.859 6.265 33 39.030 27.598 17.455 12.342 10.078 8.728 6.172 32 38.434 27.177 17.188 12.154 9.924 8.594 6.078 31 37.829 26.749 16.918 11.963 9.768 8.459 5.982 30 37.214 26.314 16.643 11.768 9.609 8.321 5.885 29 36.588 25.872 16.363 11.570 9.447 8.182 5.786 28 35.952 25.422 16.078 11.369 9.283 8.039 5.685 27 35.304 24.964 15.788 11.164 9.116 7.894 5.583 26 34.644 24.497 15.493 10.956 8.945 7.747 5.478 25 33.971 24.021 15.192 10.743 8.771 7.596 5.372 24 33.285 23.536 14.886 10.526 8.594 7.443 5.263 23 32.584 23.041 14.572 10.304 8.413 7.286 5.153 22 31.868 22.534 14.252 10.078 8.228 7.126 5.039 21 31.135 22.016 13.924 9.846 8.039 6.962 4.923 20 30.385 21.485 13.589 9.609 7.845 6.794 4.805 19 29.616 20.941 13.245 9.365 7.647 6.622 4.683 18 28.826 20.383 12.891 9.116 7.443 6.446 4.558 17 28.014 19.809 12.528 8.859 7.233 6.264 4.430 16 27.177 19.217 12.154 8.594 7.017 6.077 4.298 15 26.314 18.607 11.768 8.321 6.794 5.884 4.161 14 25.422 17.976 11.369 8.039 6.564 5.685 4.020 13 24.497 17.322 10.955 7.747 6.325 5.478 3.874 12 23.536 16.643 10.526 7.443 6.077 5.263 3.722 11 22.534 15.934 10.078 7.126 5.818 5.039 3.563 10 21.485 15.192 9.609 6.794 5.548 4.804 3.397 -----Original Message----- From: Jan D. Marshall [SMTP:jandmarshall@............. Sent: Sunday, September 29, 2002 2:52 PM To: psn-l@.............. Subject: RE: New Lehman on line (almost) see my comments beside your questions below -- Jan M Jan Marshall jandmarshall@............ www.cableone.net/jandmarshall Nampa, ID -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of ChrisAtUpw@....... Sent: Sunday, September 29, 2002 3:24 PM To: psn-l@.............. Subject: Re: New Lehman on line (almost) In a message dated 29/09/02, jandmarshall@............ writes: Please visit my web site www.cableone.net/jandmarshall and choose the Seismic Page to view my project. Problems I note right off 1 - I have a 4-5 hz oscillation in the pendulum. 2 - I seem to have a lot of environmental noise -- I can not correlate it with actions in the house 3 - Am I damped enough? Hi Jan, The photos are a great help. What is the weight of the seismic mass on the end of the arm? right at 5 pounds What undamped oscillation period are you getting? about 12 - 14 sec Only you can check the damping. Deflect the beam a very small amount, maybe by putting a screwdriver etc near it, let it go and observe it. The pendulum should swing back to the zero position, but it should not go beyond zero and come back, or show any actual oscillations. OK -- I am not damped enough -- It oscillates about 4-5 times The bearings, general construction etc look fine. Check for electrical activity in the house / movement of magnetic materials, even cars / trains outside etc to search for the environmental noise. Does the seis react when the fridge / cooker / central heating switches on / off? It is more usual to put both magnets on the baseplate and the coil and damping plate on the arm. With unscreened magnets on the arm, it can and will pick up any small changes in the local environmental magnetic field. I will consider this From the photos, I can't see where the pick up coil is in relation to it's magnet. The centre line of the coil should be roughly on the end face of the magnet with your setup. See the 6th picture down -- The 5 Hz could be due to the whole arm system nodding up and down or side to side. Try tapping the end post with your finger and see if you get this sort of frequency response. With your coil system as shown, you will likely pick up both vertical and horizontal movements of the arm. I lowered the right end a tiny bit -- the LF oscillations appear to have stopped What amplifier / filter / A/D system are you using? What is the cut-off frequency of the filter? I am using Larry Cochran's Serial A/D board and his Filter/Amp both stock as I received them -- I am using his coil also Regards, Chris Chapman << File: ATT00003.html >> __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: VP oncore boards From: Stephen & Kathy skmort@.......... Date: Mon, 30 Sep 2002 14:20:58 -0700 FYI,, Synergy Systems has a surplus of Motorola 6 ch and 8 ch VP Oncore GPS OEM boards, similar to the GT+ boards some PSNers bought a while back. Their web site is: http://www.synergy-gps.com/ They can be found under Excess Inventory Sale which is a PDF file. They are $25 to $36 The 8 ch units are used. I ordered 2 and because I am planning to play with DGPS and post processing I had them add the $15 carrier phase firmware to each, which puts a Z in the part number. The list shows about 900 of the 8 ch units (with 2 different plug types) as of Aug 12 2002. Stephen PSN Station #55 38.828N 120.979W __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: New Lehman on line (almost) From: ChrisAtUpw@....... Date: Mon, 30 Sep 2002 20:13:28 EDT In a message dated 30/09/02, shammon1@............. writes: > The standard rule is to pull the boom back a few inches and let it go. The > boom > should loose 30% of its motion on each swing past center and come to rest > in 3 1/2 swings. Hi Steve, I am puzzled as to where this *standard rule* is supposed to come from? But using it will give you a quite seriously underdamped system! A critically damped system experiences no oscillation at all. This is inherent in the maths. This is important if you apply post processing to the recorded signal with the assumption that it was critically damped to start with. It will also give problems with the amplitudes and frequencies calculated in FFT displays and may 'smear' P and S wave recordings. A procedure to get critical damping could involve deflecting the beam a very small amount (microns) and recording the amplifier output. You progressively increase the damping until the arm just returns to the balance position without having crossed the zero line. If you increase the damping further, the arm will simply take longer to get back to zero. If you use huge deflections like a few inches, you are likely to encounter non linear effects which do not apply to the tiny (hopefully!) signals that we normally record. It is helpful if the recording displays just what the earth is doing. It is really not helpful if the system adds an oscillating tail to every transient. Regards, Chris Chapman In a message dated 30/09/02, shammon1@............. writes:

The standard rule is to pull the boom back a few inches and let it go. The boom
should loose 30% of its motion on each swing past center and come to rest
in 3 1/2 swings.


Hi Steve,

      I am puzzled as to where this *standard rule* is supposed to come from? But using it will give you a quite seriously underdamped system! A critically damped system experiences no oscillation at all. This is inherent in the maths.
      This is important if you apply post processing to the recorded signal with the assumption that it was critically damped to start with. It will also give problems with the amplitudes and frequencies calculated in FFT displays and may 'smear' P and S wave recordings.
      A procedure to get critical damping could involve deflecting the beam a very small amount (microns) and recording the amplifier output. You progressively increase the damping until the arm just returns to the balance position without having crossed the zero line. If you increase the damping further, the arm will simply take longer to get back to zero. If you use huge deflections like a few inches, you are likely to encounter non linear effects which do not apply to the tiny (hopefully!) signals that we normally record.  
      It is helpful if the recording displays just what the earth is doing. It is really not helpful if the system adds an oscillating tail to every transient.

      Regards,

      Chris Chapman
Subject: RE: New Lehman on line (almost) From: "Bob Hancock" robert.hancock@........... Date: Mon, 30 Sep 2002 20:30:49 -0400 Jan – About your seismic background noise – I have no background in electronics so I cannot comment on that. However if you will check out the Lamont-Daugherty Cooperative Seismic Network (just north of New York city) at the following site: http://www.ldeo.columbia.edu/cgi-bin/LCSN/WebSeis/24hr_heli.pl You will see the background noise has been quite high for over 24 hours…….. If you will then go the following three sites in Tucson, Arizona, you will see similar broadband noise. http://saso.geo.arizona.edu/saso/Earthquakes/Current/tuc_sp.html http://saso.geo.arizona.edu/saso/Earthquakes/Current/tuc_lp.html http://saso.geo.arizona.edu/saso/Earthquakes/Current/tuc_nf.html Some of the displays look very close to your type of activity. I have a broadband sensor and have filtered most of it out as I view the screen, but it still comes through. I am not certain what the cause is, but we appear to be in a period of increased seismic background noise. This appears to have significantly increased around 0900 – 1000 UTC September 29, here in the northeast, and now appears to be relaxing a little. I am aware of a storm near Jamaica, but there are probably others around that are also influencing what we are seeing. Good Luck with your venture. Bob Hancock -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of Jan D. Marshall Sent: Sunday, September 29, 2002 12:18 PM To: Sesmic List Server Subject: New Lehman on line (almost)

Jan = –

 

About your seismic background noise – I have no background in electronics so I cannot = comment on that.  However if you will = check out the Lamont-Daugherty Cooperative Seismic Network (just north of New = York city) at the following site:

 

        = ;    h= ttp://www.ldeo.columbia.edu/cgi-bin/LCSN/WebSeis/24hr_heli.pl

 

You = will see the background noise has been quite high for over 24 = hours……..

 

If = you will then go the following three sites in Tucson, Arizona, you will see = similar broadband noise.

 

        = ;    http://saso.geo.arizona.edu/saso/Earthquakes/Current/tuc_sp.html

 

        = ;    http://saso.geo.arizona.edu/saso/Earthquakes/Current/tuc_lp.html

 

        = ;    http://saso.geo.arizona.edu/saso/Earthquakes/Current/tuc_nf.html

 

Some of the displays look very close to your type of activity.  I have a broadband sensor and have filtered most of = it out as I view the screen, but it still comes through.  I am not certain what the cause is, but we appear to = be in a period of increased seismic background noise.  This appears to have significantly increased around = 0900 – 1000 UTC September 29, here in the northeast, and now appears to be = relaxing a little.  I am aware of a = storm near Jamaica, but there are probably others around that are also influencing = what we are seeing.

 

Good Luck with your venture.

 

Bob = Hancock

 

 <= /p>

  = -----Original Message-----
From: = psn-l-request@.............. [mailto:psn-l-request@...............On Behalf Of Jan D. Marshall
Sent: Sunday, September = 29, 2002 12:18 PM
To: Sesmic List = Server
Subject: New Lehman on = line (almost)

 <= /p>

Subject: Re: New Lehman on line (almost) From: ACole65464@....... Date: Mon, 30 Sep 2002 22:04:30 EDT In a message dated 10/01/2002 12:14:06 AM !!!First Boot!!!, ChrisAtUpw@....... writes: > In a message dated 30/09/02, shammon1@............. writes: > > >> The standard rule is to pull the boom back a few inches and let it go. >> The boom >> should loose 30% of its motion on each swing past center and come to rest >> in 3 1/2 swings. > > Hi Steve, > > I am puzzled as to where this *standard rule* is supposed to come > from? But using it will give you a quite seriously underdamped system! A > critically damped system experiences no oscillation at all. This is > inherent in the maths. > This is important if you apply post processing to the recorded signal > with the assumption that it was critically damped to start with. It will > also give problems with the amplitudes and frequencies calculated in FFT > displays and may 'smear' P and S wave recordings. > A procedure to get critical damping could involve deflecting the beam > a very small amount (microns) and recording the amplifier output. You > progressively increase the damping until the arm just returns to the > balance position without having crossed the zero line. If you increase the > damping further, the arm will simply take longer to get back to zero. If > you use huge deflections like a few inches, you are likely to encounter non > linear effects which do not apply to the tiny (hopefully!) signals that we > normally record. > It is helpful if the recording displays just what the earth is doing. > It is really not helpful if the system adds an oscillating tail to every > transient. > > Regards, > > Chris Chapman Steve, In support of what Chris has stated, please go to: http://www.seismo.com/msop/msop79/inst/inst4.html#aa250 Go to section 4.5 for a text description, and then click on figure 4.5.1a to see how pendulums are supposed to be damped. About Critical is the response you should obtain. I hope this helps a little, the diagrams may not make much sense at first but it shows how professional instruments (electromagnetic, aka Lehman designs) are adjusted. Regards, Allan Coleman In a message dated 10/01/2002 12:14:06 AM !!!First Boot!!!, ChrisAtUpw@....... writes:


In a message dated 30/09/02, shammon1@............. writes:

The standard rule is to pull the boom back a few inches and let it go. The boom
should loose 30% of its motion on each swing past center and come to rest
in 3 1/2 swings.


Hi Steve,

      I am puzzled as to where this *standard rule* is supposed to come from? But using it will give you a quite seriously underdamped system! A critically damped system experiences no oscillation at all. This is inherent in the maths.
      This is important if you apply post processing to the recorded signal with the assumption that it was critically damped to start with. It will also give problems with the amplitudes and frequencies calculated in FFT displays and may 'smear' P and S wave recordings.
      A procedure to get critical damping could involve deflecting the beam a very small amount (microns) and recording the amplifier output. You progressively increase the damping until the arm just returns to the balance position without having crossed the zero line. If you increase the damping further, the arm will simply take longer to get back to zero. If you use huge deflections like a few inches, you are likely to encounter non linear effects which do not apply to the tiny (hopefully!) signals that we normally record.  
      It is helpful if the recording displays just what the earth is doing. It is really not helpful if the system adds an oscillating tail to every transient.

      Regards,

      Chris Chapman


Steve,

In support of what Chris has stated, please go to:  http://www.seismo.com/msop/msop79/inst/inst4.html#aa250  Go to section 4.5 for a text description, and then click on figure 4.5.1a to see how pendulums are supposed to be damped. About Critical is the response you should obtain. I hope this helps a little, the diagrams may not make much sense at first but it shows how professional instruments (electromagnetic, aka Lehman designs) are adjusted.

Regards,

Allan Coleman
Subject: Re: VP oncore boards From: Richard Gagnon richg_1998@......... Date: Mon, 30 Sep 2002 19:45:52 -0700 (PDT) Here is a URL to BG Micro. They have Motorola Oncore GT GPS 8 ch receivers for 14.95. I am planning on buying one as a spare. They are new according to the info. I have no connection with the company. I just buy from them occasionally. http://www.bgmicro.com/pdf/page1.pdf Richard --- Stephen & Kathy wrote: > FYI,, Synergy Systems has a surplus of Motorola 6 ch and 8 ch VP Oncore > GPS > OEM boards, similar to the GT+ boards some PSNers bought a while back. > Their web site is: > > http://www.synergy-gps.com/ > > They can be found under Excess Inventory Sale which is a PDF file. > > They are $25 to $36 The 8 ch units are used. I ordered 2 and because I > am > planning to play with DGPS and post processing I had them add the $15 carrier > phase firmware to each, which puts a Z in the part number. > > The list shows about 900 of the 8 ch units (with 2 different plug types) as > of > Aug 12 2002. > > Stephen > PSN Station #55 > 38.828N 120.979W > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________ Do you Yahoo!? New DSL Internet Access from SBC & Yahoo! http://sbc.yahoo.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: New Lehman on line (almost) From: John & Jan Lahr johnjan@........ Date: Tue, 01 Oct 2002 00:54:14 -0600 Actually, the USGS short period 1Hz systems are adjusted for a bit less than
critical damping.  0.8 is, I believe, the damping factor.  Damping issues are discussed
in this message from Sean Morrissey.  I suppose one advantage to slight underdamping
in an amateur system would be to avoid overdamping.  It may be easier to see a small
overshot and return to zero, whereas both critically damped and overdamped
systems will both return to zero without crossing zero eventually.

One can see a graph of the displacement from a damped harmonic oscillator
on this page:
http://lectureonline.cl.msu.edu/~mmp/applist/damped/d.htm

The equations to keep in mind are:

Omega (2 pi frequency) =  [sqrt(4mk  - b**2)]/2m

The damping factor is b/ [2 sqrt(mk)]

If the damping factor is zero (b = 0) then omega = sqrt(k/m)

If the damping factor is 1 (b = 2 sqrt(mk) ) damping is critical and
a displacement will return to zero exponentially.

If the damping factor is greater than 1, displacement will return
to zero at a slower exponential rate.

To see what a damping factor is 0.8 would look like, in the
applet above set m = k = 1 and b = 1.6.  There is a small overshoot
and then a return to zero.

Cheers,
John



At 08:13 PM 9/30/2002 -0400, you wrote:
In a message dated 30/09/02, shammon1@............. writes:

The standard rule is to pull the boom back a few inches and let it go. The boom
should loose 30% of its motion on each swing past center and come to rest
in 3 1/2 swings.


Hi Steve,

      I am puzzled as to where this *standard rule* is supposed to come from? But using it will give you a quite seriously underdamped system! A critically damped system experiences no oscillation at all. This is inherent in the maths.
      This is important if you apply post processing to the recorded signal with the assumption that it was critically damped to start with. It will also give problems with the amplitudes and frequencies calculated in FFT displays and may 'smear' P and S wave recordings.
      A procedure to get critical damping could involve deflecting the beam a very small amount (microns) and recording the amplifier output. You progressively increase the damping until the arm just returns to the balance position without having crossed the zero line. If you increase the damping further, the arm will simply take longer to get back to zero. If you use huge deflections like a few inches, you are likely to encounter non linear effects which do not apply to the tiny (hopefully!) signals that we normally record.  
      It is helpful if the recording displays just what the earth is doing. It is really not helpful if the system adds an oscillating tail to every transient.

      Regards,

      Chris Chapman
Subject: RE: New Lehman on line (almost) From: Jack Ivey ivey@.......... Date: Tue, 1 Oct 2002 08:08:44 -0400 In defense of the underdamped proposition, a slight amount of underdamping (that produces a second peak about, say, 10% the size of the first peak) will produce only a mild peak in the frequency response, and in fact will extend the low frequency response of the system slightly. The main advantage of this arrangement is that it is very easy to tell exactly how much damping you have. If you adjust for critical or overdamped, you can only guess, and lots of people will end up with a massively overdamped system, reducing their low frequency response unnecessarily. It is important to use realistic deflections when measuring damping, I have found that if you use large (1/8") deflections, you sometimes get very different (greater) damping than you do with micrometer deflections. Bob Barns' calibrator (see PSN site) is an excellent way to produce these small test signals. Jack -----Original Message----- From: ACole65464@....... [mailto:ACole65464@........ Sent: Monday, September 30, 2002 10:05 PM To: psn-l@.............. Subject: Re: New Lehman on line (almost) In a message dated 10/01/2002 12:14:06 AM !!!First Boot!!!, ChrisAtUpw@....... writes: In a message dated 30/09/02, shammon1@............. writes: The standard rule is to pull the boom back a few inches and let it go. The boom should loose 30% of its motion on each swing past center and come to rest in 3 1/2 swings. Hi Steve, I am puzzled as to where this *standard rule* is supposed to come from? But using it will give you a quite seriously underdamped system! A critically damped system experiences no oscillation at all. This is inherent in the maths. This is important if you apply post processing to the recorded signal with the assumption that it was critically damped to start with. It will also give problems with the amplitudes and frequencies calculated in FFT displays and may 'smear' P and S wave recordings. A procedure to get critical damping could involve deflecting the beam a very small amount (microns) and recording the amplifier output. You progressively increase the damping until the arm just returns to the balance position without having crossed the zero line. If you increase the damping further, the arm will simply take longer to get back to zero. If you use huge deflections like a few inches, you are likely to encounter non linear effects which do not apply to the tiny (hopefully!) signals that we normally record. It is helpful if the recording displays just what the earth is doing. It is really not helpful if the system adds an oscillating tail to every transient. Regards, Chris Chapman Steve, In support of what Chris has stated, please go to: http://www.seismo.com/msop/msop79/inst/inst4.html#aa250 Go to section 4.5 for a text description, and then click on figure 4.5.1a to see how pendulums are supposed to be damped. About Critical is the response you should obtain. I hope this helps a little, the diagrams may not make much sense at first but it shows how professional instruments (electromagnetic, aka Lehman designs) are adjusted. Regards, Allan Coleman
In defense of the underdamped proposition, a slight amount of underdamping
(that produces a second peak about, say, 10% the size of the first peak) will
produce only a mild peak in the frequency response, and in fact will extend the
low frequency response of the system slightly.  The main advantage of this
arrangement is that it is very easy to tell exactly how much damping you have. 
If you adjust for critical or overdamped, you can only guess, and lots of people
will end up with a massively overdamped system, reducing their low frequency
response unnecessarily.
 
It is important to use realistic deflections when measuring damping, I have found
that if you use large (1/8") deflections, you sometimes get very different (greater)
damping than you do with micrometer deflections.  Bob Barns' calibrator (see
PSN site) is an excellent way to produce these small test signals.
 
Jack
-----Original Message-----
From: ACole65464@....... [mailto:ACole65464@........
Sent: Monday, September 30, 2002 10:05 PM
To: psn-l@..............
Subject: Re: New Lehman on line (almost)

In a message dated 10/01/2002 12:14:06 AM !!!First Boot!!!, ChrisAtUpw@....... writes:


In a message dated 30/09/02, shammon1@............. writes:

The standard rule is to pull the boom back a few inches and let it go. The boom
should loose 30% of its motion on each swing past center and come to rest
in 3 1/2 swings.


Hi Steve,

      I am puzzled as to where this *standard rule* is supposed to come from? But using it will give you a quite seriously underdamped system! A critically damped system experiences no oscillation at all. This is inherent in the maths.
      This is important if you apply post processing to the recorded signal with the assumption that it was critically damped to start with. It will also give problems with the amplitudes and frequencies calculated in FFT displays and may 'smear' P and S wave recordings.
      A procedure to get critical damping could involve deflecting the beam a very small amount (microns) and recording the amplifier output. You progressively increase the damping until the arm just returns to the balance position without having crossed the zero line. If you increase the damping further, the arm will simply take longer to get back to zero. If you use huge deflections like a few inches, you are likely to encounter non linear effects which do not apply to the tiny (hopefully!) signals that we normally record.  
      It is helpful if the recording displays just what the earth is doing. It is really not helpful if the system adds an oscillating tail to every transient.

      Regards,

      Chris Chapman


Steve,

In support of what Chris has stated, please go to:  http://www.seismo.com/msop/msop79/inst/inst4.html#aa250  Go to section 4.5 for a text description, and then click on figure 4.5.1a to see how pendulums are supposed to be damped. About Critical is the response you should obtain. I hope this helps a little, the diagrams may not make much sense at first but it shows how professional instruments (electromagnetic, aka Lehman designs) are adjusted.

Regards,

Allan Coleman
Subject: RE: New Lehman on line (almost) From: steve hammond shammon1@............. Date: Tue, 1 Oct 2002 14:44:10 -0700 Let me say up front, Jan will need to think about the critical damping at some point and he has been given some excellent information by Chris and Allen and I agree, Bob Barn's info is really worth the reading. However, having built a few Lehman systems myself, and having built a few that didn't work so well... I took Jan's coarsely tuned comment to mean that he may still not be certain if the system is even working. Jan, if that is the case this may help you get started: Pull the boom back a few inches and eyeball it and see if it comes to rest some where in the ballpark of 2 to 5 swings pass the center line. If it does not, remove the damping magnet from the boom, set the top of the vertical post 1/8-inch in the direction of the mass weight, level the boom, swing the boom and check to see if the boom eventually returns to center. Screw with it until it does. Then start adjusting the vertical post to the rear (away from the mass weight) until the period is significantly longer and the boom returns to center. As you adjust the post back, keep a level on the boom itself and adjust it to be level. (Some PSN members like to keep the boom at a very slight down angle. Don't ask why it's like fine wine) Once you reach the 12-14 second period point each adjustment will become much more critical. If you reach a point that the boom drops off center to the left or right side of center and will not return to center, you have overshot the zero point and adjusted the post into what could be thought of as a negative zone and you need to move the top of the post back towards the mass weight to recreate the pendulum effect. Once you achieve the non-dampened adjustment, say a 10 - 30 seconds period, you can now start adding the dampening. I consider a 18 - 30 second non-dampened period to be the most desirable. If after setting the period you find that the device goes to one of the stops over night, then reduce the period so that the device is not so sensitive to changes in the local site such as rain and water table changes. Now let's talk about initial damping settings. Chris and Allen are right, the boom should never remain in oscillation. At this point add damping until it comes to rest in 3.5 swings. Guy's, this is the coarsely adjusted point I think Jan is initially trying to achieve. Turn it on and let it rip. See what you record. Have some fun with it-- Record a few events and see what you get. In the mean time, take a look at Bob's info and start thinking about tuning the device and setting the critical damping. Once you know it works you can start to achive the fine adjustments. Chris, to answer your question about the standard advice of 3.5 swings, in the good old days, I know I know, before the Internet, the original PSN members would meet at members homes on occasion and when the discussion would turn to damping as it always did, the standard of 3.5 swings past center seemed to be the point that most of us would record and not miss an event. Nothing is worst then to have an over dampened seismograph that didn't record an event. It didn't make the adjustment right or wrong, it is what seemed to work best on our home brew designs. Regards, Steve Hammond PSN San Jose -----Original Message----- From: Jack Ivey [SMTP:ivey@........... Sent: Tuesday, October 01, 2002 5:09 AM To: psn-l@.............. Subject: RE: New Lehman on line (almost) In defense of the underdamped proposition, a slight amount of underdamping (that produces a second peak about, say, 10% the size of the first peak) will produce only a mild peak in the frequency response, and in fact will extend the low frequency response of the system slightly. The main advantage of this arrangement is that it is very easy to tell exactly how much damping you have. If you adjust for critical or overdamped, you can only guess, and lots of people will end up with a massively overdamped system, reducing their low frequency response unnecessarily. It is important to use realistic deflections when measuring damping, I have found that if you use large (1/8") deflections, you sometimes get very different (greater) damping than you do with micrometer deflections. Bob Barns' calibrator (see PSN site) is an excellent way to produce these small test signals. Jack -----Original Message----- From: ACole65464@....... [mailto:ACole65464@........ Sent: Monday, September 30, 2002 10:05 PM To: psn-l@.............. Subject: Re: New Lehman on line (almost) In a message dated 10/01/2002 12:14:06 AM !!!First Boot!!!, ChrisAtUpw@....... writes: In a message dated 30/09/02, shammon1@............. writes: The standard rule is to pull the boom back a few inches and let it go. The boom should loose 30% of its motion on each swing past center and come to rest in 3 1/2 swings. Hi Steve, I am puzzled as to where this *standard rule* is supposed to come from? But using it will give you a quite seriously underdamped system! A critically damped system experiences no oscillation at all. This is inherent in the maths. This is important if you apply post processing to the recorded signal with the assumption that it was critically damped to start with. It will also give problems with the amplitudes and frequencies calculated in FFT displays and may 'smear' P and S wave recordings. A procedure to get critical damping could involve deflecting the beam a very small amount (microns) and recording the amplifier output. You progressively increase the damping until the arm just returns to the balance position without having crossed the zero line. If you increase the damping further, the arm will simply take longer to get back to zero. If you use huge deflections like a few inches, you are likely to encounter non linear effects which do not apply to the tiny (hopefully!) signals that we normally record. It is helpful if the recording displays just what the earth is doing. It is really not helpful if the system adds an oscillating tail to every transient. Regards, Chris Chapman Steve, In support of what Chris has stated, please go to: http://www.seismo.com/msop/msop79/inst/inst4.html#aa250 Go to section 4.5 for a text description, and then click on figure 4.5.1a to see how pendulums are supposed to be damped. About Critical is the response you should obtain. I hope this helps a little, the diagrams may not make much sense at first but it shows how professional instruments (electromagnetic, aka Lehman designs) are adjusted. Regards, Allan Coleman << File: ATT00008.html >> __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: New Lehman on line (almost) From: "Randall Pratt" randallpratts@.......... Date: Tue, 1 Oct 2002 22:14:14 -0500 Allen, Have you used the method of calibration you referenced? It is very easy = to set up but my system does not behave quite as advertised. With the = boom blocked I don't get a step function as in fig 4.5.1a but rather an = exponential decay. I find that a bit confusing since I put a steady = battery voltage across the coil but I have attempted to determine the = curve and adjust subsequent readings by the correct factor over time. = I'm also not clear about para 9 where a0 is computed. What does that = formula really mean? How would it be adjusted for swings later in the = wave train and what is the ' on the end? Why would later pairs of = values work when there is a log decay in the swings? Randy=20 ----- Original Message -----=20 From: ACole65464@.......... To: psn-l@................. Sent: Monday, September 30, 2002 9:04 PM Subject: Re: New Lehman on line (almost) In a message dated 10/01/2002 12:14:06 AM !!!First Boot!!!, = ChrisAtUpw@....... writes: In a message dated 30/09/02, shammon1@............. writes:=20 The standard rule is to pull the boom back a few inches and let it = go. The boom=20 should loose 30% of its motion on each swing past center and come = to rest=20 in 3 1/2 swings. Hi Steve,=20 I am puzzled as to where this *standard rule* is supposed to = come from? But using it will give you a quite seriously underdamped = system! A critically damped system experiences no oscillation at all. = This is inherent in the maths.=20 This is important if you apply post processing to the recorded = signal with the assumption that it was critically damped to start with. = It will also give problems with the amplitudes and frequencies = calculated in FFT displays and may 'smear' P and S wave recordings.=20 A procedure to get critical damping could involve deflecting = the beam a very small amount (microns) and recording the amplifier = output. You progressively increase the damping until the arm just = returns to the balance position without having crossed the zero line. If = you increase the damping further, the arm will simply take longer to get = back to zero. If you use huge deflections like a few inches, you are = likely to encounter non linear effects which do not apply to the tiny = (hopefully!) signals that we normally record. =20 It is helpful if the recording displays just what the earth is = doing. It is really not helpful if the system adds an oscillating tail = to every transient.=20 Regards,=20 Chris Chapman=20 Steve,=20 In support of what Chris has stated, please go to: = http://www.seismo.com/msop/msop79/inst/inst4.html#aa250 Go to section = 4.5 for a text description, and then click on figure 4.5.1a to see how = pendulums are supposed to be damped. About Critical is the response you = should obtain. I hope this helps a little, the diagrams may not make = much sense at first but it shows how professional instruments = (electromagnetic, aka Lehman designs) are adjusted. Regards, Allan Coleman
Allen,
 
Have you used the method of calibration = you=20 referenced?  It is very easy to set up but my system does not = behave quite=20 as advertised.  With the boom blocked I don't get a step function = as in fig=20 4.5.1a but rather an exponential decay.  I find that a bit = confusing since=20 I put a steady battery voltage across the coil but I have attempted to = determine=20 the curve and adjust subsequent readings by the correct factor over = time. =20 I'm also not clear about para 9 where a0 is computed.  What does = that=20 formula really mean?  How would it be adjusted for swings = later in the=20 wave train and what is the ' on the end?  Why would later pairs of = values=20 work when there is a log decay in the swings?
 
Randy 
----- Original Message -----
From:=20 ACole65464@.......
To: psn-l@..............
Sent: Monday, September 30, = 2002 9:04=20 PM
Subject: Re: New Lehman on line = (almost)

In a = message dated=20 10/01/2002 12:14:06 AM !!!First Boot!!!, ChrisAtUpw@....... = writes:


In a message dated 30/09/02, shammon1@............. = writes:=20

The standard rule is to pull the boom back a few = inches and=20 let it go. The boom
should loose 30% of its motion on each = swing past=20 center and come to rest
in 3 1/2 swings.


Hi Steve, =

      I am=20 puzzled as to where this *standard rule* is supposed to come from? = But using=20 it will give you a quite seriously underdamped system! A=20 critically damped system experiences no oscillation at = all.=20 This is inherent in the maths.
      = This is=20 important if you apply post processing to the recorded signal with = the=20 assumption that it was critically damped to start with. It will also = give=20 problems with the amplitudes and frequencies calculated in FFT = displays and=20 may 'smear' P and S wave recordings. =
      A=20 procedure to get critical damping could involve deflecting the beam = a=20 very small amount (microns) and recording the amplifier=20 output. You progressively increase the damping until the arm = just=20 returns to the balance position without having crossed the zero = line. If you=20 increase the damping further, the arm will simply take longer to get = back to=20 zero. If you use huge deflections like a few inches, you are likely = to=20 encounter non linear effects which do not apply to the tiny = (hopefully!)=20 signals that we normally record.  =20
      It is helpful if the recording = displays=20 just what the earth is doing. It is really not helpful if the system = adds an=20 oscillating tail to every transient. =

     =20 Regards,

      Chris = Chapman


Steve,

In support of what Chris has = stated,=20 please go to: =20 http://www.seismo.com/msop/msop79/inst/inst4.html#aa250  Go to = section=20 4.5 for a text description, and then click on figure 4.5.1a to see how = pendulums are supposed to be damped. About Critical is the response = you should=20 obtain. I hope this helps a little, the diagrams may not make much = sense at=20 first but it shows how professional instruments (electromagnetic, aka = Lehman=20 designs) are adjusted.

Regards,

Allan Coleman=20
Subject: RE: New Lehman on line (almost) From: "Jan D. Marshall" jandmarshall@............ Date: Tue, 1 Oct 2002 22:07:38 -0600 OK -- I have made the boom changes suggested ( see new pictures) http://24.116.175.108/Over%20all%20pictures.htm I know the coil magnet needs to come up a little and I am still not getting good damping. I am going to change my copper plate to horizontal and pass it between by magnets and see if that helps. I am having a blast learning!! Thanks for EVERY comment Jan Marshall jandmarshall@............ www.cableone.net/jandmarshall Nampa, ID -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of Randall Pratt Sent: Tuesday, October 01, 2002 9:14 PM To: psn-l@.............. Subject: Re: New Lehman on line (almost) Allen, Have you used the method of calibration you referenced? It is very easy to set up but my system does not behave quite as advertised. With the boom blocked I don't get a step function as in fig 4.5.1a but rather an exponential decay. I find that a bit confusing since I put a steady battery voltage across the coil but I have attempted to determine the curve and adjust subsequent readings by the correct factor over time. I'm also not clear about para 9 where a0 is computed. What does that formula really mean? How would it be adjusted for swings later in the wave train and what is the ' on the end? Why would later pairs of values work when there is a log decay in the swings? Randy ----- Original Message ----- From: ACole65464@....... To: psn-l@.............. Sent: Monday, September 30, 2002 9:04 PM Subject: Re: New Lehman on line (almost) In a message dated 10/01/2002 12:14:06 AM !!!First Boot!!!, ChrisAtUpw@....... writes: In a message dated 30/09/02, shammon1@............. writes: The standard rule is to pull the boom back a few inches and let it go. The boom should loose 30% of its motion on each swing past center and come to rest in 3 1/2 swings. Hi Steve, I am puzzled as to where this *standard rule* is supposed to come from? But using it will give you a quite seriously underdamped system! A critically damped system experiences no oscillation at all. This is inherent in the maths. This is important if you apply post processing to the recorded signal with the assumption that it was critically damped to start with. It will also give problems with the amplitudes and frequencies calculated in FFT displays and may 'smear' P and S wave recordings. A procedure to get critical damping could involve deflecting the beam a very small amount (microns) and recording the amplifier output. You progressively increase the damping until the arm just returns to the balance position without having crossed the zero line. If you increase the damping further, the arm will simply take longer to get back to zero. If you use huge deflections like a few inches, you are likely to encounter non linear effects which do not apply to the tiny (hopefully!) signals that we normally record. It is helpful if the recording displays just what the earth is doing. It is really not helpful if the system adds an oscillating tail to every transient. Regards, Chris Chapman Steve, In support of what Chris has stated, please go to: http://www.seismo.com/msop/msop79/inst/inst4.html#aa250 Go to section 4.5 for a text description, and then click on figure 4.5.1a to see how pendulums are supposed to be damped. About Critical is the response you should obtain. I hope this helps a little, the diagrams may not make much sense at first but it shows how professional instruments (electromagnetic, aka Lehman designs) are adjusted. Regards, Allan Coleman
OK --=20 I have made the boom changes suggested ( see new pictures) http://24.116.17= 5.108/Over%20all%20pictures.htm =20 I know the coil magnet needs to come up a little and I am still not = getting good=20 damping.  I am going to change my copper plate to horizontal and = pass it=20 between by magnets and see if that helps. 
 
I am=20 having a blast learning!!
 
Thanks=20 for EVERY comment
 

Jan=20 Marshall
jandmarshall@............
www.cableone.net/jandmarshallNampa,=20 ID

-----Original Message-----
From: = psn-l-request@................. [mailto:psn-l-request@...............On Behalf Of Randall=20 Pratt
Sent: Tuesday, October 01, 2002 9:14 PM
To:=20 psn-l@..............
Subject: Re: New Lehman on line=20 (almost)

Allen,
 
Have you used the method of = calibration you=20 referenced?  It is very easy to set up but my system does not = behave=20 quite as advertised.  With the boom blocked I don't get a step = function=20 as in fig 4.5.1a but rather an exponential decay.  I find that a = bit=20 confusing since I put a steady battery voltage across the coil but I = have=20 attempted to determine the curve and adjust subsequent readings by the = correct=20 factor over time.  I'm also not clear about para 9 where a0 is=20 computed.  What does that formula really mean?  How = would it be=20 adjusted for swings later in the wave train and what is the ' on the=20 end?  Why would later pairs of values work when there is a log = decay in=20 the swings?
 
Randy 
----- Original Message -----
From:=20 ACole65464@.......
To: psn-l@..............
Sent: Monday, September 30, = 2002 9:04=20 PM
Subject: Re: New Lehman on = line=20 (almost)

In a = message dated=20 10/01/2002 12:14:06 AM !!!First Boot!!!, ChrisAtUpw@....... = writes:


In a message dated 30/09/02, shammon1@............. = writes:=20

The standard rule is to pull the boom back a few = inches and=20 let it go. The boom
should loose 30% of its motion on each = swing=20 past center and come to rest
in 3 1/2 swings.


Hi Steve, =

      I=20 am puzzled as to where this *standard rule* is supposed to come = from? But=20 using it will give you a quite seriously underdamped = system! A=20 critically damped system experiences no oscillation at = all.=20 This is inherent in the maths.
      = This is=20 important if you apply post processing to the recorded signal with = the=20 assumption that it was critically damped to start with. It will = also give=20 problems with the amplitudes and frequencies calculated in FFT = displays=20 and may 'smear' P and S wave recordings.=20
      A procedure to get critical = damping=20 could involve deflecting the beam a very small amount = (microns)=20 and recording the amplifier output. You progressively = increase the=20 damping until the arm just returns to the balance position without = having=20 crossed the zero line. If you increase the damping further, the = arm will=20 simply take longer to get back to zero. If you use huge = deflections like a=20 few inches, you are likely to encounter non linear effects which = do not=20 apply to the tiny (hopefully!) signals that we normally=20 record.  
      It is = helpful if=20 the recording displays just what the earth is doing. It is really = not=20 helpful if the system adds an oscillating tail to every transient. =

      Regards,=20

      Chris Chapman


Steve,

In support of what Chris has = stated,=20 please go to: =20 http://www.seismo.com/msop/msop79/inst/inst4.html#aa250  Go to = section=20 4.5 for a text description, and then click on figure 4.5.1a to see = how=20 pendulums are supposed to be damped. About Critical is the response = you=20 should obtain. I hope this helps a little, the diagrams may not make = much=20 sense at first but it shows how professional instruments = (electromagnetic,=20 aka Lehman designs) are adjusted.

Regards,

Allan = Coleman=20
Subject: Re: New Lehman on line (almost) From: CapAAVSO@....... Date: Wed, 2 Oct 2002 10:05:41 EDT In a message dated 10/1/02 10:43:17 PM GMT Daylight Time, shammon1@............. writes: > the original PSN members would meet at members homes on occasion and when > the discussion would turn to damping as it always did, the standard of 3.5 > swings past center seemed to be the point that most of us would record and > not miss an > event. Hi Steve, If Jan gets it damped to 3.5 swings with a copper plate between a magnet, what do you think about further damping it with a resistor across the pick up coil? Cap In a message dated 10/1/02 10:43:17 PM GMT Daylight Time, shammon1@............. writes:


the original PSN members would meet at members homes on occasion and when the discussion would turn to damping as it always did, the standard of 3.5 swings past center seemed to be the point that most of us would record and not miss an
event.


Hi Steve,

If Jan gets it damped to 3.5 swings with a copper plate between a magnet, what do you think about further damping it with a resistor across the pick up coil?

Cap
Subject: Re: New Lehman on line (almost) From: ChrisAtUpw@....... Date: Wed, 2 Oct 2002 14:04:51 EDT In a message dated 02/10/02, randallpratts@.......... writes: > With the boom blocked I don't get a step function as in fig 4.5.1a but > rather an exponential decay. I find that a bit confusing since I put a > steady battery voltage across the coil but I have attempted to determine > the curve and adjust subsequent readings by the correct factor over time. > I'm also not clear about para 9 where a0 is computed. What does that > formula really mean? Hi Randy, Looking at you Website, I note that you are using the PSN amplifier. This has a high pass filter in it which will give an exponential response to a step signal. If you can refer to the particular section, we may be able to help you. My para 9 has no a0 in it and doing a text search, there are several references to variables, but none with just a0. Regards, Chris Chapman In a message dated 02/10/02, randallpratts@.......... writes:

With the boom blocked I don't get a step function as in fig 4.5.1a but rather an exponential decay.  I find that a bit confusing since I put a steady battery voltage across the coil but I have attempted to determine the curve and adjust subsequent readings by the correct factor over time.  I'm also not clear about para 9 where a0 is computed.  What does that formula really mean?


Hi Randy,

      Looking at you Website, I note that you are using the PSN amplifier. This has a high pass filter in it which will give an exponential response to a step signal.
      If you can refer to the particular section, we may be able to help you. My para 9 has no a0 in it and doing a text search, there are several references to variables, but none with just a0.

      Regards,

      Chris Chapman
Subject: Damping/general From: "Connie and Jim Lehman" lehmancj@........... Date: Wed, 2 Oct 2002 16:20:12 -0400 The notes on damping show the variety of how to get the job done. A = swing of 3.5 times past the equilibrium position sounds a lot "looser" = than optimum. In setting up a damping system, I would eyeball the = action by displacing--say one cm, and watch the return to overshoot two = mm, and settle to equilibrium again--or a 5 to 1 ratio was in the = ballpark. The standard check one can make is the "walk-up" test. Walk = up to the base perpendicular to the boom, stand for 20 seconds or so, = and then back away----If all is well, there will be two traces--alike, = but in opposite directions. As you walk up, the sensor moves slightly to a new equilibrium = position. The damping ratio or situation will show nicely---bearing in = mind this is a velosity readout rather than a displacement--but close = enough approximation to give us the damping condition quick & easy!!! I usually went for a 8 to 1 ratio. I know with no damping, the = boom swings forever from the energy of microseisms. With critical = damping, one kills most or all of the action, The objective of damping = is to remove the natural period or swing of the pendulum--but not kill = it---and there is some leeway-------- Good = damping--- Jim Lehman
The notes on damping show the variety of how = to get the=20 job done.  A swing of 3.5 times past the equilibrium position = sounds a lot=20 "looser" than optimum.  In setting up a damping system, I would = eyeball the=20 action by displacing--say one cm, and watch the return to overshoot two = mm, and=20 settle to equilibrium again--or a 5 to 1 ratio was in the = ballpark.  The=20 standard check one can make is the "walk-up" test.  Walk up to the = base=20 perpendicular to the boom, stand for 20 seconds or so, and then back = away----If=20 all is well, there will be two traces--alike, but in opposite=20 directions.
    As you walk up, the sensor = moves=20 slightly to a new equilibrium position.  The damping ratio or = situation=20 will show nicely---bearing in mind this is a velosity readout rather = than a=20 displacement--but close enough approximation to give us the damping = condition=20 quick & easy!!!
     I usually went for a = 8 to 1=20 ratio.  I know with no damping, the boom swings forever from the = energy of=20 microseisms.  With critical damping, one kills most or all of the=20 action,  The objective of damping is to remove the natural period = or swing=20 of the pendulum--but not kill it---and there is some = leeway--------
         &nb= sp;           &nbs= p;            = ;            =              = Good=20 damping---          &nb= sp;    =20 Jim Lehman
Subject: Price of 194RS From: John & Jan Lahr johnjan@........ Date: Wed, 02 Oct 2002 19:23:13 -0600 Dear John, I was disappointed to see the price of the DI-194RS raised from $25 to $100 with a "special limited-time price" of just $50! This is now out of the range of possibility for the EPICS project students, as they have to keep their costs to $150 or less for everything outside of the computer! I wish that the price change could have been made later, but this does give an incentive to find an alternative AD unit. They are already having to build their own amplifier and filter circuits, so an AD chip with serial output will just have to be added. Sorry if this message sounds very negative, but I feel as if I've just been kicked in the teeth. Sincerely, John Lahr __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: PSN Discussion From: John & Jan Lahr johnjan@........ Date: Wed, 02 Oct 2002 19:39:00 -0600 Dear Dr. Bauer, Thanks for getting back to me. I'll let people know to limit their use to sub-critical damping. Is it OK to keep a link on my web site? http://www.jjlahr.com/science/psn/epics/links.html Cheers, John At 02:52 PM 10/2/2002 -0400, Wolfgang Bauer wrote: >Hi, > >I am the author of the applet. In the html file, I explicitly write that >this is only the solution for sub-critical damping. This is all the >applet simulates, and for all those cases the applet provides the correct >solution. I was not interested in supercritical damping, because it would >be too involved for the students in my class. > >The case m=k=1 and b>2 is supercritical. I should, perhaps, have written >a warning into the applet output when supercritical cases are >reached. For those, the applet does not work. > >Thanks >W. Bauer > > >On Wednesday, Oct 2, 2002, at 08:51 US/Eastern, Gerd Kortemeyer wrote: > >>John, >> >>Thanks for the bug report. We will look into it. >> >>The question regarding usage rights has to be answered by the authors of >>this applet, namely Profs. Wolfgang Bauer and/or Gary Westfall. >> >>The applet is now part of the repository of a larger system, >>http://www.lon-capa.org/ >> >>- Gerd. >> >>John & Jan Lahr wrote: >> >>> Gerd Kortemeyer >>>MSU >>> >>>Dear Gerd, >>> >>>Chris has pointed out that the Java code is not displaying things >>>correctly >>>for large values of damping. >>> >>>We were looking at this page: >>>http://lectureonline.cl.msu.edu/~mmp/applist/damped/d.htm >>> >>>Try, for example, m = k = 1 and then b = 4 and b = 8. For b = 8 >>>the return to zero is faster than for b = 4, where as it should be >>>slower. >>> >>>We found the page through google.com, so I don't know if you >>>even intend for others to use it. We're working on seismometer >>>design with students at the Colorado School of Mines and thus >>>were looking at damped harmonic motion applets. See: >>>http://www.jjlahr.com/science/psn/epics/ for what we're up to. >>> >>>Cheers, >>>John Lahr >>>USGS >>>Golden, CO >>> >>>At 05:21 PM 10/1/2002 -0400, ChrisAtUpw@....... wrote: >>> >>>>Hey, that was a nice applet! It shows the response for damping at >>>>and below critical very nicely. However, there seems to be a >>>>programming error, for high values of damping, say 4, give a MORE >>>>rapid return to the zero line, when the TRUE response is to take >>>>LONGER to reach zero! If you have infinite damping, the mass stays >>>>where it is - it does NOT 'high tail' it back to the zero line! >>>> >>>> Regards, >>>> >>>> Chris >> >Wolfgang Bauer, Professor and Chairperson >Department of Physics and Astronomy >Michigan State University >4208 Biomedical Physical Sciences >East Lansing, MI 48824-2320 > >Tel.: (517) 353 8662 >Fax.: (517) 353 4500 >URL: http://www.pa.msu.edu/~bauer/ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: New Lehman on line (almost) From: ACole65464@....... Date: Wed, 2 Oct 2002 21:47:24 EDT In a message dated 10/02/2002 3:17:40 AM !!!First Boot!!!, randallpratts@.......... writes: > Allen, > > Have you used the method of calibration you referenced? It is very easy to > set up but my system does not behave quite as advertised. With the boom > blocked I don't get a step function as in fig 4.5.1a but rather an > exponential decay. I find that a bit confusing since I put a steady > battery voltage across the coil but I have attempted to determine the curve > and adjust subsequent readings by the correct factor over time. I'm also > not clear about para 9 where a0 is computed. What does that formula really > mean? How would it be adjusted for swings later in the wave train and what > is the ' on the end? Why would later pairs of values work when there is a > log decay in the swings? > > Randy > Hello Randy, I had used the calibration procedure, that I had previously referred to, many years ago. I remember that it worked out OK at the time. For the "indicator", I used an old panel meter with its needle adjusted to the mid range location on the graduated face. That way I could see the change in voltage polarity without destroying the needle movement. The output of the circuit went straight to the meter, not through any other circuits that may have contained a filter of any type. The value for a0 is determined by the formula given in paragraph (ix). This is a general formula using the amplitudes of successive swings as well. These successive swings, I had assumed, were obtained when repeating the tests. And also obtained by averaging the amplitudes of several test sets of waves. It was a complicated setup, I preferred simpler ones. I used to determine the damping of my electromagnetic seismometers by several means. The more elegant solution was using an additional calibration coil attached to the pendulum. But the simplest method was to very lightly blow air from my mouth at the pendulum. If it had a large mass, a slow fanning motion with a sheet of paper worked. A small strip of paper used as a hammer worked well too. The J. Lehman walk up method is good if the instrument is under cover, another reason to fit a cal coil, or the B. Barnes calibrator. For my 2 cents worth. I used to allow the pendulums on my instruments to come to a rest with a less than a 10% overshoot, in 1 swing, to ensure something near critical damping. That way I was sure they were not overdamped. Over the last couple of years I have been building BB and VBB instruments using the S-T Morrissey Mathcad program to determine seismometer response for near critical damping. But I still use the paper strip hammer test at times to verify that damping is somewhat correct. Regards, Allan Coleman In a message dated 10/02/2002 3:17:40 AM !!!First Boot!!!, randallpratts@.......... writes:


Allen,

Have you used the method of calibration you referenced?  It is very easy to set up but my system does not behave quite as advertised.  With the boom blocked I don't get a step function as in fig 4.5.1a but rather an exponential decay.  I find that a bit confusing since I put a steady battery voltage across the coil but I have attempted to determine the curve and adjust subsequent readings by the correct factor over time.  I'm also not clear about para 9 where a0 is computed.  What does that formula really mean?  How would it be adjusted for swings later in the wave train and what is the ' on the end?  Why would later pairs of values work when there is a log decay in the swings?

Randy


Hello Randy,

I had used the calibration procedure, that I had previously referred to, many years ago. I remember that it worked out OK at the time. For the "indicator", I used an old panel meter with its needle adjusted to the mid range location on the graduated face. That way I could see the change in voltage polarity without destroying the needle movement. The output of the circuit went straight to the meter, not through any other circuits that may have contained a filter of any type. The value for a0 is determined by the formula given in paragraph (ix). This is a general formula using the amplitudes of successive swings as well. These successive swings, I had assumed, were obtained when repeating the tests. And also obtained by averaging the amplitudes of several test sets of waves.

It was a complicated setup, I preferred simpler ones. I used to determine the damping of my electromagnetic seismometers by several means. The more elegant solution was using an additional calibration coil attached to the pendulum. But the simplest method was to very lightly blow air from my mouth at the pendulum. If it had a large mass, a slow fanning motion with a sheet of paper worked. A small strip of paper used as a hammer worked well too. The J. Lehman walk up method is good if the instrument is under cover, another reason to fit a cal coil, or the B. Barnes calibrator.

For my 2 cents worth. I used to allow the pendulums on my instruments to come to a rest with a less than a 10% overshoot, in 1 swing, to ensure something near critical damping. That way I was sure they were not overdamped. Over the last couple of years I have been building BB and VBB instruments using the S-T Morrissey Mathcad program to determine seismometer response for near critical damping. But I still use the paper strip hammer test at times to verify that damping is somewhat correct.

Regards,

Allan Coleman 
Subject: RE: New Lehman on line (almost) w/new damping From: "Jan D. Marshall" jandmarshall@............ Date: Wed, 2 Oct 2002 20:14:50 -0600 OK -- It appears that I very close to correct damping -- my fingers are a bit flatter from being smashed between the two Neodymiun magnets while I got them mounted in the mounting. After several attempts only to have the magnets slam together in a flash and send the spacers flying, and then having to separate them, I got them clamped into the holder. On a 1/16" swing of the boom it appears to be "critically" damped, that is it crosses center then back to center and stops. I do not have the cover built yet, however it is in a closed carpeted closet. The insulated cover box is this weekends project. Comments please. Jan Marshall jandmarshall@............ www.cableone.net/jandmarshall Nampa, ID -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of ChrisAtUpw@....... Sent: Wednesday, October 02, 2002 12:05 PM To: psn-l@.............. Subject: Re: New Lehman on line (almost) In a message dated 02/10/02, randallpratts@.......... writes: With the boom blocked I don't get a step function as in fig 4.5.1a but rather an exponential decay. I find that a bit confusing since I put a steady battery voltage across the coil but I have attempted to determine the curve and adjust subsequent readings by the correct factor over time. I'm also not clear about para 9 where a0 is computed. What does that formula really mean? Hi Randy, Looking at you Website, I note that you are using the PSN amplifier. This has a high pass filter in it which will give an exponential response to a step signal. If you can refer to the particular section, we may be able to help you. My para 9 has no a0 in it and doing a text search, there are several references to variables, but none with just a0. Regards, Chris Chapman
OK --=20 It appears that I very close to correct damping -- my fingers are a bit = flatter=20 from being smashed between the two Neodymiun magnets while I = got them=20 mounted in the mounting.  After several attempts only to have the = magnets=20 slam together in a flash and send the spacers flying, and then having to = separate them, I got them clamped into the holder.  =
 
On a=20 1/16" swing of the boom it appears to be "critically" damped, that is it = crosses=20 center then back to center and stops.
 
I do=20 not have the cover built yet, however it is in a closed carpeted = closet. =20 The insulated cover box is this weekends project.
 
Comments please.

Jan=20 Marshall
jandmarshall@............
www.cableone.net/jandmarshallNampa,=20 ID

-----Original Message-----
From: = psn-l-request@................. [mailto:psn-l-request@...............On Behalf Of=20 ChrisAtUpw@.......
Sent: Wednesday, October 02, 2002 = 12:05=20 PM
To: psn-l@..............
Subject: Re: New = Lehman on=20 line (almost)

In a=20 message dated 02/10/02, randallpratts@.......... writes:

With the boom blocked I don't get a step function as in = fig=20 4.5.1a but rather an exponential decay.  I find that a bit = confusing=20 since I put a steady battery voltage across the coil but I have = attempted to=20 determine the curve and adjust subsequent readings by the correct = factor=20 over time.  I'm also not clear about para 9 where a0 is = computed.=20  What does that formula really mean?


Hi Randy,=20

      Looking at you Website, I = note=20 that you are using the PSN amplifier. This has a high pass filter in = it which=20 will give an exponential response to a step signal.=20
      If you can refer to the = particular=20 section, we may be able to help you. My para 9 has no a0 in it and = doing a=20 text search, there are several references to variables, but none with = just a0.=20

      Regards,=20

      Chris Chapman
=20
Subject: RE: Price of 194RS From: Jack Ivey ivey@.......... Date: Thu, 3 Oct 2002 08:01:16 -0400 John, I just looked at Dataq's web site, it looks like the DI-194RS is still $25. The 154 is $150, were you looking at that? One thing to be cautious about, at $25 they are selling the box at or below the cost of producing it, so it is being used as a marketing tool for their software. This means the offer might go away if Dataq decides to shift marketing resources. Jack > -----Original Message----- > From: John & Jan Lahr [mailto:johnjan@......... > Sent: Wednesday, October 02, 2002 9:23 PM > To: John Bowers > Cc: psn-l@............... kspikowski@......... > Subject: Price of 194RS > > > Dear John, > > I was disappointed to see the price of the DI-194RS raised from > $25 to $100 with a "special limited-time price" of just $50! > > This is now out of the range of possibility for the EPICS > project students, > as they > have to keep their costs to $150 or less for everything > outside of the > computer! I wish > that the price change could have been made later, but this > does give an > incentive > to find an alternative AD unit. They are already having to > build their own > amplifier and filter circuits, so an AD chip with serial > output will just > have to be > added. > > Sorry if this message sounds very negative, but I feel as if > I've just been > kicked > in the teeth. > > Sincerely, > John Lahr > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Price of 194RS From: CapAAVSO@....... Date: Thu, 3 Oct 2002 08:15:39 EDT In a message dated 10/3/02 2:23:36 AM GMT Daylight Time, johnjan@........ writes: > I was disappointed to see the price of the DI-194RS raised from > $25 to $100 with a "special limited-time price" of just $50! Hey John Lahr, Please go back and read that letter from rwl@......... more carefully. The DI-194RS still cost only $25 and you can order it on line from that letter. What costs $50 is the DI-194RS *PLUS* the WinDaq/XL software. Best regards, Cap In a message dated 10/3/02 2:23:36 AM GMT Daylight Time, johnjan@........ writes:


I was disappointed to see the price of the DI-194RS raised from
$25 to $100 with a "special limited-time price" of just $50!


Hey John Lahr,

Please go back and read that letter from rwl@......... more carefully. The DI-194RS still cost only $25 and you can order it on line from that letter. What costs $50 is the DI-194RS *PLUS* the WinDaq/XL software.

Best regards,
Cap
Subject: Re: Price of 194RS From: John & Jan Lahr johnjan@........ Date: Thu, 03 Oct 2002 07:05:22 -0600 John, Please accept my apology as I had not noticed the inclusion of the more advanced software add-on. As one of the PSN members wrote to me, $25 is probably under your cost for the DI-194RS unit, so justification of this remarkably low price must revolve around advertising value. I hope that this is the case, and that we will be able to count on this or equivalent units from DATAQ for use in schools. I know that the nearly 400 freshmen at the Colorado School of Mines now know about DATAQ AD converters. Feeling much better this morning! John At 08:22 AM 10/3/2002 -0400, you wrote: >John, > >The price of the DI-194 DID NOT CHANGE it is still $24.95. The special offer >is for the DI-194 bundled with the WINDAQ/XL. We are not changing the price >of the DI-194. Go to our web site and you will see that nothing has changed. >http://www.dataq.com/194.htm > >Please call me if you have any issues that this e-mail does not resolve. > >Sincerely, > >John Bowers >www.dataq.com >(330)-668-1444 __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Lehman magnet/coil position From: Richard Gagnon richg_1998@......... Date: Thu, 3 Oct 2002 14:33:31 -0700 (PDT) I hope this does not start another war. I am building a Lehman and I wonder if the coil on the boom is better than the magnet on the boom or is it not an issue? From what I have seen, building seismometers seems to be an art form. Thank you. Richard Gagnon Easthampton MA. __________________________________________________ Do you Yahoo!? New DSL Internet Access from SBC & Yahoo! http://sbc.yahoo.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Lehman magnet/coil position From: steve hammond shammon1@............. Date: Thu, 3 Oct 2002 16:09:51 -0700 Hi Richard, there is no war-- it's an art form... I put the magnet on the boom because I don't have to contend with the coil wires interfering with the operation of the boom. I also build the cement pad and the box to house the device so I have control over the choice of screws (brass) which I use near the device. One of the biggest down sides of putting the magnet on the boom is that any metal in the cement floor etc. or near the boom can attract the boom and cause operational issues. So think about where and how you will install the device and then make the decision. If you go with the coil on the boom, then you need to make sure the connection wires do not interfere with the operation of the boom. I have seen very fine gauge wire used which has been coiled to increase flexibility. Regards, Steve Hammond PSN San Jose, Aptos, CA -----Original Message----- From: Richard Gagnon [SMTP:richg_1998@.......... Sent: Thursday, October 03, 2002 2:34 PM To: psn Subject: Lehman magnet/coil position I hope this does not start another war. I am building a Lehman and I wonder if the coil on the boom is better than the magnet on the boom or is it not an issue? From what I have seen, building seismometers seems to be an art form. Thank you. Richard Gagnon Easthampton MA. __________________________________________________ Do you Yahoo!? New DSL Internet Access from SBC & Yahoo! http://sbc.yahoo.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Damping/general From: steve hammond shammon1@............. Date: Thu, 3 Oct 2002 16:38:31 -0700 Jim, I read your post with interest and got a chance today to pull the covers on the boxes and check the damping using your walk-up-walk-away (WUWA) suggestion. That is a very cool test and I have used it many times without thinking about the trace being in the opposite direction. I took the following reading without making any changes to the device: ATE (this device has a 40cm boom with a 5 LB mass mounted at the end of the boom) WU period 12 seconds WA period 12 seconds manual eyeball displacement check displacement 5/10-inch (this is the manual pull back by hand) return overshoot 2/10-inch (this is the release) ATN (this device has a 40cm boom with the 5 LB mass mounted at 28cm behind the coil with the damping flag mounted at the 40 cm point) WU period 18 seconds WA period 19 seconds manual eyeball displacement check displacement 5/10-inches (this is the initial pull back by hand) return overshoot 1.5/10-inches (this is the release) I was wondering if there was any rule about the boom coming to complete rest as decried by Richter, Elementary Seismology (step 12a), h = 1 in terms of critical damping. I guess what I'm asking is, should there be any extremely small oscillation following the return overshoot or should it be flat line back to zero? I'm seeing a slight overshoot less than .5/10th -inches. I would be interested in your comments. I also just posted two event files on Larry's site AT1 and AT2 Aptos, CA for the 6.4 event today in the Gulf of California if you are interested in seeing actual event data from the devices. Thanks for your input. Regards, Steve Hammond PSN San Jose Aptos, CA -----Original Message----- From: Connie and Jim Lehman [SMTP:lehmancj@............ Sent: Wednesday, October 02, 2002 1:20 PM To: psn-l@.............. Subject: Damping/general The notes on damping show the variety of how to get the job done. A swing of 3.5 times past the equilibrium position sounds a lot "looser" than optimum. In setting up a damping system, I would eyeball the action by displacing--say one cm, and watch the return to overshoot two mm, and settle to equilibrium again--or a 5 to 1 ratio was in the ballpark. The standard check one can make is the "walk-up" test. Walk up to the base perpendicular to the boom, stand for 20 seconds or so, and then back away----If all is well, there will be two traces--alike, but in opposite directions. As you walk up, the sensor moves slightly to a new equilibrium position. The damping ratio or situation will show nicely---bearing in mind this is a velosity readout rather than a displacement--but close enough approximation to give us the damping condition quick & easy!!! I usually went for a 8 to 1 ratio. I know with no damping, the boom swings forever from the energy of microseisms. With critical damping, one kills most or all of the action, The objective of damping is to remove the natural period or swing of the pendulum--but not kill it---and there is some leeway-------- Good damping--- Jim Lehman << File: ATT00000.html >> __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: How do I get a Station ID From: "Jan D. Marshall" jandmarshall@............ Date: Thu, 3 Oct 2002 17:52:01 -0600 How do I get a Station or Sensor ID Jan Marshall jandmarshall@............ www.cableone.net/jandmarshall Nampa, ID
How do = I get a=20 Station or Sensor ID

Jan=20 Marshall
jandmarshall@............
www.cableone.net/jandmarshallNampa,=20 ID

 
Subject: Re: How do I get a Station ID From: "Larry Cochrane" cochrane@.............. Date: Thu, 3 Oct 2002 17:00:56 -0700 Jan, People come up with their own IDs. I then check to see if the ID has not = been used before. I just check the event file archives and *.JM*.PSN is = not used. This means you can use *.JM1.PSN or *.JMZ etc. or anything = that starts with JM. -Larry Cochrane Redwood City, PSN ----- Original Message -----=20 From: Jan D. Marshall=20 To: Psn-L@................. Sent: Thursday, October 03, 2002 4:52 PM Subject: How do I get a Station ID How do I get a Station or Sensor ID Jan Marshall jandmarshall@............ www.cableone.net/jandmarshall Nampa, ID=20
Jan,
 
People come up with their own IDs. I = then check to=20 see if the ID has not been used before. I just check the event file = archives and=20 *.JM*.PSN is not used. This means you can use *.JM1.PSN or *.JMZ = etc. or=20 anything that starts with JM.
 
-Larry Cochrane
Redwood City, PSN
----- Original Message -----
From:=20 Jan=20 D. Marshall
Sent: Thursday, October 03, = 2002 4:52=20 PM
Subject: How do I get a Station = ID

How = do I get a=20 Station or Sensor ID

Jan Marshall
jandmarshall@............www.cableone.net/jandmarsha= ll
Nampa,=20 ID

 
Subject: RE: How do I get a Station ID From: "Jan D. Marshall" jandmarshall@............ Date: Thu, 3 Oct 2002 19:34:35 -0600 How about JM1 then Jan Marshall jandmarshall@............ www.cableone.net/jandmarshall Nampa, ID -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of Larry Cochrane Sent: Thursday, October 03, 2002 6:01 PM To: psn-l@.............. Subject: Re: How do I get a Station ID Jan, People come up with their own IDs. I then check to see if the ID has not been used before. I just check the event file archives and *.JM*.PSN is not used. This means you can use *.JM1.PSN or *.JMZ etc. or anything that starts with JM. -Larry Cochrane Redwood City, PSN ----- Original Message ----- From: Jan D. Marshall To: Psn-L@.............. Sent: Thursday, October 03, 2002 4:52 PM Subject: How do I get a Station ID How do I get a Station or Sensor ID Jan Marshall jandmarshall@............ www.cableone.net/jandmarshall Nampa, ID
How=20 about JM1 then
 

Jan=20 Marshall
jandmarshall@............
www.cableone.net/jandmarshallNampa,=20 ID

-----Original Message-----
From: = psn-l-request@................. [mailto:psn-l-request@...............On Behalf Of Larry=20 Cochrane
Sent: Thursday, October 03, 2002 6:01 = PM
To:=20 psn-l@..............
Subject: Re: How do I get a Station=20 ID

Jan,
 
People come up with their own IDs. I = then check=20 to see if the ID has not been used before. I just check the event file = archives and *.JM*.PSN is not used. This means you can use *.JM1.PSN = or *.JMZ=20 etc. or anything that starts with JM.
 
-Larry Cochrane
Redwood City, PSN
----- Original Message -----
From:=20 Jan D. Marshall
Sent: Thursday, October 03, = 2002 4:52=20 PM
Subject: How do I get a = Station=20 ID

How do I get a=20 Station or Sensor ID

Jan Marshall
jandmarshall@............www.cableone.net/jandmarsha= ll
Nampa,=20 ID

 
Subject: Re: Lehman magnet/coil position From: ChrisAtUpw@....... Date: Thu, 3 Oct 2002 21:42:15 EDT In a message dated 03/10/02, richg_1998@......... writes: > I am building a Lehman and I wonder if the coil on the boom is better than > the > magnet on the boom or is it not an issue? From what I have seen, building > seismometers seems to be an art form. Hi Richard, Building seismometers may well be an art form. Getting them working well maybe where the application of some science / technology is desirable. Seismometers are designed to have the ability to detect extremely small motions and forces. Otherwise they are of little use as seismometers. If you are not in a very isolated and quiet location, putting a powerful U or bar magnet on the arm will pick up small changes in the local magnetic field from a wide variety of sources, a visit from the garbage truck, moving the car, switching on the TV, magnetic storms, down to the steel in your belt buckle. If your intention is to monitor the garbage truck, etc., that is fine. If your desire is to only detect seismic vibrations, it is not so good. It is magnetic fields which extend out from the apparatus which enable it to interact strongly with outside events. If you enclose the magnet in a screen, the interactions will be reduced. They will not be eliminated, since you have to use ferromagnetic materials to make the screen. This is done in some small modern seismometers, but they usually have a magnetic screen provided. Putting an effective magnetic screen around a 3 ft Lehman might be more difficult. If you have any doubts, why not download the PSN archives and do a keyword search? Regards, Chris Chapman In a message dated 03/10/02, richg_1998@......... writes:

I am building a Lehman and I wonder if the coil on the boom is better than the
magnet on the boom or is it not an issue? From what I have seen, building
seismometers seems to be an art form.


Hi Richard,

      Building seismometers may well be an art form. Getting them working well maybe where the application of some science / technology is desirable. Seismometers are designed to have the ability to detect extremely small motions and forces. Otherwise they are of little use as seismometers. If you are not in a very isolated and quiet location, putting a powerful U or bar magnet on the arm will pick up small changes in the local magnetic field from a wide variety of sources, a visit from the garbage truck, moving the car, switching on the TV, magnetic storms, down to the steel in your belt buckle. If your intention is to monitor the garbage truck, etc., that is fine. If your desire is to only detect seismic vibrations, it is not so good.

      It is magnetic fields which extend out from the apparatus which enable it to interact strongly with outside events. If you enclose the magnet in a screen, the interactions will be reduced. They will not be eliminated, since you have to use ferromagnetic materials to make the screen. This is done in some small modern seismometers, but they usually have a magnetic screen provided. Putting an effective magnetic screen around a 3 ft Lehman might be more difficult.

      If you have any doubts, why not download the PSN archives and do a keyword search?

      Regards,

      Chris Chapman
Subject: RE: Lehman magnet/coil position From: "Jan D. Marshall" jandmarshall@............ Date: Thu, 3 Oct 2002 19:48:27 -0600 I have to agree -- I JUST went through this same exercise -- I swapped the magnet locations (from boom to base) and it made ALL the difference in the world in the unit stability. (see the thread New Lehman on line (almost)) I was concerned about the wires too -- I used a pair of twisted #30 wire wrap wires. If you provide a nice loose coil/loop at the pivot end I don't think you will see any problem. Jan Marshall jandmarshall@............ www.cableone.net/jandmarshall Nampa, ID -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of ChrisAtUpw@....... Sent: Thursday, October 03, 2002 7:42 PM To: psn-l@.............. Subject: Re: Lehman magnet/coil position In a message dated 03/10/02, richg_1998@......... writes: I am building a Lehman and I wonder if the coil on the boom is better than the magnet on the boom or is it not an issue? From what I have seen, building seismometers seems to be an art form. Hi Richard, Building seismometers may well be an art form. Getting them working well maybe where the application of some science / technology is desirable. Seismometers are designed to have the ability to detect extremely small motions and forces. Otherwise they are of little use as seismometers. If you are not in a very isolated and quiet location, putting a powerful U or bar magnet on the arm will pick up small changes in the local magnetic field from a wide variety of sources, a visit from the garbage truck, moving the car, switching on the TV, magnetic storms, down to the steel in your belt buckle. If your intention is to monitor the garbage truck, etc., that is fine. If your desire is to only detect seismic vibrations, it is not so good. It is magnetic fields which extend out from the apparatus which enable it to interact strongly with outside events. If you enclose the magnet in a screen, the interactions will be reduced. They will not be eliminated, since you have to use ferromagnetic materials to make the screen. This is done in some small modern seismometers, but they usually have a magnetic screen provided. Putting an effective magnetic screen around a 3 ft Lehman might be more difficult. If you have any doubts, why not download the PSN archives and do a keyword search? Regards, Chris Chapman
I have=20 to agree -- I JUST went through this same exercise -- I swapped the = magnet=20 locations (from boom to base) and it made ALL the difference in the = world=20 in the unit stability. (see the thread New Lehman on line=20 (almost))
 
I was=20 concerned about the wires too -- I used a pair of twisted #30 wire wrap=20 wires.  If you provide a nice loose coil/loop at the pivot end I = don't=20 think you will see any problem.
 

Jan=20 Marshall
jandmarshall@............
www.cableone.net/jandmarshallNampa,=20 ID

-----Original Message-----
From: = psn-l-request@................. [mailto:psn-l-request@...............On Behalf Of=20 ChrisAtUpw@.......
Sent: Thursday, October 03, 2002 7:42 = PM
To: psn-l@..............
Subject: Re: Lehman=20 magnet/coil position

In a message dated 03/10/02, richg_1998@......... writes: =

I am building a Lehman and I wonder if the coil on the = boom is=20 better than the
magnet on the boom or is it not an issue? From = what I=20 have seen, building
seismometers seems to be an art = form.


Hi Richard,=20

      Building = seismometers may=20 well be an art form. Getting them working well maybe = where the=20 application of some science / technology is desirable. Seismometers = are=20 designed to have the ability to detect extremely small motions = and=20 forces. Otherwise they are of little use as seismometers. If you are = not in a=20 very isolated and quiet location, putting a powerful U or bar magnet = on the=20 arm will pick up small changes in the local magnetic field from a wide = variety=20 of sources, a visit from the garbage truck, moving the car, switching = on the=20 TV, magnetic storms, down to the steel in your belt buckle. If your = intention=20 is to monitor the garbage truck, etc., that is fine. If your desire is = to=20 only detect seismic vibrations, it is not so good.=20

      It is magnetic fields = which extend=20 out from the apparatus which enable it to interact strongly with = outside=20 events. If you enclose the magnet in a screen, the interactions will = be=20 reduced. They will not be eliminated, since you have to use = ferromagnetic=20 materials to make the screen. This is done in some small modern = seismometers,=20 but they usually have a magnetic screen provided. Putting an effective = magnetic screen around a 3 ft Lehman might be more difficult.=20

      If you have any doubts, = why not=20 download the PSN archives and do a keyword search?=20

      Regards,=20

      Chris Chapman
=20
Subject: RE: Lehman magnet/coil position From: Richard Gagnon richg_1998@......... Date: Thu, 3 Oct 2002 19:04:16 -0700 (PDT) Ok. Sounds good. I have been monitoring the psn messages off and on and I remember the recent discussion you had so I will go with the magnet on the base. I have plenty of #30 wire wrap. My area has occasional cars, school bus and a ups truck. It is a (I think) fairly quiet area. By the way, where do you find 1/4 inch copper for the damping? I have everything but that. I do have 1/4 inch aluminum but I do not know if that will work. Any ideas? Thank you. Richard --- "Jan D. Marshall" wrote: > I have to agree -- I JUST went through this same exercise -- I swapped the > magnet locations (from boom to base) and it made ALL the difference in the > world in the unit stability. (see the thread New Lehman on line (almost)) > > I was concerned about the wires too -- I used a pair of twisted #30 wire > wrap wires. If you provide a nice loose coil/loop at the pivot end I don't > think you will see any problem. > > Jan Marshall > jandmarshall@............ > www.cableone.net/jandmarshall > Nampa, ID > > -----Original Message----- > From: psn-l-request@.............. [mailto:psn-l-request@................. > Behalf Of ChrisAtUpw@....... > Sent: Thursday, October 03, 2002 7:42 PM > To: psn-l@.............. > Subject: Re: Lehman magnet/coil position > > > In a message dated 03/10/02, richg_1998@......... writes: > > > I am building a Lehman and I wonder if the coil on the boom is better > than the > magnet on the boom or is it not an issue? From what I have seen, > building > seismometers seems to be an art form. > > > Hi Richard, > > Building seismometers may well be an art form. Getting them working > well maybe where the application of some science / technology is desirable. > Seismometers are designed to have the ability to detect extremely small > motions and forces. Otherwise they are of little use as seismometers. If you > are not in a very isolated and quiet location, putting a powerful U or bar > magnet on the arm will pick up small changes in the local magnetic field > from a wide variety of sources, a visit from the garbage truck, moving the > car, switching on the TV, magnetic storms, down to the steel in your belt > buckle. If your intention is to monitor the garbage truck, etc., that is > fine. If your desire is to only detect seismic vibrations, it is not so > good. > > It is magnetic fields which extend out from the apparatus which > enable it to interact strongly with outside events. If you enclose the > magnet in a screen, the interactions will be reduced. They will not be > eliminated, since you have to use ferromagnetic materials to make the > screen. This is done in some small modern seismometers, but they usually > have a magnetic screen provided. Putting an effective magnetic screen around > a 3 ft Lehman might be more difficult. > > If you have any doubts, why not download the PSN archives and do a > keyword search? > > Regards, > > Chris Chapman > __________________________________________________ Do you Yahoo!? New DSL Internet Access from SBC & Yahoo! http://sbc.yahoo.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Lehman magnet/coil position From: ChrisAtUpw@....... Date: Thu, 3 Oct 2002 22:12:52 EDT In a message dated 04/10/02, richg_1998@......... writes: > By the way, where do you find 1/4 inch copper for the damping? I have > everything but that. I do have 1/4 inch aluminum but I do not know if that > will > work. Any ideas? Probably be OK. Soft Al is quite a bit better than Al alloy. I visited a metal merchant to get an offcut of copper. Chris In a message dated 04/10/02, richg_1998@......... writes:

By the way, where do you find 1/4 inch copper for the damping? I have
everything but that. I do have 1/4 inch aluminum but I do not know if that will
work. Any ideas?


      Probably be OK. Soft Al is quite a bit better than Al alloy. I visited a metal merchant to get an offcut of copper.

      Chris
Subject: RE: Lehman magnet/coil position From: "Jan D. Marshall" jandmarshall@............ Date: Thu, 3 Oct 2002 21:46:34 -0600 My son found an old broken power-company knife switch at the metal recycle yard -- the blade was about 2.5" x 10" x 1/4 " Jan Marshall jandmarshall@............ www.cableone.net/jandmarshall Nampa, ID -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of ChrisAtUpw@....... Sent: Thursday, October 03, 2002 8:13 PM To: psn-l@.............. Subject: Re: Lehman magnet/coil position In a message dated 04/10/02, richg_1998@......... writes: By the way, where do you find 1/4 inch copper for the damping? I have everything but that. I do have 1/4 inch aluminum but I do not know if that will work. Any ideas? Probably be OK. Soft Al is quite a bit better than Al alloy. I visited a metal merchant to get an offcut of copper. Chris
My son=20 found an old broken power-company knife switch at the metal recycle = yard -- the blade was about 2.5" x 10" x 1/4 "
 

Jan=20 Marshall
jandmarshall@............
www.cableone.net/jandmarshallNampa,=20 ID

-----Original Message-----
From: = psn-l-request@................. [mailto:psn-l-request@...............On Behalf Of=20 ChrisAtUpw@.......
Sent: Thursday, October 03, 2002 8:13 = PM
To: psn-l@..............
Subject: Re: Lehman=20 magnet/coil position

In a message dated 04/10/02, richg_1998@......... writes: =

By the way, where do you find 1/4 inch copper for the = damping? I=20 have
everything but that. I do have 1/4 inch aluminum but I do = not know=20 if that will
work. Any ideas?


      Probably = be OK.=20 Soft Al is quite a bit better than Al alloy. I visited a metal = merchant to get=20 an offcut of copper. =

      Chris
=20
Subject: Damping From: Bobhelenmcclure@....... Date: Fri, 4 Oct 2002 02:30:00 EDT Hi all, There has been a lot of discussion about damping lately, and so I am going to put my two cents worth in. I operate an old vertical Strengnether, fairly light in construction. It is presently set for a natural period of about 3.4 seconds, and about 0.8 damping. I believe that somewhat under-damped is best. For checking the instrument, I rigged up a circuit consisting of two double pole switches, a high value resistor, and a battery. The circuit is placed between the seismometer and the amplifier. One of the switches is used to reverse the battery polarity. The other switch, in one position, simply connects the sensor to the amplifier. In the other position, the amplifier is left open circuited, and the sensor is connected to the battery and the series resistor. The small current through the sensor coil drives the pendulum away from balance. While recording at faster than normal sampling rate, I throw the switch to this position for a few seconds to displace the pendulum, then switch back to normal operation to observe the velocity waveform as the pendulum returns to equilibrium. I have written a numerical simulation program which can duplicate this kind of test for any natural period and damping I choose. Using Paint, I can transparently paste its waveforms over the seismometer waveforms to get a match. One does have to recognize that the amplifier's impulse response is another factor to complicate things. I should really add that to the simulation program. Bob McClure Hi all,

  There has been a lot of discussion about damping lately, and so I am going to put my two cents worth in.

  I operate an old vertical Strengnether, fairly light in construction.  It is presently set for a natural period of about 3.4 seconds, and about 0.8 damping.  I believe that somewhat under-damped is best.  For checking the instrument, I rigged up a circuit consisting of two double pole switches, a high value resistor, and a battery.  The circuit is placed between the seismometer and the amplifier.  One of the switches is used to reverse the battery polarity.  The other switch, in one position, simply connects the sensor to the amplifier.  In the other position, the amplifier is left open circuited, and the sensor is connected to the battery and the series resistor.  The small current through the sensor coil drives the pendulum away from balance.  While recording at faster than normal sampling rate, I throw the switch to this position for a few seconds to displace the pendulum, then switch back to normal operation to observe the velocity waveform as the pendu lum returns to equilibrium.

  I have written a numerical simulation program which can duplicate this kind of test for any natural period and damping I choose.  Using Paint, I can transparently paste its waveforms over the seismometer waveforms to get a match.  One does have to recognize that the amplifier's impulse response is another factor to complicate things.  I should really add that to the simulation program.

Bob McClure
Subject: Damping Resistor Value From: Ed Ianni eianni2@........... Date: Fri, 04 Oct 2002 09:29:16 -0400 Hi All; I have been using "oil" damping on my Lehman home built seismograph. I would like to replace the "oil" damping with "resistor damping" across the coil. Can anyone tell me the ohmic value it should be, or what the procedure is to calculate it? Thanks, Ed.
Hi All;
    I have been using "oil" damping on my Lehman home built seismograph. I would like to replace the "oil" damping with "resistor damping" across the coil. Can anyone tell me the ohmic value it should be, or what the procedure is to calculate it? Thanks, Ed. 
Subject: Calibration From: "Randall Pratt" randallpratts@.......... Date: Thu, 3 Oct 2002 22:14:54 -0500 Chris and Allen, Thanks for your interest. =20 To answer questions first Chris I am referring to the old Manual of = Seismological Practice Chap 4.5.1. It seems to provide an easy = calibration method using the instrument itself. You made a good call on = the filter section. I had considered maybe a capacitor was leaking = rather than doing its intended function. Because I don't get the step = functions shown in Fig 4.5.1a, I assume a correction can be calculated = to add the decay as a function of time and get the correct result = similar to 4.5.1e with dc being the initial jump in the trace. I hadn't = thought about it but maybe this decay can be used to calculate the = cuttoff frequency for the filter section. Allen, I have reread para 9 and remain confused. It seems to imply any = peaks in the entire train can be chosen as an and an+1. Ar isn't really = defined other than being later than a1 and then there is the " on the = end like a derivative. In my first attempts I have used the first peak = as ar and the next 2 as an and an+1. Other than these points I'm finding it quite easy to set up and have in = fact left everything connected for periodic checks or to check = sensitivity of various magnet configurations. I also believe the walk = up once a day is the best way to see how things are going.=20 I put together a file of my results and posted it at = http://www.santel.net/~randallpratts as testcal at the top of the page. = It will open in Winquake or you can download it first. The first = portion from 0118 to 0125 is boom locked as para 3. Minutes 28 to 34 = are para 6. 36 to 38 I have removed most of the damping to get free = period. From minute 53 to end is the best example for para 9 and is a = connection and disconnect with V=3D346mv.
Chris and Allen,
 
Thanks for your interest.  =
 
To answer questions first Chris I am = referring to=20 the old Manual of Seismological Practice Chap 4.5.1.  It seems to = provide=20 an easy calibration method using the instrument itself.  You made a = good=20 call on the filter section.  I had considered maybe a capacitor was = leaking=20 rather than doing its intended function.  Because I don't get the = step=20 functions shown in Fig 4.5.1a, I assume a correction can be calculated = to add=20 the decay as a function of time and get the correct result similar = to=20 4.5.1e with dc being the initial jump in the trace.  I hadn't = thought about=20 it but maybe this decay can be used to calculate the cuttoff frequency = for the=20 filter section.
 
Allen, I have reread para 9 and = remain=20 confused.  It seems to imply any peaks in the entire train can be = chosen as=20 an and an+1.  Ar isn't really defined other than being later than = a1 and=20 then there is the " on the end like a derivative.  In my first = attempts I=20 have used the first peak as ar and the next 2 as an and = an+1.
 
Other than these points I'm finding it = quite easy=20 to set up and have in fact left everything connected for periodic checks = or to=20 check sensitivity of various magnet configurations.  I also believe = the=20 walk up once a day is the best way to see how things are=20 going. 
 
I put together a file of my results and = posted it=20 at http://www.santel.net/~randallpratts as testcal = at the top=20 of the page.  It will open in Winquake or you can download it = first. =20 The first portion from 0118 to 0125 is boom locked as para 3.  = Minutes 28=20 to 34 are para 6.  36 to 38 I have removed most of the damping = to get=20 free period.  From minute 53 to end is the best example for = para 9 and=20 is a connection and disconnect with=20 V=3D346mv. 
Subject: Interesting vertical "rotational" vertical From: meredithlamb meredithlamb@............. Date: Fri, 04 Oct 2002 15:23:24 -0600 Hi all, Theres a "interesting" mechanical rotational vertical arrangement at: http://quake.eas.gatech.edu/calib/Image27.gif The rest of the web article is at: http://quake.eas.gatech.edu/calib/Web%20version%20calib%20chapter.htm Mechanically it does show a way to test "unknown" mechanical spring/s for use as a short period vertical seismo, in conjunction with a sliding adjustable mass. The two pivot point/s could be major frictional problem (?) though. I wonder if say....strong music wire acting as the rotational pivots might enhance its use? Theres probably been references to such before....I don't know, but it seems most interesting overall. I don't recall seeing any individual amateur vertical built along this particular route. Take care, Meredith __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Interesting vertical "rotational" vertical From: ChrisAtUpw@....... Date: Fri, 4 Oct 2002 20:57:29 EDT Hi All, Following Meredith's note, there are other articles which may also be of general interest for apparatus and construction at http://quake.eas.gatech.edu/ Regards, Chris Chapman Hi All,

      Following Meredith's note, there are other articles which may also be of general interest for apparatus and construction at http://quake.eas.gatech.edu/

      Regards,

      Chris Chapman
Subject: Boise State University seismograph? From: "Jan D. Marshall" jandmarshall@............ Date: Sat, 5 Oct 2002 21:43:21 -0600 Does any one know if the BSU seismograph traces are available on line? I am only about 20 miles from it, and would like to compare my traces to it to see if any of my larger disturbances show up on it. I am beginning to see that the traces look the same whether we are home or not. Jan Marshall jandmarshall@............ www.cableone.net/jandmarshall Nampa, ID
Does = any one know if=20 the BSU seismograph traces are available on line?  I am only about = 20 miles=20 from it, and would like to compare my traces to it to see if any of my = larger=20 disturbances show up on it.  I am beginning to see that the traces = look the=20 same whether we are home or not.

Jan=20 Marshall
jandmarshall@............
www.cableone.net/jandmarshallNampa,=20 ID

 
Subject: Re: Damping Resistor Value From: ChrisAtUpw@....... Date: Sun, 6 Oct 2002 01:58:27 EDT In a message dated 04/10/02, eianni2@........... writes: > I have been using "oil" damping on my Lehman home built seismograph. I > would like to replace the "oil" damping with "resistor damping" across the > coil. Can anyone tell me the ohmic value it should be, or what the > Hi Ed, You have not given us enough information about your system. It is possible to use electromagnetic damping if you have a very tightly coupled coil. For instance, you can probably do it if you have a 'speaker magnet / coil' type setup. You can also wind a special damping coil and mount it in between a pair of large NdBFe wing magnets or similar. These magnets also work OK with copper or Al damping plates. Incidentally, this sort of setup can give strong signals. If you have a 'traditional' coil and one of the red U Alnico magnets, I would doubt if you could get enough coupling to damp the arm effectively. It also depends on the what weight you are using. The heavier the weight, the more force is needed to damp it. You might be successful with one of the large WWII magnetron magnets. To check, I suggest that you remove the oil damping, short out the coil and move the arm maybe 1/2" and release it. If it moves much beyond the zero position or oscillates, you can't do it with your setup in 'passive' mode. If you have a separate distance transducer, it is possible to feed an amplified signal into a coil damping system. To give a rough idea of passive damping, if you use a couple of the 1"x 1/2" x 1/4" #33 magnets, http://www.wondermagnet.com/dev/magnet33.html , mount them on a 1/4" iron backing plate and put this 1/16" from a 3" disk of 1/16" soft Al, it will critically damp a 1/2 lb 1 second pendulum OK. Hope that this is of some help. Regards, Chris Chapman In a message dated 04/10/02, eianni2@........... writes:

   I have been using "oil" damping on my Lehman home built seismograph. I would like to replace the "oil" damping with "resistor damping" across the coil. Can anyone tell me the ohmic value it should be, or what the procedure is to calculate it?


Hi Ed,

      You have not given us enough information about your system. It is possible to use electromagnetic damping if you have a very tightly coupled coil. For instance, you can probably do it if you have a 'speaker magnet / coil' type setup. You can also wind a special damping coil and mount it in between a pair of large NdBFe wing magnets or similar. These magnets also work OK with copper or Al damping plates. Incidentally, this sort of setup can give strong signals.
      If you have a 'traditional' coil and one of the red U Alnico magnets, I would doubt if you could get enough coupling to damp the arm effectively. It also depends on the what weight you are using. The heavier the weight, the more force is needed to damp it. You might be successful with one of the large WWII magnetron magnets.
      To check, I suggest that you remove the oil damping, short out the coil and move the arm maybe 1/2" and release it. If it moves much beyond the zero position or oscillates, you can't do it with your setup in 'passive' mode. If you have a separate distance transducer, it is possible to feed an amplified signal into a coil damping system.
      To give a rough idea of passive damping, if you use a couple of the 1"x 1/2" x 1/4" #33 magnets, http://www.wondermagnet.com/dev/magnet33.html , mount them on a 1/4" iron backing plate and put this 1/16" from a 3" disk of 1/16" soft Al, it will critically damp a 1/2 lb 1 second pendulum OK.
      Hope that this is of some help.

      Regards,

      Chris Chapman

      
Subject: Re: Boise State University seismograph? From: Benji & Wendi Johnson wjohnson@........ Date: Sun, 06 Oct 2002 20:17:09 -0700 Jan, I too was interested in the Boise State University seismograph data, as I am just up the road from you (La Grande, OR). I emailed the professor in charge of the network, James Zollweg, several months ago and he replied that their network had been shut down due to a lack of funding. If you'd like to contact him yourself, his email address can be found at this site by following the "faculty" link: http://earth.boisestate.edu/ - Benji Johnson __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Ideas for next versions of software From: "Jan D. Marshall" jandmarshall@............ Date: Mon, 7 Oct 2002 18:57:15 -0600 I would like to see a slider bar on the winsdr display allowing you to view back to the beginning of the current file. Also, I admit I am just learning the programs, can you view or replay record files from another PC that is networked to the WINSDR machine? Jan Marshall jandmarshall@............ www.cableone.net/jandmarshall Nampa, ID
I = would like to see=20 a slider bar on the winsdr display allowing you to view back to the = beginning of=20 the current file.
 
Also, = I admit I am=20 just learning the programs, can you view or replay record=20 files from another PC that is networked to the WINSDR=20 machine?

Jan=20 Marshall
jandmarshall@............
www.cableone.net/jandmarshallNampa,=20 ID

 
Subject: Huge Quake From: David A Nelson davenn@............... Date: Thu, 10 Oct 2002 22:02:01 +1000 hi all 1130 UTC huge event happening SW Pacific plotting grams in WQuake from TATO, SNZO, GUMO and CTAO looks like western Irian Jaya region and a magnitude of ~ 7.5 + - .2 no official release yet keen to see how close i am Dave N __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Huge Quake From: "Mark Robinson" mark.robinson@............... Date: Fri, 11 Oct 2002 01:14:24 +1300 > hi all > > 1130 UTC > huge event happening SW Pacific plotting grams in WQuake from > TATO, SNZO, GUMO and CTAO looks like western Irian Jaya region > and a magnitude of ~ 7.5 + - .2 > > no official release yet keen to see how close i am > > Dave N early results from http://www.emsc-csem.org/cgi-bin/ALERT_all_messages.sh?1 2002/10/10 10:50:26.7 1.2S 133.9E 33G Mb6.4 A NEIA IRIAN JAYA, INDONESIA, REGION 2002/10/10 10:50:20.2 1.7S 134.2E 10G M 7.1 M: NEIR IRIAN JAYA, INDONESIA, REGION 2002/10/10 10:50:10.0 4.3S 130.9E MW8.0 A PPT BANDA SEA it's driven all the short period displays at http://www.geonet.org.nz/drums.html into clipping. This site has been significantly upgraded recently. Mark __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Huge Quake From: David A Nelson davenn@............... Date: Thu, 10 Oct 2002 22:24:03 +1000 hi mark nice one looks like i was pretty close yeah it has plotted well on all the new grams of the NZ network but look at the ASLWWW grams too :) i downloaded the grams from BBrequest and them worked on them in winquake hence how i made my estimates Dave __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Huge Quake From: "Mark Robinson" mark.robinson@............... Date: Fri, 11 Oct 2002 01:37:46 +1300 > hi mark > > nice one looks like i was pretty close > > yeah it has plotted well on all the new grams of the NZ network > > but look at the ASLWWW grams too :) > > i downloaded the grams from BBrequest and them worked on them in winquake > hence how i made my estimates > > Dave Indeed I looked at the traces with my eyes and came up with your estimate as well [021011 004216] anyway - it looks like about a 7.4 NEIC puts it bang on the coast of Irian Jaya. I fear there will be many casualties. Mark __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Fwd: EqLocate for GSA From: John & Jan Lahr johnjan@........ Date: Fri, 11 Oct 2002 17:25:04 -0600 Alan Jones has written another great program. This one can be used to learn how earthquakes are located. Check it out. Cheers, John Lahr >------------- Begin Forwarded Message ------------- > >From: "Alan Jones" >Subject: EqLocate for GSA >Date: Thu, 10 Oct 2002 15:49:24 -0400 > >Jeff, Larry, John, John, and Michelle, > >The EqLocate program is (as of a few minutes ago) at the same place as >Seismic/Eruption, Seismic Waves and AmaSeis: > >www.geol.binghamton.edu/faculty/jones > >Before it was at the same place but "hidden." (You had to know the exact >URL.). Now the user can click on it. > >I did this in anticipation of the program's use at the GSA. However, >there is still no documentation for it. Its use is >pretty simple so I'm sure you'll be able to instruct workshop folks in how >it works. > >Alan > >###################### ># Alan Jones >## AlanJones@........... >### http://home.stny.rr.com/alanjones >####3717 Wildwood Drive >##### Endwell, NY 13760 >###### 607-786-5866 (voice/fax) >######################## > >------------- End Forwarded Message ------------- __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: large quake From: "Francesco" fra.nuc@........... Date: Sat, 12 Oct 2002 22:58:26 +0200 A large quake until on record Per=F9 ~7 Francesco Italy
A large quake until on = record
 
Per=F9  ~7
 
Francesco  =20 Italy
Subject: RE: large quake From: "Kareem" kareem@............. Date: Sat, 12 Oct 2002 19:20:09 -0700 Yes, a really deep one, about 580 kilometers deep within the convergent. It didn't really give me much of a record with my vertical geophone. -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of Francesco Sent: Saturday, October 12, 2002 1:58 PM To: PSN Subject: large quake A large quake until on record =20 Per=F9 ~7 =20 Francesco Italy Message
Yes, a = really deep one,=20 about 580 kilometers deep within the convergent. It didn't really give = me much=20 of a record with m Subject: RE: large quake From: "Kareem" kareem@............. Date: Sat, 12 Oct 2002 19:20:09 -0700 Yes, a really deep one, about 580 kilometers deep within the convergent. It didn't really give me much of a record with my vertical geophone. -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of Francesco Sent: Saturday, October 12, 2002 1:58 PM To: PSN Subject: large quake A large quake until on record =20 Per=F9 ~7 =20 Francesco Italy Message
Yes, a = really deep one,=20 about 580 kilometers deep within the convergent. It didn't really give = me much=20 of a record with my vertical geophone.
-----Original Message-----
From:=20 psn-l-request@.............. [mailto:psn-l-request@............... = On=20 Behalf Of Francesco
Sent: Saturday, October 12, 2002 = 1:58=20 PM
To: PSN
Subject: large = quake

A large quake until on = record
 
Per=F9  ~7
 
Francesco  =20 Italy
Subject: RE: large quake From: Hammonds hammond@........... Date: Sat, 12 Oct 2002 18:29:51 -0800 Here's what I picked up as well as NEIC's data on the quake: http://apsn.awcable.com/neweq.htm See the first one on list http://apsn.awcable.com/021012.gif My record from 1 Hz vertical seismometer http://neic.usgs.gov/neis/bulletin/neic_kebi.html NEIC location Bob http://apsn.awcable.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: new additions From: David A Nelson davenn@............... Date: Sun, 13 Oct 2002 14:47:28 +1000 hi ya all from Down Under 2 new additions to the maps and database I did mean to get these done last weekend but ended up leaving town for the holiday long weekend we had here. Its my pleasure to welcome Angel Rodriguez of Panama and Kevin McKee of Virginia, USA to the PSN database enjoy ur time with us, guys, dont forget to mail me with any updates or corrections in the future cheers Dave __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: NEIC and ASLWWW From: David A Nelson davenn@............... Date: Tue, 15 Oct 2002 22:03:12 +1000 John Lahr, do u know why or for how long the NEIC and ASLWWW sites are going to be down ? has been a couple of days so far cheers Dave __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: NEIC and ASLWWW From: "Mark Robinson" mark.robinson@............... Date: Wed, 16 Oct 2002 07:57:08 +1300 > John Lahr, > do u know why or for how long the NEIC and ASLWWW sites are > going to be down ? > has been a couple of days so far > > cheers > Dave Dave They've been working fine for me. M __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: NEIC and ASLWWW From: hammond@........... Date: Tue, 15 Oct 2002 11:54:33 -0800 (AKDT) They're working for me as well, Dave. Bob Hammond http://apsn.awcable.com >> John Lahr, >> do u know why or for how long the NEIC and ASLWWW sites >> are >> going to be down ? >> has been a couple of days so far >> >> cheers >> Dave > > Dave > > They've been working fine for me. > > M > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: NEIC and ASLWWW From: David A Nelson davenn@............... Date: Wed, 16 Oct 2002 06:34:47 +1000 At 11:54 AM 15-10-02 -0800, you wrote: >They're working for me as well, Dave. > >Bob Hammond >http://apsn.awcable.com > Weird they were down from sunday to tuesday (sat - monday USA time) the pages wouldnt load only the old chached pages all other USA sites i use were ok all pointless now hahaha as of wed morning aussie time ( tues afternoon USA) all going again :) thanks all Dave __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: link From: TESMECO@....... Date: Fri, 18 Oct 2002 23:39:53 EDT check it interesting California Sinks, Fooling GPS and Ruining Earthquake Data http://www.space.com/scienceastronomy/gps_fooled_010822-1.html Name:TIM SLUSARCZYK e-mail address:TESMECO@....... Location:PERRIS, CA, USA Receivers:FRG 7700 PRO 2006 PRO 51 Antenna:EAVESDROPPER INVERTED VEE CONF. DX interests:UTILITY MONITORING check it interesting
California Sinks, Fooling GPS and Ruining Earthquake Data
http://www.space.com/scienceastronomy/gps_fooled_010822-1.html


Name:TIM SLUSARCZYK

e-mail address:TESMECO@.......
Location:PERRIS, CA, USA
Receivers:FRG 7700   PRO 2006   PRO 51
Antenna:EAVESDROPPER INVERTED VEE CONF.
DX interests:UTILITY MONITORING
Subject: strong event From: David A Nelson davenn@............... Date: Sat, 19 Oct 2002 23:41:51 +1000 19 oct 1330UT strong event jst tailing off western pacific looks like Kuril Islands area ~ Mb 6.5 cheers Dave __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Alaska Quake at 11:27 UTC, 10/23/02 From: Hammonds hammond@........... Date: Wed, 23 Oct 2002 06:10:52 -0800 MS 6.7 at 11:27 UTC located 85 miles (135 km) S of Fairbanks, Alaska. 1 foreshock and several aftershocks. Felt from Fairbanks to Anchorage, maximum intensity VIII. And I didn't feel it! Bummer! Bob http://apsn.awcable.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Alaska Quake at 11:27 UTC, 10/23/02 From: "Jan D. Marshall" jandmarshall@............ Date: Wed, 23 Oct 2002 19:56:55 -0600 Well I shook, rattled and rolled!!! Now that I have a recording that I know is the real thing I want to put winquake through it paces. Would someone, that really understands winquake, send me their phone number so I could call them, so they can talk me through seeing what I need to see and understand. Jan Marshall jandmarshall@............ www.cableone.net/jandmarshall Nampa, ID -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@................. Behalf Of Hammonds Sent: Wednesday, October 23, 2002 8:11 AM To: psn-l@.............. Subject: Alaska Quake at 11:27 UTC, 10/23/02 MS 6.7 at 11:27 UTC located 85 miles (135 km) S of Fairbanks, Alaska. 1 foreshock and several aftershocks. Felt from Fairbanks to Anchorage, maximum intensity VIII. And I didn't feel it! Bummer! Bob http://apsn.awcable.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Fwd: geophone From: John & Jan Lahr johnjan@........ Date: Thu, 24 Oct 2002 21:54:48 -0600 Dear Alastair,

I've posted quite a bit of information related to making a seismometer on
this page:
http://jjlahr.com/science/psn/epics/links.html

I'll also forward your question to the Public Seismic Network E-mail list,
as some members may have a lead on an inexpensive, used geophone.

For high frequency demonstration purposes, it may be possible to dangle
a strong magnet inside a home wound coil to make your own sensor.

Good luck,
John

From: "alastair mcarthur" <a.mcarthur@...............>
To: <john@........>
Subject: geophone
Date: Thu, 24 Oct 2002 21:19:00 -0300

can't find a place to get a geophone. do you know anywhere? the web site addresses have run out of them.
 
tried to make one but have difficulty getting a current induced with home made coil and magnet . any tips?
 
enjoyed your web site on table top earthquake very clear and informative. thanks
Subject: Minor or Local Event From: "Bob Hancock" robert.hancock@........... Date: Wed, 30 Oct 2002 18:59:28 -0500 I am located in Randolph, New Jersey, about 40 miles west of New York City. This is a desert when it comes to local events. Last night 10/30/02, I recorded what appeared to be a local event. I recorded it on all three channels. It appears to start about 0254, and end about 0301. I can clearly see the surface waves; however, the P & S are not that distinct to me (limited experience). For filtering I use a bandpass set at 0.07 hz high and 0.1 hz low. I have checked the NEIC files and also the link for earthquakes in the northeast and can't find anything. It is visible on the LCSN site at the following link. Set the view for 10/30/02, and set the frequency band for long period. If you set the component to ALL, you can see it all three channels. http://www.ldeo.columbia.edu/cgi-bin/LCSN/WebSeis/24hr_heli.pl The waveform lasts too long to be blasting. I am not certain what the event was, but its there. If anyone has any thoughts, I would appreciate hearing them. Thanks Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Italian quake From: "Mauro Mariotti" mariotti@......... Date: Thu, 31 Oct 2002 15:10:03 +0100 Hi All, Today hour 10.33 a quake ML5.7 shaked Campobasso (south Italy, between Foggia and Naples) area with some damages. Unfortunately a school with many children inside collapsed. We are waiting for news about this. We will appreciate your recording if available. Please send them to mariotti@......... address. Freely reply for messages only in this mailing list. Regards Mauro http://www.infoeq.it http://mariottim.interfree.it/index.htm http://www.infoeq.it http://mariottim.interfree.it/index.htm __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Italian quake From: "Mauro Mariotti" mariotti@......... Date: Fri, 1 Nov 2002 21:58:13 +0100 Hi all, just to keep you all updated.. The earth continue to shake here... Another 5.5 soon followed with a slightly light event shaked the already highly damaged area. 23 children and one teacher are dead inside the school... 35 children and 2 people saved from the debris.. Regards Mauro http://www.infoeq.it http://mariottim.interfree.it/index.htm __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Italian quake From: "Francesco" fra.nuc@........... Date: Sat, 2 Nov 2002 01:22:55 +0100 Hi to all. I'm posting some of the major's events of Southern Italy's quake. The final number of iniured is 32 victims (29 childrens in San Giulianos' school). We have registered 282 events, from foreshock until now, with our station (Macchia Valfortore) sites 10km from epicenter. The quake was origined by an unknown strike-slip fault in a relatively a-seismic zone. The sequence has given a foreshock of ML 3.4, a first mainshock of ML 5.6 eight hours later, a moderate aftershock with max ML 3.7 and, today, the second mainshock of. ML 5.5. Then 5.0 , 4.8 and three events of ML 4.2 A complex seismotectonic zone, with many major faults, quiting from 200 years, encircles the epicenter zone. Regards Francesco -Italy- __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Fwd: Re: Italian quake From: John & Jan Lahr johnjan@........ Date: Fri, 01 Nov 2002 20:30:24 -0700 Dear Francesco, Thanks for the update on this tragic event. Until ALL buildings are made safe from collapse, tragedies like this will continue to occur, especially in areas of relatively low hazard where society does not want to spend the extra 10 or 15 percent to build safe buildings in the first place. Colorado is in this category! Yours, John Lahr >From: "Francesco" >To: >Subject: Re: Italian quake >Date: Sat, 2 Nov 2002 01:22:55 +0100 >X-Mailer: Microsoft Outlook Express 6.00.2600.0000 >Reply-To: psn-l@.............. >Sender: psn-l-request@.............. > >Hi to all. >I'm posting some of the major's events of Southern Italy's quake. >The final number of iniured is 32 victims (29 childrens in San Giulianos' >school). >We have registered 282 events, from foreshock until now, with our station >(Macchia Valfortore) sites 10km from epicenter. >The quake was origined by an unknown strike-slip fault in a relatively >a-seismic zone. >The sequence has given a foreshock of ML 3.4, a first mainshock of ML 5.6 >eight hours later, a moderate aftershock with max ML 3.7 and, today, the >second mainshock of. ML 5.5. Then 5.0 , 4.8 and three events of ML 4.2 >A complex seismotectonic zone, with many major faults, quiting from 200 >years, encircles the epicenter zone. > >Regards >Francesco -Italy- > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: big quake? From: "Francesco" fra.nuc@........... Date: Sun, 3 Nov 2002 23:34:48 +0100 Large P at 22.24 utc and now a long packet of S waves...here in Italy Alaska?
Large P  at 22.24 utc and = now  a long=20 packet of S waves...here in Italy
 
 
Alaska?
Subject: Large event From: "Larry Cochrane" cochrane@.............. Date: Sun, 3 Nov 2002 14:35:19 -0800 Hi Everyone, My and other PSN stations are in the process of recording a large event. Looking at the PSN Current Seismicity web page at http://www.seismicnet.com/currentseismicity.html it looks like it could be in or near Alaska. -Larry Cochrane Redwood City, PSN __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Large event From: "Francesco" fra.nuc@........... Date: Sun, 3 Nov 2002 23:36:57 +0100 Larry, very very large S until on rec Francesco Italy __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Alaska 7.9 (est) quake ino From: meredithlamb meredithlamb@............. Date: Sun, 03 Nov 2002 18:01:31 -0700 Hi all, USGS has a map and data on the quake at: http://earthquake.usgs.gov/eqinthenews/uslbbl/index.html Am still seeing seismic signals at this time in Denver, Colorado. 01:00 UTC 11/04/02 No tsunami alert issued. Do wonder if their is any forthcoming "seiche" action from lakes etc. Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Earthquake opens cracks in highways, topples fuel tanks From: "Erich Kern" efkern@............. Date: Sun, 3 Nov 2002 17:56:26 -0800 Two pages of details in this Anchorage Daily News Item http://www.adn.com/front/story/2071579p-2169367c.html Erich __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Alaska 7.9 (est) quake ino From: ACole65464@....... Date: Sun, 3 Nov 2002 20:58:15 EST In a message dated 11/04/2002 1:02:50 AM !!!First Boot!!!, meredithlamb@............. writes: > Hi all, > > USGS has a map and data on the quake at: > > http://earthquake.usgs.gov/eqinthenews/uslbbl/index.html > > Am still seeing seismic signals at this time in Denver, Colorado. > 01:00 UTC 11/04/02 > > No tsunami alert issued. Do wonder if their is any forthcoming > "seiche" action from lakes etc. > > Meredith Lamb > Hello Mereith, Seiches were reported by people in Seattle today (per the local news channels). Several house boats on Lake Union suffered broken gas and water lines running from shore to boats. Also at a local swimming center, swimmers sensed the water moving around in the pool. Here it is 1:54 11/04 UTC here at my house north of Seattle (2347Km from the epicenter) and the seismometer is still rocking very noticeably! Allan Coleman Edmonds, Washington In a message dated 11/04/2002 1:02:50 AM !!!First Boot!!!, meredithlamb@............. writes:


Hi all,

USGS has a map and data on the quake at:

http://earthquake.usgs.gov/eqinthenews/uslbbl/index.html

Am still seeing seismic signals at this time in Denver, Colorado.
01:00 UTC 11/04/02

No tsunami alert issued.  Do wonder if their is any forthcoming
"seiche" action from lakes etc.

Meredith Lamb


Hello Mereith,

Seiches were reported by people in Seattle today (per the local news channels). Several house boats on Lake Union suffered broken gas and water lines running from shore to boats. Also at a local swimming center, swimmers sensed the water moving around in the pool.

Here it is 1:54 11/04 UTC here at my house north of Seattle (2347Km from the epicenter) and the seismometer is still rocking very noticeably!

Allan Coleman
Edmonds, Washington
Subject: Re: Alaska 7.9 (est) quake ino From: Canie canie@........... Date: Sun, 03 Nov 2002 21:10:24 -0800 Here's a story on seiches in Louisiana! http://www.adn.com/front/story/2071579p-2169448c.html Canie At 06:01 PM 11/3/02 -0700, meredithlamb wrote: >Hi all, > >USGS has a map and data on the quake at: > >http://earthquake.usgs.gov/eqinthenews/uslbbl/index.html > >Am still seeing seismic signals at this time in Denver, Colorado. >01:00 UTC 11/04/02 > >No tsunami alert issued. Do wonder if their is any forthcoming >"seiche" action from lakes etc. > >Meredith Lamb > > > > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Alaska quake causes "seiches" From: meredithlamb meredithlamb@............. Date: Sun, 03 Nov 2002 22:44:56 -0700 "Seiche" storys.....reminds me back in the late 1960's of a strong quake off the coast of southern Europe. At the time I was asleep in a rocking chair by a homebrew seismo, I awakened and felt myself being slowly rocked back and forth, and could see the drum recorder showing the long period phases "rolling in". In essense....I was a type of sensor with a inverted "mass" in that circumstance. Interesting on the seiche story Canie, thanks! Meredith Lamb Canie wrote: > Here's a story on seiches in Louisiana! > http://www.adn.com/front/story/2071579p-2169448c.html > > Canie > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Large event From: hammond@........... Date: Mon, 4 Nov 2002 08:12:47 -0900 (AKST) Hi all, Sorry I didn't reply about the quake but I am away for training and unable to post my events to the http://apsn.awcable.com website. Take a look, however, at the real-time display to see the large number of aftershocks occurring at this time. There was significant shaking at my home but no damage. Evidently, the Trans-Alaska Pipeline System is shut down for inspection and repair of damaged support members. Bob APSN Fairbanks > Hi Everyone, > > My and other PSN stations are in the process of recording a large event. > Looking at the PSN Current Seismicity web page at > http://www.seismicnet.com/currentseismicity.html it looks like it could > be in or near Alaska. > > -Larry Cochrane > Redwood City, PSN > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Clean Waveform??? From: Ed Ianni eianni2@........... Date: Mon, 04 Nov 2002 15:08:02 -0500 Hi All; My homemade Lehman recently registered the large Alaska quake (2002 11 03---7.9 Mag). I live near Phila., Pa. I tried looking at some nearby "Seis sites" to compare waveshapes however the local ones (NY area) all seem to be overdriven and rather hard to read. I am rather new to this and I was wondering if anyone is aware of a site that may have a clean waveshape (if this is possible). Thank you very much. Sincerely, Ed.
Hi All;
    My homemade Lehman recently registered the large Alaska quake (2002 11 03---7.9 Mag). I live near Phila., Pa. I tried looking at some nearby "Seis sites" to compare waveshapes however the local ones (NY area) all seem to be overdriven and rather hard to read. I am rather new to this and I was wondering if anyone is aware of a site that may have a clean waveshape (if this is possible). Thank you very much. Sincerely, Ed.
Subject: concrete piers From: ian@........... Date: Tue, 05 Nov 2002 12:19:33 +0000 (GMT) having read the article on installing seismometers, http://www.seismo.berkeley.edu/seismo/bdsn/instrumentation/guidelines.html , I'm a little unclear on one aspect and would appreciate some advice. The article states that a 4 inch gap should be left around the base of the pier. What about the rest of the pier? Also, the 4 inch gap seems to be filled with insulation. Won't this cause the pier to move with the insulation/surrounding ground? I'll be building on clay soil. How deep should I go (within reason!) and are there any other tips for clay? TIA Ian Smith __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: concrete piers From: John Hernlund hernlund@............ Date: Tue, 5 Nov 2002 10:51:08 -0800 At Arizona State we had a concrete pier in the basement of the Physical Sciences building that apparently reached ten feet depth beneath the foundation...quite expensive I imagine. The pier was about 6 foot square and was raised two feet above the floor and had a 4 inch gap around the edge that was filled with a very rubbery type of substance. The filling was important for keeping water from inundating the building, since this was a basement. The building was on top of alluvial fan and river bed deposits, so very coarse grained material. This did a pretty good job for long period recordings, but was not ideal since it did not touch bed rock. A few faculty petitioned the maintainers of Sun Devil stadium some years ago to see if they could put one there since it was on a bedrock outcrop ("A" mountain), however the stadium was being prepared to host Super Bowl XXX at the time, and they didn't like the idea of putting holes in their foundation. I would recommend that you check out the type of clay to make sure it doesn't swell a great deal when saturated with water... Cheers! John On Tuesday, November 5, 2002, at 04:19 AM, ian@........... wrote: > > having read the article on installing seismometers, > http://www.seismo.berkeley.edu/seismo/bdsn/instrumentation/ > guidelines.html , > I'm a little unclear on one aspect and would appreciate some advice. > > The article states that a 4 inch gap should be left around the base of > the > pier. What about the rest of the pier? > > Also, the 4 inch gap seems to be filled with insulation. Won't this > cause the > pier to move with the insulation/surrounding ground? > > I'll be building on clay soil. How deep should I go (within reason!) > and are > there any other tips for clay? > > TIA > > Ian Smith > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: concrete piers From: steve hammond shammon1@............. Date: Tue, 5 Nov 2002 11:20:37 -0800 Hi Ian, Dr. Bob Uhrhammer lectured on this point at a PSN meeting at Berkeley a few years ago. It has been awhile, however I remember a few of his key points. The key point in the paragraph is "the affect that the pier might have on response of the earth or the seismometer." Bob's point was to keep the local noise as low as possible while still providing a platform to mount the system. He talked about an ideal broadband station in Northern California that was at the bottom of an old mine in the mountains. He said that it was an extremely quite site and because of it, they were able to study the impact of temperature changes and barometric presser changes on the enclosure design. The insulation seen in the photos in the Berkeley document you referenced are a result of this type of study. With regard to the 4 inch gap. The 4 inch gap is to reduce noise that could be communicated into the pad / device from the outer case or ground around the mounting block. Bob took the group down into the basement seismic vaults at the Berkeley Lab and showed us several very large blocks of cement 5Wx4Hx8L-feet or there about that Berkeley uses to place their equipment on. The room were left dark and locked most of the time as you might expect. These block are isolated from the connecting floor with an air gap and filled with sand. In that way, a person can walk up to the pad and adjust the instrument without affecting the performance of the device. This type of configuration is not new. For example, some of the very early smoke drum seismographs used this same configuration. The Randhall Museum in San Francisco still has their pad in the basement of the museum from the turn of the century. UCSF used it for one of their instruments and the last time I was there the museum used it for an instrument used in their 1906 exhibit. For reference, I have pasted my PSN station site photos at http://pw2.netcom.com/~shammon1/AptosStn.htm into this note. I built my site after hearing Bob's lecture / discussion and did a few things right and a few things wrong. (1) Cement mixture 50/50 sand and Portland cement. -- this was correct. (2) insulation -- this was correct (3) Full solid cover protected from the elements. -- The house and side fence shield the box. There is a tin roof over the site. -- this was correct. (3) I tried to incorporate an air gap but had very limited space were the seismograph had to be installed and ended up with more problems then I expected. I initially built a pier block 1x1x2D-feet with a 3-inch air gap around the side walls of the pad which I filled with sand and then poured a slab around it. This resulted in the seismometer base being bolted to the pad and the magnet / coil located out over and on the slab -- this was incorrect. It caused very erratic results. I failed to think this through properly. The pads need to include room for all the components of the seismograph. Because of the limitation of space, I had to give up the air gap and went with a bigger pier with more mass. As you can see in the photos of my station, I came back and removed all the sand and clay under the slab and poured more cement removing the air gap. The device is sensitive to walk-up walk-away noise but I have been having good results with the design now that I fixed the two independent slabs to be united. Regards, Steve Hammond PSN San Jose - Aptos -----Original Message----- From: ian@........... [SMTP:ian@............ Sent: Tuesday, November 05, 2002 4:20 AM To: psn-l@.............. Subject: concrete piers having read the article on installing seismometers, http://www.seismo.berkeley.edu/seismo/bdsn/instrumentation/guidelines.html , I'm a little unclear on one aspect and would appreciate some advice. The article states that a 4 inch gap should be left around the base of the pier. What about the rest of the pier? Also, the 4 inch gap seems to be filled with insulation. Won't this cause the pier to move with the insulation/surrounding ground? I'll be building on clay soil. How deep should I go (within reason!) and are there any other tips for clay? TIA Ian Smith __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Public Seismic Network Mailing List (PSN-L) Subject: Nebraska Quake From: "Randall Pratt" rpratt@............. Date: Thu, 7 Nov 2002 00:37:31 -0600 Hi All, After a couple of weeks recovering from hard drive crashes, I now have a = new email address and web address. The Nebraska quake of 3 Nov was only = about 75 miles from here and I have posted a picture and data file at = http://mit.midco.net/rpratt/ Also note the new email address on this = message.
Hi All,
 
After a couple of weeks recovering from = hard drive=20 crashes, I now have a new email address and web address.  The = Nebraska=20 quake of 3 Nov was only about 75 miles from here and I have posted a = picture and=20 data file at http://mit.midco.net/rpratt/&nb= sp; Also=20 note the new email address on this message.
Subject: T Max Sensor From: "Frank Cooper" fxc@....... Date: Fri, 8 Nov 2002 16:14:05 -0600 Hello PSN, This is an invitation to visit my web site at http://pages.prodigy.net/fxc/ to see the pictorial construction details of John Cole's new T Max Detector. I have read a great deal of discussion over the years on PSN about a proper and inexpensive base. I think John may have solved both problems with a cheap (but not cheaply made) base for amateur seismologists. Also his method of using ball bearings at the pivot point and suspension point are outstanding. (John pioneered the ball bearing method). Feedback is welcome. No doubt there are some details I should have included such as ---everthing near the magnet must be non-magnetic. And let me express my great thanks to Larry Cochrane for paying for and maintaining "seismicnet.com" and for sponsoring PSN over the years, his authorship of Winquake, SDR, his web site "Redwood City Public Seismic Network" at http://psn.quake.net/, for making available his A/D, amp, other boards, hardware and other software, and his many other great contributions to amateur seismology. Without those contributions there would be far fewer of us and the few of us would still be floundering around with our smoked drums and chart recorders. A great big thanks Larry! Best wishes and regards to all, Frank Cooper, Friendswood, Texas, USA __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Sprengnether 201 Long-Period Vertical Seismometer on EBay From: "Larry Cochrane" cochrane@.............. Date: Fri, 8 Nov 2002 20:05:30 -0800 Hi Everyone, Someone on EBay is selling one. See http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1785642626 I would bid on it but I don't need another sensor right now... -Larry Cochrane Redwood City, PSN __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: T Max Sensor From: steve hammond shammon1@............. Date: Sat, 9 Nov 2002 09:26:25 -0800 Hi Frank, I have added a link to the PSN San Jose web site at http://pw2.netcom.com/~shammon1/psnsj.htm or http://www.publicseismicnetwork.com look under "other PSN sites" and also "Lehman seismograph". When I rebuilt the PSN San Jose site over the last month, I tried to locate all the other PSN web sites to get them in the site listing. Sorry, I managed to miss your fine site. I was looking at all the information you have posted and wanted to comment. The T Max is a very interesting design. Also, that article you have on the 1938 amateur seismology is the oldest article on the topic I have seen. Great looking site-- Regards, Steve Hammond PSN San Jose Aptos, California -----Original Message----- From: Frank Cooper [SMTP:fxc@........ Sent: Friday, November 08, 2002 2:14 PM To: psn-l@.............. Subject: T Max Sensor Hello PSN, This is an invitation to visit my web site at http://pages.prodigy.net/fxc/ to see the pictorial construction details of John Cole's new T Max Detector. I have read a great deal of discussion over the years on PSN about a proper and inexpensive base. I think John may have solved both problems with a cheap (but not cheaply made) base for amateur seismologists. Also his method of using ball bearings at the pivot point and suspension point are outstanding. (John pioneered the ball bearing method). Feedback is welcome. No doubt there are some details I should have included such as ---everthing near the magnet must be non-magnetic. And let me express my great thanks to Larry Cochrane for paying for and maintaining "seismicnet.com" and for sponsoring PSN over the years, his authorship of Winquake, SDR, his web site "Redwood City Public Seismic Network" at http://psn.quake.net/, for making available his A/D, amp, other boards, hardware and other software, and his many other great contributions to amateur seismology. Without those contributions there would be far fewer of us and the few of us would still be floundering around with our smoked drums and chart recorders. A great big thanks Larry! Best wishes and regards to all, Frank Cooper, Friendswood, Texas, USA __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Sprengnether 201 Long-Period Vertical Seismometer on EBay From: meredithlamb meredithlamb@............. Date: Sat, 09 Nov 2002 20:19:15 -0700 Hi everyone, If you want a vertical and more access to seeing the early and clearer "P" wave signals (and others), this might be the machine for you. Horizontals just don't pick up the early quake signals quite as well. With a adequate vault and temperature control, such a instrument (at least for here experience wise), will probably prove to be very dependable for low drift of the mass/boom. The design came out in the 1950's-1960's or thereabouts. I'd suspect that the seller won't adequately prepare it for shipment, especially the boom/mass. When I got mine (many years ago), the pivot hinges were snapped, the cover viewing glass was broken and all the thin diameter jumper signal/damping wires were broken. Relatively minor items to replace/repair. Their could be real serious reason for it being surplus now (?). Potentially the most serious/difficult problem "could" lie with the two coils for damping/signal. If they get thrown around and damaged....their isn't any possible replacements. The coil wire it self can also break over time, due to a manufacturers sudden coil winding speed shift (a type of copper wire stress or stretch knot), which I've noted on acouple coils over time. Luckily they were both on the outside area of the coils, which didn't mean too much unwinding too find. Even in the worst case scenario (no working coils), the frame and "zero length" spring would be enviable to have; let alone the longer period vertical configuration. One "might" have to adopt other damping/signal means. Note the weight of the unpacked instrument (115 pounds), the shipping cost can be potentially higher than the winning bid price. On the other hand, it "might" still be worthwhile to have even with the tacked on costs...the massive solid aluminum frame and parts are usually excellent material. Be prepared to have to work on the brass setscrews (die), and retap the aluminum base setscrew holes due to oxidation, old dried up grease/dirt. The tap and die could cost up to $100, or thereabouts. If you win the bid, I'd suggest that the buyer request that the two mass weights be removed (unscrewed); the boom lock pin installed, and the coil magnets assembly also be removed (gently); and shipped separately, even if it means more cost initially to the buyer. Otherwise; if you can pick it up yourself, and prepare it before moving....that would be the best alternate route. The risks and reward/s are with the buyer of course. Take care, Meredith Larry Cochrane wrote: > Hi Everyone, > > Someone on EBay is selling one. See > http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1785642626 > > I would bid on it but I don't need another sensor right now... > > -Larry Cochrane > Redwood City, PSN > Hi everyone,

If you want a vertical and more access to seeing the early
and clearer "P" wave signals (and others), this might be the
machine for you.  Horizontals just don't pick up the early quake
signals quite as well.

With a adequate vault and temperature control, such a
instrument (at least for here experience wise), will probably
prove to be very dependable for low drift of the mass/boom.
The design came out in the 1950's-1960's or thereabouts.

I'd suspect that the seller won't adequately prepare it for
shipment, especially the boom/mass.  When I got mine
(many years ago), the pivot hinges were snapped, the cover viewing
glass was broken and all the thin diameter jumper signal/damping
wires were broken.  Relatively minor items to replace/repair.
Their could be real serious reason for it being surplus now (?).

Potentially the most serious/difficult problem "could" lie with the
two coils for damping/signal.  If they get thrown around and
damaged....their isn't any possible replacements.  The
coil wire it self can also break over time, due to a manufacturers
sudden coil winding speed shift (a type of copper wire stress or
stretch knot),  which I've noted on acouple coils over time.
Luckily they were both on the outside area of the coils, which
didn't mean too much unwinding too find.

Even in the worst case scenario (no working coils), the frame
and "zero length" spring would be enviable to have; let alone the
longer period vertical configuration.  One "might" have to adopt
other damping/signal means.

Note the weight of the unpacked instrument (115 pounds), the
shipping cost can be potentially higher than the winning bid price.
On the other hand, it "might" still be worthwhile to have even with
the tacked on costs...the massive solid aluminum frame and parts
are usually excellent material.

Be prepared to have to work on the brass setscrews (die), and
retap the aluminum base setscrew holes due to oxidation, old
dried up grease/dirt.  The tap and die could cost up to $100,
or thereabouts.

If you win the bid, I'd suggest that the buyer request that the
two mass weights be removed (unscrewed); the boom lock pin
installed, and the coil magnets assembly also be removed (gently);
and shipped separately, even if it means more cost initially to the
buyer.  Otherwise; if you can pick it up yourself, and prepare it
before moving....that would be the best alternate route.  The
risks and reward/s are with the buyer of course.

Take care, Meredith

Larry Cochrane wrote:

Hi Everyone,

Someone on EBay is selling one. See
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1785642626

I would bid on it but I don't need another sensor right now...

-Larry Cochrane
Redwood City, PSN
 

Subject: Re: T Max Sensor From: CapAAVSO@....... Date: Sun, 10 Nov 2002 08:46:03 EST In a message dated 11/8/02 10:23:32 PM GMT Standard Time, fxc@....... writes: > I think John may have solved both problems with a > cheap (but not cheaply made) base for amateur seismologists. Also his > method of using ball bearings at the pivot point and suspension point are > outstanding. (John pioneered the ball bearing method). Feedback is welcome. Hi PSN, Could someone please comment on how John Cole's use of a ball bearing at the top suspension point is an advantage? Does this not introduce friction where there wasn't any before? Thanks, Cap In a message dated 11/8/02 10:23:32 PM GMT Standard Time, fxc@....... writes:


I think John may have solved both problems with a
cheap (but not cheaply made) base for amateur seismologists.  Also his
method of using ball bearings at the pivot point and suspension point are
outstanding. (John pioneered the ball bearing method). Feedback is welcome.


Hi PSN,

Could someone please comment on how John Cole's use of a ball bearing at the top suspension point is an advantage? Does this not introduce friction where there wasn't any before?

Thanks,
Cap
Subject: Re: T Max Sensor From: ChrisAtUpw@....... Date: Sun, 10 Nov 2002 10:40:04 EST In a message dated 10/11/02, CapAAVSO@....... writes: > Hi PSN, > Could someone please comment on how John Cole's use of a ball bearing at > the top suspension point is an advantage? Does this not introduce friction > where there wasn't any before? > Hi Cap, It depends on friction to 'stay put', but the resistance to motion is that of a rolling contact. With a spherical onto a near flat hard surface, both polished to optical smoothness, this force can be extremely small. Moreover, there is no spring effect due to a bending foil or wire and the centre of rotation is closely defined. It is of course possible to overload any rolling contact, but you can check up on rough figures for this by looking a rated loads for ball races. It can also be calculated. For a hard smooth surface, you can also stick a bit of a razor blade onto the top of a bolt, or you can lap and polish the surface of a triangular lathe tool bit - used of course! Regards, Chris Chapman In a message dated 10/11/02, CapAAVSO@....... writes:

Hi PSN,
Could someone please comment on how John Cole's use of a ball bearing at the top suspension point is an advantage? Does this not introduce friction where there wasn't any before?
Thanks, Cap


Hi Cap,

      It depends on friction to 'stay put', but the resistance to motion is that of a rolling contact. With a spherical onto a near flat hard surface, both polished to optical smoothness, this force can be extremely small. Moreover, there is no spring effect due to a bending foil or wire and the centre of rotation is closely defined.
      It is of course possible to overload any rolling contact, but you can check up on rough figures for this by looking a rated loads for ball races. It can also be calculated. For a hard smooth surface, you can also stick a bit of a razor blade onto the top of a bolt, or you can lap and polish the surface of a triangular lathe tool bit - used of course!

      Regards,

      Chris Chapman   
Subject: My horizontal sensor From: Bobhelenmcclure@....... Date: Sun, 10 Nov 2002 11:47:49 EST Hi all, I am presently using a pre-Lehman type sensor I built more than 44 years ago, after reading an Amateur Scientist article. At that time, it was equipped with optical means for sensing pendulum displacement. I recently retrieved the sensor from storage, and modified it for velocity sensing. It really works well. It is set for 11 seconds natural period, and I post-filter the data to simulate a natural period of 32 seconds. My ability to pick up teleseisms is limited only by local noise and microseisms. The pendulum, magnet and coil design are unusual. You can see it described at John Lahr's web page: http://www.jjlahr.com/science/psn/mcclure/index.html Regards, Bob McClure Hi all,

  I am presently using a pre-Lehman type sensor I built more than 44 years ago, after reading an Amateur Scientist article.  At that time, it was equipped with optical means for sensing pendulum displacement.  I recently retrieved the sensor from storage, and modified it for velocity sensing.  It really works well.  It is set for 11 seconds natural period, and I post-filter the data to simulate a natural period of 32 seconds.  My ability to pick up teleseisms is limited only by local noise and microseisms.

  The pendulum, magnet and coil design are unusual.  You can see it described at John Lahr's web page:

      http://www.jjlahr.com/science/psn/mcclure/index.html

Regards,

Bob McClure



Subject: Long Period Geophone needed... From: "Kareem" kareem@............. Date: Sun, 10 Nov 2002 14:04:44 -0800 Does anyone know where one can find a used long-period geophone for giveaway? (OK, for sale?) Kareem Message
Does = anyone know=20 where one can find a used long-period geophone for giveaway?  = (OK, for=20 sale?)
 
 
Kareem
Subject: Re: Long Period Geophone needed... From: "Larry Cochrane" cochrane@.............. Date: Sun, 10 Nov 2002 17:45:32 -0800 MessageKareem, All of the geophones I know about are short-period devices. For a = long-period sensor you will need to build a device like a Lehman or SG = sensor.=20 -Larry Cochrane Redwood City, PSN ----- Original Message -----=20 From: Kareem=20 To: PSN=20 Sent: Sunday, November 10, 2002 2:04 PM Subject: Long Period Geophone needed... Does anyone know where one can find a used long-period geophone for = giveaway? (OK, for sale?) Kareem Message
Kareem,
 
All of the geophones I know about are = short-period=20 devices. For a long-period sensor you will need to = build a device like=20 a Lehman or SG sensor. 
 
-Larry Cochrane
Redwood City, PSN
----- Original Message -----
From:=20 Kareem=20
To: PSN
Sent: Sunday, November 10, 2002 = 2:04=20 PM
Subject: Long Period Geophone=20 needed...

Does = anyone know=20 where one can find a used long-period geophone for = giveaway?  (OK,=20 for sale?)
 
 
Kareem
= Subject: RE: Long Period Geophone needed... From: "Kareem" kareem@............. Date: Sun, 10 Nov 2002 18:18:56 -0800 I'm undergoing one of those "time is of the essence" moments and I was hoping to acquire one that is already put together. We'll see what turns up. Thanks Larry. -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of Larry Cochrane Sent: Sunday, November 10, 2002 5:46 PM To: psn-l@.............. Subject: Re: Long Period Geophone needed... Kareem, All of the geophones I know about are short-period devices. For a long-period sensor you will need to build a device like a Lehman or SG sensor. -Larry Cochrane Redwood City, PSN ----- Original Message ----- From: Kareem To: PSN Sent: Sunday, November 10, 2002 2:04 PM Subject: Long Period Geophone needed... Does anyone know where one can find a used long-period geophone for giveaway? (OK, for sale?) Kareem Message
I'm = undergoing one=20 of those "time is of the essence" moments and I was hoping to acquire = one that=20 is already put together.
We'll see = what turns up.=20 Thanks Larry.=20
-----Original Message-----
From:=20 psn-l-request@.............. [mailto:psn-l-request@............... = On=20 Behalf Of Larry Cochrane
Sent: Sunday, November 10, 2002 = 5:46=20 PM
To: psn-l@..............
Subject: Re: Long = Period=20 Geophone needed...

Kareem,
 
All of the geophones I know about are = short-period devices. For a long-period sensor you will need to=20 build a device like a Lehman or SG = sensor. 
 
-Larry Cochrane
Redwood City, PSN
----- Original Message -----
From:=20 Kareem=20
To: PSN
Sent: Sunday, November 10, = 2002 2:04=20 PM
Subject: Long Period Geophone = needed...

Does anyone know=20 where one can find a used long-period geophone for = giveaway?  (OK,=20 for sale?)
 
 
Kareem
Subject: Kevlar lehman boom support From: "Dewayne Hill" n0ssy@......... Date: Sun, 10 Nov 2002 19:23:36 -0700 Has anyone tried to us Kevlar cord to support the boom on a Lehman = Seismometer? I have found a source for .025" cord a was wondering how well it might = work. Dewayne Hill
Has anyone tried to us Kevlar cord to support the = boom on a=20 Lehman Seismometer?
I have found a source for .025" cord a was wondering = how well=20 it might work.
 
Dewayne Hill
Subject: Re: T Max Sensor From: john c cole johnccole3@........ Date: Sun, 10 Nov 2002 20:34:22 -0600 Chris , in response to your statements about the TMAX, you are 100% correct on all points . The Tmax has very little friction and these detectors can be run at 30+ seconds and retain stability . The TMAX has both upper and lower ball bearing pivot point suspension . When looking at postings on the PSN you will know who is using this method . John Cole ________________________________________________________________ Sign Up for Juno Platinum Internet Access Today Only $9.95 per month! Visit www.juno.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Kevlar lehman boom support From: CapAAVSO@....... Date: Mon, 11 Nov 2002 10:11:20 EST In a message dated 11/11/02 2:25:04 AM GMT Standard Time, n0ssy@......... writes: > > << Has anyone tried to us Kevlar cord to support the boom on a Lehman > Seismometer? > I have found a source for .025" cord a was wondering how well it might > work. >> Kevlar will probably work OK but may not be as good as metal. Music wire makes a good strong and flexible support wire. At a music store you can buy the thinnest guitar string which is 0.008" in diameter for less than $2. It will easily support a 5 pound mass. Secure the ends by clamping between two washers with a screw. Have fun, Cap In a message dated 11/11/02 2:25:04 AM GMT Standard Time, n0ssy@......... writes:

<< Has anyone tried to us Kevlar cord to support the boom on a Lehman Seismometer?
I have found a source for .025" cord a was wondering how well it might work. >>


Kevlar will probably work OK but may not be as good as metal. Music wire makes a good strong and flexible support wire. At a music store you can buy the thinnest guitar string which is 0.008" in diameter for less than $2. It will easily support a 5 pound mass. Secure the ends by clamping between two washers with a screw.

Have fun,
Cap

Subject: Re: Kevlar lehman boom support From: ChrisAtUpw@....... Date: Mon, 11 Nov 2002 11:53:38 EST In a message dated 11/11/02, n0ssy@......... writes: > Has anyone tried to us Kevlar cord to support the boom on a Lehman > Seismometer? > I have found a source for .025" cord a was wondering how well it might work. > Hi Dewayne, I would expect there to be a fair amount of internal friction in a 25 thou cord when it bends. You might want to consider something like Kapton film? Alternatively, you can buy very thin metal foils quite easily and get steel music wire down to 7 thou dia. You can get 1/2" wide steel Gauge strips 1.5 thou thick from a tool merchant. K&S metals also sell thin sheets of foil including 2 thou stainless steel (or you can cut up an old electric razor foil!) Metal foils are generally more reliable than plastic. Regards, Chris Chapman In a message dated 11/11/02, n0ssy@......... writes:

Has anyone tried to us Kevlar cord to support the boom on a Lehman Seismometer?
I have found a source for .025" cord a was wondering how well it might work.
Dewayne Hill


Hi Dewayne,

      I would expect there to be a fair amount of internal friction in a 25 thou cord when it bends. You might want to consider something like Kapton film? Alternatively, you can buy very thin metal foils quite easily and get steel music wire down to 7 thou dia. You can get 1/2" wide steel Gauge strips 1.5 thou thick from a tool merchant. K&S metals also sell thin sheets of foil including 2 thou stainless steel (or you can cut up an old electric razor foil!)
      Metal foils are generally more reliable than plastic.

      Regards,

      Chris Chapman
Subject: Parkfield is moving-- From: steve hammond shammon1@............. Date: Tue, 12 Nov 2002 10:19:07 -0800 There was a 4.2 event in Parkfield today. This should up the alert status a bit... Regards, Steve Hammond PSN San Jose Aptos, CA __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Sprengnether 201 Long-Period Vertical Seismometer on EBay From: Jack Ivey ivey@.......... Date: Tue, 12 Nov 2002 16:51:47 -0500 Hi all, I'm debating if I want another boat anchor. Do we know what period it is? Does anyone know how to tell this guy to lock the mass for shipping? Also, is anyone bidding on it? Thanks, Jack -----Original Message----- From: meredithlamb [mailto:meredithlamb@.............. Sent: Saturday, November 09, 2002 10:19 PM To: psn-l@.............. Subject: Re: Sprengnether 201 Long-Period Vertical Seismometer on EBay Hi everyone, If you want a vertical and more access to seeing the early and clearer "P" wave signals (and others), this might be the machine for you. Horizontals just don't pick up the early quake signals quite as well. With a adequate vault and temperature control, such a instrument (at least for here experience wise), will probably prove to be very dependable for low drift of the mass/boom. The design came out in the 1950's-1960's or thereabouts. I'd suspect that the seller won't adequately prepare it for shipment, especially the boom/mass. When I got mine (many years ago), the pivot hinges were snapped, the cover viewing glass was broken and all the thin diameter jumper signal/damping wires were broken. Relatively minor items to replace/repair. Their could be real serious reason for it being surplus now (?). Potentially the most serious/difficult problem "could" lie with the two coils for damping/signal. If they get thrown around and damaged....their isn't any possible replacements. The coil wire it self can also break over time, due to a manufacturers sudden coil winding speed shift (a type of copper wire stress or stretch knot), which I've noted on acouple coils over time. Luckily they were both on the outside area of the coils, which didn't mean too much unwinding too find. Even in the worst case scenario (no working coils), the frame and "zero length" spring would be enviable to have; let alone the longer period vertical configuration. One "might" have to adopt other damping/signal means. Note the weight of the unpacked instrument (115 pounds), the shipping cost can be potentially higher than the winning bid price. On the other hand, it "might" still be worthwhile to have even with the tacked on costs...the massive solid aluminum frame and parts are usually excellent material. Be prepared to have to work on the brass setscrews (die), and retap the aluminum base setscrew holes due to oxidation, old dried up grease/dirt. The tap and die could cost up to $100, or thereabouts. If you win the bid, I'd suggest that the buyer request that the two mass weights be removed (unscrewed); the boom lock pin installed, and the coil magnets assembly also be removed (gently); and shipped separately, even if it means more cost initially to the buyer. Otherwise; if you can pick it up yourself, and prepare it before moving....that would be the best alternate route. The risks and reward/s are with the buyer of course. Take care, Meredith Larry Cochrane wrote: Hi Everyone, Someone on EBay is selling one. See http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem &item=1785642626 I would bid on it but I don't need another sensor right now... -Larry Cochrane Redwood City, PSN
Hi all,
I'm debating if I want another boat anchor.  Do we know what period it is?
Does anyone know how to tell this guy to lock the mass for shipping?
Also, is anyone bidding on it? 
 
Thanks,
Jack
-----Original Message-----
From: meredithlamb [mailto:meredithlamb@..............
Sent: Saturday, November 09, 2002 10:19 PM
To: psn-l@..............
Subject: Re: Sprengnether 201 Long-Period Vertical Seismometer on EBay

Hi everyone,

If you want a vertical and more access to seeing the early
and clearer "P" wave signals (and others), this might be the
machine for you.  Horizontals just don't pick up the early quake
signals quite as well.

With a adequate vault and temperature control, such a
instrument (at least for here experience wise), will probably
prove to be very dependable for low drift of the mass/boom.
The design came out in the 1950's-1960's or thereabouts.

I'd suspect that the seller won't adequately prepare it for
shipment, especially the boom/mass.  When I got mine
(many years ago), the pivot hinges were snapped, the cover viewing
glass was broken and all the thin diameter jumper signal/damping
wires were broken.  Relatively minor items to replace/repair.
Their could be real serious reason for it being surplus now (?).

Potentially the most serious/difficult problem "could" lie with the
two coils for damping/signal.  If they get thrown around and
damaged....their isn't any possible replacements.  The
coil wire it self can also break over time, due to a manufacturers
sudden coil winding speed shift (a type of copper wire stress or
stretch knot),  which I've noted on acouple coils over time.
Luckily they were both on the outside area of the coils, which
didn't mean too much unwinding too find.

Even in the worst case scenario (no working coils), the frame
and "zero length" spring would be enviable to have; let alone the
longer period vertical configuration.  One "might" have to adopt
other damping/signal means.

Note the weight of the unpacked instrument (115 pounds), the
shipping cost can be potentially higher than the winning bid price.
On the other hand, it "might" still be worthwhile to have even with
the tacked on costs...the massive solid aluminum frame and parts
are usually excellent material.

Be prepared to have to work on the brass setscrews (die), and
retap the aluminum base setscrew holes due to oxidation, old
dried up grease/dirt.  The tap and die could cost up to $100,
or thereabouts.

If you win the bid, I'd suggest that the buyer request that the
two mass weights be removed (unscrewed); the boom lock pin
installed, and the coil magnets assembly also be removed (gently);
and shipped separately, even if it means more cost initially to the
buyer.  Otherwise; if you can pick it up yourself, and prepare it
before moving....that would be the best alternate route.  The
risks and reward/s are with the buyer of course.

Take care, Meredith

Larry Cochrane wrote:

Hi Everyone,

Someone on EBay is selling one. See
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1785642626

I would bid on it but I don't need another sensor right now...

-Larry Cochrane
Redwood City, PSN
 

Subject: Re: Sprengnether 201 Long-Period Vertical Seismometer on EBay From: Thomas W Leiper twleiper@........ Date: Tue, 12 Nov 2002 18:04:56 -0500 Yes, I bid $1600 on it... Tom On Tue, 12 Nov 2002 16:51:47 -0500 Jack Ivey writes: Hi all, I'm debating if I want another boat anchor. Do we know what period it is? Does anyone know how to tell this guy to lock the mass for shipping? Also, is anyone bidding on it? Thanks, Jack -----Original Message----- From: meredithlamb [mailto:meredithlamb@.............. Sent: Saturday, November 09, 2002 10:19 PM To: psn-l@.............. Subject: Re: Sprengnether 201 Long-Period Vertical Seismometer on EBay Hi everyone, If you want a vertical and more access to seeing the early and clearer "P" wave signals (and others), this might be the machine for you. Horizontals just don't pick up the early quake signals quite as well. With a adequate vault and temperature control, such a instrument (at least for here experience wise), will probably prove to be very dependable for low drift of the mass/boom. The design came out in the 1950's-1960's or thereabouts. I'd suspect that the seller won't adequately prepare it for shipment, especially the boom/mass. When I got mine (many years ago), the pivot hinges were snapped, the cover viewing glass was broken and all the thin diameter jumper signal/damping wires were broken. Relatively minor items to replace/repair. Their could be real serious reason for it being surplus now (?). Potentially the most serious/difficult problem "could" lie with the two coils for damping/signal. If they get thrown around and damaged....their isn't any possible replacements. The coil wire it self can also break over time, due to a manufacturers sudden coil winding speed shift (a type of copper wire stress or stretch knot), which I've noted on acouple coils over time. Luckily they were both on the outside area of the coils, which didn't mean too much unwinding too find. Even in the worst case scenario (no working coils), the frame and "zero length" spring would be enviable to have; let alone the longer period vertical configuration. One "might" have to adopt other damping/signal means. Note the weight of the unpacked instrument (115 pounds), the shipping cost can be potentially higher than the winning bid price. On the other hand, it "might" still be worthwhile to have even with the tacked on costs...the massive solid aluminum frame and parts are usually excellent material. Be prepared to have to work on the brass setscrews (die), and retap the aluminum base setscrew holes due to oxidation, old dried up grease/dirt. The tap and die could cost up to $100, or thereabouts. If you win the bid, I'd suggest that the buyer request that the two mass weights be removed (unscrewed); the boom lock pin installed, and the coil magnets assembly also be removed (gently); and shipped separately, even if it means more cost initially to the buyer. Otherwise; if you can pick it up yourself, and prepare it before moving....that would be the best alternate route. The risks and reward/s are with the buyer of course. Take care, Meredith Larry Cochrane wrote: Hi Everyone, Someone on EBay is selling one. See http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1785642626 I would bid on it but I don't need another sensor right now... -Larry Cochrane Redwood City, PSN
Yes, I bid $1600 on it...
 
Tom
 
On Tue, 12 Nov 2002 16:51:47 -0500 Jack Ivey <ivey@..........> writes:
Hi=20 all,
I'm=20 debating if I want another boat anchor.  Do= we know what=20 period it is?
Does=20 anyone know how to tell this guy to lock the mass for=20 shipping?
Also, is anyone bidding on it? 
 
Thanks,
Jack
-----Original Message-----
From: meredithlamb=20 [mailto:meredithlamb@..............
Sent: Saturday, November = 09,=20 2002 10:19 PM
To: psn-l@..............
Subject: Re:= =20 Sprengnether 201 Long-Period Vertical Seismometer on=20 EBay

Hi everyone,=20

If you want a vertical and more access to seeing the early
and=20 clearer "P" wave signals (and others), this might be the
machine = for=20 you.  Horizontals just don't pick up the early quake
signals = quite=20 as well.=20

With a adequate vault and temperature control, such a
instrument= (at=20 least for here experience wise), will probably
prove to be very=20 dependable for low drift of the mass/boom.
The design came out in = the=20 1950's-1960's or thereabouts.=20

I'd suspect that the seller won't adequately prepare it for
= shipment,=20 especially the boom/mass.  When I got mine
(many years ago), = the=20 pivot hinges were snapped, the cover viewing
glass was broken and = all=20 the thin diameter jumper signal/damping
wires were broken. =20 Relatively minor items to replace/repair.
Their could be real = serious=20 reason for it being surplus now (?).=20

Potentially the most serious/difficult problem "could" lie with the= =20
two coils for damping/signal.  If they get thrown around and=20
damaged....their isn't any possible replacements.  The
= coil=20 wire it self can also break over time, due to a manufacturers
= sudden=20 coil winding speed shift (a type of copper wire stress or
stretch=20 knot),  which I've noted on acouple coils over time.
Luckily = they=20 were both on the outside area of the coils, which
didn't mean too = much=20 unwinding too find.=20

Even in the worst case scenario (no working coils), the frame
= and=20 "zero length" spring would be enviable to have; let alone the
= longer=20 period vertical configuration.  One "might" have to adopt
= other=20 damping/signal means.=20

Note the weight of the unpacked instrument (115 pounds), the
= shipping=20 cost can be potentially higher than the winning bid price.
On the = other=20 hand, it "might" still be worthwhile to have even with
the tacked = on=20 costs...the massive solid aluminum frame and parts
are usually = excellent=20 material.=20

Be prepared to have to work on the brass setscrews (die), and
= retap=20 the aluminum base setscrew holes due to oxidation, old
dried up=20 grease/dirt.  The tap and die could cost up to $100,
or=20 thereabouts.=20

If you win the bid, I'd suggest that the buyer request that the
= two=20 mass weights be removed (unscrewed); the boom lock pin
installed, = and=20 the coil magnets assembly also be removed (gently);
and shipped=20 separately, even if it means more cost initially to the
buyer. = ;=20 Otherwise; if you can pick it up yourself, and prepare it
before=20 moving....that would be the best alternate route.  The
risks = and=20 reward/s are with the buyer of course.=20

Take care, Meredith=20

Larry Cochrane wrote:=20

Hi Everyone,=20

Someone on EBay is selling one. See
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3D= 1785642626=20

I would bid on it but I don't need another sensor right now...=20

-Larry Cochrane
Redwood City, PSN=20
 

 
Subject: Re: Sprengnether 201 Long-Period Vertical Seismometer on EBay From: ChrisAtUpw@....... Date: Tue, 12 Nov 2002 20:08:31 EST In a message dated 12/11/02, twleiper@........ writes: > Yes, I bid $1600 on it... Hey, thanks for the warning. My 1K does not seem to have registered. In a message dated 12/11/02, twleiper@........ writes:

Yes, I bid $1600 on it...


      Hey, thanks for the warning. My 1K does not seem to have registered.
Subject: Re: Sprengnether 201 Long-Period Vertical Seismometer on EBay From: meredithlamb meredithlamb@............. Date: Tue, 12 Nov 2002 18:28:40 -0700 Hi Tom and Jack, and all, When new this unit probably were sold to the USGS (NEIC) for 5K or thereabouts, as a wild guess; whereas the horizontals were likely around 3k (alot less mechanically complicated than the vertical). Going further, some of the newer style Broad-band type seismo's get alot higher in price anymore..... Jack, they were originally made for around a 30 second period; but over time it was determined they were too unstable (drifting); hence, they are usually operated at ~ 15-20 seconds. (previous Sean-Thomas Morrissey note) One can email the seller per the E-Bay item site, where it states "ask seller a question". I'd guess its locked in place now; but they don't show the front of the seismo, where normally there is a locking pin hole. See: http://www.geocities.com/meredithlamb/page028.html There is also clamping pin/s on the rear through the clamping blocks. See: http://www.geocities.com/meredithlamb/page026.html Its possible their is no pins for the holes with the unit, but a suitable rod/drill/s could be used also. One can take a sufficient size hex wrench to remove the lead mass weights holding screws through the hole on the side of the frame (centered when locked with the pin/s). I'd strongly suggest the mass weights be removed before shipping, and the locking pins installed. The picture also shows a DC motor on the boom for remotely centering/adjusting the mass position. That motor, may or may not be in working order....being ~40-50 years old now. Sean-Thomas Morrissey (deceased) once successfully converted one of their St. Louis University same item vertical instruments into a broad-band unit; which is still working there I hope. Take care, Meredith Lamb Thomas W Leiper wrote: > Yes, I bid $1600 on it... Tom On Tue, 12 Nov 2002 16:51:47 -0500 Jack > Ivey writes: > > Hi all,I'm debating if I want another boat anchor. Do we > know what period it is?Does anyone know how to tell this guy > to lock the mass for shipping?Also, is anyone bidding on > it? Thanks,Jack > Hi Tom and Jack, and all,

When new this unit probably were sold to the USGS (NEIC)
for 5K or thereabouts,  as a wild guess; whereas the horizontals
were likely around 3k (alot less mechanically complicated than
the vertical).  Going further, some of the newer style Broad-band
type seismo's get alot higher in price anymore.....

Jack, they were originally made for around a 30 second
period; but over time it was determined they were too
unstable (drifting); hence, they are usually operated at ~
15-20 seconds. (previous Sean-Thomas Morrissey note)

One can email the seller per the E-Bay item site, where it
states "ask seller a question".

I'd guess its locked in place now; but they don't show the
front of the seismo, where normally there is a locking pin hole.
See:
http://www.geocities.com/meredithlamb/page028.html
There is also clamping pin/s on the rear through the clamping
blocks. See:
http://www.geocities.com/meredithlamb/page026.html
Its possible their is no pins for the holes with the
unit, but a suitable rod/drill/s could be used also.

One can take a sufficient size hex wrench to remove the lead
mass weights holding screws through the hole on the side of the
frame (centered when locked with the pin/s).  I'd strongly
suggest the mass weights be removed before shipping, and the
locking pins installed.

The picture also shows a DC motor on the boom for remotely
centering/adjusting the mass position.  That motor, may or may
not be in working order....being ~40-50 years old now.

Sean-Thomas Morrissey (deceased) once successfully converted
one of their St. Louis University same item vertical instruments
into a broad-band unit; which is still working there I hope.

Take care, Meredith Lamb

Thomas W Leiper wrote:

 Yes, I bid $1600 on it... Tom On Tue, 12 Nov 2002 16:51:47 -0500 Jack Ivey <ivey@..........> writes:
Hi all,I'm debating if I want another boat anchor. Do we know what period it is?Does anyone know how to tell this guy to lock the mass for shipping?Also, is anyone bidding on it? Thanks,Jack
Subject: Re: Sprengnether 201 Long-Period Vertical Seismometer on EBay From: "Barry" gbl@....... Date: Wed, 13 Nov 2002 05:41:38 -0800 Hi All I bid a once on it but are not sure if my boat will handle the load. = Period and weight wise, I am very happy with the performance the two = SMT8 type verticals STM described.=20 Regards Barry ----- Original Message -----=20 From: meredithlamb=20 To: psn-l@................. Sent: Tuesday, November 12, 2002 5:28 PM Subject: Re: Sprengnether 201 Long-Period Vertical Seismometer on EBay Hi Tom and Jack, and all,=20 When new this unit probably were sold to the USGS (NEIC)=20 for 5K or thereabouts, as a wild guess; whereas the horizontals=20 were likely around 3k (alot less mechanically complicated than=20 the vertical). Going further, some of the newer style Broad-band=20 type seismo's get alot higher in price anymore.....=20 Jack, they were originally made for around a 30 second=20 period; but over time it was determined they were too=20 unstable (drifting); hence, they are usually operated at ~=20 15-20 seconds. (previous Sean-Thomas Morrissey note)=20 One can email the seller per the E-Bay item site, where it=20 states "ask seller a question".=20 I'd guess its locked in place now; but they don't show the=20 front of the seismo, where normally there is a locking pin hole.=20 See:=20 http://www.geocities.com/meredithlamb/page028.html=20 There is also clamping pin/s on the rear through the clamping=20 blocks. See:=20 http://www.geocities.com/meredithlamb/page026.html=20 Its possible their is no pins for the holes with the=20 unit, but a suitable rod/drill/s could be used also.=20 One can take a sufficient size hex wrench to remove the lead=20 mass weights holding screws through the hole on the side of the=20 frame (centered when locked with the pin/s). I'd strongly=20 suggest the mass weights be removed before shipping, and the=20 locking pins installed.=20 The picture also shows a DC motor on the boom for remotely=20 centering/adjusting the mass position. That motor, may or may=20 not be in working order....being ~40-50 years old now.=20 Sean-Thomas Morrissey (deceased) once successfully converted=20 one of their St. Louis University same item vertical instruments=20 into a broad-band unit; which is still working there I hope.=20 Take care, Meredith Lamb=20 Thomas W Leiper wrote:=20 Yes, I bid $1600 on it... Tom On Tue, 12 Nov 2002 16:51:47 -0500 = Jack Ivey writes:=20 Hi all,I'm debating if I want another boat anchor. Do we know what = period it is?Does anyone know how to tell this guy to lock the mass for = shipping?Also, is anyone bidding on it? Thanks,Jack
Hi All
 I bid a once on it but are not = sure if my=20 boat will handle the load. Period and weight wise, I am very happy with = the=20 performance the two SMT8  type verticals STM described. =
 Regards
Barry
 
----- Original Message -----
From:=20 meredithlamb
Sent: Tuesday, November 12, = 2002 5:28=20 PM
Subject: Re: Sprengnether 201 = Long-Period=20 Vertical Seismometer on EBay

Hi Tom and Jack, and all,=20

When new this unit probably were sold to the USGS (NEIC)
for 5K = or=20 thereabouts,  as a wild guess; whereas the horizontals
were = likely=20 around 3k (alot less mechanically complicated than
the = vertical). =20 Going further, some of the newer style Broad-band
type seismo's = get alot=20 higher in price anymore.....=20

Jack, they were originally made for around a 30 second
period; = but over=20 time it was determined they were too
unstable (drifting); hence, = they are=20 usually operated at ~
15-20 seconds. (previous Sean-Thomas = Morrissey note)=20

One can email the seller per the E-Bay item site, where it =
states "ask=20 seller a question".=20

I'd guess its locked in place now; but they don't show the =
front of the=20 seismo, where normally there is a locking pin hole.
See:
http://www.ge= ocities.com/meredithlamb/page028.html=20
There is also clamping pin/s on the rear through the clamping =
blocks.=20 See:
http://www.ge= ocities.com/meredithlamb/page026.html=20
Its possible their is no pins for the holes with the
unit, but = a=20 suitable rod/drill/s could be used also.=20

One can take a sufficient size hex wrench to remove the lead =
mass=20 weights holding screws through the hole on the side of the
frame = (centered=20 when locked with the pin/s).  I'd strongly
suggest the mass = weights=20 be removed before shipping, and the
locking pins installed.=20

The picture also shows a DC motor on the boom for remotely=20
centering/adjusting the mass position.  That motor, may or = may=20
not be in working order....being ~40-50 years old now.=20

Sean-Thomas Morrissey (deceased) once successfully converted =
one of=20 their St. Louis University same item vertical instruments
into a=20 broad-band unit; which is still working there I hope.=20

Take care, Meredith Lamb=20

Thomas W Leiper wrote:=20

 Yes, I bid $1600 on it... Tom On Tue, = 12 Nov=20 2002 16:51:47 -0500 Jack Ivey <ivey@..........> writes:=20
Hi all,I'm = debating if I=20 want another boat anchor. Do we=20 know what period it is?Does anyone=20 know how to tell this guy to lock the mass for = shipping?Also, is anyone bidding on = it? Thanks,Jack
<= /BLOCKQUOTE>
Subject: Re: Long Period Geophone needed... From: "Jonathan Peakall" jpeakall@............ Date: Wed, 13 Nov 2002 07:29:57 -0800 MessageKareem, I am new to this, so I don't know what is defined as a "long" period = geophone. I got a 10hz one very cheaply a few months ago on Ebay, and = the guy had more. I can dig up the address if you are interested. Regards, Jonathan Peakall ----- Original Message -----=20 From: Kareem=20 To: PSN=20 Sent: Sunday, November 10, 2002 2:04 PM Subject: Long Period Geophone needed... Does anyone know where one can find a used long-period geophone for = giveaway? (OK, for sale?) Kareem Message
Kareem,
 
I am new to this, so I don't know what = is defined=20 as a "long" period geophone. I got a 10hz one very cheaply a few months = ago on=20 Ebay, and the guy had more. I can dig up the address if you are=20 interested.
 
Regards,
 
Jonathan Peakall
----- Original Message -----
From:=20 Kareem=20
To: PSN
Sent: Sunday, November 10, 2002 = 2:04=20 PM
Subject: Long Period Geophone=20 needed...

Does = anyone know=20 where one can find a used long-period geophone for = giveaway?  (OK,=20 for sale?)
 
 
Kareem
= Subject: Re: STM 8 (previous Sprengnether subject email) From: meredithlamb meredithlamb@............. Date: Wed, 13 Nov 2002 13:28:30 -0700 Hi Barry and all, Glad your STM 8 is still working. Sean-Thomas Morrisseys vertical seismo created alot of interest ~ afew years ago of course. I think it also had alot of confusion along the line of the exact electronics components used and its adjustments involved for various reasons.....their was a long line of emails with corrections thereafter that kind of left me and perhaps others in the lurch so too speak. It just might be that you are the only "knowledgeable person " left that perhaps has some more exact circuitry/operation/setup info than anyone else. It was a rather involved circuitry I think. You may even have changed components that would be of interest also. Its perhaps prudent to say that these corrected documents (however assembled) are invaluable to those wishing to try a duplication. I've little electronics background myself, and I'd guess most individuals are in the same rough class. I think St. Louis University "was" thinking of trying to get a U.S. Patent; but as of recent date, I've seen nothing suggesting such (it could be in the "pipeline", so too speak of course). On the other hand, it may have been set aside for other financial reasons; or even abandoned. Its also possible that the STM website display with the mechanics and circuitry itself prior to any Patent application could have placed the entire unit in a "public domain" category which in itself prevents any Patent granting success. I just don't know. Regardless, its "still" likely the best broadband vertical design around for its cheapest home building approach.....which I'am sure Sean was encouraging. There was a number of individuals trying to duplicate the unit, but, I've no idea of their success. As I recall, one or two were considering other sensor/amplifier methods outside of the original design, but I've no idea of how that went. http://www.eas.slu.edu/People/STMorrissey/index.html Take care, Meredith Lamb Barry wrote: > Hi All I bid a once on it but are not sure if my boat will handle the > load. Period and weight wise, I am very happy with the performance the > two SMT8 type verticals STM described. RegardsBarry Hi Barry and all,

Glad your STM 8 is still working.  Sean-Thomas
Morrisseys vertical seismo created alot of interest ~ afew
years ago of course.  I think it also had alot of confusion
along the line of the exact electronics components used and
its adjustments involved for various reasons.....their was a
long line of emails with corrections thereafter that kind of
left me and perhaps others in the lurch so too speak.  It just
might be that you are the only "knowledgeable person " left
that perhaps has some more exact circuitry/operation/setup
info than anyone else.  It was a rather involved circuitry I
think.  You may even have changed components that would
be of interest also.  Its perhaps prudent to say that these
corrected documents (however assembled) are invaluable to
those wishing to try a duplication.  I've little electronics
background myself, and I'd guess most individuals are in the
same rough class.

I think St. Louis University "was" thinking of trying to get a
U.S. Patent; but as of recent date, I've seen nothing suggesting
such (it could be in the "pipeline", so too speak of course).  On
the other hand, it may have been set aside for other financial
reasons; or even abandoned.  Its also possible that the STM
website display with the mechanics and circuitry itself prior to
any Patent application could have placed the entire unit in a
"public domain" category which in itself prevents any Patent
granting success.  I just don't know.  Regardless, its "still"
likely the best broadband vertical design around for its
cheapest home building approach.....which I'am sure Sean
was encouraging.

There was a number of individuals trying to duplicate the unit,
but, I've no idea of their success.  As I recall, one or two
were considering other sensor/amplifier methods outside of
the original design, but I've no idea of how that went.

http://www.eas.slu.edu/People/STMorrissey/index.html

Take care, Meredith Lamb
 

Barry wrote:

Hi All I bid a once on it but are not sure if my boat will handle the load. Period and weight wise, I am very happy with the performance the two SMT8  type verticals STM described. RegardsBarry
Subject: Re: STM 8 From: ChrisAtUpw@....... Date: Wed, 13 Nov 2002 22:45:50 EST In a message dated 13/11/02, meredithlamb@............. writes: > Sean-Thomas Morrisseys vertical seismo created a lot of interest ~ a few > years ago of course. I think it also had a lot of confusion along the line > of the exact electronics components used and its adjustments involved for > various reasons..... their was a long line of emails with corrections > thereafter that kind of left me and perhaps others in the lurch so too > Hi Meredith, The circuitry seemed to me to be 'all there', eventually, but the details were spread out over several diagrams and there were, as you say, some corrections. An important one concerned an error in the spreadsheet calculation of the feedback components. There were also developments and additional design details with the foil hinges, the spring suspension and the mass trimming. You had to know how to disassemble and reassemble the miniature transformers, without destroying them. > It was a rather involved circuitry I think. You may even have changed > components that would be of interest also. Its perhaps prudent to say that > these corrected documents (however assembled) are invaluable to those > wishing to try a duplication. I've little electronics background myself, > I think that it looked more complicated than it was. And you had to design / layout and make your own PCBs, which can be a major obstacle for many. > U.S. Patent; > but as of recent date, I've seen nothing suggesting such. Its also possible > that the STM > website display with the mechanics and circuitry itself prior to any Patent > application could have placed the entire unit in a "public domain" category > This would be in line with the regulations regarding Patents. You normally have to have made an application before any publication or public disclosure. An additional difficulty here, would be that the individual techniques were not new, it was the constructional materials, design, layout and the way that things were put together which were novel / successful. Regardless, its "still" > likely the best broadband vertical design around for its > cheapest home building approach..... As I recall, one or two people were > considering other sensor / amplifier methods outside of the original > design, but I've no idea of how that went. Agreed, but there are several sensor approaches which can be successful. To my mind, there is a distinct shortage of amateur 'off the shelf' sensor designs capable of giving near professional resolution and stability. There is only one LVDT kit sensor available with a PCB, to my knowledge, which can give about 7 nano metres resolution at 10 Hz over +/-6 mm, with a max range of +/-12 mm. Regards, Chris Chapman In a message dated 13/11/02, meredithlamb@............. writes:

Sean-Thomas Morrisseys vertical seismo created a lot of interest ~ a few years ago of course. I think it also had a lot of confusion along the line of the exact electronics components used and its adjustments involved for various reasons..... their was a long line of emails with corrections thereafter that kind of left me and perhaps others in the lurch so too speak.


Hi Meredith,

      The circuitry seemed to me to be 'all there', eventually, but the details were spread out over several diagrams and there were, as you say, some corrections. An important one concerned an error in the spreadsheet calculation of the feedback components. There were also developments and additional design details with the foil hinges, the spring suspension and the mass trimming. You had to know how to disassemble and reassemble the miniature transformers, without destroying them.  

It was a rather involved circuitry I think. You may even have changed components that would be of interest also. Its perhaps prudent to say that these corrected documents (however assembled) are invaluable to those wishing to try a duplication.  I've little electronics background myself, and I'd guess most individuals are in the same rough class.


      I think that it looked more complicated than it was. And you had to design / layout and make your own PCBs, which can be a major obstacle for many.

I think St. Louis University "was" thinking of trying to get a
U.S. Patent; but as of recent date, I've seen nothing suggesting such. Its also possible that the STM
website display with the mechanics and circuitry itself prior to any Patent application could have placed the entire unit in a "public domain" category which in itself prevents any Patent granting success.


      This would be in line with the regulations regarding Patents. You normally have to have made an application before any publication or public disclosure. An additional difficulty here, would be that the individual techniques were not new, it was the constructional materials, design, layout and the way that things were put together which were novel / successful.

Regardless, its "still"
likely the best broadband vertical design around for its
cheapest home building approach..... As I recall, one or two people were considering other sensor / amplifier methods outside of the original design, but I've no idea of how that went.


      Agreed, but there are several sensor approaches which can be successful. To my mind, there is a distinct shortage of amateur 'off the shelf' sensor designs capable of giving near professional resolution and stability. There is only one LVDT kit sensor available with a PCB, to my knowledge, which can give about 7 nano metres resolution at 10 Hz over +/-6 mm, with a max range of +/-12 mm.

      Regards,

      Chris Chapman
Subject: Re: STM 8 (previous Sprengnether subject email) From: "Barry" gbl@....... Date: Thu, 14 Nov 2002 04:49:39 -0800 Hi Meredith I have wanted to put a web site together like several of you folks = have so nicely done but I seem to have a problem with documentation. I = have made some photos but not to many yet. Written descriptions----well = not yet. I can briefly describe what I have done wrt the SMT8 style = verticals.=20 I think of the SMT8 in four parts. 1. the mechanical - boom, leaf spring, hinges. On my first sensor I tried as closely as possible to duplicate the the = SMT8 geometry. The only change I made was to remove part of the leaf = spring support where it attaches to the end pins so I could slightly = squeeze the ends of the bent leaf spring together and quickly remove it = from the assembly w/o tools. On the second SMT8 I reproduced the first = sensor but made the boom about 10 " long to try to make it more portable = (for possible field use in an ammo box). 2. the displacement sensor In the first sensor, I installed a homemade LVDT with phase shift = oscillator and the demodulator that Karl Cunningham has described. In = the second sensor I installed the VRDT hardware as STM described but = with phase shift oscillator, instrumentation amp to sum and Karl's = demodulator. Both work well and are quite linear. Side note: I calibrate = the displacement sensors with a "diving board" type device that I = calibrated with precision weights. I found it was easier to apply a = precise weight than a small deflection directly. All the circuitry for = either can be crammed on a 2X6.5 size breadboard. Not too complicated of = circuitry, mostly just dual opamps. =20 3. the feedback circuitry = =20 I used the Mathcad equations STM suggested.=20 4. mechanical adjustment control. There are some adjustments I found necessary as STM had described in = depth. The vertical is not as sensitive to tilting but is sensitive to = temperature and the initial relaxation of the leaf spring. For = temperature correction I installed a bimetal thermometer coil near the = boom. With some trial and error positioning and thermal insulation I was = able to remove a substantial amount of this temperature variation. For = zero adjustment I used the Edmond Scientific low rpm motor and threaded = rod and sliding weight. Works well. = = = =20 I made most of the mechanical parts with small handtools. I have a small = drill press, files, tap set, vise, 1" micromometer and access to a = surplus store with aluminum. For the electronics I do have a DVM, = soldering iron and an inexpensive oscilloscope which I found valuable = for several things. I have wanted to use pc boards that I etch but = haven't found the time yet to learn and perfect. I initially use 2' X = 6.5" solderless breadboards. to position and check the circuitry. When I = am happy I move them to the pre-etched boards that RS sells that are = the same size and layout. =20 Though I'm still trying to improve things (as we all are) if I can help = any further let me know. Regards Barry =20 ----- Original Message -----=20 From: meredithlamb=20 To: psn-l@................. Sent: Wednesday, November 13, 2002 12:28 PM Subject: Re: STM 8 (previous Sprengnether subject email) Hi Barry and all,=20 Glad your STM 8 is still working. Sean-Thomas=20 Morrisseys vertical seismo created alot of interest ~ afew=20 years ago of course. I think it also had alot of confusion=20 along the line of the exact electronics components used and=20 its adjustments involved for various reasons.....their was a=20 long line of emails with corrections thereafter that kind of=20 left me and perhaps others in the lurch so too speak. It just=20 might be that you are the only "knowledgeable person " left=20 that perhaps has some more exact circuitry/operation/setup=20 info than anyone else. It was a rather involved circuitry I=20 think. You may even have changed components that would=20 be of interest also. Its perhaps prudent to say that these=20 corrected documents (however assembled) are invaluable to=20 those wishing to try a duplication. I've little electronics=20 background myself, and I'd guess most individuals are in the=20 same rough class.=20 I think St. Louis University "was" thinking of trying to get a=20 U.S. Patent; but as of recent date, I've seen nothing suggesting=20 such (it could be in the "pipeline", so too speak of course). On=20 the other hand, it may have been set aside for other financial=20 reasons; or even abandoned. Its also possible that the STM=20 website display with the mechanics and circuitry itself prior to=20 any Patent application could have placed the entire unit in a=20 "public domain" category which in itself prevents any Patent=20 granting success. I just don't know. Regardless, its "still"=20 likely the best broadband vertical design around for its=20 cheapest home building approach.....which I'am sure Sean=20 was encouraging.=20 There was a number of individuals trying to duplicate the unit,=20 but, I've no idea of their success. As I recall, one or two=20 were considering other sensor/amplifier methods outside of=20 the original design, but I've no idea of how that went.=20 http://www.eas.slu.edu/People/STMorrissey/index.html=20 Take care, Meredith Lamb=20 =20
Hi Meredith
     I have = wanted to put=20 a web site together like several of you folks have so nicely done but I = seem to=20 have a problem with documentation.  I have made some photos but not = to many=20 yet. Written descriptions----well  not yet. I can briefly describe = what I=20 have done wrt the SMT8 style verticals.
     I think of=20 the SMT8  in four parts.
           &nbs= p; =20 1. the mechanical - boom, leaf spring, hinges.
On my first sensor I tried as closely = as possible=20 to duplicate the the SMT8 geometry. The only change I made was to remove = part of=20 the leaf spring support where it=20 attaches to the end pins so I could slightly squeeze = the=20 ends of the bent leaf spring together and quickly remove it from = the=20 assembly w/o tools.  On the second SMT8 I reproduced the first = sensor but=20 made the boom about 10 " long to try to make it more portable (for = possible=20 field use in an ammo box).
          &nbs= p; =20  2. the displacement sensor
In the first sensor,  I = installed a=20 homemade LVDT with phase shift oscillator and the demodulator that Karl=20 Cunningham has described.  In the second sensor I installed = the VRDT=20 hardware as STM described but with phase shift oscillator, = instrumentation=20 amp to sum and Karl's demodulator. Both work well and are quite linear. = Side=20 note: I calibrate the displacement sensors with a "diving board" type = device=20 that I calibrated with precision weights. I found it = was easier=20 to apply a precise weight than a small deflection directly. All the = circuitry for either can be crammed on a 2X6.5 size breadboard. Not too=20 complicated of circuitry, mostly just dual opamps.    =20
      =20        3. the  feedback=20 circuitry          &nbs= p;            = ;            =             &= nbsp;           &n= bsp;           &nb= sp;           &nbs= p; =20
I used the Mathcad equations STM = suggested.=20
          &nbs= p;  =20 4. mechanical adjustment control.
There are some adjustments I found = necessary as STM=20 had described in depth.  The vertical is not as sensitive to = tilting=20 but is sensitive to temperature and the initial relaxation of the leaf = spring.=20 For temperature correction I installed a bimetal thermometer coil near = the boom.=20 With some trial and error positioning and thermal insulation I was = able to=20 remove a substantial amount of this temperature = variation. For zero=20 adjustment I used the Edmond Scientific low rpm motor and threaded = rod and=20 sliding  weight.=20 Works  well.        &nb= sp;           &nbs= p;            = ;            =             &= nbsp;           &n= bsp;           &nb= sp;           &nbs= p;            = ;            =             &= nbsp;           &n= bsp;           &nb= sp;           &nbs= p;            = ;            =             &= nbsp;           &n= bsp;        =20
 
I made most of the mechanical parts = with small=20 handtools. I have a small drill press, files, tap set, vise, 1"=20 micromometer and access to a surplus store  with=20 aluminum. For the electronics I do have a DVM, soldering = iron and an=20 inexpensive oscilloscope  which I found valuable for several=20 things. I have wanted to use pc boards that  I etch but = haven't=20 found the time yet to learn and perfect. I initially use 2' X 6.5" = solderless=20 breadboards. to position and check the circuitry. When I am happy I move = them to=20 the pre-etched  boards that RS sells that are the same size and=20 layout.   
 
Though I'm still trying to improve = things (as we=20 all are) if I can help any further let me know.
Regards
Barry
 
----- Original Message -----
From:=20 meredithlamb
Sent: Wednesday, November 13, = 2002 12:28=20 PM
Subject: Re: STM 8 (previous = Sprengnether=20 subject email)

Hi Barry and all,=20

Glad your STM 8 is still working.  Sean-Thomas
Morrisseys = vertical=20 seismo created alot of interest ~ afew
years ago of course.  = I think=20 it also had alot of confusion
along the line of the exact = electronics=20 components used and
its adjustments involved for various = reasons.....their=20 was a
long line of emails with corrections thereafter that kind of =
left me and perhaps others in the lurch so too speak.  It = just=20
might be that you are the only "knowledgeable person " left =
that=20 perhaps has some more exact circuitry/operation/setup
info than = anyone=20 else.  It was a rather involved circuitry I
think.  You = may even=20 have changed components that would
be of interest also.  Its = perhaps=20 prudent to say that these
corrected documents (however assembled) = are=20 invaluable to
those wishing to try a duplication.  I've = little=20 electronics
background myself, and I'd guess most individuals are = in the=20
same rough class.=20

I think St. Louis University "was" thinking of trying to get a =
U.S.=20 Patent; but as of recent date, I've seen nothing suggesting
such = (it could=20 be in the "pipeline", so too speak of course).  On
the other = hand, it=20 may have been set aside for other financial
reasons; or even=20 abandoned.  Its also possible that the STM
website display = with the=20 mechanics and circuitry itself prior to
any Patent application = could have=20 placed the entire unit in a
"public domain" category which in = itself=20 prevents any Patent
granting success.  I just don't = know. =20 Regardless, its "still"
likely the best broadband vertical design = around=20 for its
cheapest home building approach.....which I'am sure Sean =
was=20 encouraging.=20

There was a number of individuals trying to duplicate the unit, =
but,=20 I've no idea of their success.  As I recall, one or two
were=20 considering other sensor/amplifier methods outside of
the original = design,=20 but I've no idea of how that went.=20

http:= //www.eas.slu.edu/People/STMorrissey/index.html=20

Take care, Meredith Lamb
 

Subject: Re: Sprengnether Vertical Seismo From: RADIOTEL@....... Date: Fri, 15 Nov 2002 00:21:53 EST I have a vertical sensor like yours and the one that was recently on Ebay. However, no matter how I try I can not balance it so the pointer stays in the center of the indicator on the front of the unit. The best I have been able to manage is with the pointer near the top of the dial, but it does work there. Any ideas or suggestions would be appreciated. Thanks Jim Allen I have a vertical sensor like yours and the one that was recently on Ebay.  However, no matter how I try I can not balance it so the pointer stays in the center of the indicator on the front of the unit.  The best I have been able to manage is with the pointer near the top of the dial, but it does work there.  Any ideas or suggestions would be appreciated.
Thanks
Jim Allen
Subject: Re: Sprengnether Vertical Seismo From: meredithlamb meredithlamb@............. Date: Fri, 15 Nov 2002 10:42:09 -0700 Hi Jim, I had the same problem ~10 years ago with mine on ititial setup. The most immediate problem with a "good" answer is my shrinking memory cells (ha). I think (without delving into the parts manuel at this time), (us guys don't read the manuel first....ha.) is that towards the top rear is where there is a knurled round nut that is also a wire locking compression (screwing) clamp (I think with a setscrew underneath); that actually connects to the zero length spring. There was also another compression nut further down from the top nut that needs to be loosened. You would "overall" need to lower the wire somewhat to find a area of the wire to clamp down on....to where.....the mass oscillates, and can be "zeroed" the best, per the pointer from the boom that goes over the scale on the upright aluminum post with the boom clamp hole. The total wire movement "might" only be ~ 1/2", but perhaps up to 1" or more (?). I'd level the base with the setscrews and a bubble level in both directions first. Check and see if that does the trick with the boom unlocked. If no success, you need to clamp the boom in place with the locking pin in the holes provided for the front and rear areas, so it doesn't move. The locked boom protects about everything from damage if the spring gets loose on one end, which it probably can/will happen potentially. I literally marked this upper wire near a seismo part with a felt tip pen to show where it is at the present....you know it would need to be alittle further down than it was, once you unclamp the wire on the top. Of course once you unclamp, the spring contraction force will jerk it down very fast....you need to limit this amount of movement with other outside wire holding clamps locking vise wrench grips etc., means. Keep up marking the wire for a past position reference. I sanded the wire to get a clean shiny surface, to see the black marker ink. Relock the wire, unclamp you tool clamps, unlock the boom, and test. You may have to do this quite a number of times, to find a nice zeroing pointer/marker place. Of course you need to keep in mind that the setscrews and the seismo base also play a part in this balance/zero.....and also the seismo period length one sees, or wishes to have. If....you go down too far then it becomes a physical effort to pull on the upper wire (many pounds of exertion), and at the same time eyeball for the wire mark and also be ready to use the setscrew to clamp down on the wire. You may need a strong friend to help pull/stabilize the wire. It can be a pain in the maximus glutomus to do this stuff, but it did work out in the end for me. If the wire breaks, no big deal; its common music wire. Keep your fingers away from the spring during all of this, if it gets loose, it could break/smash fingers that are in the way. Whenever you move the unit, you might expect to have to do it again. Once its adjusted, their might be a month or two of "settling in" waiting time, but thereafter, it usually is very stabile... moreso than any horizontal...but make sure it has a good temperature stable environment if possible. If the drift is high after acouple months; its a strong clue/suggestion that it needs more insulation from temperature extremes. Its a very good machine I think overall, and it offers a variety of potentials for add-ons sensors actually.....if one is so inclined to try. Its worth the time/effort....verticals are always the most useful, scarce (and often difficult adjustment) machines. If I remember correctly....the manuel doesn't cover the topic, for the time (50+ years ago), they wanted to send out company techs to do the setup stuff for the original buyer. All this effort will acquaint you well with the machine. I think it took me several (grumbling, fumbling, learning) days to get it adjusted....ha. Take care, Meredith Lamb RADIOTEL@....... wrote: > I have a vertical sensor like yours and the one that was recently on > Ebay. However, no matter how I try I can not balance it so the > pointer stays in the center of the indicator on the front of the > unit. The best I have been able to manage is with the pointer near > the top of the dial, but it does work there. Any ideas or suggestions > would be appreciated. > Thanks > Jim Allen Hi Jim,

I had the same problem ~10 years ago with mine on ititial setup.
The most immediate problem with a "good" answer is my
shrinking memory cells (ha).

I think (without delving into the parts manuel at
this time), (us guys don't read the manuel first....ha.) is that
towards the top rear is where there is a knurled round nut that
is also a wire locking compression (screwing) clamp (I think
with a setscrew underneath); that actually connects to the
zero length spring.  There was also another compression
nut further down from the top nut that needs to be loosened.
You would "overall" need to lower the wire somewhat to find
a area of the wire to clamp down on....to where.....the mass
oscillates,  and can be "zeroed" the best, per the pointer from
the boom that goes over the scale on the upright
aluminum post with the boom clamp hole.  The total wire
movement "might" only be ~ 1/2", but perhaps up to 1" or
more (?).

I'd level the base with the setscrews and a bubble level in both
directions first.  Check and see if that does the trick with the boom
unlocked.  If no success, you need to clamp the boom in place
with the locking pin in the holes provided for the front and rear
areas, so it doesn't move.  The locked boom protects about
everything from damage if the spring gets loose on one end,
which it probably can/will happen potentially.

I literally marked this upper wire near a seismo part with a felt
tip pen to show where it is at the present....you know it would
need to be alittle further down than it was, once you unclamp
the wire on the top.  Of course once you unclamp, the spring
contraction force will jerk it down very fast....you need to limit
this amount of movement with other outside wire holding clamps
locking vise wrench grips etc., means.  Keep up marking the
wire for a past position reference.  I sanded the wire to get a
clean shiny surface, to see the black marker ink.

Relock the wire, unclamp you tool clamps, unlock the boom,
and test.  You may have to do this quite a number of times, to
find a nice zeroing pointer/marker place.  Of course you need
to keep in mind that the setscrews and the seismo base also
play a part in this balance/zero.....and also the seismo period
length one sees, or wishes to have.  If....you go down too far
then it becomes a physical effort to pull on the upper wire
(many pounds of exertion), and at the same time eyeball for the
wire mark and also be ready to use the setscrew to clamp down
on the wire.  You may need a strong friend to help pull/stabilize
the wire.  It can be a pain in the maximus glutomus to do this stuff,
but it did work out in the end for me.  If the wire breaks, no big
deal; its common music wire.  Keep your fingers away from the
spring during all of this, if it gets loose, it could break/smash fingers
that are in the way.

Whenever you move the unit, you might expect to have to do it
again.  Once its adjusted, their might be a month or two of
"settling in" waiting time, but thereafter, it usually is very stabile...
moreso than any horizontal...but make sure it has a good
temperature stable environment if possible.  If the drift is high
after acouple months; its a strong clue/suggestion that it needs
more insulation from temperature extremes.  Its a very good
machine I think overall, and it offers a variety of potentials for
add-ons sensors actually.....if one is so inclined to try.  Its
worth the time/effort....verticals are always the most useful,
scarce (and often difficult adjustment) machines.

If I remember correctly....the manuel doesn't cover the topic,
for the time (50+ years ago), they wanted to send out company
techs to do the setup stuff for the original buyer.  All this effort
will acquaint you well with the machine.  I think it took me
several (grumbling, fumbling, learning) days to get it adjusted....ha.

Take care, Meredith Lamb

RADIOTEL@....... wrote:

I have a vertical sensor like yours and the one that was recently on Ebay.  However, no matter how I try I can not balance it so the pointer stays in the center of the indicator on the front of the unit.  The best I have been able to manage is with the pointer near the top of the dial, but it does work there.  Any ideas or suggestions would be appreciated.
Thanks
Jim Allen
Subject: Re: STM 8 (previous Sprengnether subject email) From: meredithlamb meredithlamb@............. Date: Fri, 15 Nov 2002 11:56:54 -0700 Hi Karl and all, Barry wrote: > Hi Meredith I have wanted to put a web site together like several > of you folks have so nicely done but I seem to have a problem with > documentation. I have made some photos but not to many yet. Written > descriptions----well not yet. I can briefly describe what I have done > wrt the SMT8 style verticals. I think of the SMT8 in four > parts. 1. the mechanical - boom, leaf spring, hinges.On > my first sensor I tried as closely as possible to duplicate the the > SMT8 geometry. The only change I made was to remove part of the leaf > spring support where it attaches to the end pins so I could slightly > squeeze the ends of the bent leaf spring together and quickly remove > it from the assembly w/o tools. > > Sounds interesting on the mechanical change, although I don't > totally understand it. > > > On the second SMT8 I reproduced the first sensor but made the boom > about 10 " long to try to make it more portable (for possible field > use in an ammo box). 2. the displacement sensorIn the > first sensor, I installed a homemade LVDT with phase shift oscillator > and the demodulator that Karl Cunningham has described. In the second > sensor I installed the VRDT hardware as STM described but with phase > shift oscillator, instrumentation amp to sum and Karl's demodulator. > Both work well and are quite linear. Side note: I calibrate the > displacement sensors with a "diving board" type device that I > calibrated with precision weights. I found it was easier to apply a > precise weight than a small deflection directly. All the circuitry for > either can be crammed on a 2X6.5 size breadboard. Not too complicated > of circuitry, mostly just dual opamps. > > Most interesting on the LVDT switch from the LRDT original design > on one of your instruments! Am not really "up" to either; but its > interesting on the switching sensor capability you've already done > and the success. > > Perhaps the biggest thing I "seem" to see, is that Seans > original LRDT transformers are in likelyhood kind of a crude > nonlinear wire wrapping; whereas, your LVDT, is a painstaking > relatively > precision wire layed device. Yet.....according to Seans website, his > LRDT is sensitive to a incredible .1nm. I've zero experience > but it makes me wonder further about coils themselves between > the two. It would seem the LRDT is much simpler to make and > more sensitive overall. Interesting. > > 3. the feedback circuitryI used the Mathcad equations > STM suggested. 4. mechanical adjustment control.There are > some adjustments I found necessary as STM had described in depth. The > vertical is not as sensitive to tilting but is sensitive to > temperature and the initial relaxation of the leaf spring. For > temperature correction I installed a bimetal thermometer coil near the > boom. With some trial and error positioning and thermal insulation I > was able to remove a substantial amount of this temperature variation. > For zero adjustment I used the Edmond Scientific low rpm motor and > threaded rod and sliding weight. Works well. > > Quite a nice additon on the bi-metal thermometer coil! > > Take care, Meredith Lamb Hi Karl and all,

Barry wrote:

Hi Meredith     I have wanted to put a web site together like several of you folks have so nicely done but I seem to have a problem with documentation.  I have made some photos but not to many yet. Written descriptions----well  not yet. I can briefly describe what I have done wrt the SMT8 style verticals.     I think of the SMT8  in four parts.              1. the mechanical - boom, leaf spring, hinges.On my first sensor I tried as closely as possible to duplicate the the SMT8 geometry. The only change I made was to remove part of the leaf spring support where it attaches to the end pins so I could slightly squeeze the ends of the bent leaf spring together and quickly remove it from the assembly w/o tools.

Sounds interesting on the mechanical change, although I don't
totally understand it.
 

On the second SMT8 I reproduced the first sensor but made the boom about 10 " long to try to make it more portable (for possible field use in an ammo box).              2. the displacement sensorIn the first sensor,  I installed a homemade LVDT with phase shift oscillator and the demodulator that Karl Cunningham has described.  In the second sensor I installed the VRDT hardware as STM described but with phase shift oscillator, instrumentation amp to sum and Karl's demodulator. Both work well and are quite linear. Side note: I calibrate the displacement sensors with a "diving board" type device that I calibrated with precision weights. I found it was easier to apply a precise weight than a small deflection directly. All the circuitry for either can be crammed on a 2X6.5 size breadboard. Not too complicated of circuitry, mostly just dual opamps.

Most interesting on the LVDT switch from the LRDT original design
on one of your instruments!  Am not really "up" to either; but its
interesting on the switching sensor capability you've already done
and the success.

Perhaps the biggest thing I "seem" to see, is that Seans
original LRDT transformers are in likelyhood kind of a crude
nonlinear wire wrapping; whereas, your LVDT, is a painstaking relatively
precision wire layed device.  Yet.....according to Seans website, his
LRDT is sensitive to a incredible ..1nm.  I've zero experience
but it makes me wonder further about coils themselves between
the two.  It would seem the LRDT is much simpler to make and
more sensitive overall.  Interesting.

 
               3. the  feedback circuitryI used the Mathcad equations STM suggested.              4. mechanical adjustment control.There are some adjustments I found necessary as STM had described in depth.  The vertical is not as sensitive to tilting but is sensitive to temperature and the initial relaxation of the leaf spring. For temperature correction I installed a bimetal thermometer coil near the boom. With some trial and error positioning and thermal insulation I was able to remove a substantial amount of this temperature variation. For zero adjustment I used the Edmond Scientific low rpm motor and threaded rod and sliding  weight. Works  well.

Quite a nice additon on the bi-metal thermometer coil!

Take care, Meredith Lamb

Subject: Re: STM 8 (LVDT subject) From: meredithlamb meredithlamb@............. Date: Fri, 15 Nov 2002 13:08:27 -0700 Hi Chris and all, This message is more with the LVDT aspect than with the original LRDT sensor with Sean Morrisseys STM-8 design. ChrisAtUpw@....... wrote: > In a message dated 13/11/02, meredithlamb@............. writes: > > Regardless, its "still" > >> likely the best broadband vertical design around for its >> cheapest home building approach..... As I recall, one or two people >> were considering other sensor / amplifier methods outside of the >> original design, but I've no idea of how that went. > > Agreed, but there are several sensor approaches which can be > successful. To my mind, there is a distinct shortage of amateur 'off > the shelf' sensor designs capable of giving near professional > resolution and stability. There is only one LVDT kit sensor available > with a PCB, to my knowledge, which can give about 7 nano metres > resolution at 10 Hz over +/-6 mm, with a max range of +/-12 mm. Presume its the Italian, Nuova Electronica unit (?), you've been working with/on over time? Perhaps the greatest curiosity item I wonder about their transformer part, is whether its really a precision wound unit like mentioned as a (professional) necessity as on other web sites? It appears to be much like other general looking transformer/s. Without any access I'd guess its somewhat linearly wound but no where near precision. All this is leading up to the question of whether a fairly linear wound (but not exactly precisely layered) coil "could" somewhat work simarily (with less sensitivity) with the same general ferrite core type setup. Such coils are rather scarce I'am sure. It would probably leave out any and all relay coils on the general "market". It "might" be more prevalent to some salvagable coil transformers though. Just some (unexperienced) thoughts. I think the Nuova item costs around $103 US dollars (PCB and LVDT) plus whatever shipping/handling. Sometimes I think that a homebrew LVDT with perhaps a Phillips or Analog IC (and other parts) might be a cheaper alternative......but probably more costly for any R&D overall. Take care, Meredith Lamb Hi Chris and all,

This message is more with the LVDT aspect than with the
original LRDT sensor with Sean Morrisseys STM-8 design.

ChrisAtUpw@....... wrote:

In a message dated 13/11/02, meredithlamb@............. writes:

Regardless, its "still"

likely the best broadband vertical design around for its
cheapest home building approach..... As I recall, one or two people were considering other sensor / amplifier methods outside of the original design, but I've no idea of how that went.
      Agreed, but there are several sensor approaches which can be successful. To my mind, there is a distinct shortage of amateur 'off the shelf' sensor designs capable of giving near professional resolution and stability. There is only one LVDT kit sensor available with a PCB, to my knowledge, which can give about 7 nano metres resolution at 10 Hz over +/-6 mm, with a max range of +/-12 mm.
Presume its the Italian, Nuova Electronica unit (?), you've been
working with/on over time?

Perhaps the greatest curiosity item I wonder about their
transformer part, is whether its really a precision wound
unit like mentioned as a (professional) necessity as on other web
sites?  It appears to be much like other general looking transformer/s.
Without any access I'd guess its somewhat linearly wound
but no where near precision.

All this is leading up to the question of whether a fairly
linear wound (but not exactly precisely layered) coil "could"
somewhat work simarily (with less sensitivity) with the same
general ferrite core type setup.  Such coils are rather scarce
I'am sure.  It would probably leave out any and all relay coils
on the general "market".  It "might" be more prevalent to
some salvagable coil transformers though.

Just some (unexperienced) thoughts.  I think the Nuova item
costs around $103 US dollars (PCB and LVDT) plus
whatever shipping/handling.  Sometimes I think that a
homebrew LVDT with perhaps a Phillips or Analog IC
(and other parts) might be a cheaper alternative......but
probably more costly for any R&D overall.

Take care, Meredith Lamb

  Subject: Re: STM 8 (LVDT subject) From: "Mauro Mariotti" mariotti@......... Date: Fri, 15 Nov 2002 22:59:20 +0100 Hi All, I worked very much with this LVDT. It is based on the Phllips NE5521N phase comparator. I can supply you the schematic if needed. The cost of the unit is 50$ for the circuit and 50$ for the mechanic to=20 build up a complete horizontal sensor like to S-G type. I never disassembled the LVDT coils to but I can do it I have some spare part in my lab. The LX922 kit is no longer producted, only some spare parts are = available. The actual Nuova Elettronica production is on LX1358. All the system was conceived to use a high-speed thermal printer for producing seismograms. Actually N.E. producing a A/D interface the LX1500 that is a single channel fixed 50 SPS at 16 bit with the AD7715 converter. It have no syncronization clock. It can be used also with SEISMOWIN. Anwyay that LVDT can be used with any kind of a/d if the DC component is removed (the output is 0-12V at 6V zero offset). If needed I can provide more info about. The results of that LVDT are very good but accurate shielding of the coils and the circuit is needed to avoid interference and keep low the noise. Regards Mauro Just some (unexperienced) thoughts. I think the Nuova item=20 costs around $103 US dollars (PCB and LVDT) plus=20 whatever shipping/handling. Sometimes I think that a=20 homebrew LVDT with perhaps a Phillips or Analog IC=20 (and other parts) might be a cheaper alternative......but=20 probably more costly for any R&D overall.=20

Hi All,
 
I worked very much with this = LVDT.
It is based on the Phllips NE5521N = phase=20 comparator.
I can supply you the schematic if=20 needed.
The cost of the unit is 50$ for the = circuit and 50$=20 for the mechanic to
build up a complete horizontal sensor = like to S-G=20 type.
I never disassembled the LVDT coils to = but I can do=20 it I have some spare
part in my lab.
 
The LX922 kit is no longer producted, = only some=20 spare parts are available.
The actual Nuova Elettronica production = is on=20 LX1358.
All the system was conceived to use a = high-speed=20 thermal printer
for producing seismograms.
 
Actually N.E. producing a A/D interface = the LX1500=20 that is a single
channel fixed 50 SPS at 16 bit with the = AD7715=20 converter.
It have no syncronization = clock.
It can be used also with = SEISMOWIN.
Anwyay that LVDT can be used with any = kind of a/d=20 if the DC
component is removed (the output is = 0-12V at 6V=20 zero offset).
 
If needed I can provide more info=20 about.
The results of that LVDT are very good = but accurate=20 shielding of
the coils and the circuit is needed to = avoid=20 interference and keep
low the noise.
 
Regards
Mauro
 

Just some (unexperienced) thoughts.  I think the Nuova item =
costs=20 around $103 US dollars (PCB and LVDT) plus
whatever=20 shipping/handling.  Sometimes I think that a
homebrew LVDT = with=20 perhaps a Phillips or Analog IC
(and other parts) might be a = cheaper=20 alternative......but
probably more costly for any R&D overall. =

Subject: Re: STM 8 (LVDT subject) From: ChrisAtUpw@....... Date: Sat, 16 Nov 2002 14:29:47 EST In a message dated 15/11/02, meredithlamb@............. writes: > >> Agreed, but there are several distance transducer approaches whic= h=20 >> can be successful. To my mind, there is a distinct shortage of amateur=20 >> 'off the shelf' sensor designs capable of giving near professional=20 >> resolution and stability. There is only one LVDT Kit sensor available wit= h=20 >> a PCB, to my knowledge, which can give about 7 nano metres resolution at=20 >>=20 > Presume its the Italian, Nuova Elettronica unit (?), you've been working=20 >=20 Hi Meredith, I have done some experiments modifying / improving my Nuova=20 Elettronica LVDT board, reducing the two pole detector filter to 10 Hz, whic= h=20 is more suitable for seismic use, changing the output opamp to a low noise=20 type and increasing the time constant of the high pass filter, along with=20 several other small changes. NE seemed to have used a circuit designed by=20 Philips for wider bandwidth commercial LVDT applications. I have also been=20 working on other magnetic sensor systems using the Philips NE5521 LVDT chip,= =20 including modified transformers, somewhat like Sean's, some using ferrite=20 components and lately, a capacitative system. I have a full write up nearly=20 finished.=20 > Perhaps the greatest curiosity item I wonder about their transformer part,= =20 > is whether its really a precision wound unit like mentioned as a=20 > (professional) necessity as on other web sites? It appears to be much lik= e=20 > other general looking transformers. Without any access I'd guess its=20 >=20 If you want to measure several inches of movement and require a linea= r=20 response, you may need a precision linear winding. If you only want a few mm= =20 and the field of the sensor rod can be sensed over a physically much larger=20 sensor winding, you just need the windings to stay in a fixed position. Ther= e=20 will of course be thermal expansion and changes of resistance with=20 temperature, but these effects are very small over the 10 Hz bandwidth and=20 the 5 to 30 sec of the high pass filter time constant. =20 > Perhaps the biggest thing I "seem" to see, is that Seans original LRDT=20 > transformers are in likelyhood kind of a crude nonlinear wire wrapping;=20 > whereas, your LVDT, is a painstaking relatively precision wire layered=20 >=20 With Sean's variable reluctance transformer sensor, the magnetic=20 circuit is defined by the position of the flat iron armature plate and the=20 iron polepieces. In a LVDT, the interaction is between the position of a=20 magnetised armature and the varying distance it moves inside the sensor coil= ,=20 so the coil needs to be quite uniformly wound. For a description of an LVDT,= =20 see http= ://www.msiusa.com/schaevitz/pdf/lvdt/LVDT_Intro.pdf It is not too=20 difficult to make even windings, so long as you do not use extremely fine=20 wire, do not try to wind too fast, slow up right at the end of each layer=20 and, most importantly, use very thin paper, like cigarette or tissue paper,=20 for interleaving each layer. This makes it easy to spot and correct any=20 overwinding or incorrectly spaced turns. It also makes winding easier and=20 helps to prevent shorted turns in between layers. I made two matched 40,000=20 turn precision differential transformer coils this way, for measuring=20 paramagnetic susceptibility. A very small plastic tube makes a good wire=20 guide. It is also possible to just layer wind two LVDT secondaries end to en= d=20 on a sensor tube and use a ferrite or powder iron cored choke to provide the= =20 magnetic excitation. This avoids having to wind a central primary magnetisin= g=20 section in between, or over the top of the secondaries. =20 Yet.....according to Seans website, his LRDT is sensitive to a incredible=20 0.1nm. I've=20 > zero experience but it makes me wonder further about coils themselves=20 > between=20 > the two. It would seem the LRDT is much simpler to make and more sensitiv= e=20 >=20 Coupled with the very high sensitivity of Sean's transducer, the=20 movement range is small, perhaps +/-0.5 mm in a 2 mm total gap, and the=20 output is only linear for a limited range around the zero position. This is=20 just fine for a feedback seismometer, where you try to hold the armature=20 position constant. The out of range signal increases dramatically before=20 saturating, which can be bad news if the seismometer feedback system gets ou= t=20 of lock.=20 > All this is leading up to the question of whether a fairly linear wound (b= ut=20 > not exactly precisely layered) coil "could" somewhat work simarily (with=20 > less sensitivity) with the same general ferrite core type setup. Such=20 >=20 If you have an E core transformer type winding, the magnetic flux is=20 linked strongly to the winding, so great winding precision is not required,=20 only a good physical stability. The magnetic field interactions are=20 controlled by the positions and separations of the iron laminations, so thes= e=20 need to be firmly fixed. These E core types can be either modified audio=20 transformers similar to Sean's, ferrite cup transformers with DIY windings,=20= a=20 linear differential reluctance system of the magslip type, or two physically= =20 large coils pairs bridged by a ferrite rod, like the NE type. J > ust some (unexperienced) thoughts. I think the Nuova item costs around $1= 03=20 > US dollars (PCB and LVDT) plus whatever shipping/handling. Sometimes I=20 > think that a homebrew LVDT with perhaps a Phillips or Analog IC (and other= =20 > parts) might be a cheaper alternative......but probably more costly for an= y=20 > R& The two Analogue Devices LVDT chips have a relatively high noise floo= r=20 and are not suitable for our use. The Philips NE5521 device is about 1/3 the= =20 price and you can get right down to the intrinsic opamp noise level. =20 The LX1358 Kit price is =E2=82=AC 51.65 + Carriage. Looking up today'= s=20 exchange rate, this is just US $51.23 !! There will be a charge on your=20 Credit Card for the currency conversion and the exchange rate will be lower=20 than the International Banking Rate quoted. Air Mail packets are reasonably=20 priced and may take 10 days to arrive. Be warned that International Carriers= =20 may have a minimum charge of near $50 for any packet! They seem to be only=20 relatively reasonably priced within the USA.=20 =20 With a LX1358, I get ~7 nano metre resolution over a +/-6 mm=20 accurately linear range, with 65 mV / micron output. The output is 10% down=20 at +/-12 mm and 20% down at +/-15 mm, since the ''out of range'' response is= =20 of the usual S shape. This wide range was designed for Lehman type systems,=20 but the sensor will work equally well on simple pendulums. Regards, Chris Chapman In a message dated 15/11/= 02, meredithlamb@............. writes:

     Agreed, but there are sever= al distance transducer approaches which can be successful. To my mind, there= is a distinct shortage of amateur 'off the shelf' sensor designs capable of= giving near professional resolution and stability. There is only one LVDT K= it sensor available with a PCB, to my knowledge, which can give about 7 nano= metres resolution at 10 Hz over +/-6 mm, with a max range of +/-12 mm.
Presume its the Italian, Nuova Elettronica unit (?), you've been working= with / on over time?


Hi Meredith,

      I have done some experiments modify= ing / improving my Nuova Elettronica LVDT board, reducing the two pole detec= tor filter to 10 Hz, which is more suitable for seismic use,  changing=20= the output opamp to a low noise type and increasing the time constant of the= high pass filter, along with several other small changes. NE seemed to have= used a circuit designed by Philips for wider bandwidth commercial LVDT appl= ications. I have also been working on other magnetic sensor systems using th= e Philips NE5521 LVDT chip, including modified transformers, somewhat like S= ean's, some using ferrite components and lately, a capacitative system. I ha= ve a full write up nearly finished.=20

Perhaps the greatest curios= ity item I wonder about their transformer part, is whether its really a prec= ision wound unit like mentioned as a (professional) necessity as on other we= b sites?  It appears to be much like other general looking transformers= .. Without any access I'd guess its somewhat linearly wound but no where near= precision.


      If you want to measure several inch= es of movement and require a linear response, you may need a precision linea= r winding. If you only want a few mm and the field of the sensor rod can be=20= sensed over a physically much larger sensor winding, you just need the windi= ngs to stay in a fixed position. There will of course be thermal expansion a= nd changes of resistance with temperature, but these effects are very small=20= over the 10 Hz bandwidth and the 5 to 30 sec of the high pass filter time co= nstant.  

Perhaps the biggest thing I= "seem" to see, is that Seans original LRDT transformers are in likelyhood k= ind of a crude nonlinear wire wrapping; whereas, your LVDT, is a painstaking= relatively precision wire layered device.


      With Sean's variable reluctance tra= nsformer sensor, the magnetic circuit is defined by the position of the flat= iron armature plate and the iron polepieces. In a LVDT, the interaction is=20= between the position of a magnetised armature and the varying distance it mo= ves inside the sensor coil, so the coil needs to be quite uniformly wound. F= or a description of an LVDT, see http://www.msiusa.com/schaevitz/pdf/lvdt/LVDT_Intro= ..pdf  It is not too difficult to make even windings, so long as you= do not use extremely fine wire, do not try to wind too fast, slow up right=20= at the end of each layer and, most importantly, use very thin paper, like ci= garette or tissue paper, for interleaving each layer. This makes it easy to=20= spot and correct any overwinding or incorrectly spaced turns. It also makes=20= winding easier and helps to prevent shorted turns in between layers. I made=20= two matched 40,000 turn precision differential transformer coils this way, f= or measuring paramagnetic susceptibility. A very small plastic tube makes a=20= good wire guide. It is also possible to just layer wind two LVDT secondaries= end to end on a sensor tube and use a ferrite or powder iron cored choke to= provide the magnetic excitation. This avoids having to wind a central prima= ry magnetising section in between, or over the top of the secondaries.
=20
Yet.....according to Seans website, his LRDT is sensitive to a incredib= le 0.1nm.  I've=20
zero experience but it make= s me wonder further about coils themselves between=20
the two.  It would seem the LRDT is much simpler to make and more s= ensitive overall.


      Coupled with the very high sensitiv= ity of Sean's transducer, the movement range is small, perhaps +/-0.5 mm in=20= a 2 mm total gap, and the output is only linear for a limited range around t= he zero position. This is just fine for a feedback seismometer, where you tr= y to hold the armature position constant. The out of range signal increases=20= dramatically before saturating, which can be bad news if the seismometer fee= dback system gets out of lock.=20

All this is leading up to t= he question of whether a fairly linear wound (but not exactly precisely laye= red) coil "could" somewhat work simarily (with less sensitivity) with the sa= me general ferrite core type setup.  Such coils are rather scarce I'am=20= sure.


      If you have an E core transformer t= ype winding, the magnetic flux is linked strongly to the winding, so great w= inding precision is not required, only a good physical stability. The magnet= ic field interactions are controlled by the positions and separations of the= iron laminations, so these need to be firmly fixed. These E core types can=20= be either modified audio transformers similar to Sean's, ferrite cup transfo= rmers with DIY windings, a linear differential reluctance system of the mags= lip type, or two physically large coils pairs bridged by a ferrite rod, like= the NE type.

J
ust some (unexperienced) th= oughts.  I think the Nuova item costs around $103 US dollars (PCB and L= VDT) plus whatever shipping/handling.  Sometimes I think that a homebre= w LVDT with perhaps a Phillips or Analog IC (and other parts) might be a che= aper alternative......but probably more costly for any R&D overall.

      The two Analogue Devices LVDT chips= have a relatively high noise floor and are not suitable for our use. The Ph= ilips NE5521 device is about 1/3 the price and you can get right down to the= intrinsic opamp noise level.  

      The LX1358 Kit price is =E2=82=AC 5= 1.65 + Carriage. Looking up today's exchange rate, this is just US $51.23= !! There will be a charge on your Credit Card for the currency conversi= on and the exchange rate will be lower than the International Banking Rate q= uoted. Air Mail packets are reasonably priced and may take 10 days to arrive= .. Be warned that International Carriers may have a minimum charge of near $5= 0 for any packet! They seem to be only relatively reasonably priced within t= he USA.=20
=20
      With a LX1358, I get ~7 nano metre=20= resolution over a +/-6 mm accurately linear range, with 65 mV / micron outpu= t. The output is 10% down at +/-12 mm and 20% down at +/-15 mm, since the ''= out of range'' response is of the usual S shape. This wide range was designe= d for Lehman type systems, but the sensor will work equally well on simple p= endulums.

      Regards,

      Chris Chapman
Subject: Re: STM 8 (LVDT subject) From: meredithlamb meredithlamb@............. Date: Sat, 16 Nov 2002 15:32:10 -0700 Hi Mauro and all, Thanks for the notes. I see your reference to the LX922 & LX1358 on the web: The obsolete LX922 seismometer in its entirety, certainly was a large unit. Is the same LVDT coil and circuit board used on such, the same as on the small pendulum LX1358 that you know of? http://mariottim.interfree.it/doc13_e.htm Yes, if you can, and want to, it would be interesting to see just what they used in the LVDT squarish transformer/s inasfar as whether its precision laid out, or more ~jumbo wound. They are somewhat large, and I suspect they are salvaged coils meant originally for another use....but I could always be wrong. In a sense, even if they are not precision, it kind of suggests that other transformers could work also.....but with a reduced sensitivity compared to precision wound LVDT's (but still very good overall). Mauro Mariotti wrote: > Hi All, I worked very much with this LVDT.It is based on the Phllips > NE5521N phase comparator.I can supply you the schematic if needed.The > cost of the unit is 50$ for the circuit and 50$ for the mechanic > tobuild up a complete horizontal sensor like to S-G type.I never > disassembled the LVDT coils to but I can do it I have some sparepart > in my lab. Hi Mauro and all,

Thanks for the notes.  I see your reference to the LX922 &
LX1358 on the web:  The obsolete LX922 seismometer in its
entirety, certainly was a large unit.  Is the same LVDT coil and circuit
board used on such, the same as on the small pendulum LX1358
that you know of?

http://mariottim.interfree.it/doc13_e.htm

Yes, if you can, and want to, it would be interesting to see
just what they used in the LVDT squarish transformer/s inasfar
as whether its precision laid out, or more ~jumbo wound.
They are somewhat large, and I suspect they are salvaged
coils meant originally for another use....but I could always be
wrong.  In a sense, even if they are not precision, it kind of
suggests that other transformers could work also.....but with
a reduced sensitivity compared to precision wound LVDT's
(but still very good overall).
 

Mauro Mariotti wrote:

Hi All, I worked very much with this LVDT.It is based on the Phllips NE5521N phase comparator.I can supply you the schematic if needed.The cost of the unit is 50$ for the circuit and 50$ for the mechanic tobuild up a complete horizontal sensor like to S-G type.I never disassembled the LVDT coils to but I can do it I have some sparepart in my lab.
Subject: Re: STM 8 (LVDT subject) From: meredithlamb meredithlamb@............. Date: Sat, 16 Nov 2002 16:53:12 -0700 Hi Chris and all, ChrisAtUpw@....... wrote: >> > Agreed, but there are several distance transducer approaches which >> > can be successful. To my mind, there is a distinct shortage of >> > amateur 'off the shelf' sensor designs capable of giving near >> > professional resolution and stability. There is only one LVDT Kit >> > sensor available with a PCB, to my knowledge, which can give about >> > 7 nano metres resolution at 10 Hz over +/-6 mm, with a max range of >> > +/-12 mm. >> >> >> Presume its the Italian, Nuova Elettronica unit (?), you've been >> working with / on over time? > > Hi Meredith, > > I have done some experiments modifying / improving my Nuova > Elettronica LVDT board, reducing the two pole detector filter to 10 > Hz, which is more suitable for seismic use, changing the output opamp > to a low noise type and increasing the time constant of the high pass > filter, along with several other small changes. NE seemed to have used > a circuit designed by Philips for wider bandwidth commercial LVDT > applications. I have also been working on other magnetic sensor > systems using the Philips NE5521 LVDT chip, including modified > transformers, somewhat like Sean's, some using ferrite components and > lately, a capacitative system. I have a full write up nearly finished. Your full write up should be VERY interesting!! >> Perhaps the greatest curiosity item I wonder about their transformer >> part, is whether its really a precision wound unit like mentioned as >> a (professional) necessity as on other web sites? It appears to be >> much like other general looking transformers. Without any access I'd >> guess its somewhat linearly wound but no where near precision. > > If you want to measure several inches of movement and require a linear > response, you may need a precision linear winding. If you only want a > few mm and the field of the sensor rod can be sensed over a physically > much larger sensor winding, you just need the windings to stay in a > fixed position. There will of course be thermal expansion and changes > of resistance with temperature, but these effects are very small over > the 10 Hz bandwidth and the 5 to 30 sec of the high pass filter time > constant. > > >> Perhaps the biggest thing I "seem" to see, is that Seans original >> LRDT transformers are in likelyhood kind of a crude nonlinear wire >> wrapping; whereas, your LVDT, is a painstaking relatively precision >> wire layered device. > > With Sean's variable reluctance transformer sensor, the magnetic > circuit is defined by the position of the flat iron armature plate and > the iron polepieces. In a LVDT, the interaction is between the > position of a magnetised armature and the varying distance it moves > inside the sensor coil, so the coil needs to be quite uniformly wound. > For a description of an LVDT, see > http://www.msiusa.com/schaevitz/pdf/lvdt/LVDT_Intro.pdf It is not too > difficult to make even windings, so long as you do not use extremely > fine wire, do not try to wind too fast, slow up right at the end of > each layer and, most importantly, use very thin paper, like cigarette > or tissue paper, for interleaving each layer. This makes it easy to > spot and correct any overwinding or incorrectly spaced turns. It also > makes winding easier and helps to prevent shorted turns in between > layers. I made two matched 40,000 turn precision differential > transformer coils this way, for measuring paramagnetic susceptibility. > A very small plastic tube makes a good wire guide. It is also possible > to just layer wind two LVDT secondaries end to end on a sensor tube > and use a ferrite or powder iron cored choke to provide the magnetic > excitation. This avoids having to wind a central primary magnetising > section in between, or over the top of the secondaries. > > Yet.....according to Seans website, his LRDT is sensitive to a > incredible 0.1nm. I've > >> zero experience but it makes me wonder further about coils >> themselves between >> the two. It would seem the LRDT is much simpler to make and more >> sensitive overall. > > Coupled with the very high sensitivity of Sean's transducer, the > movement range is small, perhaps +/-0.5 mm in a 2 mm total gap, and > the output is only linear for a limited range around the zero > position. This is just fine for a feedback seismometer, where you try > to hold the armature position constant. The out of range signal > increases dramatically before saturating, which can be bad news if the > seismometer feedback system gets out of lock. Seans reluctance sensor sounds like it could be used in a "S-G" also, although one might have a devil of a time especially when any kind of small height S-G feedback system, might influence the sensor. Perhaps a fixed eddy current damping system might be workable, if far enough away from the sensor itself. >> All this is leading up to the question of whether a fairly linear >> wound (but not exactly precisely layered) coil "could" somewhat work >> simarily (with less sensitivity) with the same general ferrite core >> type setup. Such coils are rather scarce I'am sure. > > If you have an E core transformer type winding, the magnetic flux is > linked strongly to the winding, so great winding precision is not > required, only a good physical stability. The magnetic field > interactions are controlled by the positions and separations of the > iron laminations, so these need to be firmly fixed. These E core types > can be either modified audio transformers similar to Sean's, ferrite > cup transformers with DIY windings, a linear differential reluctance > system of the magslip type, or two physically large coils pairs > bridged by a ferrite rod, like the NE type. > >> Just some (unexperienced) thoughts. I think the Nuova item costs >> around $103 US dollars (PCB and LVDT) plus whatever >> shipping/handling. Sometimes I think that a homebrew LVDT with >> perhaps a Phillips or Analog IC (and other parts) might be a cheaper >> alternative......but probably more costly for any R&D overall. > > The two Analogue Devices LVDT chips have a relatively high noise floor > and are not suitable for our use. The Philips NE5521 device is about > 1/3 the price and you can get right down to the intrinsic opamp noise > level. > > The LX1358 Kit price is € 51.65 + Carriage. Looking up today's > exchange rate, this is just US $51.23 !! There will be a charge on > your Credit Card for the currency conversion and the exchange rate > will be lower than the International Banking Rate quoted. Air Mail > packets are reasonably priced and may take 10 days to arrive. Be > warned that International Carriers may have a minimum charge of near > $50 for any packet! They seem to be only relatively reasonably priced > within the USA. Am missing something here....whats the difference between a "air mail packet", and a, "International Carriers"? Did Nuova offer the distinction when you got your LVDT? Airmail v/s "ground" (ship)? > With a LX1358, I get ~7 nano metre resolution over a +/-6 mm > accurately linear range, with 65 mV / micron output. The output is 10% > down at +/-12 mm and 20% down at +/-15 mm, since the ''out of range'' > response is of the usual S shape. This wide range was designed for > Lehman type systems, but the sensor will work equally well on simple > pendulums. Thats quite a large sensor mm/mv output! Thanks for all the "feedback" info! Take care, Meredith Hi Chris and all,

ChrisAtUpw@....... wrote:

Agreed, but there are several distance transducer approaches which can be successful. To my mind, there is a distinct shortage of amateur 'off the shelf' sensor designs capable of giving near professional resolution and stability. There is only one LVDT Kit sensor available with a PCB, to my knowledge, which can give about 7 nano metres resolution at 10 Hz over +/-6 mm, with a max range of +/-12 mm.


Presume its the Italian, Nuova Elettronica unit (?), you've been working with / on over time?

Hi Meredith,

I have done some experiments modifying / improving my Nuova Elettronica LVDT board, reducing the two pole detector filter to 10 Hz, which is more suitable for seismic use,  changing the output opamp to a low noise type and increasing the time constant of the high pass filter, along with several other small changes. NE seemed to have used a circuit designed by Philips for wider bandwidth commercial LVDT applications. I have also been working on other magnetic sensor systems using the Philips NE5521 LVDT chip, including modified transformers, somewhat like Sean's, some using ferrite components and lately, a capacitative system. I have a full write up nearly finished.

Your full write up should be VERY interesting!!
Perhaps the greatest curiosity item I wonder about their transformer part, is whether its really a precision wound unit like mentioned as a (professional) necessity as on other web sites?  It appears to be much like other general looking transformers. Without any access I'd guess its somewhat linearly wound but no where near precision.
If you want to measure several inches of movement and require a linear response, you may need a precision linear winding. If you only want a few mm and the field of the sensor rod can be sensed over a physically much larger sensor winding, you just need the windings to stay in a fixed position. There will of course be thermal expansion and changes of resistance with temperature, but these effects are very small over the 10 Hz bandwidth and the 5 to 30 sec of the high pass filter time constant.
 
Perhaps the biggest thing I "seem" to see, is that Seans original LRDT transformers are in likelyhood kind of a crude nonlinear wire wrapping; whereas, your LVDT, is a painstaking relatively precision wire layered device.
With Sean's variable reluctance transformer sensor, the magnetic circuit is defined by the position of the flat iron armature plate and the iron polepieces. In a LVDT, the interaction is between the position of a magnetised armature and the varying distance it moves inside the sensor coil, so the coil needs to be quite uniformly wound. For a description of an LVDT, see http://www.msiusa.com/schaevitz/pdf/lvdt/LVDT_Intro.pdf  It is not too difficult to make even windings, so long as you do not use extremely fine wire, do not try to wind too fast, slow up right at the end of each layer and, most importantly, use very thin paper, like cigarette or tissue paper, for interleaving each layer. This makes it easy to spot and correct any overwinding or incorrectly spaced turns. It also makes winding easier and helps to prevent shorted turns in between layers. I made two matched 40,000 turn precision differential transformer coils this way, for measuring paramagnetic susceptibility. A very small plastic tube makes a good wire guide. It is also possible to just layer wind two LVDT secondaries end to end on a sensor tube and use a ferrite or powder iron cored choke to provide the magnetic excitation. This avoids having to wind a central primary magnetising section in between, or over the top of the secondaries.

Yet.....according to Seans website, his LRDT is sensitive to a incredible 0.1nm.  I've

zero experience but it makes me wonder further about coils themselves between
the two.  It would seem the LRDT is much simpler to make and more sensitive overall.
Coupled with the very high sensitivity of Sean's transducer, the movement range is small, perhaps +/-0.5 mm in a 2 mm total gap, and the output is only linear for a limited range around the zero position. This is just fine for a feedback seismometer, where you try to hold the armature position constant. The out of range signal increases dramatically before saturating, which can be bad news if the seismometer feedback system gets out of lock.
Seans reluctance sensor sounds like it could be used in a "S-G" also,
although one might have a devil of a time especially when any
kind of small height S-G feedback system, might influence the sensor.
Perhaps a fixed eddy current damping system might be workable,
if far enough away from the sensor itself.
All this is leading up to the question of whether a fairly linear wound (but not exactly precisely layered) coil "could" somewhat work simarily (with less sensitivity) with the same general ferrite core type setup.  Such coils are rather scarce I'am sure.
If you have an E core transformer type winding, the magnetic flux is linked strongly to the winding, so great winding precision is not required, only a good physical stability. The magnetic field interactions are controlled by the positions and separations of the iron laminations, so these need to be firmly fixed. These E core types can be either modified audio transformers similar to Sean's, ferrite cup transformers with DIY windings, a linear differential reluctance system of the magslip type, or two physically large coils pairs bridged by a ferrite rod, like the NE type.
Just some (unexperienced) thoughts.  I think the Nuova item costs around $103 US dollars (PCB and LVDT) plus whatever shipping/handling.  Sometimes I think that a homebrew LVDT with perhaps a Phillips or Analog IC (and other parts) might be a cheaper alternative......but probably more costly for any R&D overall.
The two Analogue Devices LVDT chips have a relatively high noise floor and are not suitable for our use. The Philips NE5521 device is about 1/3 the price and you can get right down to the intrinsic opamp noise level.

The LX1358 Kit price is € 51.65 + Carriage. Looking up today's exchange rate, this is just US $51.23 !! There will be a charge on your Credit Card for the currency conversion and the exchange rate will be lower than the International Banking Rate quoted. Air Mail packets are reasonably priced and may take 10 days to arrive. Be warned that International Carriers may have a minimum charge of near $50 for any packet! They seem to be only relatively reasonably priced within the USA.

Am missing something here....whats the difference between a "air mail
packet", and a, "International Carriers"?  Did Nuova offer the distinction
when you got your LVDT?  Airmail v/s "ground" (ship)?
With a LX1358, I get ~7 nano metre resolution over a +/-6 mm accurately linear range, with 65 mV / micron output. The output is 10% down at +/-12 mm and 20% down at +/-15 mm, since the ''out of range'' response is of the usual S shape. This wide range was designed for Lehman type systems, but the sensor will work equally well on simple pendulums.
Thats quite a large sensor mm/mv output!  Thanks for all the "feedback" info!

Take care, Meredith
  Subject: Re: STM 8 (LVDT subject) From: "Mauro Mariotti" mariotti@......... Date: Sun, 17 Nov 2002 10:13:29 +0100 Hi Meredith, the lx1358 circuit is exactly the same used in the lx922 with few=20 small variations. The LX922 and LX1358 coils are the same. I think that the coils are wound for the pourpose of the seismometer and not re-used from an another application. They are very large to make easier the assembly of the mechanic. That squared hole keep easy the assembly of the nucleus that is needed to insert for last when you assemble the mechanic components. Regards Mauro ----- Original Message -----=20 From: meredithlamb=20 To: psn-l@................. Sent: Saturday, November 16, 2002 11:32 PM Subject: Re: STM 8 (LVDT subject) Hi Mauro and all,=20 Thanks for the notes. I see your reference to the LX922 &=20 LX1358 on the web: The obsolete LX922 seismometer in its=20 entirety, certainly was a large unit. Is the same LVDT coil and = circuit=20 board used on such, the same as on the small pendulum LX1358=20 that you know of?=20 http://mariottim.interfree.it/doc13_e.htm=20 Yes, if you can, and want to, it would be interesting to see=20 just what they used in the LVDT squarish transformer/s inasfar=20 as whether its precision laid out, or more ~jumbo wound.=20 They are somewhat large, and I suspect they are salvaged=20 coils meant originally for another use....but I could always be=20 wrong. In a sense, even if they are not precision, it kind of=20 suggests that other transformers could work also.....but with=20 a reduced sensitivity compared to precision wound LVDT's=20 (but still very good overall).=20 =20 Mauro Mariotti wrote:=20 Hi All, I worked very much with this LVDT.It is based on the Phllips = NE5521N phase comparator.I can supply you the schematic if needed.The = cost of the unit is 50$ for the circuit and 50$ for the mechanic tobuild = up a complete horizontal sensor like to S-G type.I never disassembled = the LVDT coils to but I can do it I have some sparepart in my lab.

Hi Meredith,
the lx1358 circuit is exactly the same = used in the=20 lx922 with few
small variations.
The LX922 and LX1358 coils are the=20 same.
I think that the coils are wound for = the pourpose=20 of the seismometer
and not re-used from an another=20 application.
They are very large to make easier the = assembly of=20 the mechanic.
That squared hole keep easy the = assembly of the=20 nucleus that is
needed to insert for last when you = assemble the=20 mechanic components.
 
Regards
Mauro
 
----- Original Message -----
From:=20 meredithlamb
Sent: Saturday, November 16, = 2002 11:32=20 PM
Subject: Re: STM 8 (LVDT = subject)

Hi Mauro and all,=20

Thanks for the notes.  I see your reference to the LX922 & =
LX1358 on the web:  The obsolete LX922 seismometer in its=20
entirety, certainly was a large unit.  Is the same LVDT coil = and=20 circuit
board used on such, the same as on the small pendulum = LX1358=20
that you know of?=20

http://mariottim.inter= free.it/doc13_e.htm=20

Yes, if you can, and want to, it would be interesting to see =
just what=20 they used in the LVDT squarish transformer/s inasfar
as whether = its=20 precision laid out, or more ~jumbo wound.
They are somewhat large, = and I=20 suspect they are salvaged
coils meant originally for another = use....but I=20 could always be
wrong.  In a sense, even if they are not = precision,=20 it kind of
suggests that other transformers could work = also.....but with=20
a reduced sensitivity compared to precision wound LVDT's
(but = still=20 very good overall).
 =20

Mauro Mariotti wrote:=20

Hi All, I worked very much with this LVDT.It is based on the = Phllips NE5521N=20 phase comparator.I can supply you the schematic if needed.The cost = of the=20 unit is 50$ for the circuit and 50$ for the mechanic tobuild up a = complete=20 horizontal sensor like to S-G type.I never disassembled the LVDT = coils to=20 but I can do it I have some sparepart in my=20 lab.
Subject: Digital Analisys of Seismic Data From: Cristian Haulica cristianhaulica@....... Date: 17 Nov 2002 13:35:13 -0000 Hy.. My graduation project (at the Automatic and computer inginering dept. of Technical Univetsity Iasi, Romania) is an seismograph (Lehman type). If someone knows where I can find (on web) some algorithms, code, or open code projects (preferable in C,C++,VC) related to Automatic Analisis on Seismic Data, please reply. Thank You. PS. My connection to this mailing list isn't so good, so i couldn't download the archive files. My apologies if this question has been alredy answered. ---- Home, no matter how far... http://www.home.ro __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: STM 8 (LVDT subject) From: ChrisAtUpw@....... Date: Sun, 17 Nov 2002 09:39:17 EST In a message dated 16/11/02, meredithlamb@............. writes: > Sean's reluctance sensor sounds like it could be used in a "S-G" also, > although one might have a devil of a time especially when any kind of small > height S-G feedback system, might influence the sensor. Perhaps a fixed > eddy current damping system might be workable, if far enough away from the > Hi Meredith, Sean's system should be fine for a pendulum sensor, if a bit elaborate. I would not expect there to be any problem over the physical size of the sensor. The miniature transformers are 15 mm (~5/8") across the windings and 19 mm (~3/4") across the jaws of the E. The usual method of suspending the iron armature on a brass plate should provide quite adequate magnetic isolation. SG seismometers normally use active damping with a coil and a bar magnet. This can, with advantage, be coupled directly to the seismic mass. The 'true' SG systems (as opposed to damped pendulums) get much of their sensitivity from damping the otherwise underdamped pendulum. On the side issue of magnetic damping, the Wing shaped two face pole magnets sold by www.wondermagnet.com are very effective indeed at providing magnetic damping and size for size, are much more effective than single pole magnets. The smaller damping plate is placed over the joint between the two wings, where the field reverses. > >> The LX1358 Kit price is E 51.65 + Carriage. At today's exchange rate, this >> is just US $51.23. There will be a charge on your Credit Card for the >> currency conversion and the exchange rate will be lower than the >> International Banking Rate quoted. Air Mail packets are reasonably priced >> and may take 10 days to arrive. Be warned that International Carriers may >> have a minimum charge of near $50 for any packet! They seem to be only >> > Am missing something here....whats the difference between a "air mail > Air Mail goes through the normal Mail system of most countries, but there are strict limits on the size and weight for letters, packets and parcels and you have to insure seperately over certain values. By International Carriers, I am referring to Fedex, Amtrak, DHL, TNT etc. which handle heavier, industrial and urgent goods. When the UK part of Measurement Specialities, Schaevitz's distributors, folded a while back, Schaevitz offered to supply direct from the USA, but mentioned 'carriage charges'. When I enquired, these turned out to be over $40 on any item, no matter how small. Schaevitz seemed incapable or unwilling to provide near normal distributor service over some months and seemed to have the bizarre idea that their customers should happily foot the excess bill, as well as suffering a delivery delay and increased currency and import charges. You don't either keep or win customers that way, particularly when there is strong local competiton. Nuova Elettronica are a large Italian organisation producing a very wide range of well designed Kits and probably have more product lines than Heathkit ever had. They assume that the builder can recognise components and can read. They provide adequate constructional documentation, but they do not provide 'idiot's construction guides'. The sensor coils used on the LX1358 are obviously new and are similar to low wattage 1:1 mains isolation transformer windings. There are two coils mounted side by side in a sealed nylon case, which is the usual EEC construction for 'double insulated' transformers. The coils look to be well wound, but because of the geometry of the system, the output linearity of the sensor does not depend on the 'precision' of the winding, like in an LVDT. On the cutaway construction photo in the Schaevitz introduction, http://www.msiusa.com/schaevitz/pdf/lvdt/LVDT_Intro.pdf you may notice that the fatter sensor windings on their LVDTs are also split up into a series of short coil sections, on much the same principle. There is a nice java applet demonstrating a LVDT operating at http://www.rdpe.com/displacement/lvdt/lvdt-principles.htm Regards, Chris Chapman In a message dated 16/11/02, meredithlamb@............. writes:

Sean's reluctance sensor sounds like it could be used in a "S-G" also, although one might have a devil of a time especially when any kind of small height S-G feedback system, might influence the sensor. Perhaps a fixed eddy current damping system might be workable, if far enough away from the sensor itself.


Hi Meredith,

      Sean's system should be fine for a pendulum sensor, if a bit elaborate. I would not expect there to be any problem over the physical size of the sensor. The miniature transformers are 15 mm (~5/8") across the windings and 19 mm (~3/4") across the jaws of the E. The usual method of suspending the iron armature on a brass plate should provide quite adequate magnetic isolation.
      SG seismometers normally use active damping with a coil and a bar magnet.  This can, with advantage, be coupled directly to the seismic mass. The 'true' SG systems (as opposed to damped pendulums) get much of their sensitivity from damping the otherwise underdamped pendulum.

      On the side issue of magnetic damping, the Wing shaped two face pole magnets sold by www.wondermagnet.com are very effective indeed at providing magnetic damping and size for size, are much more effective than single pole magnets. The smaller damping plate is placed over the joint between the two wings, where the field reverses.

The LX1358 Kit price is E 51.65 + Carriage. At today's exchange rate, this is just US $51.23. There will be a charge on your Credit Card for the currency conversion and the exchange rate will be lower than the International Banking Rate quoted. Air Mail packets are reasonably priced and may take 10 days to arrive. Be warned that International Carriers may have a minimum charge of near $50 for any packet! They seem to be only relatively reasonably priced within the USA.

Am missing something here....whats the difference between a "air mail packet", and a, "International Carriers"?


      Air Mail goes through the normal Mail system of most countries, but there are strict limits on the size and weight for letters, packets and parcels and you have to insure seperately over certain values. By International Carriers, I am referring to Fedex, Amtrak, DHL, TNT etc. which handle heavier, industrial and urgent goods.
      When the UK part of Measurement Specialities, Schaevitz's distributors, folded a while back, Schaevitz offered to supply direct from the USA, but mentioned 'carriage charges'. When I enquired, these turned out to be over $40 on any item, no matter how small. Schaevitz seemed incapable or unwilling to provide near normal distributor service over some months and seemed to have the bizarre idea that their customers should happily foot the excess bill, as well as suffering a delivery delay and increased currency and import charges. You don't either keep or win customers that way, particularly when there is strong local competiton.  
  
      Nuova Elettronica are a large Italian organisation producing a very wide range of well designed Kits and probably have more product lines than Heathkit ever had. They assume that the builder can recognise components and can read. They provide adequate constructional documentation, but they do not provide 'idiot's construction guides'.
      The sensor coils used on the LX1358 are obviously new and are similar to low wattage 1:1 mains isolation transformer windings. There are two coils mounted side by side in a sealed nylon case, which is the usual EEC construction for 'double insulated' transformers. The coils look to be well wound, but because of the geometry of the system, the output linearity of the sensor does not depend on the 'precision' of the winding, like in an LVDT. On the cutaway construction photo in the Schaevitz introduction, http://www.msiusa.com/schaevitz/pdf/lvdt/LVDT_Intro.pdf  you may notice that the fatter sensor windings on their LVDTs are also split up into a series of short coil sections, on much the same principle. There is a nice java applet demonstrating a LVDT operating at http://www.rdpe.com/displacement/lvdt/lvdt-principles.htm

      Regards,

      Chris Chapman
Subject: Re: Digital Analisys of Seismic Data From: "Mauro Mariotti" mariotti@......... Date: Sun, 17 Nov 2002 20:06:53 +0100 "Automatic analisys of seismic data" is not so specific question. Seismic data can be treated as a flow digitized analogic signal with DSP tecniques. So any DSP guidebook can provides useful information on the algorythms... If you need more specific information you should post more specific questions. Regards Mauro ----- Original Message ----- From: "Cristian Haulica" To: Sent: Sunday, November 17, 2002 2:35 PM Subject: Digital Analisys of Seismic Data > > > Hy.. > > My graduation project (at the Automatic and computer > inginering dept. of Technical Univetsity Iasi, Romania) is an > seismograph (Lehman type). If someone knows where I can find > (on web) some algorithms, code, or open code projects > (preferable in C,C++,VC) related to Automatic Analisis on > Seismic Data, please reply. > > Thank You. > > PS. My connection to this mailing list isn't so good, so i > couldn't download the archive files. My apologies if this > question has been alredy answered. > > > ---- > > Home, no matter how far... > http://www.home.ro > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: STM 8 (LVDT subject) From: meredithlamb meredithlamb@............. Date: Mon, 18 Nov 2002 14:54:14 -0700 Hi Chris, and all, ChrisAtUpw@....... wrote: > In a message dated 16/11/02, meredithlamb@............. writes: > > >> Sean's reluctance sensor sounds like it could be used in a "S-G" >> also, although one might have a devil of a time especially when any >> kind of small height S-G feedback system, might influence the >> sensor. Perhaps a fixed eddy current damping system might be >> workable, if far enough away from the sensor itself. > > > Hi Meredith, > > Sean's system should be fine for a pendulum sensor, if a bit > elaborate. I would not expect there to be any problem over the > physical size of the sensor. The miniature transformers are 15 mm > (~5/8") across the windings and 19 mm (~3/4") across the jaws of the > E. The usual method of suspending the iron armature on a brass plate > should provide quite adequate magnetic isolation. Your statement of "a bit elaborate" for the Sean circuit is quite true to me (ha), by comparison, a general LVDT circuit indeed looks alot simplier. I see they've been around for over a hundred years (in esscense). Perhaps in general, they could be the better more sensitive and cheaper future for amateur seismology. Most U.S., companies truely want a "mint" for their LVDT coil items, which seems to be the main current problem overall in that commercial part approach. > SG seismometers normally use active damping with a coil and a bar > magnet. This can, with advantage, be coupled directly to the seismic > mass. The 'true' SG systems (as opposed to damped pendulums) get much > of their sensitivity from damping the otherwise underdamped pendulum. > > On the side issue of magnetic damping, the Wing shaped two face pole > magnets sold by www.wondermagnet.com are very effective indeed at > providing magnetic damping and size for size, are much more effective > than single pole magnets. The smaller damping plate is placed over the > joint between the two wings, where the field reverses. Very true on the "wing" or 4 pole magnets. I'am rather surprised more amateurs are not using this cheaper and more effective damping (and even coil sensor pickup) route. Perhaps (?), to be fair in that regard, its usually the larger the neodymium magnet/s, the better the results. Most neodymium magnets are rather small, whereas alot of the Alnico magnets are larger poled but with alot less "potential" maximum gauss interaction. On the other hand, two, "wing" magnets facing (attracting to each other), can enhance results moreso. >> > The LX1358 Kit price is E 51.65 + Carriage. At today's exchange >> > rate, this is just US $51.23. There will be a charge on your Credit >> > Card for the currency conversion and the exchange rate will be >> > lower than the International Banking Rate quoted. Air Mail packets >> > are reasonably priced and may take 10 days to arrive. Be warned >> > that International Carriers may have a minimum charge of near $50 >> > for any packet! They seem to be only relatively reasonably priced >> > within the USA. >> Most interesting on the cost. I'd guess the actual cost could be ~ double with the shipping charges added just for the LVDT and circuit alone. Getting the mechanical S-G part added would likely make it prohibitively alot more expensive.... ~ 2-4 times. >> Am missing something here....whats the difference between a "air >> mail packet", and a, "International Carriers"? > > Air Mail goes through the normal Mail system of most countries, but > there are strict limits on the size and weight for letters, packets > and parcels and you have to insure seperately over certain values. By > International Carriers, I am referring to Fedex, Amtrak, DHL, TNT etc. > which handle heavier, industrial and urgent goods. Thanks for the info. Have shipped out to other countries before, and sometimes the actual cost can even far exceed the value of the item actually shipped. Its always quite expensive it seems. > When the UK part of Measurement Specialities, Schaevitz's > distributors, folded a while back, Schaevitz offered to supply direct > from the USA, but mentioned 'carriage charges'. When I enquired, these > turned out to be over $40 on any item, no matter how small. Schaevitz > seemed incapable or unwilling to provide near normal distributor > service over some months and seemed to have the bizarre idea that > their customers should happily foot the excess bill, as well as > suffering a delivery delay and increased currency and import charges. > You don't either keep or win customers that way, particularly when > there is strong local competiton. True; alot of U.S. companies seem to go the same "self defeating" route. > Nuova Elettronica are a large Italian organisation producing a very > wide range of well designed Kits and probably have more product lines > than Heathkit ever had. They assume that the builder can recognise > components and can read. They provide adequate constructional > documentation, but they do not provide 'idiot's construction guides'. Too bad they don't promote more of their items information via the internet; but I think it might be related to a less hectic "way of life" approach. > The sensor coils used on the LX1358 are obviously new and are similar > to low wattage 1:1 mains isolation transformer windings. There are two > coils mounted side by side in a sealed nylon case, which is the usual > EEC construction for 'double insulated' transformers. The coils look > to be well wound, but because of the geometry of the system, the > output linearity of the sensor does not depend on the 'precision' of > the winding, like in an LVDT. On the cutaway construction photo in the > Schaevitz introduction, > http://www.msiusa.com/schaevitz/pdf/lvdt/LVDT_Intro.pdf you may > notice that the fatter sensor windings on their LVDTs are also split > up into a series of short coil sections, on much the same principle. > There is a nice java applet demonstrating a LVDT operating at > http://www.rdpe.com/displacement/lvdt/lvdt-principles.htm Thanks for the info! Take care, Meredith Lamb Hi Chris, and all,

ChrisAtUpw@....... wrote:

In a message dated 16/11/02, meredithlamb@............. writes:
 
Sean's reluctance sensor sounds like it could be used in a "S-G" also, although one might have a devil of a time especially when any kind of small height S-G feedback system, might influence the sensor. Perhaps a fixed eddy current damping system might be workable, if far enough away from the sensor itself.


Hi Meredith,

Sean's system should be fine for a pendulum sensor, if a bit elaborate. I would not expect there to be any problem over the physical size of the sensor. The miniature transformers are 15 mm (~5/8") across the windings and 19 mm (~3/4") across the jaws of the E. The usual method of suspending the iron armature on a brass plate should provide quite adequate magnetic isolation.

Your statement of "a bit elaborate" for the Sean circuit is quite true
to me (ha), by comparison, a general LVDT circuit indeed looks
alot simplier.  I see they've been around for over a hundred years
(in esscense).  Perhaps in general, they could be the better more
sensitive and cheaper future for amateur seismology.  Most U.S.,
companies truely want a "mint" for their LVDT coil items, which
seems to be the main current problem overall in that commercial
part approach.
SG seismometers normally use active damping with a coil and a bar magnet.  This can, with advantage, be coupled directly to the seismic mass. The 'true' SG systems (as opposed to damped pendulums) get much of their sensitivity from damping the otherwise underdamped pendulum.

On the side issue of magnetic damping, the Wing shaped two face pole magnets sold by www.wondermagnet.com are very effective indeed at providing magnetic damping and size for size, are much more effective than single pole magnets. The smaller damping plate is placed over the joint between the two wings, where the field reverses.

Very true on the "wing" or 4 pole magnets.  I'am rather
surprised more amateurs are not using this cheaper and more
effective damping (and even coil sensor pickup) route.  Perhaps
(?), to be fair in that regard, its usually the larger the neodymium
magnet/s, the better the results.  Most neodymium magnets are
rather small, whereas alot of the Alnico magnets are larger poled
but with alot less "potential" maximum gauss interaction.  On the
other hand, two, "wing" magnets facing (attracting to each
other), can enhance results moreso.
The LX1358 Kit price is E 51.65 + Carriage. At today's exchange rate, this is just US $51.23. There will be a charge on your Credit Card for the currency conversion and the exchange rate will be lower than the International Banking Rate quoted. Air Mail packets are reasonably priced and may take 10 days to arrive. Be warned that International Carriers may have a minimum charge of near $50 for any packet! They seem to be only relatively reasonably priced within the USA.
Most interesting on the cost.  I'd guess the actual cost could be
~ double with the shipping charges added just for the LVDT and
circuit alone.  Getting the mechanical S-G part added would
likely make it prohibitively alot more expensive.... ~ 2-4 times.
Am missing something here....whats the difference between a "air mail packet", and a, "International Carriers"?
Air Mail goes through the normal Mail system of most countries, but there are strict limits on the size and weight for letters, packets and parcels and you have to insure seperately over certain values. By International Carriers, I am referring to Fedex, Amtrak, DHL, TNT etc. which handle heavier, industrial and urgent goods.
Thanks for the info.  Have shipped out to other countries before,
and sometimes the actual cost can even far exceed the value of the
item actually shipped.  Its always quite expensive it seems.
When the UK part of Measurement Specialities, Schaevitz's distributors, folded a while back, Schaevitz offered to supply direct from the USA, but mentioned 'carriage charges'. When I enquired, these turned out to be over $40 on any item, no matter how small. Schaevitz seemed incapable or unwilling to provide near normal distributor service over some months and seemed to have the bizarre idea that their customers should happily foot the excess bill, as well as suffering a delivery delay and increased currency and import charges. You don't either keep or win customers that way, particularly when there is strong local competiton.
True; alot of U.S. companies seem to go the same "self defeating"
route.
Nuova Elettronica are a large Italian organisation producing a very wide range of well designed Kits and probably have more product lines than Heathkit ever had. They assume that the builder can recognise components and can read. They provide adequate constructional documentation, but they do not provide 'idiot's construction guides'.
Too bad they don't promote more of their items information via
the internet; but I think it might be related to a less hectic "way of
life" approach.
The sensor coils used on the LX1358 are obviously new and are similar to low wattage 1:1 mains isolation transformer windings. There are two coils mounted side by side in a sealed nylon case, which is the usual EEC construction for 'double insulated' transformers. The coils look to be well wound, but because of the geometry of the system, the output linearity of the sensor does not depend on the 'precision' of the winding, like in an LVDT. On the cutaway construction photo in the Schaevitz introduction, http://www.msiusa.com/schaevitz/pdf/lvdt/LVDT_Intro.pdf  you may notice that the fatter sensor windings on their LVDTs are also split up into a series of short coil sections, on much the same principle. There is a nice java applet demonstrating a LVDT operating at http://www.rdpe.com/displacement/lvdt/lvdt-principles.htm
Thanks for the info!  Take care, Meredith Lamb
 
  Subject: Re: STM 8 (LVDT subject) From: meredithlamb meredithlamb@............. Date: Mon, 18 Nov 2002 14:54:57 -0700 Hi Mauro, I'd now think you are correct, in the aspect of the LVDT coils likely being made just for the seismo unit; just from the aspect of the NE, being a large organization/company. I do wonder what the size/diameter of the ferrite rod that comes with the LVDT and circuit? Suspect its quite "loose" clearance (~ 1-2 mm?) on any side. In the same sense, I wonder what the dimension/s are of the transformer hole/s? In ways, it seems possible that a tighter (larger) fitting ferrite rod might enhance the sensitivity somewhat....but not likely really needed at all. Take care, Meredith Lamb Mauro Mariotti wrote: > Hi Meredith,the lx1358 circuit is exactly the same used in the lx922 > with fewsmall variations.The LX922 and LX1358 coils are the same.I > think that the coils are wound for the pourpose of the seismometerand > not re-used from an another application.They are very large to make > easier the assembly of the mechanic.That squared hole keep easy the > assembly of the nucleus that isneeded to insert for last when you > assemble the mechanic components. RegardsMauro Hi Mauro,

I'd now think you are correct, in the aspect of the LVDT coils
likely being made just for the seismo unit; just from the aspect
of the NE, being a large organization/company.

I do wonder what the size/diameter of the ferrite rod that
comes with the LVDT and circuit?  Suspect its quite "loose"
clearance (~ 1-2 mm?) on any side.  In the same sense, I
wonder what the dimension/s are of the transformer hole/s?
In ways, it seems possible that a tighter (larger) fitting ferrite
rod might enhance the sensitivity somewhat....but not likely
really needed at all.

Take care, Meredith Lamb

Mauro Mariotti wrote:

 Hi Meredith,the lx1358 circuit is exactly the same used in the lx922 with fewsmall variations.The LX922 and LX1358 coils are the same.I think that the coils are wound for the pourpose of the seismometerand not re-used from an another application.They are very large to make easier the assembly of the mechanic.That squared hole keep easy the assembly of the nucleus that isneeded to insert for last when you assemble the mechanic components. RegardsMauro
Subject: Fw: Infrasonic sound From: "Larry Cochrane" cochrane@.............. Date: Mon, 18 Nov 2002 17:03:39 -0800 ----- Original Message ----- From: "Lewis,Bob" To: Sent: Monday, November 18, 2002 5:03 AM Subject: Infrasonic sound > Larry: Please post this for me.... > > Bob Lewis > Plano, Texas > > This morning, a little after midnight Dallas time, I heard (or rather felt) > what seemed like > an 8-10 Hz. sine wave. It lasted about 40 seconds, long enough for me to go > out into > the back yard and try to figure out where it was coming from. It was not > sharp or > staccato, sounded like a clean sine wave. My seismometer, of course was off > at the > time, but this seemed airborne rather than through the earth. I could not > determine any > direction; seemed to be coming from all around. Does any one have any ideas > as to > what this may have been ?? __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Fw: Infrasonic sound From: meredithlamb meredithlamb@............. Date: Tue, 19 Nov 2002 01:53:19 -0700 Hi Bob, ???? perhaps its "somewhat" related to the "Taos hum". This pneumonia has been "sensed" world wide, but most promently in the US and the UK according to this website: http://www.eskimo.com/~bilb/hum/hum.html Am sure a web search engine, probably has alot of references to the "Taos hum", and probably other "title" descriptions and theories. Take care, Meredith > ----- Original Message ----- > From: "Lewis,Bob" > To: > Sent: Monday, November 18, 2002 5:03 AM > Subject: Infrasonic sound > > > Larry: Please post this for me.... > > > > Bob Lewis > > Plano, Texas > > > > This morning, a little after midnight Dallas time, I heard (or rather > felt) > > what seemed like > > an 8-10 Hz. sine wave. It lasted about 40 seconds, long enough for me to > go > > out into > > the back yard and try to figure out where it was coming from. It was not > > sharp or > > staccato, sounded like a clean sine wave. My seismometer, of course was > off > > at the > > time, but this seemed airborne rather than through the earth. I could not > > determine any > > direction; seemed to be coming from all around. Does any one have any > ideas > > as to > > what this may have been ?? > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Fw: Infrasonic sound From: "Larry Cochrane" cochrane@.............. Date: Tue, 19 Nov 2002 01:16:40 -0800 Meredith, The link below doesn't work, but as a Monty Python fan I love the file not found message: The file is deceased. It is no longer. It has passed on. You can not have that file in this life! The file is dead, lifeless, departed, demised, late, extinct, no more. It has broken on through to the other side. I need to see if I can modify my web server to display this message and a image of a Parrot with it's feet up in the air.... -Larry Cochrane Redwood City, PSN ----- Original Message ----- From: "meredithlamb" To: Sent: Tuesday, November 19, 2002 12:53 AM Subject: Re: Fw: Infrasonic sound > Hi Bob, > > ???? perhaps its "somewhat" related to the "Taos hum". This > pneumonia has been "sensed" world wide, but most promently > in the US and the UK according to this website: > > http://www.eskimo.com/~bilb/hum/hum.html > > Am sure a web search engine, probably has alot of references > to the "Taos hum", and probably other "title" descriptions > and theories. > > Take care, Meredith > > > > > ----- Original Message ----- > > From: "Lewis,Bob" > > To: > > Sent: Monday, November 18, 2002 5:03 AM > > Subject: Infrasonic sound > > > > > Larry: Please post this for me.... > > > > > > Bob Lewis > > > Plano, Texas > > > > > > This morning, a little after midnight Dallas time, I heard (or rather > > felt) > > > what seemed like > > > an 8-10 Hz. sine wave. It lasted about 40 seconds, long enough for me to > > go > > > out into > > > the back yard and try to figure out where it was coming from. It was not > > > sharp or > > > staccato, sounded like a clean sine wave. My seismometer, of course was > > off > > > at the > > > time, but this seemed airborne rather than through the earth. I could not > > > determine any > > > direction; seemed to be coming from all around. Does any one have any > > ideas > > > as to > > > what this may have been ?? > > > > __________________________________________________________ > > > > Public Seismic Network Mailing List (PSN-L) > > > > To leave this list email PSN-L-REQUEST@.............. with > > the body of the message (first line only): unsubscribe > > See http://www.seismicnet.com/maillist.html for more information. > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Fw: Infrasonic sound From: meredithlamb meredithlamb@............. Date: Tue, 19 Nov 2002 02:50:38 -0700 Hi Larry, OK on the humor, its probably appropriate for the "wee hours" (presume you're watching the Leonids meteor shower?) there .....ha. I've only seen one out of the right direction, but 3 other meteors from other directions. No great "meteor show" yet in Denver at 2am. Ho-hUM....(excuse me...ha) Think the address is correct, however, I saw what you got once also, but it was addressed as: http://www.eskimo.com/notfound.html Perhaps a server problem, or, gosh knows? Take care, Meredith Larry Cochrane wrote: > Meredith, > > The link below doesn't work, but as a Monty Python fan I love the file not > found message: > > The file is deceased. > It is no longer. It has passed on. > You can not have that file in this life! > The file is dead, lifeless, departed, demised, late, extinct, no more. > It has broken on through to the other side. > > I need to see if I can modify my web server to display this message and a > image of a Parrot with it's feet up in the air.... > > -Larry Cochrane > Redwood City, PSN > > ----- Original Message ----- > From: "meredithlamb" > To: > Sent: Tuesday, November 19, 2002 12:53 AM > Subject: Re: Fw: Infrasonic sound > > > Hi Bob, > > > > ???? perhaps its "somewhat" related to the "Taos hum". This > > pneumonia has been "sensed" world wide, but most promently > > in the US and the UK according to this website: > > > > http://www.eskimo.com/~bilb/hum/hum.html > > > > Am sure a web search engine, probably has alot of references > > to the "Taos hum", and probably other "title" descriptions > > and theories. > > > > Take care, Meredith > > > > > > > > > ----- Original Message ----- > > > From: "Lewis,Bob" > > > To: > > > Sent: Monday, November 18, 2002 5:03 AM > > > Subject: Infrasonic sound > > > > > > > Larry: Please post this for me.... > > > > > > > > Bob Lewis > > > > Plano, Texas > > > > > > > > This morning, a little after midnight Dallas time, I heard (or rather > > > felt) > > > > what seemed like > > > > an 8-10 Hz. sine wave. It lasted about 40 seconds, long enough for me > to > > > go > > > > out into > > > > the back yard and try to figure out where it was coming from. It was > not > > > > sharp or > > > > staccato, sounded like a clean sine wave. My seismometer, of course > was > > > off > > > > at the > > > > time, but this seemed airborne rather than through the earth. I could > not > > > > determine any > > > > direction; seemed to be coming from all around. Does any one have any > > > ideas > > > > as to > > > > what this may have been ?? > > > > > > __________________________________________________________ > > > > > > Public Seismic Network Mailing List (PSN-L) > > > > > > To leave this list email PSN-L-REQUEST@.............. with > > > the body of the message (first line only): unsubscribe > > > See http://www.seismicnet.com/maillist.html for more information. > > > > > > __________________________________________________________ > > > > Public Seismic Network Mailing List (PSN-L) > > > > To leave this list email PSN-L-REQUEST@.............. with > > the body of the message (first line only): unsubscribe > > See http://www.seismicnet.com/maillist.html for more information. > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: hum....another better hum reference... From: meredithlamb meredithlamb@............. Date: Tue, 19 Nov 2002 03:07:44 -0700 Hi Bob and Larry, OK, this web site looks more through, with text, map, and even a audio recording link (.wav) at the bottom. The wav file/s takes quite awhile to load/play...and its "sounds" similar to your description Bob. Their is even previous reports places in Texas...I'am not sure where Plano, Texas is right off. See: http://www.crystalinks.com/taoshum.html hum.....meredith __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Fw: Infrasonic sound From: ian@........... Date: Tue, 19 Nov 2002 10:43:55 +0000 (GMT) Translated: the hum has stopped! Quoting Larry Cochrane : > Meredith, > > The link below doesn't work, but as a Monty Python fan I love the file > not > found message: > > The file is deceased. > It is no longer. It has passed on. > You can not have that file in this life! > The file is dead, lifeless, departed, demised, late, extinct, no more. > It has broken on through to the other side. > > I need to see if I can modify my web server to display this message and > a > image of a Parrot with it's feet up in the air.... > > -Larry Cochrane > Redwood City, PSN > > ----- Original Message ----- > From: "meredithlamb" > To: > Sent: Tuesday, November 19, 2002 12:53 AM > Subject: Re: Fw: Infrasonic sound > > > > Hi Bob, > > > > ???? perhaps its "somewhat" related to the "Taos hum". This > > pneumonia has been "sensed" world wide, but most promently > > in the US and the UK according to this website: > > > > http://www.eskimo.com/~bilb/hum/hum.html > > > > Am sure a web search engine, probably has alot of references > > to the "Taos hum", and probably other "title" descriptions > > and theories. > > > > Take care, Meredith > > > > > > > > > ----- Original Message ----- > > > From: "Lewis,Bob" > > > To: > > > Sent: Monday, November 18, 2002 5:03 AM > > > Subject: Infrasonic sound > > > > > > > Larry: Please post this for me.... > > > > > > > > Bob Lewis > > > > Plano, Texas > > > > > > > > This morning, a little after midnight Dallas time, I heard (or > rather > > > felt) > > > > what seemed like > > > > an 8-10 Hz. sine wave. It lasted about 40 seconds, long enough > for me > to > > > go > > > > out into > > > > the back yard and try to figure out where it was coming from. It > was > not > > > > sharp or > > > > staccato, sounded like a clean sine wave. My seismometer, of > course > was > > > off > > > > at the > > > > time, but this seemed airborne rather than through the earth. I > could > not > > > > determine any > > > > direction; seemed to be coming from all around. Does any one have > any > > > ideas > > > > as to > > > > what this may have been ?? > > > > > > __________________________________________________________ > > > > > > Public Seismic Network Mailing List (PSN-L) > > > > > > To leave this list email PSN-L-REQUEST@.............. with > > > the body of the message (first line only): unsubscribe > > > See http://www.seismicnet.com/maillist.html for more information. > > > > > > __________________________________________________________ > > > > Public Seismic Network Mailing List (PSN-L) > > > > To leave this list email PSN-L-REQUEST@.............. with > > the body of the message (first line only): unsubscribe > > See http://www.seismicnet.com/maillist.html for more information. > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: stability of a Lehman From: "Charles R. Patton" charles.r.patton@........ Date: Tue, 19 Nov 2002 09:00:12 -0800 There have been numerous discussions about lengthening the period of a Lehman beyond the approximately 10 sec period and it becomes "unstable." The question is - unstable in what way? The period changes, the centering fails, sensitivity goes haywire? In particular, if the answer is, "The centering fails," does the center just move around, or does the beam "flop" to one side or the other? I'm doing some thought experiments during my long commute, and I'm thinking about the sources of error. In particular it's been mentioned before that the center of rotation changes on the flexible hinge designs. That's intuitive, but how much and in what direction - toward stability or instability? Has anybody figured out the actual path of the center of rotation for a typical Lehman? Crossed-X flex hinges were mentioned, but in this application with side force, I don't think they would be any less susceptible to the same de-centering. Another question is the upright's rigidity. Several pounds of weight at the end of a boom is a fair torque moment which is resisted by the spring constant of the 'pipe' (in the pipe constructed versions) vertical. How much does this constant vary with temperature in standard steel? Anyway, if there is an answer I should have looked up in the past posts, just flame me, but please include an approximate date and subject header I can go looking for! Thanks, Charles R. Patton __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: stability of a Lehman From: "Larry Cochrane" cochrane@.............. Date: Tue, 19 Nov 2002 16:18:09 -0800 Charles, Long period sensors like a Lehman are sensitive to ground tilt. The longer the period the more sensitive it is to tilt changes. What happens is the boom wonders around when the tilt of the ground changes. The changing of the position of the boom effects the sensitivity since the distance between the magnet and pickup coil changes over time. My Lehman has even more of a problem because it is sitting on a wood floor. Whenever the humidity changes I need to re adjust the sensor. At this point I have given up on my Lehman do to this problem. I just don't have the time to constantly monitor the sensor. To record teleseismic events I use my SG sensor and for local events either a geophone or accelerometer. Regards, Larry Cochrane Redwood City, PSN ----- Original Message ----- From: "Charles R. Patton" To: Sent: Tuesday, November 19, 2002 9:00 AM Subject: stability of a Lehman > There have been numerous discussions about lengthening the period of a > Lehman beyond the approximately 10 sec period and it becomes > "unstable." > > The question is - unstable in what way? The period changes, the > centering fails, sensitivity goes haywire? In particular, if the answer > is, "The centering fails," does the center just move around, or does the > beam "flop" to one side or the other? > > I'm doing some thought experiments during my long commute, and I'm > thinking about the sources of error. In particular it's been mentioned > before that the center of rotation changes on the flexible hinge > designs. That's intuitive, but how much and in what direction - toward > stability or instability? Has anybody figured out the actual path of the > center of rotation for a typical Lehman? Crossed-X flex hinges were > mentioned, but in this application with side force, I don't think they > would be any less susceptible to the same de-centering. > > Another question is the upright's rigidity. Several pounds of weight at > the end of a boom is a fair torque moment which is resisted by the > spring constant of the 'pipe' (in the pipe constructed versions) > vertical. How much does this constant vary with temperature in standard > steel? > > Anyway, if there is an answer I should have looked up in the past posts, > just flame me, but please include an approximate date and subject header > I can go looking for! > > Thanks, > Charles R. Patton > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Help with self leveling Lehman From: "Dewayne Hill" n0ssy@......... Date: Tue, 19 Nov 2002 19:03:50 -0700 I want to make my Lehman self leveling as it is in the crawl space and = I'm getting to the age I hate crawling on my hands and knees as I did when I was 3. What I have in mind, but need help with is to connect a common wire to = the base plate which in turn will also put the same electrical potential on the boom as my Lehman is = all metal. I want to insulate my boom stops from the base plate and connect a plus voltage to it and a = minus voltage to the other stop. When the boom touches one of the stops it will complete a circuit = that will activate a DC motor that in turn will driver one of my leveling screws a preset amount of = rotations or for X amount of time. What I need help with is a circuit to control the motor. I have read = that a step motor can have a controller that will control the number of rotations or steps and then stop. Can anyone Help? Regards, Dewayne Hill=20

I want to make my Lehman self leveling as it is in the crawl space = and I'm=20 getting to the age I hate

crawling on my hands and knees as I did when I was 3.

What I have in mind, but need help with is to connect a common wire = to the=20 base plate which in turn

will also put the same electrical potential on the boom as my Lehman = is all=20 metal. I want to insulate

my boom stops from the base plate and connect a plus voltage to it = and a=20 minus voltage to the other

stop. When the boom touches one of the stops it will complete a = circuit that=20 will activate a DC motor that

in turn will driver one of my leveling screws a preset amount of = rotations or=20 for X amount of time.

What I need help with is a circuit to control the motor. I have read = that a=20 step motor can have a controller

that will control the number of rotations or steps and then stop.

Can anyone Help?

Regards,

Dewayne Hill

Subject: Help with self leveling Lehman From: Kplblange@....... Date: Tue, 19 Nov 2002 21:52:41 EST I am not sending you any suggestions except to say that what you wish to do can be done but it will be very involved and you will need to crawl in the get it to work. I had a Lehman working some years ago and know what a time it is to have it stay in neutral. I wonder if I should have make a vertical one and have plans in an old Scientific American. The problem is that it needs springs that best would be make by a machine shop. They are not coil springs but flat pieces of metal. Ken from Gardena, CA __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Want a drum recorder From: Kplblange@....... Date: Tue, 19 Nov 2002 22:01:39 EST I do not wish to go to digital for several reason. I have the Lehman and used it for several years with a strip-chart recorder. The cost of ink and paper became prohibitive and I turned it off. I want to find a drum recorder and have had no success in finding a source. Can anyone help me? I can repair it bother mechanically and electrically. I think the seismic labs are phasing them out and I wonder where they are going. Ken in Gardena, CA __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Help with self leveling Lehman From: Thomas W Leiper twleiper@........ Date: Wed, 20 Nov 2002 00:54:38 -0500 Why don't you put a tank (half filled) of water on each side of the Lehman and use two little aquarium pumps to pump the water back and forth between them, thus shifting the floor slightly. You could then adjust the flow rate with a throttle valve to get the desired hysterisis, since you would want it to pump more water than that which was simply required to move off the "stops". Each one simply pumps from the bottom into the top of the other. A pair of chemical tanks for water conditioners would be cheap, have tight-fitting lids to eliminate evaporation, and, at 15 gal would weigh up to 120 lbs, which should be more than enough to do the job. No fancy circuitry, machining or vibrations to deal with. In addition, they would guard your sensitive detector from stray cosmic rays. Tom On Tue, 19 Nov 2002 19:03:50 -0700 "Dewayne Hill" writes: I want to make my Lehman self leveling as it is in the crawl space and I'm getting to the age I hate crawling on my hands and knees as I did when I was 3. What I have in mind, but need help with is to connect a common wire to the base plate which in turn will also put the same electrical potential on the boom as my Lehman is all metal. I want to insulate my boom stops from the base plate and connect a plus voltage to it and a minus voltage to the other stop. When the boom touches one of the stops it will complete a circuit that will activate a DC motor that in turn will driver one of my leveling screws a preset amount of rotations or for X amount of time. What I need help with is a circuit to control the motor. I have read that a step motor can have a controller that will control the number of rotations or steps and then stop. Can anyone Help? Regards, Dewayne Hill
Why don't you put a tank (half filled) of water on each side of the=20 Lehman
and use two little aquarium pumps to pump the water back and forth=20 between
them, thus shifting the floor slightly. You could then adjust the flow= rate=20 with
a throttle valve to get the desired hysterisis, since you would want = it to=20 pump
more water than that which was simply required to move off the "stops"= ..=20 Each
one simply pumps from the bottom into the top of the other. A pair of= =20 chemical
tanks for water conditioners would be cheap, have tight-fitting lids = to=20 eliminate
evaporation, and, at 15 gal would weigh up to 120 lbs, which should be= =20 more
than enough to do the job. No fancy circuitry, machining or = vibrations=20 to deal with.
In addition, they would guard your sensitive detector from stray = cosmic=20 rays.
 
Tom
 
On Tue, 19 Nov 2002 19:03:50 -0700 "Dewayne Hill" <n0ssy@.........> writes:

I want to make my Lehman self leveling as it is in the crawl space and= I'm=20 getting to the age I hate

crawling on my hands and knees as I did when I was 3.

What I have in mind, but need help with is to connect a common wire to= the=20 base plate which in turn

will also put the same electrical potential on the boom as my Lehman = is all=20 metal. I want to insulate

my boom stops from the base plate and connect a plus voltage to it and= a=20 minus voltage to the other

stop. When the boom touches one of the stops it will complete a = circuit=20 that will activate a DC motor that

in turn will driver one of my leveling screws a preset amount of = rotations=20 or for X amount of time.

What I need help with is a circuit to control the motor. I have read = that a=20 step motor can have a controller

that will control the number of rotations or steps and then stop.

Can anyone Help?

Regards,

Dewayne Hill

 
Subject: Re: Want a drum recorder From: Thomas W Leiper twleiper@........ Date: Wed, 20 Nov 2002 00:57:39 -0500 You might think about the strip recorder I made that uses adding machine paper and Scripto pens. Photos and a brief description are in my arcticle "Nice little seismo..." on the PSN Redwood City Web page. Tom On Tue, 19 Nov 2002 22:01:39 EST Kplblange@....... writes: > I do not wish to go to digital for several reason. I have the > Lehman and > used it for several years with a strip-chart recorder. The cost of > ink and > paper became prohibitive and I turned it off. > I want to find a drum recorder and have had no success in > finding a > source. Can anyone help me? I can repair it bother mechanically and > > electrically. I think the seismic labs are phasing them out and I > wonder > where they are going. > > Ken in Gardena, CA > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Help with self leveling Lehman From: meredithlamb meredithlamb@............. Date: Tue, 19 Nov 2002 23:08:30 -0700 Hi Dewayne, Ramsey Electronics "might" have what you want/need. They list a Stepper Motor Driver, and a DC Motor Speed Control, kit/s. They look to be complete, and I'd guess with minimum circuitry. One can also buy a chassis for the specific kit/s. http://www.ramseykits.com Click on Hobby Kits, and use the search there. I've not bought anything from them, so I can't really recommend them, but, they've been in business some 30 odd years or so. Their items would have to match up with what you have now, or, are comtemplating getting. Perhaps the bigger problem is just the motor and/or gears to be driven with? One would likely need a "harder to find" DC motor with a "high" gear speed reduction ratio attachment to where it can be somewhat controlled/limited. One might connect it all up, and simply drive a on/off switch while watching your SDR monitor I suppose. I'd think it would be rather very difficult to mechanically match it all up well. The motor activation itself might create so much sensor coil pickup noise from vibration, that the total effort/cost might all be counterproductive. If I vaguely remember (?), your unit/s sit on concrete pavers on bare soil? If so... the best (and strenuious) next thing is to actually make a solid concrete pier and house/insulate it. If its moderately well done, the number of adjustment trips should drop considerably. I had the same problem as you, but the vault/pier approach really helped alot here. The bigger the pier the less the ground water tilt overall. Insulation is also a must, the temperature effects do contribute to the metals expansion and contractions of the seismo/s. Take care, Meredith Dewayne Hill wrote: > I want to make my Lehman self leveling as it is in the crawl space and > I'm getting to the age I hate > > crawling on my hands and knees as I did when I was 3. > > What I have in mind, but need help with is to connect a common wire to > the base plate which in turn > > will also put the same electrical potential on the boom as my Lehman > is all metal. I want to insulate > > my boom stops from the base plate and connect a plus voltage to it and > a minus voltage to the other > > stop. When the boom touches one of the stops it will complete a > circuit that will activate a DC motor that > > in turn will driver one of my leveling screws a preset amount of > rotations or for X amount of time. > > What I need help with is a circuit to control the motor. I have read > that a step motor can have a controller > > that will control the number of rotations or steps and then stop. > > Can anyone Help? > > Regards, > > Dewayne Hill Hi Dewayne,

Ramsey Electronics "might" have what you want/need.  They
list a Stepper Motor Driver, and a DC Motor Speed Control,
kit/s.  They look to be complete, and I'd guess with minimum
circuitry.  One can also buy a chassis for the specific kit/s.

http://www.ramseykits.com

Click on Hobby Kits, and use the search there.  I've not
bought anything from them, so I can't really recommend them,
but, they've been in business some 30 odd years or so.  Their
items would have to match up with what you have now, or,
are comtemplating getting.

Perhaps the bigger problem is just the motor and/or gears
to be driven with?  One would likely need a "harder to find" DC
motor with a "high" gear speed reduction ratio attachment to
where it can be somewhat controlled/limited.  One might connect
it all up, and simply drive a on/off switch while watching your
SDR monitor I suppose.

I'd think it would be rather very difficult to mechanically match it
all up well.  The motor activation itself might create so much sensor
coil pickup noise from vibration, that the total effort/cost might all
be counterproductive.

If I vaguely remember (?), your unit/s sit on concrete pavers
on bare soil?  If so... the best (and strenuious) next thing is to
actually make a solid concrete pier and house/insulate it.  If
its moderately well done, the number of adjustment trips should
drop considerably.  I had the same problem as you, but the
vault/pier approach really helped alot here.  The bigger the pier
the less the ground water tilt overall.  Insulation is also a must,
the temperature effects do contribute to the metals expansion
and contractions of the seismo/s.

Take care, Meredith

Dewayne Hill wrote:

I want to make my Lehman self leveling as it is in the crawl space and I'm getting to the age I hate

crawling on my hands and knees as I did when I was 3.

What I have in mind, but need help with is to connect a common wire to the base plate which in turn

will also put the same electrical potential on the boom as my Lehman is all metal. I want to insulate

my boom stops from the base plate and connect a plus voltage to it and a minus voltage to the other

stop. When the boom touches one of the stops it will complete a circuit that will activate a DC motor that

in turn will driver one of my leveling screws a preset amount of rotations or for X amount of time.

What I need help with is a circuit to control the motor. I have read that a step motor can have a controller

that will control the number of rotations or steps and then stop.

Can anyone Help?

Regards,

Dewayne Hill

Subject: Re: Help with self leveling Lehman (vertical spring thought) From: meredithlamb meredithlamb@............. Date: Tue, 19 Nov 2002 23:25:22 -0700 Hi Ken, Perhaps a hacksaw blade/s might work (?) for your unspecified size flat spring material? I've read of some email mention in the past with such, but never tried it. Its not the best "spring" material, as it can be bent, but it can bend within some mechanical constraints and not get damaged. Even real spring material has its bending limits. Take care, Meredith Kplblange@....... wrote: > (Previous Clipped) I wonder if I should have make a vertical > one and have plans in an old Scientific American. The problem is that it > needs springs that best would be make by a machine shop. They are not coil > springs but flat pieces of metal. > > Ken from Gardena, CA> __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Help with self leveling Lehman From: "Larry Cochrane" cochrane@.............. Date: Tue, 19 Nov 2002 22:27:42 -0800 Meredith wrote: "Perhaps the bigger problem is just the motor and/or gears to be driven with? One would likely need a "harder to find" DC motor with a "high" gear speed reduction ratio attachment to where it can be somewhat controlled/limited." Jameco Electronics (www.jameco.com) has a reversible DC motor that has a speed of ~2 RPM. It as a 3000 to 1 gear head that is perfect for adjusting sensors. I use one on my SG sensor so I don't have to lift off the box to get to the leveling screw. The Jameco part number is 176049 and the cost is $18.95. I manually adjust my sensor my temporarily connecting up a 9 volt battery to the motor. -Larry Cochrane Redwood City, PSN __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Help with self leveling Lehman From: meredithlamb meredithlamb@............. Date: Wed, 20 Nov 2002 00:16:24 -0700 Hi all, The "worst possible helpful reality resolution" (ha), to frequent horizontal seismometer adjustments is to actually get down and dirty and make a large/thick isolated ground pier out of concrete and house it all with a surrounding insulated box/vault/building. For the "physical work allergic" members....I'd suggest you somehow get your wife, kids, (someone else) to do all the digging, mixing of concrete (yea....sure!!...."you say"...ha). Their will still be house influenced tilt when its made underneath such; even in loose soil, but it should yield considerably less need for set screw adjustments in the long term. I'd even suggest that the pier be made over thick insulation pliable plastic sheet/s, to keep the ground moisture/water out of the concrete pier itself. A surrounding covering "vault" thats well insulated will also help somewhat. I used to use concrete patio squares on loose dirt and that required several adjustments a week (for a horizontal). With the present "vault" and pier, its now ~ once a month. A vertical is not very influenced by "ground" tilt of course ...... but....they tend to be much more temperature sensitive, where a coiled or flat spring is involved....hence adding ALOT of insulation "R factor" is quite helpful. Without insulation and on a simple dirt/concrete paver, I used to have to adjust it ~ once a day.... but with a insulated vault, its ~ every 6 months or so. Take care, Meredith __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Help with self leveling Lehman From: ian@........... Date: Wed, 20 Nov 2002 09:23:25 +0000 (GMT) a few dimensions would help, width, length and depth of the peer. I hope to be making one in the next 6 months. Does the peer have to be the same size as the platform it supports all the way down or can it have a small circular cross section? TIA Ian Smith Quoting meredithlamb : > Hi all, > > The "worst possible helpful reality resolution" (ha), to frequent > horizontal seismometer adjustments is to actually get down and > dirty and make a large/thick isolated ground pier out of concrete > and house it all with a surrounding insulated box/vault/building. > > For the "physical work allergic" members....I'd suggest you > somehow get your wife, kids, (someone else) to do all the > digging, mixing of concrete (yea....sure!!...."you say"...ha). > > Their will still be house influenced tilt when its made > underneath such; even in loose soil, but it should yield > considerably less need for set screw adjustments in the long term. > > I'd even suggest that the pier be made over thick insulation > pliable plastic sheet/s, to keep the ground moisture/water > out of the concrete pier itself. A surrounding covering "vault" > thats well insulated will also help somewhat. I used to use > concrete patio squares on loose dirt and that required > several adjustments a week (for a horizontal). With the > present "vault" and pier, its now ~ once a month. > > A vertical is not very influenced by "ground" tilt of course ...... > but....they tend to be much more temperature sensitive, where a > coiled or flat spring is involved....hence adding ALOT of insulation > "R factor" is quite helpful. Without insulation and on a simple > dirt/concrete paver, I used to have to adjust it ~ once a day.... > but with a insulated vault, its ~ every 6 months or so. > > Take care, Meredith > > > > > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: stability of a Lehman From: "Frank Cooper" fxc@....... Date: Wed, 20 Nov 2002 03:36:46 -0600 Hi Charles and other PSN members, I think too much is being made of the "unstable" characteristics of the Lehman. Both of mine (T Max and Old Lehman) are set up in my garage with a sloping concrete floor. They are in the same garage with a washing machine and drier with only about six or eight feet separating them from my ham shack in a small garage room. They are next to the front garage door and only about 20 feet from a busy street. A car and a van park only about six feet from them. Foot traffic on the porch is several feet away. Here on the Gulf Coast of Texas (near Houston) our houses are constructed with concrete slabs resting on clay soil. All the houses in my subdivision have constant problems with concrete slabs that shift with each rain or dry period. Our sheet rock walls frequently crack and the wall corners shift and open for this reason. My modified Lehman has been in constant operation resting on my garage floor since January, 1997. After a heavy rain I have learned to check the pendulum to see if it is centered. If it is not, it only take me a few seconds to center it. I usually check it every night before going to bed to see if it needs centering. I have worked on my Old Lehman only once and that was to change the pendulum. It was producing a period of only 12 seconds or so. It had a pendulum with its end ground to a point that rested in a dimple of a steel bolt head. 12 seconds seemed to be the limit. Then along came John Cole with his ball bearing method. John lives only a few miles from me and he presented me with a polished bolt and a pendulum with a ball bearing inserted in one end. We changed the pendulum out to where the ball bearing rested on the polished bolt. I was able to immediately increase the period to about 18 seconds and after an adjustment or two the period has remained over 20 seconds. John recently presented me with his T Max detector which is a modified Lehman with a nickel chrome ball bearing resting upon a slightly convex nickel chrome polished steel surface at the lower pivot point. The upper suspension point has a nickel chrome ball bearing resting on a slightly convex polished nickel chrome surface. The nickel chrome steel convex surface is impervious to dimpling or scratching by the ball. The period of this instrument remains at 27 to 30 seconds. It is difficult to time the period exactly because the pendulum moves so slowly. I checked the pendulum tonight and it is still centered from 24 hours ago. If polishing a nickel chrome surface is too much trouble I suggest using the ball bearing with a polished bolt at the lower pivot point and fine piano wire at the upper suspension point. The Lehman is a simple instrument that produces great results (especially with a ball bearing pivot point) but the owner must devote a couple of minutes a day to keep the pendulum centered. I do not try to upload all the quakes I detect to PSN but there are enough posted for anyone to check how my simple sensors resting on a concrete garage floor with much nearby traffic produces results. Pictures and descriptions of my Lehman detectors are included in my web page at http://pages.prodigy.net/fxc/ May you keep your pendulum centered, Frank Cooper, Friendswood, Texas, USA ----- Original Message ----- From: Charles R. Patton To: Sent: Tuesday, November 19, 2002 11:00 AM Subject: stability of a Lehman > There have been numerous discussions about lengthening the period of a > Lehman beyond the approximately 10 sec period and it becomes > "unstable." > > The question is - unstable in what way? The period changes, the > centering fails, sensitivity goes haywire? In particular, if the answer > is, "The centering fails," does the center just move around, or does the > beam "flop" to one side or the other? > > I'm doing some thought experiments during my long commute, and I'm > thinking about the sources of error. In particular it's been mentioned > before that the center of rotation changes on the flexible hinge > designs. That's intuitive, but how much and in what direction - toward > stability or instability? Has anybody figured out the actual path of the > center of rotation for a typical Lehman? Crossed-X flex hinges were > mentioned, but in this application with side force, I don't think they > would be any less susceptible to the same de-centering. > > Another question is the upright's rigidity. Several pounds of weight at > the end of a boom is a fair torque moment which is resisted by the > spring constant of the 'pipe' (in the pipe constructed versions) > vertical. How much does this constant vary with temperature in standard > steel? > > Anyway, if there is an answer I should have looked up in the past posts, > just flame me, but please include an approximate date and subject header > I can go looking for! > > Thanks, > Charles R. Patton > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Specific questions relative to \"Digital Digital Analisis of Seismic Data\" From: Cristian Haulica cristianhaulica@....... Date: 20 Nov 2002 10:46:22 -0000 As well said Mauro Mariotti, here are some specific questions: I am interested in algorithms and open source projects in: 1: The detection of P & S waves. 2: The mathematical functions for: a: determining the distance to epicenter from the time difference between P & S waves. b: determining the magnitude of the earthquake. c: determining the actual time of the begining of the earthquake (at the epicenter). d: determining the magnitude at the epicenter. etc. Note: I could found only graphics, dubious function , discrete values or inverse founctions (relative to what I needed) My project itends to get a minimum amounth of basical earthquake data from a horisontal Lehman pendulum recordings. Note that I am a Computer science student and seismology isn't my strong point (yet ;) ). If someone nows some sites where i can find such data please reply. Regards CristianH. ---- Home, no matter how far... http://www.home.ro __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Want a drum recorder From: CapAAVSO@....... Date: Wed, 20 Nov 2002 09:37:47 EST In a message dated 11/20/02 3:01:56 AM GMT Standard Time, Kplblange@....... writes: > I do not wish to go to digital for several reason. I have the Lehman and > > used it for several years with a strip-chart recorder. The cost of ink and > > paper became prohibitive and I turned it off. > I want to find a drum recorder and have had no success in finding a > source. Can anyone help me? I can repair it bother mechanically and > electrically. I think the seismic labs are phasing them out and I wonder > where they are going. Hi Ken, I have two Sprengnether drums brand new in the box, never been unpacked. You can have one of these for $50 if you will pay the shipping charges. They are packed in the original wooden crates by Sprengnether and ready to ship. They are the top-of-the line Sprengnether drums only. You will have to mount a pen motor on them and a pen. You can then scotch tape a piece of plain paper onto the drum to make a classic analog seismogram. Alternatively you could run the drum with photosensitive paper that Sprengnether designed them to use. The manual and the optics and everything you need to do this is packed in the crate with the drum. It consists of a beautiful very sensitive galvanometer that reflects a light beam onto the photosensitive paper to draw the line. The galvanometer is sensitive enough to record the seismic signal directly from a seismometer without an amplifier. The output of your Lehman would probably drive it without amplification. Best regards, Cap (Casper Hossfield.......New Jersey) In a message dated 11/20/02 3:01:56 AM GMT Standard Time, Kplblange@....... writes:


    I do not wish to go to digital for several reason. I have the Lehman and
used it for several years with a strip-chart recorder.  The cost of ink and
paper became prohibitive and I turned it off.
    I want to find a drum recorder and have had no success in finding a
source. Can anyone help me? I can repair it bother mechanically and
electrically. I think the seismic labs are phasing them out and I wonder
where they are going
.


Hi Ken,

I have two Sprengnether drums brand new in the box, never been unpacked. You can have one of these for $50 if you will pay the shipping charges. They are packed in the original wooden crates by Sprengnether and ready to ship. They are the top-of-the line Sprengnether drums only. You will have to mount a pen motor on them and a pen. You can then scotch tape a piece of plain paper onto the drum to make a classic analog seismogram. Alternatively you could run the drum with photosensitive paper that Sprengnether designed them to use. The manual and the optics and everything you need to do this is packed in the crate with the drum. It consists of a beautiful very sensitive galvanometer that reflects a light beam onto the photosensitive paper to draw the line. The galvanometer is sensitive enough to record the seismic signal directly from a seismometer without an amplifier. The output of your Lehman would probably drive it without amplification.

Best regards,
Cap
(Casper Hossfield.......New Jersey)

Subject: Re: Want a drum recorder From: Kplblange@....... Date: Wed, 20 Nov 2002 10:19:20 EST Cap, so good to hear from you on the drum record. Sounds as if that is just what I want. I confess I know little about the drum recorders. I have only seen them from a distance. Saw one at San Juan Batista near the mission and almost sitting on the San Andreas Fault! Have seen them working at Griffith Observatory, too. Tell me, is there the feature where tick marks are put ever minute or so? Also, what about ink supply? You mention the pens. As for the assembly, no problem. Do you have an idea about shipping costs? I do not see that as a factor and I almost surely want to buy one of them. Ken in Gardena, CA __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Help with self leveling Lehman From: CapAAVSO@....... Date: Wed, 20 Nov 2002 10:30:52 EST In a message dated 11/20/02 2:51:37 AM GMT Standard Time, Kplblange@....... writes: > I had a Lehman working some years ago and know what a time > it is to have it stay in neutral. I wonder if I should have make a > vertical > one and have plans in an old Scientific American. The problem is that it > needs springs that best would be make by a machine shop. They are not coil > springs but flat pieces of metal. > > Ken from Gardena, CA Hi Ken, A good flat spring is the one Sean-Thomas used in his leaf spring seismometer. I bought one of these, a plasterer's 14" spackling trowel for about $20 at Home Depot and removed the handle by drilling out the rivets. This gave me a 0.025" thick flat spring 4" by 14" which I mounted vertically and bent over 90 degrees with a lead weight so the free end was horizontal. An outrigger carried a coil from a 120-Volt relay that dipped between the poles of a big Alnico magnet to generate a signal voltage. A flat sheet of copper 4" X 4" farther out on the outrigger sandwiched between eight flat ceramic magnets provided critical damping and enough additional weight to give a period of about 1 1/4 seconds. With one of Dave Saum's amp/filters there was more than enough sensitivity to record microseisims continuously even on quiet days. Cap (Casper Hossfield) In a message dated 11/20/02 2:51:37 AM GMT Standard Time, Kplblange@....... writes:


I had a Lehman working some years ago and know what a time
it is to have it stay in neutral.  I wonder if I should have make a vertical
one and have plans in an old Scientific American. The problem is that it
needs springs that best would be make by a machine shop. They are not coil
springs but flat pieces of metal.

Ken from Gardena, CA


Hi Ken,

A good flat spring is the one Sean-Thomas used in his leaf spring seismometer. I bought one of these, a plasterer's 14" spackling trowel for about $20 at Home Depot and removed the handle by drilling out the rivets. This gave me a 0.025" thick flat spring 4" by 14" which I mounted vertically and bent over 90 degrees with a lead weight so the free end was horizontal. An outrigger carried a coil from a 120-Volt relay that dipped between the poles of a big Alnico magnet to generate a signal voltage. A flat sheet of copper 4" X 4" farther out on the outrigger sandwiched between eight flat ceramic magnets provided critical damping and enough additional weight to give a period of about 1 1/4 seconds. With one of Dave Saum's amp/filters there was more than enough sensitivity to record microseisims continuously even on quiet days.

Cap
(Casper Hossfield)
Subject: Re: Self leveling and about spurious noise From: Kplblange@....... Date: Wed, 20 Nov 2002 11:45:19 EST Tom that suggestion of yours to use water tanks is great. It will not work in my setup due to a lack of space but it is a good idea. My seismo has been off for years but may soon be going again. I find so much on our web and pleased I found it. When I had it going I was bothered with spurious responses. Many times the trace was one quarter inch peak to peak. I think it was because I am seven miles from the Pacific at Manhattan Beach, CA. I have read that waves cause a shift for miles. Any ideas on that? I have made a rough calculation of how much the sift was but didn't keep the figures and not sure if all was valid. Ken __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Want a drum recorder From: CapAAVSO@....... Date: Wed, 20 Nov 2002 11:54:21 EST In a message dated 11/20/02 3:19:59 PM GMT Standard Time, Kplblange@....... writes: > > Tell me, is there the feature where tick marks are put ever minute or > so? > Also, what about ink supply? You mention the pens. As for the assembly, no > > problem. > Do you have an idea about shipping costs? I do not see that as a factor > > and I almost surely want to buy one of them. > > Ken in Gardena, CA Hi Ken, You will have to generate your own tick marks. I did this on a "Geotech" drum I converted to pen and ink. I used an ordinary quartz kitchen clock. I glued a little piece of aluminum foil on the second hand and mounted an infra red diode and a photo transistor side by side on the face of the clock. Once each minute the second hand reflector jumped under these for exactly one second and reflected the infrared into the phototransistor to generate a current that closed a relay mechanically connected to the pen so it lifted the pen off the paper putting a 1-second gap in the trace every minute. The pen was the tip assembly of a "Rapidograph" drawing pen that held enough ink to last 24 hours which was how often the paper recording had to be changed. Each morning I checked the clock error against WWV and marked it on the starting edge of the recording. The error was pretty consistent at loosing about four tenths of a second/day. This was back in ~1990 and I was able to time the first impulse usually to with a few tenths of a second for USGS as station TXNY in Tuxedo, NY. I will ship it by "Yellow Freight" because I can take the crate to their main terminal which is nearby and save some $$s. The weight is marked on the crate as 192 pounds which I would guess might cost somewhere in the neighborhood of 200-300 dollars from New jersey to California. If you will give me your zip code I'll get an exact price. Regards, Cap (Casper Hossfield.....New Jersey) ------------------------------------------------------------------- Original Message: Cap, so good to hear from you on the drum record. Sounds as if that is just what I want. I confess I know little about the drum recorders. I have only seen them from a distance. Saw one at San Juan Batista near the mission and almost sitting on the San Andreas Fault! Have seen them working at Griffith Observatory, too. Tell me, is there the feature where tick marks are put ever minute or so? Also, what about ink supply? You mention the pens. As for the assembly, no problem. Do you have an idea about shipping costs? I do not see that as a factor and I almost surely want to buy one of them. Ken in Gardena, CA __________________________________________________________ In a message dated 11/20/02 3:19:59 PM GMT Standard Time, Kplblange@....... writes:



    Tell me, is there the feature where tick marks are put ever minute or so?
Also, what about ink supply? You mention the pens.  As for the assembly, no
problem.
    Do you have an idea about shipping costs? I do not see that as a factor
and I almost surely want to buy one of them.

Ken in Gardena, CA


Hi Ken,

You will have to generate your own tick marks. I did this on a "Geotech" drum I converted to pen and ink. I used an ordinary quartz kitchen clock. I glued a little piece of aluminum foil on the second hand and mounted an infra red diode and a photo transistor side by side on the face of the clock. Once each minute the second hand reflector jumped under these for exactly one second and reflected the infrared into the phototransistor to generate a current that closed a relay mechanically connected to the pen so it lifted the pen off the paper putting a 1-second gap in the trace every minute. The pen was the tip assembly of a "Rapidograph" drawing pen that held enough ink to last 24 hours which was how often the paper recording had to be changed. Each morning I checked the clock error against WWV and marked it on the starting edge of the recording. The error was pretty consistent at loosing about four tenths of a second/day. This was back in ~1990 and I was able to time the first impulse usually to with a few t enths of a second for USGS as station TXNY in Tuxedo, NY.

I will ship it by "Yellow Freight" because I can take the crate to their main terminal which is nearby and save some $$s. The weight is marked on the crate as 192 pounds which I would guess might cost somewhere in the neighborhood of 200-300 dollars from New jersey to California. If you will give me your zip code I'll get an exact price.

Regards,
Cap
(Casper Hossfield.....New Jersey)
-------------------------------------------------------------------     
Original Message:

Cap, so good to hear from you on the drum record.  Sounds as if that is
just what I want. I confess I know little about the drum recorders.  I have
only seen them from a distance. Saw one at San Juan Batista near the mission
and almost sitting on the San Andreas Fault!  Have seen them working at
Griffith Observatory, too.
    Tell me, is there the feature where tick marks are put ever minute or so?
Also, what about ink supply? You mention the pens.  As for the assembly, no
problem.
    Do you have an idea about shipping costs? I do not see that as a factor
and I almost surely want to buy one of them.

Ken in Gardena, CA
__________________________________________________________
Subject: Re: Want a drum recorder From: Kplblange@....... Date: Wed, 20 Nov 2002 12:04:44 EST Cap, I terribly sorry to say that because of the tremendous weight I decline to continue with the transaction. I am alone and while I could get someone to help, do not wish to do so. I am amazed that the unit is that heavy. I would have problems getting it in place and not sure how that would be handled. Thanks for your effort. Ken __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Want a drum recorder From: CapAAVSO@....... Date: Wed, 20 Nov 2002 12:25:11 EST In a message dated 11/20/02 5:05:50 PM GMT Standard Time, Kplblange@....... writes: > Cap, I terribly sorry to say that because of the tremendous weight I decline > > to continue with the transaction. I am alone and while I could get someone > > to help, do not wish to do so. I am amazed that the unit is that heavy. I > > would have problems getting it in place and not sure how that would be > handled. > Thanks for your effort. > Ken The problem is Sprengnether makes things too good. They are built like a battleship. I have another one unpacked and just the drum alone is over 100 pounds and to heavy for an old man like me to lift. Geotech also builds stuff too strong and heavy for me to lift their drum. These things cost thousands of dollars when they are new and are built to last forever I guess. Cap In a message dated 11/20/02 5:05:50 PM GMT Standard Time, Kplblange@....... writes:


Cap, I terribly sorry to say that because of the tremendous weight I decline
to continue with the transaction.  I am alone and while I could get someone
to help, do not wish to do so.  I am amazed that the unit is that heavy.  I
would have problems getting it in place and not sure how that would be
handled. 
    Thanks for your effort.
Ken


The problem is Sprengnether makes things too good. They are built like a battleship. I have another one unpacked and just the drum alone is over 100 pounds and to heavy for an old man like me to lift. Geotech also builds stuff too strong and heavy for me to lift their drum. These things cost thousands of dollars when they are new and are built to last forever I guess.

Cap
Subject: Re: Help...(Building a pier) From: meredithlamb meredithlamb@............. Date: Wed, 20 Nov 2002 12:40:21 -0700 Hi Ian, For myself and likely for you, alot about making a pier/s depends on you; how much you can do or want, your space, your soil/rock underneath, picking a "quiet" location away from most upstairs traffic/tilt/furnace/washer/dryer, away from too much water moisture seeping in, running in the signal/power lines and with consideration of whether you can physically do it all. Only the individual can estimate/acquire/judge their specific plus's and minus's of their location for making their own piers of course. As for your specific pier dimensions question....it depends on what you plan to have or have in your possession now. Of course the pier has to be a greater size (width/length) than any seismo you have or is planned for. Mine are rectangular, but I see no problem with round piers....they might be better. Generally I would say the bigger the better. As for thickness, I'd give at least 6" if possible....the thicker pier would be less prone to cracking from environmental influences and weight put upon it....you've likely be standing/kneeling on it occasionally. Another important thought to add to the mix of questions....is whether you want more than one pier per instrument you have or are planning for. I made 3 piers, but now wish I'd made more. However, it "maybe" possible to share one pier with more than one instrument...another consideration as too the size of the pier. It may also be evident with multiple piers, that you find that certain piers are more susceptible to tilt than others you have...I'd put the vertical/s atop the more susceptible tilting pier and the horizontals atop the more stable ones in time. Assuming you survey your available area....the next step would be to do a test dig in your soil. If the soil is real loose, how far down does it become more compacted than it was on top? If its loose no matter how far down you go....you may have to settle for that depth. If you run into a water seepage pothole, thats not good. If you run into solid rock, thats great; as its about the best foundation you can have. Of course, the height of your seismo/s is another consideration to plan for, and also the available anticipated height of your pier from the underside of the house, just for clearance. Their is alot to consider overall. Another problem might be whether you want a solid poured concrete pier or have to improvise with paving blocks and brick mortar. If space for movement is limited, or its physically too difficult to mix concrete under your house or move such, you may have to be forced to choose between the two. One can only do whats possible in the end for their circumstances. Adding to the above.....is the likely necessity of enclosing your piers with a wall/box, and adding any insulation to try to limit any gross environmental temperature excursions you may have. Insulation does help alot. I ended up with a rough R42 value, except for the ground area....its the coolest place I have even in high temp summer conditions. The vault floor is double covered with flexible plastic layers, to keep water/moisture out; and it works well...no rust either that I've noted on the seismos and misc iron/steel tools/parts therein for some ~7 years of use. I don't use any electric heating or temp control; all the heavy insulation seems relatively temperature consistant and/or very slow changing over time....a real help. So....there is alot to mentally "chew on", or plan or inspect for. Take care, Meredith ian@........... wrote: > a few dimensions would help, width, length and depth of the peer. I hope to be > making one in the next 6 months. Does the peer have to be the same size as the > platform it supports all the way down or can it have a small circular cross > section? > > TIA > > Ian Smith > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: stability of a Lehman From: john c cole johnccole3@........ Date: Wed, 20 Nov 2002 14:05:33 -0600 Larry, in response to your message sent to Charles about the stability of the Lehman detector. In support of the stability of the Lehman or modified lehman detector , here is what i do. I have one detector set up at approximately 20 stable seconds and it has been running for over two years .It is housed in a 8'x8' utility building on a concrete slab. It requires only a minimum of adjustments. I have another modified Lehman detector set up on a concrete slab in a bigger storage building that is run at over 30 stable seconds with a minimum and acceptable amount of adjustments . This detector has both upper and lower ball bearing pivot points . If the Lehman detector is constructed on a good solid base and is set up in a fair location then, it will have acceptable stability. As a rule , i do not post to PSN the data from these detectors but from time to time i do post from experimental detectors . I know of more than a few amateur seismologist that are using the Lehman or modified Lehman and are posting to PSN on a regular basis. JC PS, Larry , you of all people should know better than to try to set up and run a seismic detector on a wood floor. Take care .JOHN ________________________________________________________________ Sign Up for Juno Platinum Internet Access Today Only $9.95 per month! Visit www.juno.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Want a drum recorder From: Thomas W Leiper twleiper@........ Date: Wed, 20 Nov 2002 17:47:38 -0500 I'll take the other one for $100... I can pick it up when I am down in South Jersey tomorrow or Friday. Tom On Wed, 20 Nov 2002 09:37:47 EST CapAAVSO@....... writes: I have two Sprengnether drums brand new in the box, never been unpacked. You can have one of these for $50...
I'll take the other one for $100... I can pick it up when
I am down in South Jersey tomorrow or Friday.
 
Tom
 
On Wed, 20 Nov 2002 09:37:47 EST CapAAVSO@....... writes:
I have two Sprengnether = drums brand=20 new in the box, never been unpacked. You can have one of these for=20 $50...
Subject: Re: Want a drum recorder From: CapAAVSO@....... Date: Wed, 20 Nov 2002 18:49:37 EST In a message dated 11/20/02 10:49:06 PM GMT Standard Time, twleiper@........ writes: > I'll take the other one for $100... I can pick it up when > I am down in South Jersey tomorrow or Friday. Hi Tom, Good. Its yours for $50 because I am glad to find a good home for it. It's in my son's barn so you should make arrangements with him to pick it up. His name is Bill Hossfield and his address is 935 Warwick Turnpike, Vernon, New Jersey. Call him at 973 853 9053 and email him at << hosfield@................ >> to get directions and make arrangements. Good luck with it, Cap In a message dated 11/20/02 10:49:06 PM GMT Standard Time, twleiper@........ writes:


I'll take the other one for $100... I can pick it up when
I am down in South Jersey tomorrow or Friday
.


Hi Tom,

Good. Its yours for $50 because I am glad to find a good home for it. It's in my son's barn so you should make arrangements with him to pick it up. His name is Bill Hossfield and his address is 935 Warwick Turnpike, Vernon, New Jersey. Call him at 973 853 9053 and email him at <<  hosfield@................  >> to get directions and make arrangements.

Good luck with it,
Cap

Subject: Stability of a Lehman From: ChrisAtUpw@....... Date: Wed, 20 Nov 2002 19:27:11 EST Hello Charles Patton, >> There have been numerous discussions about lengthening the period of a Lehman beyond the approximately 10 sec period and it becomes "unstable." Let's consider a 'big' 1 metre length boom. The 'natural' period is 2 seconds, so to get a period of 10 sec, we have to reduce g to g/25. This corresponds to about 2.3 degrees off the vertical, lowering the mass by 40 mm below the horizontal. To get 20 sec, we need 0.56 degrees. To get 30 sec we need 0.255 deg.... x60 = 15.3 minutes of arc.... This corresponds to lowering the mass 4.44 mm below the horizontal position, roughly 175 thou. Now lets consider a small 25 cm boom, with a natural period of 1 sec. To get a period of 10 sec, we now have to reduce g to g/100. This corresponds to 0.573 degrees off the vertical, lowering the mass by 2.5 mm below the horizontal. To get to 20 sec, we need an angle of 0.143 deg. To increase the period to 30 sec, we need an angle of 0.0637 degrees, 3.8 minutes of arc, lowering the mass by 0.28 mm below the horizontal, roughly 11 thou. This requires considerable precision. The best that I can easily get with differential thread supports is ~10 thou per turn. >> The question is - unstable in what way? The period changes, the centring fails, sensitivity goes haywire? In particular, if the answer is, "The centring fails," does the centre just move around, or does the beam "flop" to one side or the other? You name it.... With the small suspension angles, a Lehman is very sensitive to tilt effects. The support needs to be very rigid. With very small restoring forces, like g/900, the response becomes sensitive to any frictional and springy effects in the suspension. The original Lehmans had a knife edge suspension. Some even had a point suspension. The forces in these suspensions are high enough to cause deformation of the contact points / edges. This can give an erratic response such that no two successive swings are similar. This can be avoided by using either rolling contacts, either a sphere on a flat, or a cylinder on a crossed cylinder, or by using flexing wire or foil suspensions. >> I'm doing some thought experiments during my long commute, and I'm thinking about the sources of error. In particular it's been mentioned before that the centre of rotation changes on the flexible hinge designs. That's intuitive, but how much and in what direction - toward stability or instability? Has anybody figured out the actual path of the centre of rotation for a typical Lehman? In the single foil / wire hinge of the 'Cardan' type, the material must not be so highly stressed that it can take on a permanent 'set'. The centre of rotation will be quite close to the frame clamps. You can get erratic effects with foils 'crinkling' if the two axes are not quite in line or not parallel. With the crossed foil hinges clamped onto the edges of a plate, the flex axis moves in an ellipse. Both of these types have a small spring effect. In the zero force rolling contact type where the foil is essentially wrapped in a figure of 8 around two cylinders, the flex axis moves in a circle. The centres of rotation will be at the centres of these curves. >> Crossed-X flex hinges were mentioned, but in this application with side force, I don't think they would be any less susceptible to the same de-centering. I would expect crossed foil hinges to be ~completely rigid. >> Another question is the upright's rigidity. Several pounds of weight at the end of a boom is a fair torque moment which is resisted by the spring constant of the 'pipe' vertical. How much does this constant vary with temperature in standard steel? From memory, Young's modulus varies by about -2x10^-4 / C Deg. for steel. While this is not a lot, you don't need a lot to change the period or upset the balance. Professional seismometers of this type use a braced upright post. Bracing the upright with either more tube or with L angle would tend to prevent flexing problems. The orientation of the horizontal arm needs to be rigid and any resonances in the system should be suppressed. Some quick calculations suggest that direct thermal expansion effects on the suspension are not very large. Hope that this helps. Regards, Chris Chapman __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: A jewelry "slinky" spring earring, with vertical potential? From: meredithlamb meredithlamb@............. Date: Wed, 20 Nov 2002 19:57:27 -0700 Hi all, I noted in a local K-Mart store, in the jewelry section, that there is a display hangup card with what appears to be a miniture "slinkey" spring in various sprayed on (bizarre)colors. The spring in its natural compressed state looks to be ~ 1" outside diameter and ~ 1.5" long....with other "junk" connection metal attached. It stretches quite easily and looks to be quite similar to the much larger (and very old) Slinkey spring toy from "yesteryear". It stretches out some 6-8 inches. I guess it was somehow "adopted" for a large "earring". My best local hardware store has a big spring variety, but nothing like this particular shape/size. In short....it "could" make a small weight mass vertical spring. Two might allow more added mass weight. Nope, I wasn't there for myself, my wife was looking at jewelry.....ha. No, I don't remember the brand, or "theme". I also didn't have the presense of mind to tell the wife how beautiful they would be on her.....and later get her items for myself to tear apart! So....take your wife....errr...Christmas shopping....to a K-Mart store guys...she can pick the color out. Get at least three "springs/earrings"...one for each ear and a "spare"....in case one is somehow lost you know.... One might as well have something to look forward too when otherwise this "shopping" is a real drag. Just don't get too enthusiastic if you bring up the shopping binge thing....women have a way of getting carried away with jewelry. Of course, as a last resort you could risk telling the truth; otherwise she might look at you rather strangely. BTW, this is all very confidential information from a "secret" source. Take care, "X" __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: stability of a Lehman From: "Rolando Benitez" rbenitez@........ Date: Wed, 20 Nov 2002 23:43:14 -0600 Charles, I have two modified Lehman derivative sensors, both made by John C. Cole, one is a Mini-Lehman with a stable pendulum period of 14 seconds, it has the ball bearing/flat surface mountings, the other is a Tmax with a stable period of 32 seconds, it has the roller bearings supports. I check them once a week and the last time I have to "center" the Mini, was about 4 months ago. I am currently tuning/playing with the Tmax but it remains centered if I do nothing with it. You can check their performance by the results posted at the PSN web page. I am fortunate enough to have local quakes all the time, because living in an active area as Central America, there is no single day without an event. Besides I have 1 of the 10 most active volcanoes 16 miles away, so my sensors detect high freq events as close as they can be and as far as the recent 14k Km away, in Asia. The Mini starts "flopping" at 20 seconds, and the Tmax at around 36 seconds. You can take a look at pictures and details at John Cole's web page at http://pages.prodigy.net/fxc/JC.html and at Frank Cooper's at http://pages.prodigy.net/fxc/. Hope this helps. Best regards from Fraijanes, Guatemala. Rolando ... ... ... __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Another horizontal boom/mast pivot to consider From: meredithlamb meredithlamb@............. Date: Thu, 21 Nov 2002 00:59:39 -0700 Hi all, With all the discussion on a horizontal boom/mast pivot, it might be alot simpler to use/make another type mentioned in the past emails. Its based on the Sprengnether horizontals general design and has been "revised" for use by John Lahr on his horizontal; but it essentially is the same type pivot. See the 5th photo/diagram down from the top of this web page: http://www.jjlahr.com/science/psn/gldn_psn.html For other views of the same hinge, See the 2nd & 4th photos down on this web page: http://www.geocities.com/meredithlamb/page022.html The Sprengnether shown beside/with Johns seismo, in the other same page photos uses the same basic pivot....only laid out mechanically alittle differently. I think its one of the best pivot innovations I know of, and most ingenious of John to come up with the variation. Theres probably about zero long term problems with this conpared to other pivot designs. Its frictionless as John describes in his text. Take care, Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: stability of a Lehman From: john c cole johnccole3@........ Date: Thu, 21 Nov 2002 11:50:23 -0600 Rolando, when our more educated comrades write to PSN i feel somewhat inferior because they speak with the utmost authority and speak well . A simple carpenter like myself would not dare challenge their authority . I am sure that they have total knowledge of all things pertaining to seismology. However , when checking all postings world wide i find little or no evidence in their postings to PSN to confirm this . Some of our fellow travelers must be using sophisticated professional equipment . but, is not reflected in their postings . It is common and un disputed knowledge that the best that any home made long period detector will do is 8 seconds . A Lehman even when run at that time is somewhat unstable and is not to be considered a serious instrument. I challenge that assumption . For the second time in recent weeks the opportunity has presented itself to promote the convex to convex theory of suspension . This idea is the brain child of Mr AL Hrubetz of Dallas ,TX. If your detectors work well or do not work well the blame or credit should go to him because it was his original idea .Yes, it is true that i made the gun that did the ghastly deed but , he was the instigator. I know little of legal matters but, i believe that makes him and not me responsible . Seriously, the convex to convex suspension method should become common knowledge for all the beginning amateur seismologist. When discussing this thing , please leave my name out of it . I have nothing to sell or gain . MY one and only motive is to give the amateur seismologist a decent ,economical and simple seismic detector to use . Rolando , your response to PSN was absolutely beautiful and made the point about as good as it could have been made but,with one exception . . My name should have been omitted . I want no credit or recognition and i am sure that goes for Al also. You did a wonderful thing for amateur seismology today Rolando . This was your finest hour. JC And yes, i feel real good . How sweet it is . PPS, All responsibility should rest with Frank Cooper,he got me hooked on this stuff . ________________________________________________________________ Sign Up for Juno Platinum Internet Access Today Only $9.95 per month! Visit www.juno.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Another horizontal boom/mast pivot to consider From: CapAAVSO@....... Date: Fri, 22 Nov 2002 11:34:51 EST In a message dated 11/21/02 8:01:16 AM GMT Standard Time, meredithlamb@............. writes: > With all the discussion on a horizontal boom/mast pivot, it > might be alot simpler to use/make another type mentioned in > the past emails. Its based on the Sprengnether horizontals > general design and has been "revised" for use by John Lahr > on his horizontal; but it essentially is the same type pivot. > .............I think its one of the best pivot innovations I know of, > and most ingenious of John to come up with the variation. > Theres probably about zero long term problems with this > conpared to other pivot designs. Its frictionless as > John describes in his text. Hi Meridith You don't have to be an engineer to realize friction in the lower pivot of a Lehman will decrease its sensitivity. Lehman I'm sure was aware of that but he was designing a simple instrument for amateurs that was good enough to get started. The point-in-a -dimple bottom pivot will always have some stick-slip friction which will interfere with its sensitivity to small earthquake movements. if you replace the point with a ball its rolling friction is less but nevertheless there will still be small residual stick-slip friction. John Lahr's completely frictionless Sprengnether type wire-under-tension pivot is much better than ball bearings and just as easy, if not easier to make, and it stays put rather than slithering around like ball bearings. I use John Lahr's system with 0.008" music wire, obtainable from any music store, and it shows the finest detail in the microseisms if I turn up the gain. However, and this is important, even with frictionless pivots my Lehman is unstable over time unless I set its period for about 10-15 seconds. I doubt anyone can do much better with ball bearing pivots unless they are on bed rock and even then I don't see how they could possibly get month's-long stability at 30-40 second periods as has been claimed in recent postings. My guess is what these people actually have are strong-motion detectors rather than the Lehmans they think they have. Best regards, Cap In a message dated 11/21/02 8:01:16 AM GMT Standard Time, meredithlamb@............. writes:


With all the discussion on a horizontal boom/mast pivot, it
might be alot simpler to use/make another type mentioned in
the past emails.  Its based on the Sprengnether horizontals
general design and has been "revised" for use by John Lahr
on his horizontal; but it essentially is the same type pivot.
..............I think its one of the best pivot innovations I know of,
and most ingenious of John to come up with the variation.
Theres probably about zero long term problems with this
conpared to other pivot designs.  Its frictionless as
John describes in his text.


Hi Meridith

You don't have to be an engineer to realize friction in the lower pivot of a Lehman will decrease its sensitivity. Lehman I'm sure was aware of that but he was designing a simple instrument for amateurs that was good enough to get started. The point-in-a -dimple bottom pivot will always have some stick-slip friction which will interfere with its sensitivity to small earthquake movements. if you replace the point with a ball its rolling friction is less but nevertheless there will still be small residual stick-slip friction. John Lahr's completely frictionless Sprengnether type wire-under-tension pivot is much better than ball bearings and just as easy, if not easier to make, and it stays put rather than slithering around like ball bearings. I use John Lahr's system with 0.008" music wire, obtainable from any music store, and it shows the finest detail in the microseisms if I turn up the gain. However, and this is important, even with frictionless pivots my Lehman is unstable over time unless I set its period for about 10-15 seconds. I doubt anyone can do much better with ball bearing pivots unless they are on bed rock and even then I don't see how they could possibly get month's-long stability at 30-40 second periods as has been claimed in recent postings. My guess is what these people actually have are strong-motion detectors rather than the Lehmans they think they have.

Best regards,
Cap
Subject: Did quark matter strike Earth? (BBC News) From: George Bush ke6pxp@....... Date: Fri, 22 Nov 2002 09:14:13 -0800 Hello- I just ran across this intersting article on the BBC news. It links two of my interests together, space and geology: http://news.bbc.co.uk/1/hi/sci/tech/2502755.stm I wonder if our PLA network could continue looking for these anamolous events? George __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Another horizontal boom/mast pivot to consider From: "Frank Cooper" fxc@....... Date: Fri, 22 Nov 2002 13:50:43 -0600 OK Cap as a member of the "these people" or the "they" ball bearing = party, I'll bite, I'll respond even though I think your purpose is to have a little fun = and stir the pot a bit. Perhaps we take ourselves too seriously at times = since "we" all enjoy and are all engaged in a very interesting HOBBY. I = have to differ with you on a couple of statements in your recent = postings. You say "John Lahr's completely frictionless Sprengnether = type wire-under-tension pivot is much better than ball bearings and just = as easy, if not easier to make, and it stays put rather than slithering = around like ball bearings." Have you ever used the ball bearing method? I assume you must speak = from long experience to back-up your slithering ball bearing = pronouncement. I have been using a ball bearing at the pivot point of = my Lehman pendulum for years and it has not "slithered around" once. = But perhaps I should only "claim." Maybe you also have long experience = in maintaining a 30 second period with a modified ball bearing Lehman. = However, that must not be the case since you say "I don't see how they = could possibly get month's-long stability at 30-40 second periods as has = been claimed in recent postings." My only suggestion is to try it --- = you might like it and become "one of these people."=20 And you say "My guess is what these people actually have are = strong-motion detectors rather than the Lehmans they think they have." = You speak from the abyss --- you evidently do not check the posting of = teleseismic events by "these people.". "They" speak louder than your = words. Perhaps even louder than "they think they have." Regards to all and a Merry Christmas! Frank Cooper, Friendswood, Texas, USA Seismology web site at http://pages.prodigy.net/fxc/ ----- Original Message -----=20 From: CapAAVSO@.......... To: psn-l@................. Sent: Friday, November 22, 2002 10:34 AM Subject: Re: Another horizontal boom/mast pivot to consider In a message dated 11/21/02 8:01:16 AM GMT Standard Time, = meredithlamb@............. writes: With all the discussion on a horizontal boom/mast pivot, it might be alot simpler to use/make another type mentioned in the past emails. Its based on the Sprengnether horizontals general design and has been "revised" for use by John Lahr on his horizontal; but it essentially is the same type pivot. .............I think its one of the best pivot innovations I know = of, and most ingenious of John to come up with the variation. Theres probably about zero long term problems with this conpared to other pivot designs. Its frictionless as John describes in his text. Hi Meridith You don't have to be an engineer to realize friction in the lower = pivot of a Lehman will decrease its sensitivity. Lehman I'm sure was = aware of that but he was designing a simple instrument for amateurs that = was good enough to get started. The point-in-a -dimple bottom pivot will = always have some stick-slip friction which will interfere with its = sensitivity to small earthquake movements. if you replace the point with = a ball its rolling friction is less but nevertheless there will still be = small residual stick-slip friction. John Lahr's completely frictionless = Sprengnether type wire-under-tension pivot is much better than ball = bearings and just as easy, if not easier to make, and it stays put = rather than slithering around like ball bearings. I use John Lahr's = system with 0.008" music wire, obtainable from any music store, and it = shows the finest detail in the microseisms if I turn up the gain. = However, and this is important, even with frictionless pivots my Lehman = is unstable over time unless I set its period for about 10-15 seconds. I = doubt anyone can do much better with ball bearing pivots unless they are = on bed rock and even then I don't see how they could possibly get = month's-long stability at 30-40 second periods as has been claimed in = recent postings. My guess is what these people actually have are = strong-motion detectors rather than the Lehmans they think they have. Best regards, Cap
OK Cap as a member of the "these people" or the = "they"=20 ball bearing party, I'll bite,
I'll respond even though I think your purpose = is to have=20 a little fun and stir the pot a bit. Perhaps we take ourselves too=20 seriously at times since "we" all enjoy and are all engaged in = a very interesting HOBBY.  I have to differ with you on a = couple of=20 statements in your recent postings.  You say "John Lahr's = completely=20 frictionless Sprengnether type wire-under-tension pivot is much better = than ball=20 bearings and just as easy, if not easier to make, and it stays put = rather than=20 slithering around like ball bearings."
 
Have you ever used the ball bearing method?  I = assume you=20 must speak from long experience to back-up your slithering ball = bearing=20 pronouncement.  I have been using a ball bearing at the pivot point = of my=20 Lehman pendulum for years and it has not "slithered around" = once.  But=20 perhaps I should only "claim." Maybe you also have long experience in=20 maintaining a 30 second period with a modified ball bearing = Lehman. =20 However, that must not be the case since you say "I don't see how they = could=20 possibly get month's-long stability at 30-40 second periods as has been = claimed=20 in recent postings."  My only suggestion is to try it --- you might = like it=20 and become "one of these people."
 
And you say "My guess is what these people actually = have are=20 strong-motion detectors rather than the Lehmans they think they = have."  You=20 speak from the abyss --- you evidently do not check the posting of = teleseismic=20 events by "these people.". "They" speak louder than your words.  = Perhaps=20 even louder than "they think they have."
 
Regards to all and a Merry Christmas!
 
Frank Cooper, Friendswood, Texas, USA
 
Seismology web site at  http://pages.prodigy.net/fxc/<= BR>
 
 
 
 
 
----- Original Message -----
From:=20 CapAAVSO@.......=20
Sent: Friday, November 22, 2002 = 10:34=20 AM
Subject: Re: Another horizontal = boom/mast=20 pivot to consider

In a message dated 11/21/02 8:01:16 AM GMT = Standard Time,=20 meredithlamb@.............= =20 writes:


With all the discussion on a horizontal boom/mast pivot, = it
might be alot simpler to use/make another type mentioned = in
the=20 past emails.  Its based on the Sprengnether = horizontals
general=20 design and has been "revised" for use by John Lahr
on his = horizontal; but=20 it essentially is the same type pivot.
.............I think its = one of=20 the best pivot innovations I know of,
and most ingenious of John = to come=20 up with the variation.
Theres probably about zero long term = problems with=20 this
conpared to other pivot designs.  Its frictionless = as
John=20 describes in his text.


Hi Meridith

You = don't have=20 to be an engineer to realize friction in the lower pivot of a Lehman = will=20 decrease its sensitivity. Lehman I'm sure was aware of that but he was = designing a simple instrument for amateurs that was good enough to get = started. The point-in-a -dimple bottom pivot will always have some = stick-slip=20 friction which will interfere with its sensitivity to small earthquake = movements. if you replace the point with a ball its rolling friction = is less=20 but nevertheless there will still be small residual stick-slip = friction. John=20 Lahr's completely frictionless Sprengnether type wire-under-tension = pivot is=20 much better than ball bearings and just as easy, if not easier to = make, and it=20 stays put rather than slithering around like ball bearings. I use John = Lahr's=20 system with 0.008" music wire, obtainable from any music store, and it = shows=20 the finest detail in the microseisms if I turn up the gain. However, = and this=20 is important, even with frictionless pivots my Lehman is unstable over = time=20 unless I set its period for about 10-15 seconds. I doubt anyone can do = much=20 better with ball bearing pivots unless they are on bed rock and even = then I=20 don't see how they could possibly get month's-long stability at 30-40 = second=20 periods as has been claimed in recent postings. My guess is what these = people=20 actually have are strong-motion detectors rather than the Lehmans they = think=20 they have.

Best=20 regards,
Cap
Subject: Re: Another horizontal boom/mast pivot to consider From: CapAAVSO@....... Date: Fri, 22 Nov 2002 16:54:30 EST In a message dated 11/22/02 7:49:11 PM GMT Standard Time, fxc@....... writes: > OK Cap as a member of the "these people" or the "they" ball bearing party, > I'll bite, > I'll respond even though I think your purpose is to have a little fun and > stir the pot a bit. Well, yes, Frank. As a matter of fact I did mean to maybe "have some fun" as you say, stirring the pot a bit and hopefully get some discussion going concerning some the wild claims you guys have made that are not in keeping with what others have said over the years on the PSN. First of all I'm sure most will agree John Cole's ball bearings have less friction than a simple point-in-a-dimple pivot. But good as they are, they are not as good as John Lahr's modified Sprengnether pivot that has no friction at all and can't slither and is simpler and easy to make. And what does pivot friction have to do with long term stability anyway? Recent postings have been about the pier and the soil it's on and how soil moisture and temperature and nearby traffic affect stability of the period. Nobody even mentioned the pivots until you guys came along claiming to solve all these problems with ball bearings. Where is your evidence other than testimonials? What are the mechanical principles and engineering evidence that pivot friction is the reason Lehmans are unstable? You say: "My only suggestion is to try it --- you might like it and become "one of these people". Well, I would, Frank, if I thought it would work but I already have a frictionless pivot that is better than John Cole's and no way can I set my Lehman's period at >20 seconds and have it stay there. I am not conviced the ball bearings will do what you say they will. I am not one to buy snake oil :-) Best regards, Cap In a message dated 11/22/02 7:49:11 PM GMT Standard Time, fxc@....... writes:


OK Cap as a member of the "these people" or the "they" ball bearing party, I'll bite,
I'll respond even though I think your purpose is to have a little fun and stir the pot a bit.


Well, yes, Frank. As a matter of fact I did mean to maybe "have some fun" as you say, stirring the pot a bit and hopefully get some discussion going concerning some the wild claims you guys have made that are not in keeping with what others have said over the years on the PSN. First of all I'm sure most will agree John Cole's ball bearings have less friction than a simple point-in-a-dimple pivot. But good as they are, they are not as good as John Lahr's modified Sprengnether pivot that has no friction at all and can't slither and is simpler and easy to make. And what does pivot friction have to do with long term stability anyway? Recent postings have been about the pier and the soil it's on and how soil moisture and temperature and nearby traffic affect stability of the period. Nobody even mentioned the pivots until you guys came along claiming to solve all these problems with ball bearings. Where is your evidence other than testimonials? What are the mechanical principles and engineering evidence that pivot friction is the reason Lehmans are unstable? You say: "My only suggestion is to try it --- you might like it and become "one of these people". Well, I would, Frank, if I thought it would work but I already have a frictionless pivot that is better than John Cole's and no way can I set my Lehman's period at >20 seconds and have it stay there. I am not conviced the ball bearings will do what you say they will. I am not one to buy snake oil :-)


Best regards,
Cap

Subject: Re: Another horizontal boom/mast pivot to consider From: "Frank Cooper" fxc@....... Date: Fri, 22 Nov 2002 18:52:23 -0600 Hello Cap, You write, "the wild claims you guys have made that are not in keeping = with what others have said over the years on the PSN." I am not aware = of codified PSN doctrine. Should we heretics kneel in humble submission = and admit our sins and ask for forgiveness? I vote for the scientific = method.=20 And you write, "You say, My only suggestion is to try it --- you might = like it and become "one of these people". Well, I would, Frank, if I = thought it would work but I already have a frictionless pivot that is = better than John Cole's and no way can I set my Lehman's period at >20 = seconds and have it stay there. I am not convinced the ball bearings = will do what you say they will. I am not one to buy snake oil :-)" I = thought your attitude died with the middle ages. Most of us accept = evidence over "I am convinced." And you write, "But good as they are, they are not as good as John = Lahr's modified Sprengnether pivot that has no friction at all and can't = slither and is simpler and easy to make. " I do not have any experience = with John Lahr's modified Sprengnether pivot and therefore withhold = judgment. I have a lot of respect for John Lahr and I think he would = have been the first to withhold judgment about the ball bearing method = until he had all the facts which you lack. Regards, Frank ----- Original Message -----=20 From: CapAAVSO@.......... To: psn-l@................. Sent: Friday, November 22, 2002 3:54 PM Subject: Re: Another horizontal boom/mast pivot to consider In a message dated 11/22/02 7:49:11 PM GMT Standard Time, fxc@....... = writes: OK Cap as a member of the "these people" or the "they" ball bearing = party, I'll bite, I'll respond even though I think your purpose is to have a little = fun and stir the pot a bit. Well, yes, Frank. As a matter of fact I did mean to maybe "have some = fun" as you say, stirring the pot a bit and hopefully get some = discussion going concerning some the wild claims you guys have made that = are not in keeping with what others have said over the years on the PSN. = First of all I'm sure most will agree John Cole's ball bearings have = less friction than a simple point-in-a-dimple pivot. But good as they = are, they are not as good as John Lahr's modified Sprengnether pivot = that has no friction at all and can't slither and is simpler and easy to = make. And what does pivot friction have to do with long term stability = anyway? Recent postings have been about the pier and the soil it's on = and how soil moisture and temperature and nearby traffic affect = stability of the period. Nobody even mentioned the pivots until you guys = came along claiming to solve all these problems with ball bearings. It = amazes me that you critize a method with which you have no experience? = What are the mechanical principles and engineering evidence that pivot = friction is the reason Lehmans are unstable? You say: "My only = suggestion is to try it --- you might like it and become "one of these = people". Well, I would, Frank, if I thought it would work but I already = have a frictionless pivot that is better than John Cole's and no way can = I set my Lehman's period at >20 seconds and have it stay there. I am not = conviced the ball bearings will do what you say they will. I am not one = to buy snake oil :-) Best regards, Cap
Hello Cap,
You write, "the wild claims you guys have made = that are=20 not in keeping with what others have said over the years on the = PSN."  I am=20 not aware of codified PSN doctrine.  Should we heretics = kneel in=20 humble submission and admit our sins and ask for = forgiveness?  I=20 vote for the scientific method.
 
And you write, "You say, My only suggestion is = to try it=20 --- you might like it and become "one of these people". Well, I would, = Frank, if=20 I thought it would work but I already have a frictionless pivot that is = better=20 than John Cole's and no way can I set my Lehman's period at >20 = seconds and=20 have it stay there. I am not convinced the ball bearings will do what = you say=20 they will. I am not one to buy snake oil :-)"   I thought your = attitude died with the middle ages.  Most of us accept evidence = over "I am=20 convinced."

And you write, = "But good as=20 they are, they are not as good as John Lahr's modified Sprengnether = pivot that=20 has no friction at all and can't slither and is simpler and easy to = make.=20 "  I do not have any experience with John Lahr's modified = Sprengnether=20 pivot and therefore withhold judgment. I have a lot of respect for = John=20 Lahr and I think he would have been the first to withhold judgment about = the=20 ball bearing method until he had all the facts which = you lack.
 
Regards,
Frank

----- Original Message -----
From:=20 CapAAVSO@.......=20
Sent: Friday, November 22, 2002 = 3:54=20 PM
Subject: Re: Another horizontal = boom/mast=20 pivot to consider

In a message dated 11/22/02 7:49:11 PM GMT = Standard Time,=20 fxc@....... writes:


OK Cap as a member of the "these people" or the "they" = ball=20 bearing party, I'll bite,

I'll respond even though I think your purpose = is to have=20 a little fun and stir the pot a bit.


Well,=20 yes, Frank. As a matter of fact I did mean to maybe "have some fun" as = you=20 say, stirring the pot a bit and hopefully get some discussion going = concerning=20 some the wild claims you guys have made that are not in keeping with = what=20 others have said over the years on the PSN. First of all I'm sure most = will=20 agree John Cole's ball bearings have less friction than a simple=20 point-in-a-dimple pivot. But good as they are, they are not as good as = John=20 Lahr's modified Sprengnether pivot that has no friction at all and = can't=20 slither and is simpler and easy to make. And what does pivot friction = have to=20 do with long term stability anyway? Recent postings have been about = the pier=20 and the soil it's on and how soil moisture and temperature and nearby = traffic=20 affect stability of the period. Nobody even mentioned the pivots until = you=20 guys came along claiming to solve all these problems with ball = bearings. It=20 amazes me that you critize a method with which you have no experience? = What=20 are the mechanical principles and engineering evidence that pivot = friction is=20 the reason Lehmans are unstable? You say: "My only suggestion is to = try it ---=20 you might like it and become "one of these people". Well, I would, = Frank, if I=20 thought it would work but I already have a frictionless pivot that is = better=20 than John Cole's and no way can I set my Lehman's period at >20 = seconds and=20 have it stay there. I am not conviced the ball bearings will do what = you say=20 they will. I am not one to buy snake oil :-)


Best=20 regards,
Cap

Subject: Re: Another horizontal boom/mast pivot to consider From: ChrisAtUpw@....... Date: Fri, 22 Nov 2002 20:17:21 EST In a message dated 22/11/2002, CapAAVSO@....... writes: > The point-in-a -dimple bottom pivot will always have some stick-slip > friction which will interfere with its sensitivity to small earthquake > movements. If you replace the point with a ball its rolling friction is > less but nevertheless there will still be small residual stick-slip > friction. Hi there Cap, Sorry, but there should be no residual stick slip friction in a rolling contact on a perfectly flat surface. Obviously, if you try to roll a ball on a rough surface there would be variable resistance, but a surface can be polished to optical precision and any resistance reduced below observable limits. The axis of rotation with a sphere on a flat is very precisely defined. John Lahr's completely frictionless Sprengnether type wire-under-tension pivot is > much better than ball bearings and just as easy, if not easier to make, and > it stays put rather than slithering around like ball bearings. I use John > Lahr's system with 0.008" music wire, obtainable from any music store, and > it shows the finest detail in the microseisms if I turn up the gain. Flexing wires and foils have very low friction, but it is not identically zero due to changing stresses, metal flow and relaxation over time. Single flexing wires and foils do not have an entirely stable hinge point with time and temperature. The crossed foils and wires are better in this respect. You want the rotation axis to be extremely stable. However, and this is important, even with frictionless pivots my Lehman is unstable > over time unless I set its period for about 10-15 seconds. I doubt anyone > can do much better with ball bearing pivots unless they are on bed rock and > even then I don't see how they could possibly get month's-long stability at > 30-40 second periods as has been claimed in recent postings. My guess is > what these people actually have are strong-motion detectors rather than the > Lehmans they think they have. OK, your system is not completely stable over time. Can you tell us why this is? If nothing changes, it should be perfectly stable! Do temperature changes, or large rates of change of temperature, effect it? Does it react to rain? Wind? Frost? Time of day? Do the offsets build up gradually, are they sudden or random? Do the mounting screws rest on flat plates glued to the base plinth? There are many factors which can effect the stability. Look at the Tmax design. What do you notice? I noticed that the base was made out of steel which is more rigid than Aluminum and more importantly, that it was much wider than 'traditional' Lehman designs. Ideally, you should use an equilateral triangle, like Sprengnether. The support screws will be steel in steel, not steel or brass in Al, so differential expansion movements should be less of a problem. If someone is getting better results than me, I ask myself what I am doing or not doing differently and what are the limitiations of my equipment and my site. Regards, Chris Chapman In a message dated 22/11/2002, CapAAVSO@....... writes:

The point-in-a -dimple bottom pivot will always have some stick-slip friction which will interfere with its sensitivity to small earthquake movements. If you replace the point with a ball its rolling friction is less but nevertheless there will still be small residual stick-slip friction.


Hi there Cap,

     Sorry, but there should be no residual stick slip friction in a rolling contact on a perfectly flat surface. Obviously, if you try to roll a ball on a rough surface there would be variable resistance, but a surface can be polished to optical precision and any resistance reduced below observable limits. The axis of rotation with a sphere on a flat is very precisely defined.
 
John Lahr's completely frictionless Sprengnether type wire-under-tension pivot is

much better than ball bearings and just as easy, if not easier to make, and it stays put rather than slithering around like ball bearings. I use John Lahr's system with 0.008" music wire, obtainable from any music store, and it shows the finest detail in the microseisms if I turn up the gain.


     Flexing wires and foils have very low friction, but it is not identically zero due to changing stresses, metal flow and relaxation over time. Single flexing wires and foils do not have an entirely stable hinge point with time and temperature. The crossed foils and wires are better in this respect. You want the rotation axis to be extremely stable.

However, and this is important, even with frictionless pivots my Lehman is unstable

over time unless I set its period for about 10-15 seconds. I doubt anyone can do much better with ball bearing pivots unless they are on bed rock and even then I don't see how they could possibly get month's-long stability at 30-40 second periods as has been claimed in recent postings. My guess is what these people actually have are strong-motion detectors rather than the Lehmans they think they have.


     OK, your system is not completely stable over time. Can you tell us why this is? If nothing changes, it should be perfectly stable! Do temperature changes, or large rates of change of temperature, effect it? Does it react to rain? Wind? Frost? Time of day? Do the offsets build up gradually, are they sudden or random? Do the mounting screws rest on flat plates glued to the base plinth?

     There are many factors which can effect the stability. Look at the Tmax design. What do you notice? I noticed that the base was made out of steel which is more rigid than Aluminum and more importantly, that it was much wider than 'traditional' Lehman designs. Ideally, you should use an equilateral triangle, like Sprengnether. The support screws will be steel in steel, not steel or brass in Al, so differential expansion movements should be less of a problem.

     If someone is getting better results than me, I ask myself what I am doing or not doing differently and what are the limitiations of my equipment and my site.
    
     Regards,

     Chris Chapman
Subject: Lightweight sensors From: Bobhelenmcclure@....... Date: Sat, 23 Nov 2002 00:40:26 EST Hi all, Many years ago, after reading an Amateur Scientist article (July 1957) on swinging gate seismometers, I built a sensor based in part on the information in the article. Its design, of course, was greatly affected by what raw material I had around, and what could be obtained from friends and the local hardware store. You can read a description of it at John Lahr's web page, http://www.jjlahr.com/science/psn/mcclure/index.html Originally, it was fitted out with photo-optical sensing of pendulum position. The image of a pilot lamp filament was projected through a short focal length lens on the pendulum to a pair of photocells, hooked up parallel in voltage opposition. The differential voltage output was fed to a homebuilt potentiometric recorder. It was plagued with drift problems. It never took long for the filament image to end up totally on one of the photocells. I gave up my efforts and went on to other interests. In the past two years, my interest was revived by a former colleague, who wanted me to participate in a tripartite local network he was wanting to set up. He loaned me an old vertical short period Strengnether to operate. This got me going very heavily into programming and signal processing, using Visual Basic. We also had to solve the problem of time synchronization of recordings made at separated sites, and how to set up the sensors to have the same period and damping, so that response differences would not distort our time-of-arrival estimates. After all this, I was inspired to take my old sensor and fit it out with a pickup coil and magnet to convert it to velocity sensing. The pendulum is short, about 12 inches to the radius of gyration, with a total mass of 66 grams. I had no intention of trying for a natural period of more than 12 seconds, because in my tripartite work, I designed a digital filter that could extend the useful range of the sensor to as much as 50 seconds, and which furthermore matched the amplitude and phase response of such a long period sensor. It is presently set for a natural period of 11 seconds, and holds its centering without any attention. I really don't know what natural period could be achieved. Certainly more than 11 seconds. The data obtained from it after broadband digital filtering to emulate a 32 second period sensor, matches well what I see from the nearby LDEO PAL site, 19 miles from me, except for my higher local noise level. My seismo colleague and I are now motivated to build some more sensors of lightweight design. Pivots are critical. The old sensor uses steel needles and sapphire bearing cups. I do not know where I could obtain more sapphire bearings, so I am considering the use of mini ball pivots. From experiments with diagmagnetic supported upright pendulums, I have discovered (following a suggestion from Chris Chapman) that the ball point nib from a BIC pen makes a very good pivot. The ball is highly polished, about 1 mm diameter. You just insert the whole little brass nib into a hole in the boom, epoxy it in place, and you have your pivot. It should rest against a hard flat polished surface. Glass works, but a sapphire plate would be better. I favor a rigid strut (no wire) for mounting the upper pivot. If the upper pivot plate normal points to the center of gravity of the pendulum, there will be no lateral forces at balance on the pivots. I encourage others build lightweight sensors, large or small, something like John Cole's T Max, for example. After all, we are no longer driving galvanometers, just high impedance input dc amplifiers. The only justification for weight that I can see is greater resistance to air currents. You will also find, if you use my magnet and coil design, that you will not need any damping other than that obtained by a shunt resistance across the coil. The resistance required will be much higher than the coil resistance, so that there will be no loss of signal. I am willing to provide more information on how to wind the 800-turn coil, and how to filter your data to achieve long period results. I can write post-filter programs for you for enhancing any data file, but I have to know the file format. Cheers, Bob McClure Hi all,

  Many years ago, after reading an Amateur Scientist article (July 1957) on swinging gate seismometers, I built a sensor based in part on the information in the article.  Its design, of course, was greatly affected by what raw material I had around, and what could be obtained from friends and the local hardware store.  You can read a description of it at John Lahr's web page,

  http://www.jjlahr.com/science/psn/mcclure/index.html

  Originally, it was fitted out with photo-optical sensing of pendulum position.  The image of a pilot lamp filament was projected through a short focal length lens on the pendulum to a pair of photocells, hooked up parallel in voltage opposition.  The differential voltage output was fed to a homebuilt potentiometric recorder.  It was plagued with drift problems.  It never took long for the filament image to end up totally on one of the photocells.  I gave up my efforts and went on to other interests.

  In the past two years, my interest was revived by a former colleague, who wanted me to participate in a tripartite local network he was wanting to set up.  He loaned me an old vertical short period Strengnether to operate.  This got me going very heavily into programming and signal processing, using Visual Basic.  We also had to solve the problem of time synchronization of recordings made at separated sites, and how to set up the sensors to have the same period and damping, so that response differences would not distort our time-of-arrival estimates.

  After all this, I was inspired to take my old sensor and fit it out with a pickup coil and magnet to convert it to velocity sensing.  The pendulum is short, about 12 inches to the radius of gyration, with a total mass of 66 grams.  I had no intention of trying for a natural period of more than 12 seconds, because in my tripartite work, I designed a digital filter that could extend the useful range of the sensor to as much as 50 seconds, and which furthermore matched the amplitude and phase response of such a long period sensor.  It is presently set for a natural period of 11 seconds, and holds its centering without any attention.  I really don't know what natural period could be achieved.  Certainly more than 11 seconds.  The data obtained from it after broadband digital filtering to emulate a 32 second period sensor, matches well what I see from the nearby LDEO PAL site, 19 miles from me, except for my higher local noise level.

  My seismo colleague and I are now motivated to build some more sensors of lightweight design.  Pivots are critical.  The old sensor uses steel needles and sapphire bearing cups.  I do not know where I could obtain more sapphire bearings, so I am considering the use of mini ball pivots. From experiments with diagmagnetic supported upright pendulums, I have discovered (following a suggestion from Chris Chapman) that the ball point nib from a BIC pen makes a very good pivot.  The ball is highly polished, about 1 mm diameter.  You just insert the whole little brass nib into a hole in the boom, epoxy it in place, and you have your pivot.  It should rest against a hard flat polished surface.  Glass works, but a sapphire plate would be better.  I favor a rigid strut (no wire) for mounting the upper pivot.  If the upper pivot plate normal points to the center of gravity of the pendulum, there will be no lateral forces at balance on the pivots.

  I encourage others build lightweight sensors, large or small, something like John Cole's T Max, for example.  After all, we are no longer driving galvanometers, just high impedance input dc amplifiers.  The only justification for weight that I can see is greater resistance to air currents.  You will also find, if you use my magnet and coil design, that you will not need any damping other than that obtained by a shunt resistance across the coil.  The resistance required will be much higher than the coil resistance, so that there will be no loss of signal.

  I am willing to provide more information on how to wind the 800-turn coil, and how to filter your data to achieve long period results.  I can write post-filter programs for you for enhancing any data file, but I have to know the file format.

Cheers,

Bob McClure
Subject: Re: Another horizontal boom/mast pivot to consider From: meredithlamb meredithlamb@............. Date: Fri, 22 Nov 2002 23:00:12 -0700 Hi all, I read plus's and minus's into this topic.....ball v/s torsion pivots. Perhaps a part of the aspect of a torsion pivot is that it likely is a type of somewhat unstable double pivot pendum in essense, one at the top (of the mast) and the lower torsion wires flexible movement itself. There is a name for such, but a brief search engine search yielded nothing for the moment. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Suspension From: "Office of Emperor Norton, Bummer and Lazarus" SFQUAKE06@........... Date: Fri, 22 Nov 2002 23:33:25 -0800 Hi All: Is that suspension called "Zollner"? Dave Close
Hi All:
 
Is that suspension called "Zollner"?
 
Dave Close
Subject: Re: Another horizontal boom/mast pivot to consider From: meredithlamb meredithlamb@............. Date: Sat, 23 Nov 2002 01:04:18 -0700 Hi all, Excuse my prior incomplete email....I hit the send button by mistake. The original message only suggested a torsion/tension pivot to .....consider......in a Lehman/garden gate/etc., seismometer. .............................................................. David Close....I believe you are right, the Sprengnether suspension (torsion/tension) could be called a "Zollner" pendulum....its actually like the old Wood/Andersion torsion seismometers of yesteryear. They were also period limited. Thanks for the undate David! .............................................................. Ball bearing v/s torsion/tension (Zollner) pivots I read plus's and minus's into this topic. A "Sprengnether", "torsion/tension pivot", is actually a type of more susceptible dual tilt pendulum if one observes the upper pivot suspension wire and the lower (boom/mass) pivot; and imagines a line drawn vertically and centralized down between the two. You offset one side (the mass) and their is a lesser movement laterally on the other end of the boom (the torsion/tension pivot) by its own nature. I just can't for the moment remember the name of such a pendulum....a web "name" search comes up with nothing relivant. Essentially the lower torsion/tension pivot "point" in itself contributes a enhanced degree of instability, by its own flexible nature and various influences of time, temperature, etc. Being somewhat influenced by this in operation, their is a limit to the period of a torsion/tension pivot in practice...perhaps a max of up to ~20 seconds. I suppose one could say its not as stable for longer periods and be correct....I've seen it myself. Thats not all terrible of course.....up to 20 seconds is fine for most amateurs. Of course, to add to that, one has to recognize that a inertia based/operated seismic mass is also susceptible to tilt induced phases by quakes....where the mass will "follow" the troughs and peaks of passing seismic phases; and one can see much longer "period waves" on their grams. For the topic...I've left out "feed-back" seismos....which can register much longer periods. On the other hand, its not the long period surface waves thats really understood nor wanted; (except for magnitude), its the shorter period waves that derive the "p" & "s" wave, that is used to determine distance. Of course the longer the period of the seismo, and the "looser" the pivot, one should be able to observe more of the seismic phases beneath the set period it has. I've never used a "ball bearing" seismo. I don't know what they are like. I can understand though, that perhaps with that rock solid lower pivot, that its quite possible to have a longer period stability.....as because now....one only has, the upper hinge wire support/hinge angle wire to contend with, instead of the overall "double hinge flexure" of a "torsion/tension" pivot.....hence a "Lehman" seismo should have a lesser stability problem for longer periods of operation. I'd "think" the ball bearing contact approach is much better than some of the past approaches we've seen; but even there, the bearing idea is still within the old concept goal of using a more hardened surface/s contact to prevent material failure, reduce friction etc; was rather ongoing. I've heard of razors, rounded metal tips various metals), carbide etc., on hardened tool steel, glass etc. One very nice thing about ball bearings is that they are fairly readily available and the very idea/approach itself is nice to read about, as it adds some potential construction material one could comtemplate using. So...theres plus's and minus's with either pivot. I "think" the ball bearing pivot can yes exhibit a longer period (read as stability), but, it also will be abit less sensitive too actual earth movement than a torsion/tension pivot with its essentially zero friction design. For a amateur it may come down to only what they believe will work and/or what material they are able to get/find for their project....either one has limits. Theres other approachs with horizontal seismometers and their own various hinges/pivot designs of course. All these tilts, drift, instability all have a cause and effect. For myself; its usually the water/moisture in the ground and its variations of content which change the shape/tilt of the piers. All outside changes in temperature affects the ground moisture evaporation along with natural drainage, as does added rain/snow storms of course. Personally I like the "S-G" (hanging pendulum), as the "bulk" of the normal seismo can be greatly reduced in volume, and the results are fairly good.....and of course gravity itself kind of forces the thin "pivot" flexure hinge, to not deviate laterally where its usual sensor pickup reads. Its ultimate sensitivity comes down to using the thinnest material available on the hinge/s...too stiff a hinge/s and you lose some of the free potential pendulum inertia "movement". A "S-G" normally points straight down, and doesn't depend on any certain angle to derive its "period". One can of course, add other displacement sensors and circuits to a "S-G", to go beyond its normal or natural oscillation period. In essence all horizontal seismometers are also tiltmeters. Take care, Meredith __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Another horizontal boom/mast pivot to consider From: CapAAVSO@....... Date: Sat, 23 Nov 2002 11:02:59 EST In a message dated 11/23/02 8:06:15 AM GMT Standard Time, meredithlamb@............. writes: > All these tilts, drift, instability all have a cause and effect. > For myself; its usually the water/moisture in the ground and its > variations of content which change the shape/tilt of the piers. > All outside changes in temperature affects the ground moisture > evaporation along with natural drainage, as does added rain/snow > storms of course. Hi all, Even with a perfect suspension most if not all of us would still have the limitations Meredith mentions above to deal with. For most of us probably the most effective way of getting a longer period Lehman to be stable would be to build a good pier. For those of us who have our Lehman sitting on the garage or basement floor this could probably best be done by chopping a big hole in the concrete floor so we could build a good pier. Perish the thought!! I would not dare even think about such a thing for my Lehman at my son's house in Florida where I am a guest: grandpapa who comes down from up north for the winter to escape shoveling snow and slipping on the ice and breaking bones fragile from old age. No way!! But there is a way out, a way mentioned several times by Sean-Thomas Morrissey when he was still with us. He said amateurs might do well to forsake their favorite Lehmans for a vertical with a period of ~ 1 second. He was designing a leaf spring vertical about which he posted several long letters describing its advantages. A big advantage was an excellent leaf spring is readily available by removing the handle from a 14-inch plasterer's spackling trowel you can buy at Home Depot. Last winter I built a modified version of his leaf spring vertical by mounting one of the these excellent 4" X 14" flat springs on a base vertically and put enough lead on the other end to put a 90 degree bend in it so the other end was horizontal. I then mounted a coil, the winding for a 120 volt relay, on an outrigger so it dipped down between a the poles of a big Alnico magnet. I hooked this sensor coil to one of Dave Saum's A/D converter/amplifiers and used Allen Jones's Amaseis free software to record by computer in a Helicorder format just like you can see at: http://aslwww.cr.usgs.gov/Seismic_Data/heli2.htm By taking Sean Thomas's advice I eliminated all the problems with the garage floor instability and now it doesn't matter what kind of suspension I have on my abandoned Lehman. I'll return to Orlando, FL next Saturday and set up the trouble free leaf spring vertical and record earthquakes. I'll let you know more about how it works then. Best regards, Cap In a message dated 11/23/02 8:06:15 AM GMT Standard Time, meredithlamb@............. writes:


All these tilts, drift, instability all have a cause and effect.
For myself; its usually the water/moisture in the ground and its
variations of content which change the shape/tilt of the piers.
All outside changes in temperature affects the ground moisture
evaporation along with natural drainage, as does added rain/snow
storms of course. 


Hi all,

Even with a perfect suspension most if not all of us would still have the limitations Meredith mentions above to deal with. For most of us probably the most effective way of getting a longer period Lehman to be stable would be to build a good pier. For those of us who have our Lehman sitting on the garage or basement floor this could probably best be done by chopping a big hole in the concrete floor so we could build a good pier. Perish the thought!! I would not dare even think about such a thing for my Lehman at my son's house in Florida where I am a guest: grandpapa who comes down from up north for the winter to escape shoveling snow and slipping on the ice and breaking bones fragile from old age. No way!!

But there is a way out, a way mentioned several times by Sean-Thomas Morrissey when he was still with us. He said amateurs might do well to forsake their favorite Lehmans for a vertical with a period of ~ 1 second. He was designing a leaf spring vertical about which he posted several long letters describing its advantages. A big advantage was an excellent leaf spring is readily available by removing the handle from a 14-inch plasterer's spackling trowel you can buy at Home Depot. Last winter I built a modified version of his leaf spring vertical by mounting one of the these excellent 4" X 14" flat springs on a base vertically and put enough lead on the other end to put a 90 degree bend in it so the other end was horizontal. I then mounted a coil, the winding for a 120 volt relay, on an outrigger so it dipped down between a the poles of a big Alnico magnet. I hooked this sensor coil to one of Dave Saum's A/D converter/amplifiers and used Allen Jones's Amaseis free software to record by computer in a Helicorde r format just like you can see at:

http://aslwww.cr.usgs.gov/Seismic_Data/heli2.htm

By taking Sean Thomas's advice I eliminated all the problems with the garage floor instability and now it doesn't matter what kind of suspension I have on my abandoned  Lehman. I'll return to Orlando, FL next Saturday and set up the trouble free leaf spring vertical and record earthquakes. I'll let you know more about how it works then.

Best regards,
Cap
Subject: RE: Another horizontal boom/mast pivot to consider From: steve hammond shammon1@............. Date: Sat, 23 Nov 2002 08:28:39 -0800 I'm looking for info or a drawing of a Fletcher joint and that may not be the correct spelling of Fletcher. It is a joint with two rings and two cross wires and has zero friction. Thanks -- Regards, Steve Hammond -----Original Message----- From: meredithlamb [SMTP:meredithlamb@.............. Sent: Friday, November 22, 2002 10:00 PM To: psn-l@.............. Subject: Re: Another horizontal boom/mast pivot to consider Hi all, I read plus's and minus's into this topic.....ball v/s torsion pivots. Perhaps a part of the aspect of a torsion pivot is that it likely is a type of somewhat unstable double pivot pendum in essense, one at the top (of the mast) and the lower torsion wires flexible movement itself. There is a name for such, but a brief search engine search yielded nothing for the moment. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Another horizontal boom/mast pivot to consider From: steve hammond shammon1@............. Date: Sat, 23 Nov 2002 11:05:12 -0800 Hi all, I've been using the pin-in-cup design for some time now and must change the pin about 2 times each year. Over time, the pin has a tendency to get mashed a bit and the performance drops way off. A large local event can damage it beyond use. I perform maintenance by changing the pin and upper piano wire about every three months. I clean the spiders out of the box because it is outside on a cement pad, change the wire, and level everything in about one hour. I live near the sea and if I don't change the wire, the wire rusts and eventually will snap under tension. Usually in less than 6 months. If you would like to see this site here is the URL. http://pw2.netcom.com/~shammon1/AptosStn.htm When the pin is nice and sharp, I can set the period as long as 28+ seconds. Based on the formula provided by the late Sean-Thomas Morrissey, the angle of the 30-cm boom would be between .05 and .1 degree at this setting. The real issue when running at this length period is stability. Any change in the site will cause the boom to go all the way to the stop over night. A good example of this is the first rain following summer. Rain water will also dramatically change the site response as well as the leveling of the device. Site response has a major impact on the sensitivity of the device. The background site response noise level rises as much as 50% when rain water is present. I have seen this on all three sites I've maintained for more than 2 years. For example, in San Jose, I had a light-rail train run at the end of my block for several years. Each year I took sample of the site frequency response from the passing train. The train had 8-sets of wheels and the length of the train was 168 feet with two cars. The train rain past the end of my block at 40 - 45 MPH. At the end of summer, an FFT of the sample data yielded scattered resulting frequencies showing several dominate frequencies below 12Hrz. Following the first rain, the only dominate frequency was 11-12hrz. The water in the ground made a dramatic difference. I still have several example files and was planning on publishing the results of my study on my website. My hypothesis was the rain would increase site response therefor the site would have differing results in summer and winter. While I don't have a light-rail train where I live in Aptos, I do have a real Southern Pacific train pass twice a day less than a block away at speeds less than 5-10 MPH. Now that it has rained for the first time, I will be looking at past and current data to comparing it to see if I can show the same results with the SP train as I saw with the light-rail. Both of my Lehman's went to the stops following the first rain in the Bay area about a week ago as they did in the three other locations. Regards, Steve Hammond PSN San Jose, Aptos California -----Original Message----- From: Frank Cooper [SMTP:fxc@........ Sent: Friday, November 22, 2002 4:52 PM To: psn-l@.............. Subject: Re: Another horizontal boom/mast pivot to consider Hello Cap, You write, "the wild claims you guys have made that are not in keeping with what others have said over the years on the PSN." I am not aware of codified PSN doctrine. Should we heretics kneel in humble submission and admit our sins and ask for forgiveness? I vote for the scientific method. And you write, "You say, My only suggestion is to try it --- you might like it and become "one of these people". Well, I would, Frank, if I thought it would work but I already have a frictionless pivot that is better than John Cole's and no way can I set my Lehman's period at >20 seconds and have it stay there. I am not convinced the ball bearings will do what you say they will. I am not one to buy snake oil :-)" I thought your attitude died with the middle ages. Most of us accept evidence over "I am convinced." And you write, "But good as they are, they are not as good as John Lahr's modified Sprengnether pivot that has no friction at all and can't slither and is simpler and easy to make. " I do not have any experience with John Lahr's modified Sprengnether pivot and therefore withhold judgment. I have a lot of respect for John Lahr and I think he would have been the first to withhold judgment about the ball bearing method until he had all the facts which you lack. Regards, Frank ----- Original Message ----- From: CapAAVSO@....... To: psn-l@.............. Sent: Friday, November 22, 2002 3:54 PM Subject: Re: Another horizontal boom/mast pivot to consider In a message dated 11/22/02 7:49:11 PM GMT Standard Time, fxc@....... writes: OK Cap as a member of the "these people" or the "they" ball bearing party, I'll bite, I'll respond even though I think your purpose is to have a little fun and stir the pot a bit. Well, yes, Frank. As a matter of fact I did mean to maybe "have some fun" as you say, stirring the pot a bit and hopefully get some discussion going concerning some the wild claims you guys have made that are not in keeping with what others have said over the years on the PSN. First of all I'm sure most will agree John Cole's ball bearings have less friction than a simple point-in-a-dimple pivot. But good as they are, they are not as good as John Lahr's modified Sprengnether pivot that has no friction at all and can't slither and is simpler and easy to make. And what does pivot friction have to do with long term stability anyway? Recent postings have been about the pier and the soil it's on and how soil moisture and temperature and nearby traffic affect stability of the period. Nobody even mentioned the pivots until you guys came along claiming to solve all these problems with ball bearings. It amazes me that you critize a method with which you have no experience? What are the mechanical principles and engineering evidence that pivot friction is the reason Lehmans are unstable? You say: "My only suggestion is to try it --- you might like it and become "one of these people". Well, I would, Frank, if I thought it would work but I already have a frictionless pivot that is better than John Cole's and no way can I set my Lehman's period at >20 seconds and have it stay there. I am not conviced the ball bearings will do what you say they will. I am not one to buy snake oil :-) Best regards, Cap << File: ATT00000.html >> __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Ball Pivots From: "Randall Pratt" rpratt@............. Date: Sat, 23 Nov 2002 14:36:52 -0600 Hi All, In pondering this issue, it would seem to me that as 2 convex surfaces = roll, the contact point would move in the same direction as the mass. = This would put the pivot off center and effectively shorten the boom. = Depending on the radii involved the geometry with respect to the upper = pivot will also be affected. The effects would be magnified on a small = instrument because the boom angles of motion for the same displacement = will be larger. In addition the small instrument is operating at a much = finer angle between the upper and lower pivots so again the effect will = be more pronounced. Possibly the ball is more stable because the period = is in effect lessening with displacement from center. Any thoughts or = calculations to either support or shoot me down? I am using an archery = point against an aircraft bolt head. My FFT always has a peak between = 18 and 25 seconds with very little adjustment needed. I did go = completely off the side when the river flooded 2 miles east of here and = had to reset then and again when the water dropped. =20
Hi All,
 
In pondering this issue, it would seem = to me that=20 as 2 convex surfaces roll, the contact point would move in the same = direction as=20 the mass.  This would put the pivot off center and effectively = shorten the=20 boom.  Depending on the radii involved the geometry with = respect to=20 the upper pivot will also be affected.  The effects would be=20 magnified on a small instrument because the boom angles of motion = for the=20 same displacement will be larger.  In addition the small instrument = is=20 operating at a much finer angle between the upper and lower pivots so = again the=20 effect will be more pronounced.  Possibly the ball is more stable = because=20 the period is in effect lessening with displacement from = center.  Any=20 thoughts or calculations to either support or shoot me down?  I am = using an=20 archery point against an aircraft bolt head.  My FFT always has a = peak=20 between 18 and 25 seconds with very little adjustment needed.  I = did go=20 completely off the side when the river flooded 2 miles east of here and = had to=20 reset then and again when the water dropped.
 
 
    =
Subject: Re: Another horizontal boom/mast pivot to consider From: "George Harris" gjharris@............. Date: Sat, 23 Nov 2002 16:37:14 -0800 From George Harris: The Fletcher type joint is probably similar to the one which consists of two round elements connected by flat tapes in such a way that the tapes cross in an "X" between the rollers. The joint has the unusual combination of no friction, and no torque due to the fact that as one tape unrolls, the other end rolls up so there is no net energy used in bending the tapes. The tapes must be intension (obviously I guess), but their thickness is not important as long as they are working within the elastic limit. ----- Original Message ----- From: "steve hammond" To: Sent: Saturday, November 23, 2002 8:28 AM Subject: RE: Another horizontal boom/mast pivot to consider > I'm looking for info or a drawing of a Fletcher joint and that may not be > the correct spelling of Fletcher. It is a joint with two rings and two > cross wires and has zero friction. > Thanks -- > Regards, Steve Hammond > > -----Original Message----- > From: meredithlamb [SMTP:meredithlamb@.............. > Sent: Friday, November 22, 2002 10:00 PM > To: psn-l@.............. > Subject: Re: Another horizontal boom/mast pivot to consider > > Hi all, > > I read plus's and minus's into this topic.....ball v/s torsion pivots. > > Perhaps a part of the aspect of a torsion pivot is that it likely is a > type of somewhat unstable double pivot pendum in essense, one > at the top (of the mast) and the lower torsion wires flexible movement > itself. There is a name for such, but a brief search engine search > yielded nothing for the moment. > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Ball Pivots From: ChrisAtUpw@....... Date: Sat, 23 Nov 2002 20:07:33 EST In a message dated 23/11/2002, rpratt@............. writes: > In pondering this issue, it would seem to me that as 2 convex surfaces roll, > the contact point would move in the same direction as the mass. This would > put the pivot off center and effectively shorten the boom. Depending on > the radii involved the geometry with respect to the upper pivot will also > be affected. Hi Randall, The contact point will certainly shift, but the boom angle changes at the same time. There will be some axis lying under the curved surface about which the mass rotates. The effects would be magnified on a small instrument because the boom angles of > motion for the same displacement will be larger. If the bearing sizes are scaled with the boom length, the angles for a given boom deflection should be the same. In addition the small instrument is operating at a much finer angle between the > upper and lower pivots so again the effect will be more pronounced. > Possibly the ball is more stable because the period is in effect lessening > with displacement from center. The major difference between a large instrument and a small one lies in the period lengthening required. A 1 metre boom has a natural pendulum period of 2 sec. To get it to give a 20 second period (1/10), you have to suspend it at an angle to give a restoring force of g/100 -> 0.573 degrees. A 25 cm boom has a natural pendulum period of 1 sec. To get it to give a 20 second period (1/20), you have to suspend it at an angle to give a restoring force of g/400 -> 0.143 degrees. The smaller boom will be more difficult to set up and will give four times the deflection for any given ground tilt. It will also be proportionately more sensitive to any springyness in the suspension and to any frictional effects. In response to Steve Hammond's problem with wire suspensions rusting, you can buy nickel plated piano wire. This should give additional protection. D'Addario list several ranges of strings which are widely available http://www.daddariostrings.com/products.asp Regards, Chris Chapman In a message dated 23/11/2002, rpratt@............. writes:

In pondering this issue, it would seem to me that as 2 convex surfaces roll, the contact point would move in the same direction as the mass.  This would put the pivot off center and effectively shorten the boom.  Depending on the radii involved the geometry with respect to the upper pivot will also be affected. 


Hi Randall,

     The contact point will certainly shift, but the boom angle changes at the same time. There will be some axis lying under the curved surface about which the mass rotates.

The effects would be magnified on a small instrument because the boom angles of
motion for the same displacement will be larger.


     If the bearing sizes are scaled with the boom length, the angles for a given boom deflection should be the same.

In addition the small instrument is operating at a much finer angle between the
upper and lower pivots so again the effect will be more pronounced.  Possibly the ball is more stable because the period is in effect lessening with displacement from center.


     The major difference between a large instrument and a small one lies in the period lengthening required. A 1 metre boom has a natural pendulum period of 2 sec. To get it to give a 20 second period (1/10), you have to suspend it at an angle to give a restoring force of g/100 -> 0.573 degrees.
     A 25 cm boom has a natural pendulum period of 1 sec. To get it to give a 20 second period (1/20), you have to suspend it at an angle to give a restoring force of g/400 -> 0.143 degrees.
     The smaller boom will be more difficult to set up and will give four times the deflection for any given ground tilt. It will also be proportionately more sensitive to any springyness in the suspension and to any frictional effects.

     In response to Steve Hammond's problem with wire suspensions rusting, you can buy nickel plated piano wire. This should give additional protection. D'Addario list several ranges of strings which are widely available http://www.daddariostrings.com/products.asp

     Regards,

     Chris Chapman
Subject: roller hinges, etc. From: BOB BARNS royb1@........... Date: Sat, 23 Nov 2002 21:41:23 -0500 Hi gang, Here is some info (via Google) about hinges. For the rolamite hinge: http://www.rexresearch.com/wilkes/1wilkes.htm See Fig. 4 for a rolling hinge in: http://www-civ.eng.cam.ac.uk/dsl/TSR_hinge.pdf A good discussion from our own archives: http://www.seismicnet.com/psnlist/990909_123918_1.html For pics of the Geotech 220 (up to 30 sec. period, 8" boom length, boom mounted with crossed flexures.) I got this via ebay, where else? http://mywebpages.comcast.net/ROYB1/ (my web site) I have not yet put this in service--still using my big, old, ugly home-made Lehman. Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Another horizontal boom/mast pivot to consider From: steve hammond shammon1@............. Date: Sat, 23 Nov 2002 18:36:30 -0800 Thanks George. When I heard about this hinge I originally envisioned "two crossed wires" in two round rings... and no matter how I spun those rings around in my head I could get them to work as a hinge. Now that you have explained it, I understand-- It is the same type of hinge that is commonly used on model airplanes for the vertical and horizontal rudders. Thanks-- Steve PSN San Jose, Aptos Calif. -----Original Message----- From: George Harris [SMTP:gjharris@.............. Sent: Saturday, November 23, 2002 4:37 PM To: psn-l@.............. Subject: Re: Another horizontal boom/mast pivot to consider From George Harris: The Fletcher type joint is probably similar to the one which consists of two round elements connected by flat tapes in such a way that the tapes cross in an "X" between the rollers. The joint has the unusual combination of no friction, and no torque due to the fact that as one tape unrolls, the other end rolls up so there is no net energy used in bending the tapes. The tapes must be intension (obviously I guess), but their thickness is not important as long as they are working within the elastic limit. ----- Original Message ----- From: "steve hammond" To: Sent: Saturday, November 23, 2002 8:28 AM Subject: RE: Another horizontal boom/mast pivot to consider > I'm looking for info or a drawing of a Fletcher joint and that may not be > the correct spelling of Fletcher. It is a joint with two rings and two > cross wires and has zero friction. > Thanks -- > Regards, Steve Hammond > > -----Original Message----- > From: meredithlamb [SMTP:meredithlamb@.............. > Sent: Friday, November 22, 2002 10:00 PM > To: psn-l@.............. > Subject: Re: Another horizontal boom/mast pivot to consider > > Hi all, > > I read plus's and minus's into this topic.....ball v/s torsion pivots. > > Perhaps a part of the aspect of a torsion pivot is that it likely is a > type of somewhat unstable double pivot pendum in essense, one > at the top (of the mast) and the lower torsion wires flexible movement > itself. There is a name for such, but a brief search engine search > yielded nothing for the moment. > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Another horizontal boom/mast pivot to consider From: "Charles R. Patton" charles.r.patton@........ Date: Sat, 23 Nov 2002 20:07:22 -0800 A few random thoughts. I agree that the ball bearing/hardened plate is extremely low friction and has well defined pivot motion, but I consider that it has a major fault if used in a potential hi-G (read local earthquake) areas such as California, and that is the possibility of the pivot slipping since there is very little constraint to forces parallel to the pivot surface, horizontal or vertical. With a modern 24 bit A/D, you could shoot for a dynamic range of about 16,000,000 to one, which somewhat equates from noise floor to a 7.0 earthquake - bigger than I hope I ever experience. I may be way off base, but it seems to me the use of a 24 bit A/D over a 16 bit opens up the possibility of both a sensitive distance detector, but also capable of recording local strong motion during such events. If true, then the possibility of the pivot jumping or sliding is important to consider. The answers that have been posted to my original question about stability seem to fall in one of two camps - pivot related and local soil condition (tilt) related. I subjectively thought this to probably be true, but it seems to be confirmed. I've always been partial to the Rolamite style bearings with regard to well constrained motion. In practice their loss should be no more than a foil hinge of equivalent foil width. With the additional benefit that the foil spring force is balanced, so that doesn't enter into the equation, only the hysteresis loss. The big problem with them in this application is that if you trap dust in between the bands and the rollers, they probably will act badly from a seismograph pivot viewpoint. However to provide the temperature control, the seismograph is pretty much enclosed and could be made dust proof, so this may be a viable approach. Now for a way out concept - and be prepared to shoot it down! A possible solution for making a self adjusting Lehman or similar pendulum system that can ignore slow soil tilt changes. Imagine floating the entire Lehman on a boat-like platform in water. Two problems jump to attention: 1) the damping of the 'boat' in the water is terrible and 2) now how do we transmit the ground motion to the seismo? The simplistic answer is float the seismograph in Silly Putty (Dow Corning 3179 Dilantant Compound). It is a 'dilatant" compound as opposed to a thixotropic compound, i.e., it flows very slowly, but hardens with fast shear/force. (see http://home.earthlink.net/~gschenberg/puttyfaq.htm) So when fast motion occurs to the tub of Silly Putty, the seismo would be carried along, just what is needed. A variation to conserve the amount of Silly Putty would be to have 'outriggers' on the seismo which reach over the tub of water and stick into small amounts of Putty. Then the seismo motions would be coupled through the Putty into the 'outriggers' and activate the seismograph. Now as the earth tilts over periods of hours, the seismo self-levels, never requiring readjustment. However, realize that the amount of putty necessary does not have to be very much if the 'boat' and the tub are very close fitting, you only have to provide a gap that is larger than the tilt which in practice is probably only a few tens of thousandths and tub height sufficient to'float' the boat. The putty SP is 1.14, slighty more than water. So build and test with water, then replace with putty, and you should float just a schosh higher. Just a wild thought - any takers? (Incidentally the site quoted above, but at: http://home.earthlink.net/~gschenberg/sillyput.htm does bulk buys and will sel you Dow Corning 3179 Dilantant Compound in poundage quantities at considerably better prices than buying Silly Putty at the toy store.) Regards, Charles R. Patton __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Another horizontal boom/mast pivot to consider From: Thomas W Leiper twleiper@........ Date: Sun, 24 Nov 2002 00:07:22 -0500 On Sat, 23 Nov 2002 20:07:22 -0800 "Charles R. Patton" writes: > A few random thoughts. [Continuing discussion about pivots redacted] This is one area where the "force balanced" approach always seemed to make sense since the actual movement of the pivot(s), regardless of type, is insignificant and thus so are the various disadvantages thereof. Tom __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: desensitivity due damping vs hinge From: "Roger Sparks" rsparks@........... Date: Sat, 23 Nov 2002 21:35:52 -0800 Hi all, Of course the restoring moment which is developed by the hinge in any seismometer is important, but it fades in importance compared to the restoring moment which is introduced by the damping method. A hydraulic damper will use some sort of piston or blade. Motion of the piston or blade through the liquid will involve setting some of the liquid into motion. To set anything into motion requires overcoming inertia, which will make the initial piston or blade movement "sticky". I think this can be minimized by using a liquid with higher viscosity at the same time as the minimum blade or piston size is used. I am less familiar with magnetic damping so I hesitate to comment. The hysteresis of metal will be important. Perhaps someone could comment on magnetic damping. Roger __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: roller hinges, etc. From: steve hammond shammon1@............. Date: Sun, 24 Nov 2002 00:59:06 -0800 Thanks Bob-- What I thought I had heard was Fletcher. Too many years on the flight deck of the Kittyhawk... Regards, Steve Hammond PSN San Jose, Aptos CA -----Original Message----- From: BOB BARNS [SMTP:royb1@............ Sent: Saturday, November 23, 2002 6:41 PM To: psn mail Subject: roller hinges, etc. Hi gang, Here is some info (via Google) about hinges. For the rolamite hinge: http://www.rexresearch.com/wilkes/1wilkes.htm See Fig. 4 for a rolling hinge in: http://www-civ.eng.cam.ac.uk/dsl/TSR_hinge.pdf A good discussion from our own archives: http://www.seismicnet.com/psnlist/990909_123918_1.html For pics of the Geotech 220 (up to 30 sec. period, 8" boom length, boom mounted with crossed flexures.) I got this via ebay, where else? http://mywebpages.comcast.net/ROYB1/ (my web site) I have not yet put this in service--still using my big, old, ugly home-made Lehman. Bob __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Another horizontal boom/mast pivot to consider From: BOB BARNS royb1@........... Date: Sun, 24 Nov 2002 10:40:05 -0500 Charles, I greatly admire truly original thinking! The Silly Putty scheme sounds like it might work. Bob ---snip--- > Now for a way out concept - and be prepared to shoot it down! A > possible solution for making a self adjusting Lehman or similar pendulum > system that can ignore slow soil tilt changes. Imagine floating the > entire Lehman on a boat-like platform in water. Two problems jump to > attention: 1) the damping of the 'boat' in the water is terrible and 2) > now how do we transmit the ground motion to the seismo? The simplistic > answer is float the seismograph in Silly Putty (Dow Corning 3179 > Dilantant Compound). It is a 'dilatant" compound as opposed to a > thixotropic compound, i.e., it flows very slowly, but hardens with fast > shear/force. (see > http://home.earthlink.net/~gschenberg/puttyfaq.htm) > So when fast motion occurs to the tub of Silly Putty, the seismo would > be carried along, just what is needed. A variation to conserve the > amount of Silly Putty would be to have 'outriggers' on the seismo which > reach over the tub of water and stick into small amounts of Putty. Then > the seismo motions would be coupled through the Putty into the > 'outriggers' and activate the seismograph. Now as the earth tilts over > periods of hours, the seismo self-levels, never requiring readjustment. > However, realize that the amount of putty necessary does not have to be > very much if the 'boat' and the tub are very close fitting, you only > have to provide a gap that is larger than the tilt which in practice is > probably only a few tens of thousandths and tub height sufficient > to'float' the boat. The putty SP is 1.14, slighty more than water. So > build and test with water, then replace with putty, and you should float > just a schosh higher. Just a wild thought - any takers? > > (Incidentally the site quoted above, but at: > http://home.earthlink.net/~gschenberg/sillyput.htm > does bulk buys and will sel you Dow Corning 3179 Dilantant Compound in > poundage quantities at considerably better prices than buying Silly > Putty at the toy store.) > > Regards, > Charles R. Patton > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Another horizontal boom/mast pivot to consider From: ChrisAtUpw@....... Date: Sun, 24 Nov 2002 11:00:25 EST In a message dated 23/11/2002, shammon1@............. writes: > I live near the sea and if I don't change the wire, the wire rusts and > eventually will snap under tension. Usually in less than 6 months. Hi Steve. One practical suggestion is to coat the wire with 'pure' soap solution and let it dry. This is the 'secret' behind the soaped wire wool scouring pads (Brillo Pads) for kitchen use. Soap is also added to 'ordinary' steel wire wool to prevent it corroding. A Cardan hinge is a single foil hinge in tension with the length much greater than the separation of the clamp bars. This enables it to carry loads parallel to the hinge axis. A pair off them, accurately aligned, may be used in a Lehman seismometer. Regards, Chris Chapman In a message dated 23/11/2002, shammon1@............. writes:

I live near the sea and if I don't change the wire, the wire rusts and eventually will snap under tension. Usually in less than 6 months.


Hi Steve.

     One practical suggestion is to coat the wire with 'pure' soap solution and let it dry. This is the 'secret' behind the soaped wire wool scouring pads (Brillo Pads) for kitchen use. Soap is also added to 'ordinary' steel wire wool to prevent it corroding. 

     A Cardan hinge is a single foil hinge in tension with the length much greater than the separation of the clamp bars. This enables it to carry loads parallel to the hinge axis. A pair off them, accurately aligned, may be used in a Lehman seismometer.

     Regards,

     Chris Chapman
Subject: Re: desensitivity due damping vs hinge From: ChrisAtUpw@....... Date: Sun, 24 Nov 2002 14:20:02 EST In a message dated 24/11/2002, rsparks@........... writes: > Of course the restoring moment which is developed by the hinge in any > seismometer is important, but it fades in importance compared to the > restoring moment which is introduced by the damping method. > > A hydraulic damper will use some sort of piston or blade. Motion of the > piston or blade through the liquid will involve setting some of the liquid > into motion. To set anything into motion requires overcoming inertia, which > will make the initial piston or blade movement "sticky". I think this can > be minimized by using a liquid with higher viscosity at the same time as > the > minimum blade or piston size is used. Hi Roger, I think that you may not quite have appreciated the difference between sliding friction between solids and the resistance to motion of a vane through a viscous liquid. A vane in a liquid experiences a resistive force due to motion, but there is none of the 'stick / slip' hysteresis that you get in friction between solids. One serious problem with liquid damping is that the viscosity of most fluids is very strongly temperature dependant. A seismometer which is correctly damped at 20 C will be underdamped at 30 C and overdamped at 10 C. > I am less familiar with magnetic damping so I hesitate to comment. The > hysteresis of metal will be important. Perhaps someone could comment on > magnetic damping. I am not sure what 'metal hysteresis' you mean. A magnetic damping system involves moving an electrically conducting vane, usually made of Aluminum or Copper, through a very strong magnetic field. These metals are 'non-magnetic'. Electric currents are induced in the vane proportional to the velocity, which slowly die away due to the electrical resistance of the metal. Again, there is NO stick / slip hysteresis. The forces are only slightly effected by the change in the field strength with temperature of the magnet and the change in resistivity with temperature of the vane metal. This has become a simple, cheap and practical method with the ready availability of very strong NdBFe magnets. The four pole 'wing' shaped magnets recovered from old computer hard drive systems are ideal for this. Regards, Chris Chapman In a message dated 24/11/2002, rsparks@........... writes:

Of course the restoring moment which is developed by the hinge in any
seismometer is important, but it fades in importance compared to the
restoring moment which is introduced by the damping method.

A hydraulic damper will use some sort of piston or blade.  Motion of the
piston or blade through the liquid will involve setting some of the liquid
into motion. To set anything into motion requires overcoming inertia, which
will make the initial piston or blade movement "sticky". I think this can
be minimized by using a liquid with higher viscosity at the same time as the
minimum blade or piston size is used.


Hi Roger,

     I think that you may not quite have appreciated the difference between sliding friction between solids and the resistance to motion of a vane through a viscous liquid. A vane in a liquid experiences a resistive force due to motion, but there is none of the 'stick / slip' hysteresis that you get in friction between solids. One serious problem with liquid damping is that the viscosity of most fluids is very strongly temperature dependant. A seismometer which is correctly damped at 20 C will be underdamped at 30 C and overdamped at 10 C.

I am less familiar with magnetic damping so I hesitate to comment.  The
hysteresis of metal will be important.  Perhaps someone could comment on
magnetic damping.


     I am not sure what 'metal hysteresis' you mean. A magnetic damping system involves moving an electrically conducting vane, usually made of Aluminum or Copper, through a very strong magnetic field. These metals are 'non-magnetic'. Electric currents are induced in the vane proportional to the velocity, which slowly die away due to the electrical resistance of the metal. Again, there is NO stick / slip hysteresis. The forces are only slightly effected by the change in the field strength with temperature of the magnet and the change in resistivity with temperature of the vane metal. This has become a simple, cheap and practical method with the ready availability of very strong NdBFe magnets. The four pole 'wing' shaped magnets recovered from old computer hard drive systems are ideal for this.

       Regards,

       Chris Chapman
Subject: Re: Sailing on a silly putty sea From: meredithlamb meredithlamb@............. Date: Sun, 24 Nov 2002 13:16:40 -0700 Ahoy! Charles and all, I'd imagine that the "seismo boat", would have to be quite precisely leveled with distributed weight "ballast", and need to be line "moored" at 3 "piers" points in this sailing sea of silly putty soup ....aaaey mate. Perhaps a force balance seismo could work, but I'd think a ordinary "hanging gate" horizontal seismo's mass wouldn't. Its sounds very difficult to do; but I don't think I'am ready to voluteer on this experimental voyage....who can we shanghai/bait to try it out? I'd think a "dingy" size seismo would be better than a "galleon" here for all the weight displacement in the silly sea. OK....couldn't help myself here...just a dab of humor and other thoughts..ha. Meredith "Charles R. Patton" wrote: > Now for a way out concept - and be prepared to shoot it down! A > possible solution for making a self adjusting Lehman or similar pendulum > system that can ignore slow soil tilt changes. Imagine floating the > entire Lehman on a boat-like platform in water. Two problems jump to > attention: 1) the damping of the 'boat' in the water is terrible and 2) > now how do we transmit the ground motion to the seismo? The simplistic > answer is float the seismograph in Silly Putty (Dow Corning 3179 > Dilantant Compound). It is a 'dilatant" compound as opposed to a > thixotropic compound, i.e., it flows very slowly, but hardens with fast > shear/force. (see > http://home.earthlink.net/~gschenberg/puttyfaq.htm) > So when fast motion occurs to the tub of Silly Putty, the seismo would > be carried along, just what is needed. A variation to conserve the > amount of Silly Putty would be to have 'outriggers' on the seismo which > reach over the tub of water and stick into small amounts of Putty. Then > the seismo motions would be coupled through the Putty into the > 'outriggers' and activate the seismograph. Now as the earth tilts over > periods of hours, the seismo self-levels, never requiring readjustment. > However, realize that the amount of putty necessary does not have to be > very much if the 'boat' and the tub are very close fitting, you only > have to provide a gap that is larger than the tilt which in practice is > probably only a few tens of thousandths and tub height sufficient > to'float' the boat. The putty SP is 1.14, slighty more than water. So > build and test with water, then replace with putty, and you should float > just a schosh higher. Just a wild thought - any takers? > > (Incidentally the site quoted above, but at: > http://home.earthlink.net/~gschenberg/sillyput.htm > does bulk buys and will sel you Dow Corning 3179 Dilantant Compound in > poundage quantities at considerably better prices than buying Silly > Putty at the toy store.) > > Regards, > Charles R. Patton > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: concrete piers From: Ian Smith ian@........... Date: Sun, 24 Nov 2002 21:58:58 +0000 Many thanks to all who responded to my qs about concrete piers - Dewayne, Steve, Meredith & John. Much appreciated. I'm building a house extension in the next few months and will have some latitude in installing a pier. The soil is clay like and the bedrock is a long way down. So I'll dig as deep as I can afford and work by the many suggestions in the emails received. The good news is that my house is in the middle of a farm and the nearest (really quiet) road is over half a mile away. So if I get the pier right, I should get some good results. Of course, the extension will keep me busy for a while before I can turn to the seismo. Thanks Ian Smith __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Horizontal boom length, for stability and period lengthening From: meredithlamb meredithlamb@............. Date: Sun, 24 Nov 2002 16:05:30 -0700 Hi Chris and all, Excellent educational note you wrote below. Its probably a much better answer over the question of stability/tilt/drift/period in some recent emails "debates", than I've realized before. I've never been a fan of long booms myself, but perhaps the ones with such, do operate with more stability, and longer possible periods, than those with the shorter booms. The original email "debate" involved the "ball bearing pivot" v/s the "Zollner" pivot suspension, and went from there into stability and long period aspects. There is alot of photographed web amateur "coil/magnet" horizontals ("old Betsys"), ( ha) with seemingly excessively long and thin diameter (weak?) booms using various boom/mast "contact" pivots. I do think alot of these were constructed in the "hope" that the "mechanical length or amplification" would somehow yield a better signal; rather than for any prior known stability/period lengthing building thought. About all I can say for the only "Zollner" seismo pivot I have (Sprengnether), is that its boom length is perhaps quite short, some ~ 15" between the coil sensor and the pivot area. It does have a stability problem much over 15-20 seconds. Anyway.....I'd expect a Zollner pivot seismo might (?) also improve in this stability/long period aspect "if" the boom were longer....but exactly how much it could improve is unknown. On the other hand, I'am not about to tear it apart...ha. Take care, Meredith ChrisAtUpw@....... wrote: > The major difference between a large instrument and a small one lies > in the period lengthening required. A 1 metre boom has a natural > pendulum period of 2 sec. To get it to give a 20 second period (1/10), > you have to suspend it at an angle to give a restoring force of g/100 > -> 0.573 degrees. > A 25 cm boom has a natural pendulum period of 1 sec. To get it to > give a 20 second period (1/20), you have to suspend it at an angle to > give a restoring force of g/400 -> 0.143 degrees. > The smaller boom will be more difficult to set up and will give > four times the deflection for any given ground tilt. It will also be > proportionately more sensitive to any springyness in the suspension > and to any frictional effects. > Chris Chapman Hi Chris and all,

Excellent educational note you wrote below.  Its probably a much
better answer over the question of stability/tilt/drift/period  in some
recent emails "debates", than I've realized before.

I've never been a fan of long booms myself, but perhaps the
ones with such, do operate with more stability, and longer possible
periods, than those with the shorter booms.  The original email
"debate" involved the "ball bearing pivot" v/s the "Zollner" pivot
suspension, and went from there into stability and long period
aspects.

There is alot of photographed web amateur "coil/magnet"
horizontals ("old Betsys"), ( ha) with seemingly excessively long
and thin diameter (weak?) booms using various boom/mast
"contact" pivots.   I do think alot of these were constructed in
the "hope" that the "mechanical length or amplification"
would somehow yield a better signal; rather than for any prior
known stability/period lengthing building thought.

About all I can say for the only "Zollner" seismo pivot I have
(Sprengnether), is that its boom length is perhaps quite short,
some ~ 15" between the coil sensor and the pivot area.  It
does have a stability problem much over 15-20 seconds.
Anyway.....I'd expect a Zollner pivot seismo might (?) also
improve in this stability/long period aspect "if" the boom were
longer....but exactly how much it could improve is unknown.
On the other hand, I'am not about to tear it apart...ha.

Take care, Meredith

ChrisAtUpw@....... wrote:

The major difference between a large instrument and a small one lies in the period lengthening required. A 1 metre boom has a natural pendulum period of 2 sec. To get it to give a 20 second period (1/10), you have to suspend it at an angle to give a restoring force of g/100 -> 0.573 degrees.
     A 25 cm boom has a natural pendulum period of 1 sec. To get it to give a 20 second period (1/20), you have to suspend it at an angle to give a restoring force of g/400 -> 0.143 degrees.
     The smaller boom will be more difficult to set up and will give four times the deflection for any given ground tilt. It will also be proportionately more sensitive to any springyness in the suspension and to any frictional effects.
Chris Chapman
Subject: Re: Ball Pivots From: John & Jan Lahr johnjan@........ Date: Sun, 24 Nov 2002 17:33:50 -0700 Hi Randall,

Consider a circular magnet hanging from a horizontal iron bar:

(see: http://jjlahr.com/science/psn/pivots )

If the center of mass of the magnet is at its center, then there will be no
preferred position which could be considered an infinite period in terms of
a pendulum.

Next consider the situation with the center of mass on the edge of the
magnet.

(see: http://jjlahr.com/science/psn/pivots )

The center of mass will rise a bit with rotation of the magnet, but not as much
as would a simple pendulum with length equal to the diameter of the magnet.
Thus the period is longer than the "equivalent" pendulum.

If a rod were connected to this magnet with a weight on it's end, then the
period will always be a bit longer than would be expected from the
pendulum with the length of the rod, but the longer the rod the less the
difference would be.

If the magnet were stuck to another magnet with the same diameter,
then the center of rotation would always be the center of the upper magnet.

If the lower pivot of a Lehman were designed to give the equivalent of
a very long boom, one would still be limited in the period if the upper
pivot remained a single point.  If both pivots worked with large round
surfaces running on parallel planar surfaces, then long periods could be
achieved without having to make the axis between the upper and=20 lower
pivots so nearly vertical.

I'm not really suggesting this as a viable mechanical arrangement,
but just as food for thought.

Cheers,
John



At 01:36 PM 11/23/2002, you wrote:
Hi All,
 
In pondering this issue, it would seem to me that as 2 convex surfaces roll, the contact point would move in the same direction as the mass.  This would put the pivot off center and effectively shorten the boom.  Depending on the radii involved the geometry with respect to the upper pivot will also be affected.  The effects would be magnified on a small instrument because the boom angles of motion for the same displacement will be larger.  In addition the small instrument is operating at a much finer angle between the upper and lower pivots so again the effect will be more pronounced.  Possibly the ball is more stable because the period is in effect lessening with displacement from center.  Any thoughts or calculations to either support or shoot me down?  I am using an archery point against an aircraft bolt head.  My FFT always has a peak between 18 and 25 seconds with very little adjustment needed.  I did go completely off the side when the river flooded 2 miles east of here and had to reset then and again when the water dropped.
 
 
   
Subject: Ball pivot From: "Randall Pratt" rpratt@............. Date: Mon, 25 Nov 2002 00:08:08 -0600 Chris, In rolling contact the center of rotation of the ball will be the center = of the ball and it will be in translation. The instantanious center of = rotation of the total boom will be the contact point. (wheel and axle) = If the compressive force in the boom is axial then any deflection from = center will throw the force off axis. There will have to be contact = friction sufficient to prevent the rotated boom from sliding on the = plate since the boom is no longer perpendicular and this force will be = tangent to the ball. The friction force will be in the direction of = pushing the boom toward center. =20 As to my earlier thought that the axis will be offset, I calculate that = for a 24" boom and .125" motion the pivot will move .0003" left or right = using a .125" ball. With 12" between upper and lower pivot this would = be less than 1% of the tilt angle you suggested and may not be a = significant factor. =20 May I suggest an experiment for the proponents of the ball? Operate = with as little damping as possible and compare to a true sine wave = equally damped. If the ball pivot is somehow causing stability with a = restoring force it should alter the peaks of the sine wave. =20
Chris,
 
In rolling contact the center of = rotation of the=20 ball will be the center of the ball and it will be in translation.  = The=20 instantanious center of rotation of the total boom will be the contact=20 point. (wheel and axle)  If the compressive force in the boom = is axial=20 then any deflection from center will throw the force off axis. There = will have=20 to be contact friction sufficient to prevent the rotated boom from = sliding on=20 the plate since the boom is no longer perpendicular and this force will = be=20 tangent to the ball.  The friction force will be in the direction = of=20 pushing the boom toward center. 
As to my earlier thought that the axis = will be=20 offset, I calculate that for a 24" boom and .125" motion the pivot will = move=20 ..0003" left or right using a .125" ball.  With 12" between upper = and lower=20 pivot this would be less than 1% of the tilt angle you suggested and=20 may not be a significant factor. 
May I suggest an experiment for the = proponents of=20 the ball?  Operate with as little damping as possible and = compare to a=20 true sine wave equally damped.  If the ball pivot is somehow = causing=20 stability with a restoring force it should alter the peaks of the = sine=20 wave.   
Subject: Scientists on Alert for Hidden Island Off Sicily From: "David Saum" DSaum@............ Date: Mon, 25 Nov 2002 12:48:06 -0500 Science - Reuters Mon, Nov 25, 2002 Scientists on Alert for Hidden Island Off Sicily ROME (Reuters) - A volcanic island submerged off the coast of Sicily for the last 170 years could reappear in the coming weeks if furious seismic rumblings continue, Italy's chief seismologist said Monday. "We've seen Etna erupting, seismic activity to the north and east of Sicily and gas activity around the Aeolian Islands," Enzo Boschi, head of Italy's Institute of Geophysics and Vulcanology, told Reuters. "The island could come back to the surface, but we'll have to wait and see... It could be a few weeks or months." Formed by the tip of a submerged volcano, the island last popped up in 1831, sparking a diplomatic spat among several nations, before it sank beneath the Mediterranean waves six months later. The volcano's peak now sits just 26 feet under water about 19 miles south of Sicily, near Tunisia. "We are monitoring things very closely," Boschi said. "The process could begin at any time... It would be a very beautiful and fascinating event." Over the centuries, the island has emerged four times, with underwater volcanic eruptions first recorded during the first Punic War of 264-241 BC. The last emergence on July 2, 1831, caused months of international wrangling with four nations making territorial claims including Britain, Spain and the Bourbon court of Sicily. The rock, which rose some 213 feet above the surface and had a circumference of about 3 miles, emerged for six months, giving the British time to claim it as Graham Island, while Sicily's King Ferdinand II called it Ferdinandea. Scientists refer to it as Graham Bank, but Italians still call it Ferdinandea. This time, Sicilian divers have gone down and planted a flag on the rock in the hope of claiming it as Italian the moment it rises above the surface, Boschi said. While it may not spark the same diplomatic spat as 170 years ago if it emerges, there could well be a new claimant. "I'm sure the European Union will want it as a member, won't they?" Boschi said. -------------- __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Ball pivot From: ChrisAtUpw@....... Date: Mon, 25 Nov 2002 16:43:11 EST In a message dated 25/11/2002, rpratt@............. writes: > In rolling contact the center of rotation of the ball will be the center of > the ball and it will be in translation. The instantanious center of > rotation of the total boom will be the contact point. (wheel and axle) Hi Randall, Sorry, but I disagree. Assume that the radius of the ball is R. Consider the boom rotating by a small angle A. The contact point moves a distance RA to one side and the boom load acts through the point of contact. This line intersects with the axis at a point R below the surface. This is the centre of rotation for small angular movements. If the compressive force in the boom is axial then any deflection from centre will > throw the force off axis. There will have to be contact friction sufficient > to prevent the rotated boom from sliding on the plate since the boom is no > longer perpendicular and this force will be tangent to the ball. The > friction force will be in the direction of pushing the boom toward centre. Sure there will be a small frictional force between the ball and the surface, but this lies in the plane of the surface and it does not effect the rolling motion, to a first order approximation. It is also quite small, it is a balanced force and is just sufficient to prevent the contact point from sliding. Do not confuse the coefficient of friction with the frictional force, or the resistance to rolling movement with static friction. > As to my earlier thought that the axis will be offset, I calculate that for > a 24" boom and .125" motion the pivot will move .0003" left or right using > a .125" ball. With 12" between upper and lower pivot this would be less > than 1% of the tilt angle you suggested and may not be a significant > factor. You need to consider the centre of rotation as a point on the axis R below the plane surface. This is one point that you consider when measuring the angle of the rotational axis to the vertical axis. > May I suggest an experiment for the proponents of the ball? Operate with as > little damping as possible and compare to a true sine wave equally damped. It may be easier to just measure 1) the period and 2) the damping factor. The damping gives an exponential fall off in the amplitude of the oscillation. These should be easy to do using your A/D logging program. Regards, Chris Chapman In a message dated 25/11/2002, rpratt@............. writes:

In rolling contact the center of rotation of the ball will be the center of the ball and it will be in translation.  The instantanious center of rotation of the total boom will be the contact point. (wheel and axle) 


Hi Randall,

     Sorry, but I disagree. Assume that the radius of the ball is R. Consider the boom rotating by a small angle A. The contact point moves a distance RA to one side and the boom load acts through the point of contact. This line intersects with the axis at a point R below the surface. This is the centre of rotation for small angular movements.

If the compressive force in the boom is axial then any deflection from centre will

throw the force off axis. There will have to be contact friction sufficient to prevent the rotated boom from sliding on the plate since the boom is no longer perpendicular and this force will be tangent to the ball.  The friction force will be in the direction of pushing the boom toward centre.


       Sure there will be a small frictional force between the ball and the surface, but this lies in the plane of the surface and it does not effect the rolling motion, to a first order approximation. It is also quite small, it is a balanced force and is just sufficient to prevent the contact point from sliding. Do not confuse the coefficient of friction with the frictional force, or the resistance to rolling movement with static friction.

As to my earlier thought that the axis will be offset, I calculate that for a 24" boom and .125" motion the pivot will move .0003" left or right using a .125" ball.  With 12" between upper and lower pivot this would be less than 1% of the tilt angle you suggested and may not be a significant factor.


     You need to consider the centre of rotation as a point on the axis R below the plane surface. This is one point that you consider when measuring the angle of the rotational axis to the vertical axis.
 

May I suggest an experiment for the proponents of the ball?  Operate with as little damping as possible and compare to a true sine wave equally damped.


     It may be easier to just measure 1) the period and 2) the damping factor. The damping gives an exponential fall off in the amplitude of the oscillation. These should be easy to do using your A/D logging program.

     Regards,

     Chris Chapman
Subject: Ball Pivots From: "Randall Pratt" rpratt@............. Date: Mon, 25 Nov 2002 23:30:02 -0600 John, Thanks for the nice explanation and drawing. You are correct about the = lengthening effect. http://jjlahr.com/science/psn/pivots To further the discussion, would not the center of rotation move from = the contact point at no displacement to a point behind the plane and in = the direction of travel as the boom is displaced rather than be = considered a lengthening of the boom on the boom side? The radius to = any point from the center of rotation must be perpendicular to the = velocity of the point. Thus the center of the pivot ball to the contact = point will define one line and a line perpendicular to the now flatter = motion of the mass on the end define a second line. When the system is = rotated to the horizontal, the movement of the center away from the mass = to a point behind the support will also tilt the axis of rotation = between the pivots to a more stable direction. =20 As you say, the upper pivot would best be designed to accomodate axis = change. In the arrangements I have seen in PSN, the upper ball is on = the opposite side of a support so as to be in compression. Therefore = the rolling would now move the center of rotation in the upper pivot = toward the mass with an end result of the new axis tilting the boom down = to a shorter period. A ball style support will require a good bit more = engineering than just using a conveniently sized ball. Do the = proponents have anything to offer regarding design? Randy
John,
 
Thanks for the nice explanation and = drawing. =20 You are correct about the lengthening effect.
http://jjlahr.com/science/p= sn/pivots
 
To further the discussion, would not the center of rotation move = from the=20 contact point at no displacement to a point behind the plane and in the=20 direction of travel as the boom is displaced rather than be considered a = lengthening of the boom on the boom side?  The radius to any point = from the=20 center of rotation must be perpendicular to the velocity of the=20 point.  Thus the center of the pivot ball to the contact point will = define=20 one line and a line perpendicular to the now flatter motion of the mass = on the=20 end define a second line.  When the system is rotated to the = horizontal,=20 the movement of the center away from the mass to a point behind the = support will=20 also tilt the axis of rotation between the pivots to a more stable=20 direction. 
 
As you say, the upper pivot would best be designed = to=20 accomodate axis change.  In the arrangements I have seen in = PSN, the=20 upper ball is on the opposite side of a support so as to be in=20 compression.  Therefore the rolling would now move the center of=20 rotation in the upper pivot toward the mass with an end result of = the new=20 axis tilting the boom down to a shorter period.  A ball style = support will=20 require a good bit more engineering than just using a conveniently sized = ball.  Do the proponents have anything to offer regarding = design?
 
Randy
Subject: Re: Ball Pivots From: Thomas W Leiper twleiper@........ Date: Tue, 26 Nov 2002 00:14:25 -0500 Mobius hinges are excellent because the flex strips only have one side, thus forcing motion in just two dimensions instead of three. Likewise, ball bearings fashioned from Klein bottles would probably be quite innovative, and I think somebody should do it. A. E. Neuman On Mon, 25 Nov 2002 23:30:02 -0600 "Randall Pratt" writes: [redacted] Do the proponents have anything to offer regarding design?
Mobius hinges are excellent because the flex strips only
have one side, thus forcing motion in just two dimensions
instead of three. Likewise, ball bearings fashioned from
Klein bottles would probably be quite innovative, and
I think somebody should do it.
 
A. E. Neuman
 
On Mon, 25 Nov 2002 23:30:02 -0600 "Randall Pratt" <rpratt@.............> writes:
[redacted]
 
  Do the proponents have anything to offer regarding=20 design?
Subject: Re: Another horizontal boom/mast pivot to consider From: ChrisAtUpw@....... Date: Tue, 26 Nov 2002 19:06:06 EST In a message dated 24/11/2002, charles.r.patton@........ writes: > Now for a way out concept - and be prepared to shoot it down! A possible > solution for making a self adjusting Lehman or similar pendulum system that > can ignore slow soil tilt changes. Imagine floating the entire Lehman on a > boat-like platform in water. Two problems jump to attention: 1) the > damping of the 'boat' in the water is terrible and 2) now how do we > transmit the ground motion to the seismo? The simplistic answer is float > the seismograph in Silly Putty (Dow Corning 3179 > Dilantant Compound). Hi Charles, OK, you set up your self levelling floating system. You then put a Lehman on top with maybe a 2 kilo mass. Along comes a nice large slow seismic wave and the boom goes to one side. In response, the platform tilts over a bit in the same direction and so the mass never re-centralises. No thanks. Regards, Chris Chapman In a message dated 24/11/2002, charles.r.patton@........ writes:

Now for a way out concept - and be prepared to shoot it down!  A possible solution for making a self adjusting Lehman or similar pendulum system that can ignore slow soil tilt changes.  Imagine floating the entire Lehman on a boat-like platform in water.  Two problems jump to attention: 1) the damping of the 'boat' in the water is terrible and 2) now how do we transmit the ground motion to the seismo?  The simplistic answer is float the seismograph in Silly Putty (Dow Corning 3179
Dilantant Compound).


Hi Charles,

     OK, you set up your self levelling floating system. You then put a Lehman on top with maybe a 2 kilo mass. Along comes a nice large slow seismic wave and the boom goes to one side. In response, the platform tilts over a bit in the same direction and so the mass never re-centralises. No thanks.

     Regards,

     Chris Chapman
Subject: Something completly different. From: Jan Froom Froom@............. Date: Tue, 26 Nov 2002 20:17:28 -0800 I don't know if any of you have discovered the California Coastal Records site. Kenneth Adelman and his wife have taken over 12,000 pictures of the California coast from Oregon to Mexico in the past three months; his wife is a helicopter pilot. These pictures are posted at the California Coastal Records web site and are free to anyone who wants to use them for non commercial purposes. His motivation, the protection of the California coast, by documenting its current state. They have done all this at their own expense and are not looking to raise any money to further this project, but their goal is to fund the California Coastal Protection Network (CCPN). CCPN, a California Nonprofit Organization, is going to be marketing the commercial rights to these photographs to raise money for coastal conservation. Needless to say it has become somewhat controversial.... And he received this note from an irate citizen regarding national security and some sort of geological problem associated with these pictures... Sorry for the long lead in..... Do any of you know what this guy is "hinting" about..... Thanks Jan From: "Kumar Subramaniam" To: sjordan51@....... Subject: Suggestion Date: Tue, 05 Nov 2002 08:38:01 -0800 Hi Susan, I deeply appreciate your website. You are trying to do something that is great and useful to protect California environment. I lived in CA and took all those fabulous rides around the coast. Your photographs are amazing. But I have a suggestion that you may want to strongly consider. I come from a background which you may not understand fully. I have 2 Masters degree in engineering related to geotech etc. and perfoming advanced research on earthquake prediction etc. I track quakes that involve people lives and have been more successful than even the best agencies spending billions on it. To me the exposure of California coastline to the public this way is extremely dangerous for the following reasons: After 9/11 exposing your coastline without proper computer system policies (preferred users) will achieve dangerous results i.e. opposite to what you are trying to do. I beg you not to expose CA to the whole world at this time. It is pretty easy for terrorists to target your sites. I speak with great scientific backing after studying with the top most scientist related to geology on earth. There are many many ways that one could cause serious harm to CA with least of equipments not from the traditional weapons of mass destruction but with something totally different which people like me and few know and do not tell it out for security reasons. Even if they may or may not be able to do it today they can certainly in say 5 years when all this 9/11 would have been forgotten. The security system in this nation cannot cover all those things as it is very very expensive to save the whole Coast that too there are no geologist with such a background who work for your top security agencies. I know that. So, I beg you to not expose these coastlines as it will achieve something that you can never ever imagine. No geologist will tell you all this openly because of security reasons................. To me you should have restricted access to your site and you have to have a reasonably good mechanism as to whom you expose this site. You can contact the experts in the field of system policy and how to implement it. Even otherwise, please wait with your environmental concerns for at least a year till the national security system is in place. Please. I studied in the top health and safety and earth science school. Thanks Kumar I don't know if any of you have discovered the California Coastal Records site. Kenneth Adelman and his wife have taken over 12,000 pictures of the California coast from Oregon to Mexico in the past three months; his wife is a helicopter pilot. These pictures are posted at the California Coastal Records web site and are free to anyone who wants to use them for non commercial purposes.

His motivation, the protection of the California coast, by documenting its current state.  They have done all this at their own expense and are not looking to raise any money to further this project, but their goal is to fund the California Coastal Protection Network (CCPN). CCPN, a California Nonprofit Organization, is going to be marketing the commercial rights to these photographs to raise money for coastal conservation.

Needless to say it has become somewhat controversial....  And he received this note from an irate citizen regarding national security and some sort of geological problem associated with these pictures...

Sorry for the long lead in.....

Do any of you know what this guy is "hinting" about.....        Thanks Jan

	From: "Kumar Subramaniam" <paulmar3@...........>
	To: sjordan51@.......
	Subject: Suggestion
	Date: Tue, 05 Nov 2002 08:38:01 -0800

	Hi Susan,

	I deeply appreciate your website.  You are trying to do something
	that is great and useful to protect California environment.  I
	lived in CA and took all those fabulous rides around the coast.
	Your photographs are amazing.

	But I have a suggestion that you may want to strongly consider.  I
	come from a background which you may not understand fully.  I have
	2 Masters degree in engineering related to geotech etc.  and
	perfoming advanced research on earthquake prediction etc.  I
	track quakes that involve people lives and have been more
	successful than even the best agencies spending billions on
	it.

	To me the exposure of California coastline to the public this way
	is extremely dangerous for the following reasons:

	After 9/11 exposing your coastline without proper computer system
	policies (preferred users) will achieve dangerous results i.e.
	opposite to what you are trying to do.

	I beg you not to expose CA to the whole world at this time.  It is
	pretty easy for terrorists to target your sites.  I speak with
	great scientific backing after studying with the top most
	scientist related to geology on earth.	There are many many ways
	that one could cause serious harm to CA with least of equipments
	not from the traditional weapons of mass destruction but with
	something totally different which people like me and few know and
	do not tell it out for security reasons.

	Even if they may or may not be able to do it today they can
	certainly in say 5 years when all this 9/11 would have been
	forgotten.

	The security system in this nation cannot cover all those things
	as it is very very expensive to save the whole Coast that too
	there are no geologist with such a background who work for your
	top security agencies.	I know that.

	So, I beg you to not expose these coastlines as it will achieve
	something that you can never ever imagine.  No geologist will tell
	you all this openly because of security reasons.................

	To me you should have restricted access to your site and you have
	to have a reasonably good mechanism as to whom you expose this
	site.

	You can contact the experts in the field of system policy and how
	to implement it.

	Even otherwise, please wait with your environmental concerns for
	at least a year till the national security system is in place.
	Please.  I studied in the top health and safety and earth science
	school.

	Thanks
	Kumar
 
Subject: Re: Another horizontal boom/mast pivot to consider From: Thomas W Leiper twleiper@........ Date: Wed, 27 Nov 2002 01:05:57 -0500 That's where the ball bearing rolls off the base and falls onto the lever that pops a dog biscuit into the air, which is caught by one of the two puppies, which turns around and farts at the pendulum, causing it to swing back the other way. R. Goldberg On Tue, 26 Nov 2002 19:06:06 EST ChrisAtUpw@....... writes: OK, you set up your self levelling floating system. You then put a Lehman on top with maybe a 2 kilo mass. Along comes a nice large slow seismic wave and the boom goes to one side. In response, the platform tilts over a bit in the same direction and so the mass never re-centralises. No thanks.
That's where the ball bearing rolls off the base and
falls onto the lever that pops a dog biscuit into the
air, which is caught by one of the two puppies, which
turns around and farts at the pendulum, causing it to
swing back the other way.
 
R. Goldberg
 
On Tue, 26 Nov 2002 19:06:06 EST ChrisAtUpw@....... writes:
  =   =20 OK, you set up your self levelling floating system. You then put a Lehman= on=20 top with maybe a 2 kilo mass. Along comes a nice large slow seismic wave = and=20 the boom goes to one side. In response, the platform tilts over a bit in = the=20 same direction and so the mass never re-centralises. No=20 thanks.
Subject: Re: Another horizontal boom/mast pivot to consider From: ChrisAtUpw@....... Date: Wed, 27 Nov 2002 08:49:50 EST In a message dated 27/11/2002, twleiper@........ writes: > That's where the ball bearing rolls off the base and > falls onto the lever that pops a dog biscuit into the > air, which is caught by one of the two puppies, which > turns around and farts at the pendulum, causing it to > swing back the other way. Hi all, Sounds like a 'haven't a clue'! But is it an attempt at 'blank verse', or just 'doggerel'? Regards, Chris In a message dated 27/11/2002, twleiper@........ writes:

That's where the ball bearing rolls off the base and
falls onto the lever that pops a dog biscuit into the
air, which is caught by one of the two puppies, which
turns around and farts at the pendulum, causing it to
swing back the other way.


Hi all,

     Sounds like a 'haven't a clue'!
     But is it an attempt at 'blank verse', or just 'doggerel'?

     Regards,

     Chris
Subject: Thanksgiving day wish From: meredithlamb meredithlamb@............. Date: Wed, 27 Nov 2002 13:13:35 -0700 Hi all, Wish you all a happy Thanksgiving day out there, for all those who observe such; and "happy future trails" to those that don't. Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Ball Pivots From: ChrisAtUpw@....... Date: Wed, 27 Nov 2002 20:03:53 EST Hi John, There is really no problem with ball pivots, only with some people's understanding of them! If you have a ball on the end of the arm rotating up against a flat, the centre of rotation is on the axis at a point equal to the radius of the ball beneath the surface. If you have a flat on the end of the arm rotating up against a ball, the center of rotation is at the centre of the ball. I can send you drawings if it would help. Happy thanksgiving! Chris Chapman Hi John,

     There is really no problem with ball pivots, only with some people's understanding of them! If you have a ball on the end of the arm rotating up against a flat, the centre of rotation is on the axis at a point equal to the radius of the ball beneath the surface. If you have a flat on the end of the arm rotating up against a ball, the center of rotation is at the centre of the ball. I can send you drawings if it would help.

     Happy thanksgiving!

     Chris Chapman

Subject: Ball Pivots From: "Randall Pratt" rpratt@............. Date: Wed, 27 Nov 2002 23:59:03 -0600 Chris, Refering to earlier. > May I suggest an experiment for the proponents of the ball? Operate = with as=20 > little damping as possible and compare to a true sine wave equally = damped. It may be easier to just measure 1) the period and 2) the damping=20 factor. The damping gives an exponential fall off in the amplitude of = the=20 oscillation. These should be easy to do using your A/D logging program.=20 I wasn't thinking of just period and damping. My thought was that if = the pivot axis is changing toward a more stable configuration (different = sized ball pivots or no upper ball) the pure sine wave will be deformed = by a higher restoring force with an increase in displacement and provide = experimental evidence for ball pivots being more stable at least in the = extreme. Randy.
Chris,
Refering to earlier.
>=20 May I=20 suggest an experiment for the proponents of the ball?  Operate with = as=20
> little damping as possible and compare to a true sine wave = equally=20 damped.

     It may be easier to just measure = 1) the=20 period and 2) the damping
factor. The damping gives an exponential = fall off=20 in the amplitude of the
oscillation. These should be easy to do = using your=20 A/D logging program.
 
I wasn't thinking of just period and = damping. =20 My thought was that if the pivot axis is changing toward a more stable=20 configuration (different sized ball pivots or no upper ball) the pure = sine wave=20 will be deformed by a higher restoring force with an increase in=20 displacement and provide experimental evidence for ball pivots being = more stable=20 at least in the extreme.
 
Randy.


Subject: Casper Hossfield 1918-2002 From: CapAAVSO@....... Date: Thu, 28 Nov 2002 09:15:02 EST To all Public Seismic Network members: I am writing to let you all know that my father Casper suffered a stroke at about 11 am on 25 November. He was immediately taken to a nearby VA hospital where it was determined that he had inoperable bleeding in his brain. He passed away at about 5 pm the next day, 26 November. He was not in pain as a result of his stroke and died with great dignity. PLEASE DO NOT SEND MESSAGES OF CONDOLENCE. I have taken on the task of notifying my father's email friends to let you all know all know of his passing. As you can imagine he has been receiving large volumes of email, and my top priority is to wade through it all to determine who needs to be notified. While I certainly appreciate everyone's sentiments, messages of condolence will only clog his email account and make my task more difficult. PLEASE REMOVE CAPAAVSO FROM THE PSN DISTRIBUTION LIST. If there is a procedure I need to follow to discontinue psn messages, do let me know. I CANNOT HELP COMPLETE ANY PROJECTS OR TRANSACTIONS. I am sorry about this, but none of my Father's survivors knows anything about his projects or how to complete them. RUSTRACK RECORDERS. One thing we are aware of is that my father has a large number of Rustrack recorders and recording tapes that are useful to many of you. Some of them are here in Florida and most are in New Jersey. We will not respond to any individual requests for either recorders or tape, BUT we would like to find one person to whom all other the Rustrack items can be sent. I am not sure whether that one person will be found among you the PSN members or among the AAVSO members. I want to ask that you all discuss this among yourselves and tell me where the recorders and tape can be shipped. For this purpose you are welcome to contact me at this email account, which we will keep active for about one month. I hope this Thanksgiving finds you all well. I know my father would wish you all the best. Bruce Hossfield __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: General-Stability of "Lehman" sensor From: "Connie and Jim Lehman" lehmancj@........... Date: Thu, 28 Nov 2002 11:28:55 -0500 PSN-Friends--I have read with interest the exchanges regarding stability = and modifications to the so-called "Lehman" seismic design. The plans = as published in July, 1979 Sci. American were the result of 5 years of = running the system in a number of environments, ---if I remember we = tried 4 different types of Milne cantilever long period units, and = settled on the design published. As I have said before, the system--as = most seismic designs--lends itself to modifications & improvements. The BallBearing and Tensional Wire designs for the boom end sound = ingenious--although I have never tried them. I stayed with the 15-cent = hardware 5/16 or so bolt ground to a knife edge. When mounted properly = against a hard plate or flattened bolt head epoxied to the upright, I = never experienced any undo friction or flattening of the knife edge. = Microseisms were always there--in fact one would have to run fast to get = away from microseisms. One amateur enthusiast in Puerto Rico had to = settle for his system on the 14th floor of a high-rise apartment = building. In windy weather the building swayed, and the microseisms = just "rode the swells" as he put it. It is easy to "overkill" the location of the sensor. Ground level = on a concrete floor with little temperature or humidity changes is = ideal. Direct connection with bedrock is not necessary. One of the = best locations during the testing time was in an unused room of a = laboratory building. Several feet of fill clay had been leveled, and = several inches of gravel on top. Any bedrock (limestone here is = Virginia) was probably 10 or so feet away. We laid down 3 small garden- = shop masonry step-stones------mounted our system--let it settle for a = day or two, and began recording. Later the area was finished with = concrete floor, etc, and placing our sensor there gave similar = satisfaction--only now more building noise was evident--vibrations from = the Chiller 150 ft. away, and stresses in the building and stairwells as = students moved to and from classes. I do feel a kinship with persons frustrated in setting up and = stabilizing a system especially in a closed space. The Sci. American = design should be stable for weeks at at least 15 second period. A good = heavy base material other than wood is best. Composite material like = laboratory table tops is ideal. Rather than have adjustable tri --feet = on the base, I would suggest firm solid feet--fixed bolts or similar, = and then use thin shims to complete the task once you have the mechanics = of the system in the "ball park". Five or ten mil thick sheet metal = pieces work great here. Once you have a 10 second or so period = centering ok, then all you have to do is add shims to the "front" leg = and the period goes up in a nicely until you reach instability--then = back off a shim or two. If there is a steady trend to drift to one side, chances are the = base is tilting a bit due to a structural weakness---or more likely the = slab on which the sensor is placed is moving. I have known of systems = placed in the corner of a home basement, and periodically drift was = noted as the house foundation settles a bit--and this can happen over = years and not be detected by sight. If you really wish to overkill = your sensor base you can do what amateur astronomers do--pour a concrete = slab block to attach their scope base, and surround the block with = several inches of sand---then there is no walkup tilt of the base, and = any lateral mechanical vibrations at minimized as well.=20 Well I have rambled enough--good stability to all, and Season's = Greetings! = Jim Lehman=20
 
PSN-Friends--I have = read with=20 interest the exchanges regarding stability and modifications to the = so-called=20 "Lehman" seismic design.  The plans as published in July, 1979 Sci. = American were the result of 5 years of running the system in a number of = environments, ---if I remember we tried 4 different types of Milne = cantilever=20 long period units, and settled on the design published.  As I have = said=20 before, the system--as most seismic designs--lends itself to = modifications &=20 improvements.
   The = BallBearing and=20 Tensional Wire designs for the boom end sound ingenious--although I have = never=20 tried them.  I stayed with the 15-cent hardware 5/16 or so bolt = ground to a=20 knife edge.  When mounted properly against a hard plate or = flattened bolt=20 head epoxied to the upright, I never experienced any undo friction or = flattening=20 of the knife edge.  Microseisms were always there--in fact one = would have=20 to run fast to get away from microseisms.  One amateur enthusiast = in Puerto=20 Rico had to settle for his system on the 14th floor of a high-rise = apartment=20 building.  In windy weather the building swayed, and the = microseisms just=20 "rode the swells" as he put it.
    It = is easy to=20 "overkill" the location of the sensor.  Ground level on a concrete = floor=20 with little temperature or humidity changes is ideal.  Direct = connection=20 with bedrock is not necessary.  One of the best locations during = the=20 testing time was in an unused room of a laboratory building.  = Several feet=20 of fill clay had been  leveled, and several inches of = gravel on=20 top.  Any bedrock (limestone here is Virginia) was probably 10 or = so feet=20 away.  We laid down 3 small garden- shop masonry = step-stones------mounted=20 our system--let it settle for a day or two, and began recording.  = Later the=20 area was finished with concrete floor, etc, and placing our sensor there = gave=20 similar satisfaction--only now more building noise was = evident--vibrations from=20 the Chiller 150 ft. away, and stresses in the building and stairwells as = students moved to and from classes.
   I do = feel a kinship=20 with persons frustrated in setting up and stabilizing a system = especially in a=20 closed space.  The Sci. American design should be stable for weeks = at at=20 least 15 second period.  A good heavy base material other than = wood is=20 best.  Composite material like laboratory table tops is = ideal.  Rather=20 than have adjustable tri --feet on the base, I would suggest firm solid=20 feet--fixed bolts or similar, and then use thin shims to complete the = task once=20 you have the mechanics of the system in the "ball park".  Five or = ten mil=20 thick sheet metal pieces work great here.  Once you have a 10 = second or so=20 period centering ok, then all you have to do is add shims to the "front" = leg and=20 the period goes up in a nicely until you reach instability--then back = off a shim=20 or two.
    If = there is a=20 steady trend to drift to one side, chances are the base is tilting a = bit =20 due to a structural weakness---or more likely the slab on which the = sensor is=20 placed is moving.  I have known of systems placed in the corner of = a home=20 basement, and periodically drift was noted as the house foundation = settles a=20 bit--and this can happen over years and not be detected  by = sight.  If=20 you really wish to overkill your sensor base you can do what amateur = astronomers=20 do--pour a concrete slab block to attach their scope base, and surround = the=20 block with several inches of sand---then there is no walkup tilt of the = base,=20 and  any lateral mechanical vibrations at minimized as=20 well. 
   Well I = have rambled=20 enough--good stability to all, and Season's Greetings!
 
          &nbs= p;            = ;            =             &= nbsp;           &n= bsp;         =20 Jim Lehman 
Subject: Re: Ball Pivots From: ChrisAtUpw@....... Date: Thu, 28 Nov 2002 21:25:22 EST In a message dated 28/11/02, rpratt@............. writes: > Refering to earlier. > > May I suggest an experiment for the proponents of the ball? Operate with > as > > little damping as possible and compare to a true sine wave equally damped. > > It may be easier to just measure 1) the period and 2) the damping > factor. The damping gives an exponential fall off in the amplitude of the > oscillation. These should be easy to do using your A/D logging program. > > I wasn't thinking of just period and damping. My thought was that if the > pivot axis is changing toward a more stable configuration (different sized > ball pivots or no upper ball) the pure sine wave will be deformed by a > higher restoring force with an increase in displacement and provide > experimental evidence for ball pivots being more stable at least in the > Hi Randy, I should have explained my suggestions more fully. Even if the suspension system is not quite linear, the difference that you will see on the real pendulum motion by comparing it to a sine wave, will be tiny. Simple pendulums also show small deviations from pure sine wave due to sin(angle) being assumed to be = angle. Trying to observe deviations directly on the waveform, particularly when the amplitude is changing, is a 'non starter'. I suggested two measurements that may react to the averaged effects and might be more helpful. The distortion that will occur will be mostly third harmonic. You have two possible sources. One is the pendulum itself and the other is non linearity of the sensor response. If you had a very linear sensor system, you could set the seismometer up for say 6 sec oscillations and look for signals of 2 sec period, but the usual coil + U magnet systems are likely to generate far more distortion than the pendulum! You could try putting the coil output into a twin Tee filter set to reject the natural pendulum frequency and then amplify the remaining signal. You can get ~55 dB rejection this way from a single filter, so deviations of a few parts in 1000 will show up and you can watch the decay in real time with a 'scope. We need a suspension system which has minimum natural damping, minimum hysteresis and more importantly, one in which the rotational axis is constant and very closely defined. Now how good is good? The period of a pendulum with an arm length L suspended with the rotational axis at angle A to the vertical is P = 2 x Pi x Sqrt(L / (g x sinA)). I visited Bob Barns' Website at http://mywebpages.comcast.net/ROYB1/ and he quotes a Teledyne Geotech SL-220 horizontal seismometer with an 8" arm attaining a period of 30 sec. g = 9.81 m^2/sec and L = 0.2 m. I fed this into the equation and A = 3 min of arc. Moreover, you have to be able to set this up reliably, so we are considering setup angles of just a few sec of arc. The suspension system also has to be rigid / stable to near this order. This is perhaps an extreme example and is obtained by the use of crossed foil suspensions, but see my previous EMails for A for pendulums with 25 and 100 cm arms. Meredith says that his Sprengnether with single wire suspensions and a boom length of ~ 15" between the coil sensor and the pivot area, does have a stability problem much over 15-20 seconds. Since this is a very rigid seismometer, it may well be the wire suspension which is the limiting factor. Summing up, you may be limited in the period that you can set by the suspension system, or by the rigidity / stability of the apparatus, or by the stability of the local ground. It would be very interesting to make two seismometers identical in all respects except for the suspension systems and compare the damping and the limiting periods. I suspect that the limiting periods of 'traditional' systems could be improved by additional bracing, since this would prevent changes in the support angle due to temperature changes. I hope that this answers your question well enough. Regards, Chris Chapman In a message dated 28/11/02, rpratt@............. writes:

Refering to earlier.
> May I suggest an experiment for the proponents of the ball?  Operate with as
> little damping as possible and compare to a true sine wave equally damped.

    It may be easier to just measure 1) the period and 2) the damping
factor. The damping gives an exponential fall off in the amplitude of the
oscillation. These should be easy to do using your A/D logging program.


I wasn't thinking of just period and damping.  My thought was that if the pivot axis is changing toward a more stable configuration (different sized ball pivots or no upper ball) the pure sine wave will be deformed by a higher restoring force with an increase in displacement and provide experimental evidence for ball pivots being more stable at least in the extreme.


Hi Randy,

      I should have explained my suggestions more fully. Even if the suspension system is not quite linear, the difference that you will see on the real pendulum motion by comparing it to a sine wave, will be tiny. Simple pendulums also show small deviations from pure sine wave due to sin(angle) being assumed to be = angle. Trying to observe deviations directly on the waveform, particularly when the amplitude is changing, is a 'non starter'. I suggested two measurements that may react to the averaged effects and might be more helpful.

      The distortion that will occur will be mostly third harmonic. You have two possible sources. One is the pendulum itself and the other is non linearity of the sensor response. If you had a very linear sensor system, you could set the seismometer up for say 6 sec oscillations and look for signals of 2 sec period, but the usual coil + U magnet systems are likely to generate far more distortion than the pendulum! You could try putting the coil output into a twin Tee filter set to reject the natural pendulum frequency and then amplify the remaining signal. You can get ~55 dB rejection this way from a single filter, so deviations of a few parts in 1000 will show up and you can watch the decay in real time with a 'scope.

      We need a suspension system which has minimum natural damping, minimum hysteresis and more importantly, one in which the rotational axis is constant and very closely defined. Now how good is good? The period of a pendulum with an arm length L suspended with the rotational axis at angle A to the vertical is P = 2 x Pi x Sqrt(L / (g x sinA)). I visited Bob Barns' Website at http://mywebpages.comcast.net/ROYB1/  and he quotes a Teledyne Geotech SL-220 horizontal seismometer with an 8" arm attaining a period of 30 sec. g = 9.81 m^2/sec and L = 0.2 m. I fed this into the equation and A = 3 min of arc. Moreover, you have to be able to set this up reliably, so we are considering setup angles of just a few sec of arc. The suspension system also has to be rigid / stable to near this order. This is perhaps an extreme example and is obtained by the use of crossed foil suspensions, but see my previous EMails for A for pendulums with 25 and 100 cm arms. Meredith says that his Sprengnether with single wire suspensions and a boom length of ~ 15" between the coil sensor and the pivot area, does have a stability problem much over 15-20 seconds. Since this is a very rigid seismometer, it may well be the wire suspension which is the limiting factor.

      Summing up, you may be limited in the period that you can set by the suspension system, or by the rigidity / stability of the apparatus, or by the stability of the local ground. It would be very interesting to make two seismometers identical in all respects except for the suspension systems and compare the damping and the limiting periods. I suspect that the limiting periods of 'traditional' systems could be improved by additional bracing, since this would prevent changes in the support angle due to temperature changes.   

      I hope that this answers your question well enough.

      Regards,

      Chris Chapman
Subject: Re: Another horizontal boom/mast pivot to consider From: Bobhelenmcclure@....... Date: Thu, 28 Nov 2002 23:01:58 EST Hi Charles and Chris, If you want to float your horizontal seismometer in Silly Putty or whatever, you must have flotation stability. If you have a 20 second period, the effective length of the pendulum is 100 meters. You have to assume the mass of the pendulum is 100 meters above the deck, so far as tipping moment in the sensing direction is concerned, and design your "barge" to be stable with such a top-heavy load. This is another reason to use a lightweight pendulum. The "barge" is going to have to be very long in the sensing direction otherwise. It is still worth considering for those who suffer from instability from the ground or pier, but you might need to consult a naval architect. My idea is to mount the sensor on the pivot end of a gimbal-supported hanging pendulum, and have the bob end sitting in viscous liquid, but then the pier would have to be hollow, like maybe an unused chimney. Regards, Bob McClure Hi Charles and Chris,

  If you want to float your horizontal seismometer in Silly Putty or whatever, you must have flotation stability.  If you have a 20 second period, the effective length of the pendulum is 100 meters.  You have to assume the mass of the pendulum is 100 meters above the deck, so far as tipping moment in the sensing direction is concerned, and design your "barge" to be stable with such a top-heavy load.  This is another reason to use a lightweight pendulum.  The "barge" is going to have to be very long in the sensing direction otherwise.  It is still worth considering for those who suffer from instability from the ground or pier, but you might need to consult a naval architect.

  My idea is to mount the sensor on the pivot end of a gimbal-supported hanging pendulum, and have the bob end sitting in viscous liquid, but then the pier would have to be hollow, like maybe an unused chimney.

Regards,

Bob McClure
Subject: Re: Casper Hossfield 1918-2002 From: "Larry Cochrane" cochrane@.............. Date: Thu, 28 Nov 2002 22:15:19 -0800 Bruce, I'm so sorry to hear about the death of your father. His email address has been removed from the PSN-L list. Regards, Larry Cochrane Redwood City, PSN ----- Original Message ----- From: To: Sent: Thursday, November 28, 2002 6:15 AM Subject: Casper Hossfield 1918-2002 > To all Public Seismic Network members: > > I am writing to let you all know that my father Casper suffered a stroke at > about 11 am on 25 November. He was immediately taken to a nearby VA hospital > where it was determined that he had inoperable bleeding in his brain. He > passed away at about 5 pm the next day, 26 November. He was not in pain as a > result of his stroke and died with great dignity. > > PLEASE DO NOT SEND MESSAGES OF CONDOLENCE. I have taken on the task of > notifying my father's email friends to let you all know all know of his > passing. As you can imagine he has been receiving large volumes of email, > and my top priority is to wade through it all to determine who needs to be > notified. While I certainly appreciate everyone's sentiments, messages of > condolence will only clog his email account and make my task more difficult. > > PLEASE REMOVE CAPAAVSO FROM THE PSN DISTRIBUTION LIST. If there is a > procedure I need to follow to discontinue psn messages, do let me know. > > I CANNOT HELP COMPLETE ANY PROJECTS OR TRANSACTIONS. I am sorry about this, > but none of my Father's survivors knows anything about his projects or how to > complete them. > > RUSTRACK RECORDERS. One thing we are aware of is that my father has a large > number of Rustrack recorders and recording tapes that are useful to many of > you. Some of them are here in Florida and most are in New Jersey. We will > not respond to any individual requests for either recorders or tape, BUT we > would like to find one person to whom all other the Rustrack items can be > sent. I am not sure whether that one person will be found among you the PSN > members or among the AAVSO members. I want to ask that you all discuss this > among yourselves and tell me where the recorders and tape can be shipped. For > this purpose you are welcome to contact me at this email account, which we > will keep active for about one month. > > I hope this Thanksgiving finds you all well. I know my father would wish you > all the best. > > Bruce Hossfield > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Sorry about my last message From: "Larry Cochrane" cochrane@.............. Date: Thu, 28 Nov 2002 23:30:22 -0800 Sorry, I hit the send button too soon. My last message should have gone to Bruce not the list.... -Larry __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: concrete piers From: meredithlamb meredithlamb@............. Date: Wed, 04 Dec 2002 16:59:39 -0700 Hi Ian, If you have that much unknown clay depth, there may not be much one can do to make it stabile outside of increasing the concrete pier width as much as possible. I do think it might be helpful to drive some iron/steel rebars or whatever, into the clay to whatever depth, and concrete pouring a portion of the tops of the iron/steel into the pier to help improve the stability. Normally....using steel (horizontal re-inforcement) isn't recommended of course; but the vertical iron/steel might help stabilize it abit more. The clay might be more resistant to a "test" driven rebar than known; so the feasibity, depth/length might be gauged from that. I envy your quiet location! Good deal on the house extension! Take care, Meredith Ian Smith wrote: > Many thanks to all who responded to my qs about concrete piers - > Dewayne, Steve, Meredith & John. Much appreciated. I'm building a > house extension in the next few months and will have some latitude in > installing a pier. The soil is clay like and the bedrock is a long way > down. So I'll dig as deep as I can afford and work by the many > suggestions in the emails received. > > The good news is that my house is in the middle of a farm and the > nearest (really quiet) road is over half a mile away. So if I get the > pier right, I should get some good results. Of course, the extension > will keep me busy for a while before I can turn to the seismo. > > Thanks > > Ian Smith __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: seismograph item? From: BOB BARNS royb1@........... Date: Thu, 05 Dec 2002 21:09:32 -0500 Hi gang, Ebay offers: Kinemetrics SMA-1 Seismograph Event Indicator Item # 1923224052 ends Dec 10 I have no idea what this is but it looks complicated. Bob Barns __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: seismograph item? From: hammond hammond@........... Date: Thu, 05 Dec 2002 18:39:51 -0900 Bob, it's a strong motion accelerograph which uses film as the recording medium. The unit gets triggered if the ground acceleration exceeds a set value and then records the ground motion on a wide film strip. These are still widely used but superceded by digital strong motion recorders. Bob Hammond Public Seismic Network - Alaska Fairbanks http://apsn.awcable.com At 05:09 PM 12/5/2002, you wrote: >Hi gang, > Ebay offers: >Kinemetrics SMA-1 Seismograph Event Indicator >Item # 1923224052 ends Dec 10 > I have no idea what this is but it looks complicated. >Bob Barns >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: seismograph item? From: meredithlamb meredithlamb@............. Date: Thu, 05 Dec 2002 23:34:56 -0700 Hi Bob/s, and all, Not familar with it, but viewed the ebay pic's. It looks like only the electronics/film medium there with the case opened. The larger round oblong object looks to be the film container. Presume the actual sensors are (not there) normally separate and connected via a cable plug-in on the case. So, its without the sensors I presume. Note the same seller has two SMA-2's up for bid also, but they appear to be without any sensors either. Ebay #1923227423 Take care, Meredith hammond wrote: > Bob, it's a strong motion accelerograph which uses film as the recording > medium. > The unit gets triggered if the ground acceleration exceeds a set value and > then records > the ground motion on a wide film strip. These are still widely used but > superceded by > digital strong motion recorders. > > Bob Hammond > Public Seismic Network - Alaska > Fairbanks > http://apsn.awcable.com > > At 05:09 PM 12/5/2002, you wrote: > >Hi gang, > > Ebay offers: > >Kinemetrics SMA-1 Seismograph Event Indicator > >Item # 1923224052 ends Dec 10 > > I have no idea what this is but it looks complicated. > >Bob Barns __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: seismograph item? From: "Doug Crice" dcrice@............ Date: Fri, 6 Dec 2002 06:19:58 -0800 The SMA-1 looks complete to me. The sensors are those odd devices on the left in the photograph. The accelerometer in an SMA-1 is just a damped mass with a small mirror attached. In the presence of acceleration, the mirror rotates and moves the spot of light on the film. The film is moving, and thus a seismograph (or more properly, an accelerograph) is drawn on the film. An event marker put time ticks on the film at 100 ms intervals. It is a 3-component system recording on 100 mm film in a canister. The canister can be removed and opened in a dark space for developing. The unit is triggered into activity by a separate sensor (also built into the unit) and keeps recording for the duration of the event (or until it runs out of film). The sensitivity is on the order of +/- 1 g. And of course its purpose is to record vibrations from strong earthquakes. I remember that quite a stir was created when an SMA-1 recorded an acceleration of 1.01 g during the Paicoma Dam earthquake in Southern California. Up until then, it was believed that the maximum possible acceleration in any earthquake was about 1/4 g. The SMA-2 was the next generation and replaced the film with magnetic tape recording. Kinemetrics figured out how to get an electrical signal from the damping current in those optical sensors and record it on tape (analog FM). Thousands of these units were installed around the world to study ground spectral amplification and structural response in earthquakes. Every high rise in the LA area got three units: one in the basement, one in the center, and one in the roof to look at how the building reacted to the earthquake. They were wired together for synchronized timing so you see how the roof zigged when the basement zagged. The cases are rigid cast aluminum, air and water tight, and are worth the price for the case alone, but it would be a shame to dismantle these classic instruments. Doug Crice Geostuff/GeoRadar Inc. http://www.georadar.com/geostuff.htm 12996 Somerset Drive phone 1-530-274-4445 Grass Valley, CA 95945 USA fax 1-530-274-4446 -----Original Message----- From: psn-l-request@.............. [mailto:psn-l-request@............... On Behalf Of meredithlamb Sent: Thursday, December 05, 2002 10:35 PM To: psn-l@.............. Subject: Re: seismograph item? Hi Bob/s, and all, Not familar with it, but viewed the ebay pic's. It looks like only the electronics/film medium there with the case opened. The larger round oblong object looks to be the film container. Presume the actual sensors are (not there) normally separate and connected via a cable plug-in on the case. So, its without the sensors I presume. Note the same seller has two SMA-2's up for bid also, but they appear to be without any sensors either. Ebay #1923227423 Take care, Meredith hammond wrote: > Bob, it's a strong motion accelerograph which uses film as the recording > medium. > The unit gets triggered if the ground acceleration exceeds a set value and > then records > the ground motion on a wide film strip. These are still widely used but > superceded by > digital strong motion recorders. > > Bob Hammond > Public Seismic Network - Alaska > Fairbanks > http://apsn.awcable.com > > At 05:09 PM 12/5/2002, you wrote: > >Hi gang, > > Ebay offers: > >Kinemetrics SMA-1 Seismograph Event Indicator > >Item # 1923224052 ends Dec 10 > > I have no idea what this is but it looks complicated. > >Bob Barns __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: seismograph item? From: meredithlamb meredithlamb@............. Date: Fri, 06 Dec 2002 08:53:20 -0700 Hi Doug and all, Thanks Doug for the info. Can see where they are as you describe; the sensors are especially clearer on the SMA-2 photo. Meredith Doug Crice wrote: > The SMA-1 looks complete to me. The sensors are those odd devices on > the left in the photograph. The accelerometer in an SMA-1 is just a > damped mass with a small mirror attached. In the presence of > acceleration, the mirror rotates and moves the spot of light on the > film. The film is moving, and thus a seismograph (or more properly, an > accelerograph) is drawn on the film. An event marker put time ticks on > the film at 100 ms intervals. > > It is a 3-component system recording on 100 mm film in a canister. The > canister can be removed and opened in a dark space for developing. The > unit is triggered into activity by a separate sensor (also built into > the unit) and keeps recording for the duration of the event (or until it > runs out of film). > > The sensitivity is on the order of +/- 1 g. And of course its purpose is > to record vibrations from strong earthquakes. I remember that quite a > stir was created when an SMA-1 recorded an acceleration of 1.01 g during > the Paicoma Dam earthquake in Southern California. Up until then, it was > believed that the maximum possible acceleration in any earthquake was > about 1/4 g. > > The SMA-2 was the next generation and replaced the film with magnetic > tape recording. Kinemetrics figured out how to get an electrical signal > from the damping current in those optical sensors and record it on tape > (analog FM). > > Thousands of these units were installed around the world to study ground > spectral amplification and structural response in earthquakes. Every > high rise in the LA area got three units: one in the basement, one in > the center, and one in the roof to look at how the building reacted to > the earthquake. They were wired together for synchronized timing so you > see how the roof zigged when the basement zagged. > > The cases are rigid cast aluminum, air and water tight, and are worth > the price for the case alone, but it would be a shame to dismantle these > classic instruments. > > Doug Crice > Geostuff/GeoRadar Inc. http://www.georadar.com/geostuff.htm > 12996 Somerset Drive phone 1-530-274-4445 > Grass Valley, CA 95945 USA fax 1-530-274-4446 > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: GPS fault From: "Mauro Mariotti" mariotti@......... Date: Sat, 7 Dec 2002 10:06:43 +0100 Hi All, does anyone experienced a fault of the active antenna of the GPS systems? It seems that my two antennas labelled: AeroAntenna Technology Inc AT575-109-OSRX-48-05-12-nm stopped to function after be used not for long time only sometimes. Any ideas on how check the system? The receiver seems to respond to all function WinOncore software executes... but no satellite is tracked anytime... Regards Mauro
Hi All,
does anyone experienced a fault of the active=20 antenna
of the GPS systems?
 
It seems that my two antennas = labelled:
 
AeroAntenna Technology Inc
AT575-109-OSRX-48-05-12-nm
 
stopped to function after be used not for long=20 time
only sometimes.
 
Any ideas on how check the system?
 
The receiver seems to respond to all = function
WinOncore software executes... but no satellite = is=20 tracked
anytime...
 
 
Regards
Mauro
 
Subject: GPS Fault.... From: "Mauro Mariotti" mariotti@......... Date: Sat, 7 Dec 2002 10:09:53 +0100 Additional information... WinOncore reports, just now... Antenna Undercurrent: False Antenna Overcurrent: True The cable is not shorted... Cheers Mauro ----- Original Message -----=20 From: ChrisAtUpw@.......... To: psn-l@................. Sent: Sunday, November 24, 2002 5:00 PM Subject: Re: Another horizontal boom/mast pivot to consider In a message dated 23/11/2002, shammon1@............. writes: I live near the sea and if I don't change the wire, the wire rusts = and eventually will snap under tension. Usually in less than 6 months. Hi Steve. One practical suggestion is to coat the wire with 'pure' soap = solution and let it dry. This is the 'secret' behind the soaped wire = wool scouring pads (Brillo Pads) for kitchen use. Soap is also added to = 'ordinary' steel wire wool to prevent it corroding. =20 A Cardan hinge is a single foil hinge in tension with the length = much greater than the separation of the clamp bars. This enables it to = carry loads parallel to the hinge axis. A pair off them, accurately = aligned, may be used in a Lehman seismometer.=20 Regards, Chris Chapman=20
Additional information...
WinOncore reports, just = now...
 
Antenna Undercurrent: = False
Antenna Overcurrent: True
 
The cable is not = shorted...
 
Cheers
Mauro
 
----- Original Message -----
From:=20 ChrisAtUpw@.......
Sent: Sunday, November 24, 2002 = 5:00=20 PM
Subject: Re: Another horizontal = boom/mast=20 pivot to consider

In a message dated 23/11/2002, shammon1@.............=20 writes:

I live near the sea and if I don't change the wire, the = wire=20 rusts and eventually will snap under tension. Usually in less than 6 = months.

Hi=20 Steve.

     One practical suggestion is to = coat the=20 wire with 'pure' soap solution and let it dry. This is the 'secret' = behind the=20 soaped wire wool scouring pads (Brillo Pads) for kitchen use. Soap is = also=20 added to 'ordinary' steel wire wool to prevent it corroding. =20

     A Cardan hinge is a single foil hinge = in=20 tension with the length much greater than the separation of the clamp = bars.=20 This enables it to carry loads parallel to the hinge axis. A pair off = them,=20 accurately aligned, may be used in a Lehman seismometer.=20

     = Regards,

    =20 Chris Chapman
Subject: GPS and EDA From: "Mauro Mariotti" mariotti@......... Date: Thu, 12 Dec 2002 09:12:54 +0100 Hi All, GPS I found that the two GPS antenna I have here have thermal problems. If I put the antenna outside the window (10 C degrees) it become inoperative in 15 second. If i keep it indoor, 20 degress, it is ok even if it pick only 1 or 2 satellites per time... When it is fauly, it is overcurrent on the WinOncore software. The impedance become very low. Anyone experienced this problem? ------ EDA I obtained a PRS-4 Scintrex EDA station. I have any software for it, only a small owner's manual. It seems that the station needs a firmware to be uploaded inside. It uses an hitachi processor and a 12 bit a/d converter with a double dynamic amplifier, low/high gain and samples both the signals and choose the low gain signal if high gain is clipped. Does anyone know where download something about it? Thanks Mauro http://www.infoeq.it http://mariottim.interfree.it/index.htm __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: GPS and EDA From: hammond hammond@........... Date: Thu, 12 Dec 2002 05:03:08 -0900 Mauro, EDA Instruments, Ltd, (Earth Science Division) was purchased by Scintrex, Ltd in 1988. You can contact Scintrex support at: service@............... They may be able to help you. Also, their web site is: http://www.scintrexltd.com/index.htm Regards, Bob Hammond Public Seismic Network - Alaska http://apsn.awcable.com At 11:12 PM 12/11/2002, you wrote: >EDA >I obtained a PRS-4 Scintrex EDA station. >I have any software for it, only a small owner's manual. >It seems that the station needs a firmware to be uploaded inside. >It uses an hitachi processor and a 12 bit a/d converter with a double >dynamic >amplifier, low/high gain and samples both the signals and choose the low >gain >signal if high gain is clipped. >Does anyone know where download something about it? > >Thanks >Mauro __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Several small events in Palmdale and Lancaster, CA area From: steve hammond shammon1@............. Date: Thu, 12 Dec 2002 10:43:01 -0800 http://quake.wr.usgs.gov/recenteqs/latest.htm The time is 18:42:00 UTC. I don't think I have ever seen so many small events over such a wide area. Regards, Steve Hammond PSN San Jose -- Aptos __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Several small events in Palmdale and Lancaster, CA area From: Bob Fryer bfryer@............ Date: Thu, 12 Dec 2002 11:27:31 -0800 HOLY BLEEP !! Number is rapidly rising into the hundreds! Generally within 25 miles of Mojave and string down towards Cajon Pass. Could be a glitch ? None of significant intensity. Bob >http://quake.wr.usgs.gov/recenteqs/latest.htm The time is 18:42:00 UTC. I >don't think I have ever seen so many small events over such a wide area. > >Regards, Steve Hammond PSN San Jose -- Aptos -- earthquake WARNING research Animals, People, Scientific Evidence www.earthquakewarning.org __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Wireless 12 bit sensor link From: "Jonathan Peakall" jpeakall@............ Date: Thu, 12 Dec 2002 17:03:54 -0800 Hi All, I have been working on a 12 bit wireless sensor link. The transmit side is built around a LTC1298 ADC and a PIC12F675 microprocessor feeding a TWS-434 transmitter. The reciever is based around a Basic Stamp B2sx microprocessor, with of course a RWS-434 receiver. I plan to use a PIC for the final version, so total for the entire TX/RX system will be around $50. I've got it working pretty well, and am just about to hook it up to my earthquake sensor. Pity the sensor isn't working right, but that's another project! Anyway, I need some data logging software to feed it all into, something that uses the com port on a PC. WinSDR won't work, as it has to use Larry's A/D board. What other options are there, and any help on how to get it all to communicate would be great. If anyone wants details of the project, let me know. It's looking good, as long as I can get it talking to some good data logging software! Regards, Jonathan Peakall __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Wireless 12 bit sensor link From: John & Jan Lahr johnjan@........ Date: Thu, 12 Dec 2002 19:44:58 -0700 Hi Jonathan, Alan Jones' AmaSeis program can log one channel of seismic data via a serial port or a USB port and an USB to serial adaptor. I'm not sure what format the data needs to be in, but your could contact Alan to find out. I believe three formats are currently supported. See: http://www.geol.binghamton.edu/faculty/jones/jones.html Cheers, John Lahr At 06:03 PM 12/12/2002, you wrote: >Hi All, > >I have been working on a 12 bit wireless sensor link. The transmit side is >built around a LTC1298 ADC and a PIC12F675 microprocessor feeding a TWS-434 >transmitter. The reciever is based around a Basic Stamp B2sx microprocessor, >with of course a RWS-434 receiver. I plan to use a PIC for the final >version, so total for the entire TX/RX system will be around $50. I've got >it working pretty well, and am just about to hook it up to my earthquake >sensor. Pity the sensor isn't working right, but that's another project! >Anyway, I need some data logging software to feed it all into, something >that uses the com port on a PC. WinSDR won't work, as it has to use Larry's >A/D board. What other options are there, and any help on how to get it all >to communicate would be great. If anyone wants details of the project, let >me know. It's looking good, as long as I can get it talking to some good >data logging software! > >Regards, > >Jonathan Peakall > > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Wireless 12 bit sensor link From: "a.rodriguez" stuff@................. Date: Thu, 12 Dec 2002 21:43:52 -0500 Hello Jonathan, Seislog is free data capture software and you can get the source code and you can get some standard simple communications protocols to talk to it. You can download it at: http://www.ifjf.uib.no/Seismologi/software/software.html Seislog file are easy to convert to PSN file in the end. angel Thursday, December 12, 2002, 8:03:54 PM, you wrote: JP> Hi All, JP> I have been working on a 12 bit wireless sensor link. The transmit side is JP> built around a LTC1298 ADC and a PIC12F675 microprocessor feeding a TWS-434 JP> transmitter. The reciever is based around a Basic Stamp B2sx microprocessor, JP> with of course a RWS-434 receiver. I plan to use a PIC for the final JP> version, so total for the entire TX/RX system will be around $50. I've got JP> it working pretty well, and am just about to hook it up to my earthquake JP> sensor. Pity the sensor isn't working right, but that's another project! JP> Anyway, I need some data logging software to feed it all into, something JP> that uses the com port on a PC. WinSDR won't work, as it has to use Larry's JP> A/D board. What other options are there, and any help on how to get it all JP> to communicate would be great. If anyone wants details of the project, let JP> me know. It's looking good, as long as I can get it talking to some good JP> data logging software! JP> Regards, JP> Jonathan Peakall JP> __________________________________________________________ JP> Public Seismic Network Mailing List (PSN-L) JP> To leave this list email PSN-L-REQUEST@.............. with JP> the body of the message (first line only): unsubscribe JP> See http://www.seismicnet.com/maillist.html for more information. -- Best regards, a.rodriguez mailto:stuff@................. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Several small events in Palmdale and Lancaster, CA area From: John & Jan Lahr johnjan@........ Date: Thu, 12 Dec 2002 19:53:41 -0700 They had a noisy AD that was generating LOTS of false picks! John At 12:27 PM 12/12/2002, you wrote: > HOLY BLEEP !! > >Number is rapidly rising into the hundreds! > >Generally within 25 miles of Mojave and string down towards Cajon Pass. > >Could be a glitch ? None of significant intensity. > > >Bob > > >>http://quake.wr.usgs.gov/recenteqs/latest.htm The time is 18:42:00 UTC. I >>don't think I have ever seen so many small events over such a wide area. >> >>Regards, Steve Hammond PSN San Jose -- Aptos >-- > earthquake WARNING research >Animals, People, Scientific Evidence > www.earthquakewarning.org >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with the body of the >message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: R: Wireless 12 bit sensor link From: "Mauro Mariotti" mariotti@......... Date: Fri, 13 Dec 2002 05:01:04 +0100 Jonathan, A simple protocol is used for Infiltec board and lx1500 board i applied to my Seismowin datalogging software. www.infoeq.it Considering the target of users of a 12 bit sensor I suggest you to download seismowin and see if it could be usefulf for you. I can eventually provides assistance to implement your board for it but if you give out an exact number of SPS and provide ASCII data output format with CR at the end of each sample, probably no code is needed to add up. Amaseis could also be a good solution. Regards Mauro ----- Original Message ----- From: Jonathan Peakall To: Sent: Friday, December 13, 2002 2:03 AM Subject: Wireless 12 bit sensor link > Hi All, > > I have been working on a 12 bit wireless sensor link. The transmit side is > built around a LTC1298 ADC and a PIC12F675 microprocessor feeding a TWS-434 > transmitter. The reciever is based around a Basic Stamp B2sx microprocessor, > with of course a RWS-434 receiver. I plan to use a PIC for the final > version, so total for the entire TX/RX system will be around $50. I've got > it working pretty well, and am just about to hook it up to my earthquake > sensor. Pity the sensor isn't working right, but that's another project! > Anyway, I need some data logging software to feed it all into, something > that uses the com port on a PC. WinSDR won't work, as it has to use Larry's > A/D board. What other options are there, and any help on how to get it all > to communicate would be great. If anyone wants details of the project, let > me know. It's looking good, as long as I can get it talking to some good > data logging software! > > Regards, > > Jonathan Peakall > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Software from Bob McClure From: John & Jan Lahr johnjan@........ Date: Sat, 14 Dec 2002 22:43:16 -0700 Bob McClure has written two helpful and educational programs that may be found here: http://jjlahr.com/science/psn/mcclure/ J-B_Plotter plots and curve fits data read in from J-B files in the format provided on Larry's Public Seismic Network (PSN) site. This is a good companion to Alan Jones' Seismic Waves program. SeisSim illustrates the response of a damped pendulum seismometer to various driving functions and output filters. Many variables can be adjusted, such as the period of the pendulum, the damping, and the filtering. Both can be downloaded and run on a PC. Enjoy! John Lahr __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Vertical "SG" sensor? From: "Larry Conklin" lconklin@............ Date: Tue, 17 Dec 2002 14:10:30 -0500 Hi all, I've been thinking about building a vertical sensor. One design I've been considering would use a bowed leaf spring similar to the Sean-Thomas Morisssey design, combined with the differential capacitor sensor using Larry's SG electronics board. I'd be interested in hearing whether anyone else has tried this or if anyone has any thoughts regarding the viability of this approach. Larry Conklin Liverpool, NY lconklin@............ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Vertical "SG" sensor? From: ChrisAtUpw@....... Date: Tue, 17 Dec 2002 16:20:57 EST In a message dated 17/12/02, lconklin@............ writes: > I've been thinking about building a vertical sensor. One design I've been > considering would use a bowed leaf spring similar to the Sean-Thomas > Morisssey design, combined with the differential capacitor sensor using > Larry's SG electronics board. I'd be interested in hearing whether anyone > else has tried this or if anyone has any thoughts regarding the viability of > this approach. Hi Larry, The SG oscillator / capacitor / tuned circuit design is quite temperature sensitive and the technique is 'out of date', by maybe twenty years. Allan Coleman has a good capacitor sensor design on his Website. There is also one capacitor bridge design in the Linear Technology archive notes dated early '96, "Bridge Measures Small Capacitance" by Jeff Witt. There are several subsequent designs for capacitance measurement, but they seem designed to actually measure capacity, rather than be useful as a differential movement sensor. (The capacity is inversely proportional to the separation of the plates, which is what you are interested in.) Alternatively, you could use a modified NE5521 LVDT circuit with a fet amplifier on the sense input. They work pretty well. Leaf springs tend to suffer from fewer resonance problems than coil springs. Again, why not have a look at Allan's design for a vertical? His MKXV vertical is a compact and most interesting design. Regards, Chris Chapman In a message dated 17/12/02, lconklin@............ writes:

I've been thinking about building a vertical sensor.  One design I've been
considering would use a bowed leaf spring similar to the Sean-Thomas
Morisssey design, combined with the differential capacitor sensor using
Larry's SG electronics board.  I'd be interested in hearing whether anyone
else has tried this or if anyone has any thoughts regarding the viability of
this approach.


Hi Larry,

      The SG oscillator / capacitor / tuned circuit design is quite temperature sensitive and the technique is 'out of date', by maybe twenty years. Allan Coleman has a good capacitor sensor design on his Website. There is also one capacitor bridge design in the Linear Technology archive notes dated early '96, "Bridge Measures Small Capacitance" by Jeff Witt. There are several subsequent designs for capacitance measurement, but they seem designed to actually measure capacity, rather than be useful as a differential movement sensor. (The capacity is inversely proportional to the separation of the plates, which is what you are interested in.) Alternatively, you could use a modified NE5521 LVDT circuit with a fet amplifier on the sense input. They work pretty well.
 
      Leaf springs tend to suffer from fewer resonance problems than coil springs. Again, why not have a look at Allan's design for a vertical? His MKXV vertical is a compact and most interesting design.

      Regards,

      Chris Chapman
Subject: Re: Vertical "SG" sensor? From: "Larry Conklin" lconklin@............ Date: Wed, 18 Dec 2002 22:03:21 -0500 Hi Chris, Thanks for your input. Could you steer me to a web address where = Coleman's design is described? I have found his description for a very = elegant looking horizontal sensor, also called the MKXV. However, I've = decided that my next project will be a vertical of some sort. The = electronics for the horizontal would certainly work. If he has come up = with a vertical design that is as solid looking as his horizontal one, = I'd sure like to see it. Larry ----- Original Message -----=20 From: ChrisAtUpw@.......... To: psn-l@................. Sent: Tuesday, December 17, 2002 4:20 PM Subject: Re: Vertical "SG" sensor? In a message dated 17/12/02, lconklin@............ writes:=20 I've been thinking about building a vertical sensor. One design = I've been=20 considering would use a bowed leaf spring similar to the Sean-Thomas = Morisssey design, combined with the differential capacitor sensor = using=20 Larry's SG electronics board. I'd be interested in hearing whether = anyone=20 else has tried this or if anyone has any thoughts regarding the = viability of=20 this approach. Hi Larry,=20 The SG oscillator / capacitor / tuned circuit design is quite = temperature sensitive and the technique is 'out of date', by maybe = twenty years. Allan Coleman has a good capacitor sensor design on his = Website. There is also one capacitor bridge design in the Linear = Technology archive notes dated early '96, "Bridge Measures Small = Capacitance" by Jeff Witt. There are several subsequent designs for = capacitance measurement, but they seem designed to actually measure = capacity, rather than be useful as a differential movement sensor. (The = capacity is inversely proportional to the separation of the plates, = which is what you are interested in.) Alternatively, you could use a = modified NE5521 LVDT circuit with a fet amplifier on the sense input. = They work pretty well.=20 =20 Leaf springs tend to suffer from fewer resonance problems than = coil springs. Again, why not have a look at Allan's design for a = vertical? His MKXV vertical is a compact and most interesting design.=20 Regards,=20 Chris Chapman=20
Hi Chris,
 
Thanks for your input.  Could you steer me to a = web=20 address where Coleman's design is described?  I have found his = description=20 for a very elegant looking horizontal sensor, also called the = MKXV. =20 However, I've decided that my next project will be a vertical of some=20 sort.  The electronics for the horizontal would certainly = work.  If he=20 has come up with a vertical design that is as solid looking as his = horizontal=20 one, I'd sure like to see it.
 
Larry
----- Original Message -----
From:=20 ChrisAtUpw@.......
Sent: Tuesday, December 17, = 2002 4:20=20 PM
Subject: Re: Vertical "SG" = sensor?

In a = message dated=20 17/12/02, lconklin@............=20 writes:

I've been thinking about building a vertical sensor. =  One=20 design I've been
considering would use a bowed leaf spring = similar to=20 the Sean-Thomas
Morisssey design, combined with the differential = capacitor sensor using
Larry's SG electronics board.  I'd = be=20 interested in hearing whether anyone
else has tried this or if = anyone=20 has any thoughts regarding the viability of
this = approach.


Hi Larry,=20

      The SG oscillator / = capacitor /=20 tuned circuit design is quite temperature sensitive and the technique = is 'out=20 of date', by maybe twenty years. Allan Coleman has a good capacitor = sensor=20 design on his Website. There is also one capacitor bridge design in = the Linear=20 Technology archive notes dated early '96, "Bridge Measures Small = Capacitance"=20 by Jeff Witt. There are several subsequent designs for capacitance=20 measurement, but they seem designed to actually measure capacity, = rather than=20 be useful as a differential movement sensor. (The capacity is = inversely=20 proportional to the separation of the plates, which is what you are = interested=20 in.) Alternatively, you could use a modified NE5521 LVDT circuit with = a fet=20 amplifier on the sense input. They work pretty well.
 =20
      Leaf springs tend to suffer = from fewer=20 resonance problems than coil springs. Again, why not have a look at = Allan's=20 design for a vertical? His MKXV vertical is a compact and most = interesting=20 design.

      Regards,=20

      Chris Chapman
=20
Subject: slow quakes From: David A Nelson davenn@............... Date: Thu, 19 Dec 2002 20:45:34 +1100 Hi all i recall some months ago discussion about a slow quake occurrence in the WA state sth of Seattle. I have to admit that i was a little sceptical on the subject. But here is yet another report, this time from my homeland, New Zealand. http://www.gns.cri.nz/news/release/gisborne.html cheers all have a wonderful xmas and new year Dave __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Vertical design/1-sec From: "Connie and Jim Lehman" lehmancj@........... Date: Thu, 19 Dec 2002 10:48:49 -0500 Larry C & others-- About 10 year ago at James Madison Un. we devised a vertical = instrument--made mostly from hardware store items--I wrote the design up = and will be glad to send anyone a copy of construction details. The = unit is now in the Moravian College seismic center in Bethlehem PA. Write me a note at: J. Lehman Physics Dept., James Madison Un. Harrisonburg, VA. 22807
Larry C &=20 others--
   About 10 = year ago at=20 James Madison Un. we devised a vertical instrument--made mostly from = hardware=20 store items--I wrote the design up and will be glad to send anyone a = copy of=20 construction details.  The unit is now in the Moravian College = seismic=20 center in Bethlehem PA.
    = Write me a=20 note at:
          &nbs= p;           =20 J. Lehman  Physics Dept.,
          &nbs= p;           =20 James Madison Un.
          &nbs= p;            = ;=20 Harrisonburg, VA.
          &nbs= p;            = ;=20 22807
Subject: Re: Vertical design/1-sec From: "Larry Conklin" lconklin@............ Date: Thu, 19 Dec 2002 11:02:50 -0500 Jim, I'd like to have a copy. Right now I'm collecting as many ideas as I = can find. Since I live in a "seismicaly deprived" region (Central NY), = I'm interested in sensors that are suitable for teleseismic events. Larry ----- Original Message -----=20 From: Connie and Jim Lehman=20 To: psn-l@................. Sent: Thursday, December 19, 2002 10:48 AM Subject: Vertical design/1-sec Larry C & others-- About 10 year ago at James Madison Un. we devised a vertical = instrument--made mostly from hardware store items--I wrote the design up = and will be glad to send anyone a copy of construction details. The = unit is now in the Moravian College seismic center in Bethlehem PA. Write me a note at: J. Lehman Physics Dept., James Madison Un. Harrisonburg, VA. 22807
Jim,
 
I'd like to have a copy.  Right now I'm = collecting as=20 many ideas as I can find.  Since I live in a "seismicaly deprived" = region=20 (Central NY), I'm interested in sensors that are suitable for = teleseismic=20 events.
 
Larry
----- Original Message -----
From:=20 Connie and=20 Jim Lehman
Sent: Thursday, December 19, = 2002 10:48=20 AM
Subject: Vertical = design/1-sec

Larry C &=20 others--
   About = 10 year ago=20 at James Madison Un. we devised a vertical instrument--made mostly = from=20 hardware store items--I wrote the design up and will be glad to send = anyone a=20 copy of construction details.  The unit is now in the Moravian = College=20 seismic center in Bethlehem PA.
    = Write me a=20 note at:
          &nbs= p;           =20 J. Lehman  Physics Dept.,
          &nbs= p;           =20 James Madison Un.
          &nbs= p;            = ;=20 Harrisonburg, VA.
          &nbs= p;            = ;=20 22807
Subject: Re: Vertical design/1-sec From: meredithlamb meredithlamb@............. Date: Thu, 19 Dec 2002 13:29:10 -0700 Larry, Jim and all, For those searching for a "possible" vertical seismometer, and/or exploring variations: Georgia Tech has had a web reference to a interesting vertical seismometer "for Classroom Demonstrations", since 1998. It appears to offer a "long adjustable period" (quite possibly noteworthy, but ? on stability) per the text; however the dampening and electronics is still "under development" since 1998 according to the text. I've not seen nor heard of any amateur that has followed up and actually made a similar vertical such as this; but the aspect of the "long period" (stability?) alone; might be worth considering. If the stability (mass drift) is bad, it might still reasonably work with a coil/magnet sensor. I presume that it being a "teaching" model that the abcense of dampening and even other variations of a sensor apart from the photo resistor they used; could be enticing for other better means by any amateur R&D explorer. It would be nice to know if anyone on the PSN list has tried such? Of course, with Georgia Tech being a teaching institution, it could just be that this instrument is more meant to inspire just enough curiosity about it, that people like me (and others) might go further into it...ha. http://quake.eas.gatech.edu/Instruments/LPVERT0.htm For my netscape browser 4.7 version I did have trouble with "Chapter 3", with acouple photos initially, but when I used the web site URL: "Index of /Instruments", (below), the problem was resolved there. http://quake.eas.gatech.edu/Instruments/ The above also has "doc" files, which are Microsoft Word versions. Take care, Meredith Lamb Larry Conklin wrote: > Jim, I'd like to have a copy. Right now I'm collecting as many ideas > as I can find. Since I live in a "seismicaly deprived" region > (Central NY), I'm interested in sensors that are suitable for > teleseismic events.Larry > > ----- Original Message ----- > From:Connie and Jim Lehman > To: psn-l@.............. > Sent: Thursday, December 19, 2002 10:48 AM > Subject: Vertical design/1-sec > Larry C & others-- About 10 year ago at James Madison Un. > we devised a vertical instrument--made mostly from hardware > store items--I wrote the design up and will be glad to send > anyone a copy of construction details. The unit is now in > the Moravian College seismic center in Bethlehem PA. > Write me a note at: J. Lehman Physics > Dept., James Madison > Un. Harrisonburg, > VA. 22807 > Larry, Jim and all,

For those searching for a "possible" vertical seismometer,
and/or exploring variations:

Georgia Tech has had a web reference to a interesting vertical
seismometer "for Classroom Demonstrations", since 1998.  It
appears to offer a "long adjustable period" (quite possibly
noteworthy, but ? on stability) per the text; however the dampening
and electronics is still "under development" since 1998 according
to the text.

I've not seen nor heard of any amateur that has followed
up and actually made a similar vertical such as this; but the aspect
of the "long period" (stability?) alone; might be worth considering.
If the stability (mass drift) is bad, it might still reasonably work
with a coil/magnet sensor.  I presume that it being a "teaching"
model that the abcense of dampening and even other variations
of a sensor apart from the photo resistor they used; could be
enticing for other better means by any amateur R&D explorer.
It would be nice to know if anyone on the PSN list has tried such?

Of course, with Georgia Tech being a teaching institution, it
could just be that this instrument is more meant to inspire just
enough curiosity about it, that people like me (and others) might
go further into it...ha.

http://quake.eas.gatech.edu/Instruments/LPVERT0.htm

For my netscape browser 4.7 version I did have trouble with
"Chapter 3", with acouple photos initially, but when I used the
web site URL: "Index of /Instruments", (below), the problem was
resolved there.

http://quake.eas.gatech.edu/Instruments/

The above also has "doc" files, which are Microsoft Word
versions.

Take care, Meredith Lamb

Larry Conklin wrote:

Jim, I'd like to have a copy.  Right now I'm collecting as many ideas as I can find.  Since I live in a "seismicaly deprived" region (Central NY), I'm interested in sensors that are suitable for teleseismic events.Larry
----- Original Message -----
Sent: Thursday, December 19, 2002 10:48 AM
Subject: Vertical design/1-sec
 Larry C & others--   About 10 year ago at James Madison Un. we devised a vertical instrument--made mostly from hardware store items--I wrote the design up and will be glad to send anyone a copy of construction details.  The unit is now in the Moravian College seismic center in Bethlehem PA.    Write me a note at:                       J. Lehman  Physics Dept.,                       James Madison Un.                        Harrisonburg, VA.                        22807
Subject: Re: Vertical design/1-sec From: Ben Bradley benbradley@.............. Date: Fri, 20 Dec 2002 13:12:28 -0500 Hi everyone, I'm new to the list, though I've read through much of the list archives. My interest in making a seismometer was kindled a few months ago, and some web searching turned up many interesting things, such as this list. At 01:29 PM 12/19/02 -0700, meredithlamb wrote: >Larry, Jim and all, > >For those searching for a "possible" vertical seismometer, >and/or exploring variations: >Of course, with Georgia Tech being a teaching institution, it >could just be that this instrument is more meant to inspire just >enough curiosity about it, that people like me (and others) might >go further into it...ha. > >http://quake.eas.gatech.edu/Instruments/LPVERT0.htm This design is interesting in that appears simple to assemble as well as being low in cost, and so one can get it up and running quickly. The first thing I would do with it is replace the photoresistive sensor with a photodiode, phototransistor, or optointerrupter (simply a phototransistor and light-emitting diode aligned in one package with a gap between them). The cost is about the same (a dollar or so), and photoresistive elements, depending on models, can take many milliseconds to respond to changes in light, limiting frequency response, posibly below the maximum of interest. A photodiode/phototransistor has more than adequate frequency response. For a rather more complex and sensitive vertical seismometer, there is the device described here: http://www.central-jersey-sas.org/projects/tidal_forces/magnetic_gravimeter/baker/ The Scientific American article on it is here: http://www.central-jersey-sas.org/projects/tidal_forces/01/sciam/0100amsci.html --- http://mindspring.com/~benbradley __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Vertical design From: ChrisAtUpw@....... Date: Fri, 20 Dec 2002 23:03:32 EST Hi Meredith, Short period verticals are not too difficult to make, but they are of somewhat limited use. There are a number of practical / engineering constraints. I note that at least one design uses the U Alnico magnet as the seismic mass on the end of the arm. This is not a good idea and it will react to environmental changes in the local magnetic field. In the normal home, you are likely to see a very noisy trace. It is quite easy to damp a seismometer using readily available NdBFe magnets. Fluid damping is very temperature sensitive and can be quite messy. The much higher field supplied by NdBFe magnets can also be used to increase the output of coil detector systems and improve their range and linearity. A survey of a range of systems can be found at http://quake.eas.gatech.edu/Instruments/InstrumentSurvey.htm. Prof.Braile's link may be found by removing the seismometer reference. To get much longer periods, there have been two successful approaches, one largely mechanical and the other involving quite a lot of electronics. The La Coste mechanical design dates from 1934 and developments on it rely on your being able to reduce the effects of temperature on the spring constants, on the linear expansion and on any slow 'creep' changes. Springs normally get 'weaker' as the temperature increases, while the metal of the arm expands and the load 'moment' increases. There are no useful materials which shrink, or get stiffer, as they get hotter. You can design a temperature compensated arm, but getting adequate rigidity may be more difficult. They are used on pendulum clocks (eg a gridiron pendulum) to give good temperature compensation and high accuracy. To wind a zero length spring, you have to use metal which can be cold formed and this inevitably has high stresses 'built in'. Leaf springs can be made with a higher temper and lower initial stress, but it is desirable to use a NiSpan material to reduce the effects of temperature. There probably are sources of NiSpanC, but I do not know of any. Leaf springs have less problems with stray resonances than coil springs. A seismometer has to be highly stable over a range of temperature and over time, or it is not of much use. With a purely mechanical system, this is not too easy or cheap to do to the required precision. You only stand a reasonable chance of success if you design the system to be stable and can also adjust it. 'Cut and try' attempts are unlikely to have much success. Sean Morrissey took an alternative practical approach in choosing a fairly easily made design using a leaf spring (similar in principle to a La Coste) and damping it with small magnets. He provided a very sensitive distance transducer, a magnet / coil force feedback system and a box of electronics to control it all. The electronics damps the system and in doing so it is possible to control the frequency response; in doing this, it measures the force necessary to keep the mass fixed in relation to the ground and outputs any seismic signals; it also separates out the effects due to temperature changes and drift and puts these into the 'integrated' feedback, which you do not measure. Even so, Sean had to provide an additional mechanical weight adjustment with a small electric motor. Unless you can put your vertical seismometer in a sealed pressure container, it will react to small naturally occurring changes in air pressure. These tend to 'float' the seismic mass and cover a wide band of frequencies. This is a major and serious source of noise in vertical sensors. It should be possible in principle to significantly reduce this noise by using a sealed float mounted on an extension to the arm beyond the hinge. This would make the apparatus appreciably longer and Sean was not enthusiastic over the idea. Another possible approach is to use a 1 or 2 Hz geophone and fit it with a precision distance transducer and a set of electronics similar to Sean's. This is rather more like precision engineering, but the mass, the spring and the feedback coil are ready made. There are constructional adaptations other than the one Aaron Barzilai used, which could be more successful. See http://micromachine.stanford.edu/smssl/projects/Geophones/ He also used a rather bulky square wave excited capacitative distance transducer, which seemed to be rather noisy. An LVDT or a magnetic reluctance system might be more appropriate for this type of miniaturised application. Summing up, it is more difficult to make a vertical seismometer than to make a horizontal one due to difficulties in making the suspension, in balancing and in compensating the system. Short period vertical sensors are not too difficult to make, but are of limited use. Sean's design seems to offer the amateur the best chance of success for a broad band instrument, but a fair amount of constructional skill is required. Regards, Chris Chapman Hi Meredith,

      Short period verticals are not too difficult to make, but they are of somewhat limited use. There are a number of practical / engineering constraints. I note that at least one design uses the U Alnico magnet as the seismic mass on the end of the arm. This is not a good idea and it will react to environmental changes in the local magnetic field. In the normal home, you are likely to see a very noisy trace. It is quite easy to damp a seismometer using readily available NdBFe magnets. Fluid damping is very temperature sensitive and can be quite messy. The much higher field supplied by NdBFe magnets can also be used to increase the output of coil detector systems and improve their range and linearity. A survey of a range of systems can be found at http://quake.eas.gatech.edu/Instruments/InstrumentSurvey.htm. Prof.Braile's link may be found by removing the seismometer reference.

      To get much longer periods, there have been two successful approaches, one largely mechanical and the other involving quite a lot of electronics. The La Coste mechanical design dates from 1934 and developments on it rely on your being able to reduce the effects of temperature on the spring constants, on the linear expansion and on any slow 'creep' changes. Springs normally get 'weaker' as the temperature increases, while the metal of the arm expands and the load 'moment' increases. There are no useful materials which shrink, or get stiffer, as they get hotter. You can design a temperature compensated arm, but getting adequate rigidity may be more difficult. They are used on pendulum clocks (eg a gridiron pendulum) to give good temperature compensation and high accuracy.
      To wind a zero length spring, you have to use metal which can be cold formed and this inevitably has high stresses 'built in'. Leaf springs can be made with a higher temper and lower initial stress, but it is desirable to use a NiSpan material to reduce the effects of temperature. There probably are sources of NiSpanC, but I do not know of any. Leaf springs have less problems with stray resonances than coil springs. A seismometer has to be highly stable over a range of temperature and over time, or it is not of much use. With a purely mechanical system, this is not too easy or cheap to do to the required precision. You only stand a reasonable chance of success if you design the system to be stable and can also adjust it. 'Cut and try' attempts are unlikely to have much success.

      Sean Morrissey took an alternative practical approach in choosing a fairly easily made design using a leaf spring (similar in principle to a La Coste) and damping it with small magnets. He provided a very sensitive distance transducer, a magnet / coil force feedback system and a box of electronics to control it all. The electronics damps the system and in doing so it is possible to control the frequency response; in doing this, it measures the force necessary to keep the mass fixed in relation to the ground and outputs any seismic signals; it also separates out the effects due to temperature changes and drift and puts these into the 'integrated' feedback, which you do not measure. Even so, Sean had to provide an additional mechanical weight adjustment with a small electric motor.

      Unless you can put your vertical seismometer in a sealed pressure container, it will react to small naturally occurring changes in air pressure. These tend to 'float' the seismic mass and cover a wide band of frequencies. This is a major and serious source of noise in vertical sensors. It should be possible in principle to significantly reduce this noise by using a sealed float mounted on an extension to the arm beyond the hinge. This would make the apparatus appreciably longer and Sean was not enthusiastic over the idea.

      Another possible approach is to use a 1 or 2 Hz geophone and fit it with a precision distance transducer and a set of electronics similar to Sean's. This is rather more like precision engineering, but the mass, the spring and the feedback coil are ready made. There are constructional adaptations other than the one Aaron Barzilai used, which could be more successful. See
http://micromachine.stanford.edu/smssl/projects/Geophones/  He also used a rather bulky square wave excited capacitative distance transducer, which seemed to be rather noisy. An LVDT or a magnetic reluctance system might be more appropriate for this type of miniaturised application.

      Summing up, it is more difficult to make a vertical seismometer than to make a horizontal one due to difficulties in making the suspension, in balancing and in compensating the system. Short period vertical sensors are not too difficult to make, but are of limited use. Sean's design seems to offer the amateur the best chance of success for a broad band instrument, but a fair amount of constructional skill is required.
      
      Regards,

      Chris Chapman
Subject: Short Period Vertical/ Geophones?? From: "Connie and Jim Lehman" lehmancj@........... Date: Sat, 21 Dec 2002 07:33:38 -0500 C. Patton, A. Hrubetz, & J. Lahr--your copies of the short period design = are in the mail. =20 I need some help on mailing addresses for S. Hammond, L. Conklin & F. = Cooper--- Thanks Chris for your comments on geophones. I remember showing the = short period vertical design to a geophysicist who had considerable = experience in exploration using geophones. He said--"Why not use a = geophone?" We got hold of several used discards in good condition and = tried them. They are "strong motion" in nature, but with todays = amplification one can adapt. The units we had were periods less than a = 1 second, and were underdamped for our purposes. We wanted parameters = to match the 1 second vertical Springnether (sp) professional sensor the = Geology Dept. was using at that time--for comparison purposes. We never = pursued the idea further--but felt it had possibilities. No doubt there are persons out there like Chris that have had some = experience with geophones. They are compact--a neat package and = reasonably economical--a quick way to go vertical-- if you can adapt the = parameters to be within the wishes of an amateur seismologist. Season's = Best---Jim Lehman = =20
C. Patton, A. = Hrubetz, & J.=20 Lahr--your copies of the short period design are in the mail. =20
   I need = some help on=20 mailing addresses for S. Hammond, L. Conklin & F. = Cooper---
    = Thanks Chris=20 for your comments on geophones.  I remember showing the short = period=20 vertical design to a geophysicist who had considerable experience in = exploration=20 using geophones.  He said--"Why not use a geophone?"  We got = hold of=20 several used discards in good condition and tried them.  They  = are=20 "strong motion" in nature, but with todays amplification one can = adapt. =20 The units we had were periods less than a 1 second, and were underdamped = for our=20 purposes.  We wanted parameters to match the 1 second vertical = Springnether=20 (sp) professional sensor the Geology Dept. was using at that time--for=20 comparison purposes.  We never pursued the idea further--but felt = it had=20 possibilities.
     No doubt=20 there are persons out there like Chris that have had some experience = with=20 geophones.  They are compact--a neat package and reasonably = economical--a=20 quick way to go vertical-- if you can adapt the parameters to be within = the=20 wishes of an amateur seismologist.
          &nbs= p;            = ;            =             &= nbsp;           &n= bsp;   =20 Season's Best---Jim Lehman
 
          &nbs= p;            = ;            =             &= nbsp;           &n= bsp;           &nb= sp;      =20
Subject: Re: Short Period Vertical/ Geophones?? From: "Larry Conklin" lconklin@............ Date: Sat, 21 Dec 2002 09:57:02 -0500 Jim, I can help you with my address at least: Larry Conklin 105 Riverglen Rd. Liverpool, NY 13090 lconklin@............ Larry ----- Original Message -----=20 From: Connie and Jim Lehman=20 To: psn-l@................. Sent: Saturday, December 21, 2002 7:33 AM Subject: Short Period Vertical/ Geophones?? C. Patton, A. Hrubetz, & J. Lahr--your copies of the short period = design are in the mail. =20 I need some help on mailing addresses for S. Hammond, L. Conklin & = F. Cooper--- Thanks Chris for your comments on geophones. I remember showing = the short period vertical design to a geophysicist who had considerable = experience in exploration using geophones. He said--"Why not use a = geophone?" We got hold of several used discards in good condition and = tried them. They are "strong motion" in nature, but with todays = amplification one can adapt. The units we had were periods less than a = 1 second, and were underdamped for our purposes. We wanted parameters = to match the 1 second vertical Springnether (sp) professional sensor the = Geology Dept. was using at that time--for comparison purposes. We never = pursued the idea further--but felt it had possibilities. No doubt there are persons out there like Chris that have had = some experience with geophones. They are compact--a neat package and = reasonably economical--a quick way to go vertical-- if you can adapt the = parameters to be within the wishes of an amateur seismologist. = Season's Best---Jim Lehman = =20
Jim,
 
I can help you with my address at = least:
 
    Larry Conklin
    105 Riverglen Rd.
    Liverpool, NY 13090
 
    lconklin@............
 
Larry
 
----- Original Message -----
From:=20 Connie and=20 Jim Lehman
Sent: Saturday, December 21, = 2002 7:33=20 AM
Subject: Short Period Vertical/ = Geophones??

C. Patton, A. = Hrubetz, & J.=20 Lahr--your copies of the short period design are in the mail. =20
   I need = some help=20 on mailing addresses for S. Hammond, L. Conklin & F.=20 Cooper---
    = Thanks Chris=20 for your comments on geophones.  I remember showing the short = period=20 vertical design to a geophysicist who had considerable experience in=20 exploration using geophones.  He said--"Why not use a = geophone?"  We=20 got hold of several used discards in good condition and tried = them. =20 They  are "strong motion" in nature, but with todays = amplification one=20 can adapt.  The units we had were periods less than a 1 second, = and were=20 underdamped for our purposes.  We wanted parameters to match the = 1 second=20 vertical Springnether (sp) professional sensor the Geology Dept. was = using at=20 that time--for comparison purposes.  We never pursued the idea=20 further--but felt it had possibilities.
     No=20 doubt there are persons out there like Chris that have had some = experience=20 with geophones.  They are compact--a neat package and reasonably=20 economical--a quick way to go vertical-- if you can adapt the = parameters to be=20 within the wishes of an amateur seismologist.
          &nbs= p;            = ;            =             &= nbsp;           &n= bsp;   =20 Season's Best---Jim Lehman
 
          &nbs= p;            = ;            =             &= nbsp;           &n= bsp;           &nb= sp;      =20
Subject: RE: Short Period Vertical/ Geophones?? From: steve hammond shammon1@............. Date: Sat, 21 Dec 2002 10:21:45 -0800 I have sent Jim my address. If you are not in too much of a rush on this, I'll be posting the information on the PSN San Jose web site http://www.PublicSeismicNetwork.com once I receive it and get it converted to web format it will be located on page http://pw2.netcom.com/~shammon1/equip.htm#Lehman Regards, Steve Hammond PSN San Jose, Aptos, CA -----Original Message----- From: Connie and Jim Lehman [SMTP:lehmancj@............ Sent: Saturday, December 21, 2002 4:34 AM To: psn-l@.............. Subject: Short Period Vertical/ Geophones?? C. Patton, A. Hrubetz, & J. Lahr--your copies of the short period design are in the mail. I need some help on mailing addresses for S. Hammond, L. Conklin & F. Cooper--- Thanks Chris for your comments on geophones. I remember showing the short period vertical design to a geophysicist who had considerable experience in exploration using geophones. He said--"Why not use a geophone?" We got hold of several used discards in good condition and tried them. They are "strong motion" in nature, but with todays amplification one can adapt. The units we had were periods less than a 1 second, and were underdamped for our purposes. We wanted parameters to match the 1 second vertical Springnether (sp) professional sensor the Geology Dept. was using at that time--for comparison purposes. We never pursued the idea further--but felt it had possibilities. No doubt there are persons out there like Chris that have had some experience with geophones. They are compact--a neat package and reasonably economical--a quick way to go vertical-- if you can adapt the parameters to be within the wishes of an amateur seismologist. Season's Best---Jim Lehman << File: ATT00006.html >> __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re Notes to UK? From: "Connie and Jim Lehman" lehmancj@........... Date: Sat, 21 Dec 2002 14:11:45 -0500 Nick--all I need is an address--no problem, Frank Cooper if you are tuned in, no need to send postage.. ----Jim
Nick--all I need is = an=20 address--no problem,
 
  Frank Cooper = if you are=20 tuned in, no need to send postage..
          &nbs= p;            = ;            = =20 ----Jim
Subject: Re: Vertical design From: meredithlamb meredithlamb@............. Date: Sat, 21 Dec 2002 13:38:41 -0700 Hi Chris, Jim and all other interested partys, That was a very good summation Chris. Perhaps, however, the best use of a vertical is predominately for simply getting the earliest phases of any quake/event, with the longest period (p thru s) of roughly up to, 3-4-5 seconds. Of course a longer period vertical than that would likely sense those signals best. Most verticals are predominately used for just that aspect in realtity, which is why the professionals pursue their use so heavily. In the PSN amateur related sense, and from the horizontal seismomograms presented; one often sees the designated "p", somewhere to the left of any obvious significant quake induced activity trace deflections....they just CAN'T sense the vertical phase quake components. All of this just leads up to the "need" for a vertical of some design in the individuals amateur seismometer setting.....perhaps to the extent of its value over and above the use of a horizontal seismometer. I'am dubious that a broadband vertical with all their problems is really all that worthy of the effort involved, when it comes down to the more practical short period phases that are actually "read"; in the general amateur (and likely the professional) realm. On the other hand, I don't have a broadband vertical, so, perhaps my thought judgement isn't really totally accurate for their use. It might just be, that any one design should incorporate the best aspects of other previously proven function pieces and parts. A big problem arises when it seems that some of the best use or functional pieces/parts are in themselves fairly mechanically complicated when addressed to a likely majority of ill-equipped individual readers and their own capabilities for its completion. I guess I'am always hopeful that there exists some simpler or better way to do things, than how some of the present designs are laid out. It may well be that Sean's vertical design (SM) could also be construed in a variety of degrees (amateur/professional) of approach; to satisfy any existing variety of potential use; simply by utilizing the base designed mechanics for other less sensitive sensor adoptions. This has apparently been done (implied in past PSN emails) in the past by others, or suggested but I'am not aware of their success in doing so, at the moment. Take care, Meredith ChrisAtUpw@....... wrote: > Hi Meredith, > > Short period verticals are not too difficult to make, but they > are of somewhat limited use. There are a number of practical / > engineering constraints. I note that at least one design uses the U > Alnico magnet as the seismic mass on the end of the arm. This is not a > good idea and it will react to environmental changes in the local > magnetic field. In the normal home, you are likely to see a very noisy > trace. It is quite easy to damp a seismometer using readily available > NdBFe magnets. Fluid damping is very temperature sensitive and can be > quite messy. The much higher field supplied by NdBFe magnets can also > be used to increase the output of coil detector systems and improve > their range and linearity. A survey of a range of systems can be found > at http://quake.eas.gatech.edu/Instruments/InstrumentSurvey.htm. > Prof.Braile's link may be found by removing the seismometer reference. > > .................clipped......... Hi Chris, Jim and all other interested partys,

That was a very good summation Chris.  Perhaps, however, the
best use of a vertical is predominately for simply getting the earliest
phases of any quake/event, with the longest period (p thru s) of
roughly up to, 3-4-5 seconds.  Of course a longer period vertical
than that would likely sense those signals best.   Most verticals are
predominately used for just that aspect in realtity, which is why
the professionals pursue their use so heavily.  In the PSN amateur
related sense, and from the horizontal seismomograms presented;
one often sees the designated "p", somewhere to the left of any
obvious significant quake induced activity trace deflections....they
just CAN'T sense the vertical phase quake components.  All
of this just leads up to the "need" for a vertical of some design in the
individuals amateur seismometer setting.....perhaps to the extent
of its value over and above the use of a horizontal seismometer.

I'am dubious that a broadband vertical with all their problems
is really all that worthy of the effort involved, when it comes down
to the more practical short period phases that are actually "read";
in the general amateur (and likely the professional) realm.  On the
other hand, I don't have a broadband vertical, so, perhaps my
thought judgement isn't really totally accurate for their use.

It might just be, that any one design should incorporate the best
aspects of other previously proven function pieces and parts.
A big problem arises when it seems that some of the best use
or functional pieces/parts are in themselves fairly mechanically
complicated when addressed to a likely majority of ill-equipped
individual readers and their own capabilities for its completion.
I guess I'am always hopeful that there exists some simpler or
better way to do things, than how some of  the present designs
are laid out.

It may well be that Sean's vertical design (SM) could also be
construed in a variety of degrees (amateur/professional) of
approach; to satisfy any existing variety of potential use;
simply by utilizing the base designed mechanics for other less
sensitive sensor adoptions.  This has apparently been done
(implied in past PSN emails) in the past by others, or suggested
but I'am not aware of their success in doing so, at the moment.

Take care, Meredith

ChrisAtUpw@....... wrote:

Hi Meredith,

      Short period verticals are not too difficult to make, but they are of somewhat limited use. There are a number of practical / engineering constraints. I note that at least one design uses the U Alnico magnet as the seismic mass on the end of the arm. This is not a good idea and it will react to environmental changes in the local magnetic field. In the normal home, you are likely to see a very noisy trace. It is quite easy to damp a seismometer using readily available NdBFe magnets. Fluid damping is very temperature sensitive and can be quite messy. The much higher field supplied by NdBFe magnets can also be used to increase the output of coil detector systems and improve their range and linearity. A survey of a range of systems can be found at http://quake.eas.gatech.edu/Instruments/InstrumentSurvey.htm. Prof.Braile's link may be found by removing the seismometer reference.

.................clipped.........


  Subject: Re: Vertical design From: hammond hammond@........... Date: Sat, 21 Dec 2002 12:04:11 -0900 Chris, with regard to your comments on vertical seismometers, I invite you to visit my web page http://apsn.awcable.com and specifically look at "earthquakes recorded at station GSV" at http://apsn.awcable.com/neweq.htm. Every earthquake I record and display is using a Mark Products L4 1Hz short-period vertical seismometer. Surely, you must be joking that short period vertical seismometers are of limited use! Regards, Bob Hammond Public Seismic Network - Alaska http://apsn.awcable.com At 11:38 AM 12/21/2002, you wrote: >Hi Chris, Jim and all other interested partys, > >That was a very good summation Chris. Perhaps, however, the >best use of a vertical is predominately for simply getting the earliest >phases of any quake/event, with the longest period (p thru s) of >roughly up to, 3-4-5 seconds. Of course a longer period vertical >than that would likely sense those signals best. Most verticals are >predominately used for just that aspect in realtity, which is why >the professionals pursue their use so heavily. In the PSN amateur >related sense, and from the horizontal seismomograms presented; >one often sees the designated "p", somewhere to the left of any >obvious significant quake induced activity trace deflections....they >just CAN'T sense the vertical phase quake components. All >of this just leads up to the "need" for a vertical of some design in the >individuals amateur seismometer setting.....perhaps to the extent >of its value over and above the use of a horizontal seismometer. > >I'am dubious that a broadband vertical with all their problems >is really all that worthy of the effort involved, when it comes down >to the more practical short period phases that are actually "read"; >in the general amateur (and likely the professional) realm. On the >other hand, I don't have a broadband vertical, so, perhaps my >thought judgement isn't really totally accurate for their use. > >It might just be, that any one design should incorporate the best >aspects of other previously proven function pieces and parts. >A big problem arises when it seems that some of the best use >or functional pieces/parts are in themselves fairly mechanically >complicated when addressed to a likely majority of ill-equipped >individual readers and their own capabilities for its completion. >I guess I'am always hopeful that there exists some simpler or >better way to do things, than how some of the present designs >are laid out. > >It may well be that Sean's vertical design (SM) could also be >construed in a variety of degrees (amateur/professional) of >approach; to satisfy any existing variety of potential use; >simply by utilizing the base designed mechanics for other less >sensitive sensor adoptions. This has apparently been done >(implied in past PSN emails) in the past by others, or suggested >but I'am not aware of their success in doing so, at the moment. > >Take care, Meredith > >ChrisAtUpw@....... wrote: >>Hi Meredith, >> >> Short period verticals are not too difficult to make, but they are >> of somewhat limited use. There are a number of practical / engineering >> constraints. I note that at least one design uses the U Alnico magnet as >> the seismic mass on the end of the arm. This is not a good idea and it >> will react to environmental changes in the local magnetic field. In the >> normal home, you are likely to see a very noisy trace. It is quite easy >> to damp a seismometer using readily available NdBFe magnets. Fluid >> damping is very temperature sensitive and can be quite messy. The much >> higher field supplied by NdBFe magnets can also be used to increase the >> output of coil detector systems and improve their range and linearity. A >> survey of a range of systems can be found at >> http://quake.eas.gatech.edu/Instruments/InstrumentSurvey.htm. >> Prof.Braile's link may be found by removing the seismometer reference. >> >>.................clipped......... > > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Vertical design From: ChrisAtUpw@....... Date: Sat, 21 Dec 2002 19:14:16 EST In a message dated 21/12/02, hammond@........... writes: > Chris, with regard to your comments on vertical seismometers, I invite you > to visit my web page http://apsn.awcable.com and specifically look at > "earthquakes recorded at station GSV". Every earthquake I record and > display > is using a Mark Products L4 1Hz short-period vertical seismometer. Surely, > you must be joking that short period vertical seismometers are of limited > use! Hi Bob, You make my point very well! Unless you have done some modifications, the L4 is a commercial 1 Hz geophone. It is a sealed unit and so is immune to atmospheric pressure changes. It is fully magnetically screened and uses a professional standard suspension. It also costs over $1 K new. I note that the majority of the quakes are 'local'. If you care to extend it's range down to 0.1 Hz electronically, you will get improved detection of lower frequency P and S tele seismic waves. Now, if you could actually demonstrate a simple 1 to 2 second period vertical seismometer of comparable quality which can easily be made by an amateur, I am sure that it would generate a whole lot of interest. I am not joking about the utility, or otherwise, of the current construction designs that I have seen on offer. Regards, Chris Chapman In a message dated 21/12/02, hammond@........... writes:

Chris, with regard to your comments on vertical seismometers, I invite you
to visit my web page http://apsn.awcable.com  and specifically look at "earthquakes recorded at station GSV". Every earthquake I record and display
is using a Mark Products L4 1Hz short-period vertical seismometer. Surely, you  must be joking that short period vertical seismometers are of limited use!


Hi Bob,

      You make my point very well! Unless you have done some modifications, the L4 is a commercial 1 Hz geophone. It is a sealed unit and so is immune to atmospheric pressure changes. It is fully magnetically screened and uses a professional standard suspension. It also costs over $1 K new. I note that the majority of the quakes are 'local'. If you care to extend it's range down to 0.1 Hz electronically, you will get improved detection of lower frequency P and S tele seismic waves.

      Now, if you could actually demonstrate a simple 1 to 2 second period vertical seismometer of comparable quality which can easily be made by an amateur, I am sure that it would generate a whole lot of interest. I am not joking about the utility, or otherwise, of the current construction designs that I have seen on offer.

      Regards,

      Chris Chapman
Subject: Re: Short Period Vertical/ Geophones?? From: ChrisAtUpw@....... Date: Sat, 21 Dec 2002 19:15:20 EST In a message dated 21/12/02, lehmancj@........... writes: Hi Jim Lehman, Geophones have a high sensitivity and can reach the noise floor. While the higher frequency models are commonly used for seismic prospectingy, the 1, 2 and 4.5 Hz models are useful for seismic monitoring, particularly in volcanic regions. See http://www.geospacelp.com/ and http://www.sercel.com/Products/frproduct2.htm The response of a geophone can be extended down to about 1/10 of it's natural resonant frequency by two methods. The simplest type uses a circuit similar to a bass boost circuit on an audio amplifier to amplify the falling response below the resonant frequency. You are eventually limited by amplifier, 1/f and thermo-emf noise. Another system uses a negative impedance converter to severely damp the geophone. This flattens the normal 'dog leg' in the response but reduces the signal a lot. A very low noise amplifier / filter system is used to boost the lower frequency signals. The extended range covers P and S seismic wave frequencies. The more elaborate system reported by Barzilai of Standford involved opening up the geophone, fitting a precision distance transducer to the armature and using feedback through the built in sense coil to control the response. If you choose a geophone between 1 and 4.5 Hz, they have an armature mass of 1 oz or more, which is about the minimum from Brownian motion noise considerations. The 2 and 4.5 Hz ones are relatively 'affordable'. The electronics controls the effective period and a broad band response from 30 sec to 50 Hz has been achieved. See http://micromachine.stanford.edu/smssl/projects/Geophones/ for several papers. Regards, Chris Chapman In a message dated 21/12/02, lehmancj@........... writes:

Hi Jim Lehman,

      Geophones have a high sensitivity and can reach the noise floor. While the higher frequency models are commonly used for seismic prospectingy, the 1, 2 and 4.5 Hz models are useful for seismic monitoring, particularly in volcanic regions. See http://www.geospacelp.com/ and http://www.sercel.com/Products/frproduct2.htm

      The response of a geophone can be extended down to about 1/10 of it's natural resonant frequency by two methods. The simplest type uses a circuit similar to a bass boost circuit on an audio amplifier to amplify the falling response below the resonant frequency. You are eventually limited by amplifier, 1/f and thermo-emf noise. Another system uses a negative impedance converter to severely damp the geophone. This flattens the normal 'dog leg' in the response but reduces the signal a lot. A very low noise amplifier / filter system is used to boost the lower frequency signals. The extended range covers P and S seismic wave frequencies.

      The more elaborate system reported by Barzilai of Standford involved opening up the geophone, fitting a precision distance transducer to the armature and using feedback through the built in sense coil to control the response. If you choose a geophone between 1 and 4.5 Hz, they have an armature mass of 1 oz or more, which is about the minimum from Brownian motion noise considerations. The 2 and 4.5 Hz ones are relatively 'affordable'. The electronics controls the effective period and a broad band response from 30 sec to 50 Hz has been achieved. See http://micromachine.stanford.edu/smssl/projects/Geophones/ for several papers.

      Regards,

      Chris Chapman
Subject: Vertical sensors From: "Roger Sparks" rsparks@........... Date: Mon, 23 Dec 2002 09:23:15 -0800 Hi Larry, Regarding vertical seismometers, I built one and have been very happy with it. Mauro Mariotti has some pictures of it on his site at http://www.infoeq.it/doc02v_e.htm#spring. The pictures of my sensor are at the end of a very long page on vertical sensors. I am using the amplifier board from Dave Saum and the Amaseis software from Allen Jones. I am picking up about one earthquake a day average from distant parts of the world in addition to local quakes here in Washington state. One big problem for me is the background noise that I am told results from wave action along the pacific coast. Living about 200 miles inland, I notice that the signal from many quakes is hidden in the background noise. I recently added a 1 Hz filter/resonator loop to the Amaseis program which is very effective in bringing the quake out of the noise. Comments that indicate that the vertical sensor is affected by local noise and air pressure changes are correct. All the bigger quakes have a much different pattern from local noise so are easily distinguished. I can see a distinctive pattern resulting from walking to the mail box, walking into the room where the seismometer is located (my office ), and kitchen activity. Yes, local noise can cover a quake signal but you can still see lots of seismic activity during local quiet periods. This is my first seismic project, and I have only been active in seismology for about a year so I have a lot to learn. Never-the-less, I am very happy with my vertical sensor and have seen a lot of distant quakes with it. Best wishes, Roger > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. > | Message 1 | > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > Subject: Vertical "SG" sensor? > From: "Larry Conklin" > Date: Tue, 17 Dec 2002 14:10:30 -0500 > > Hi all, > > I've been thinking about building a vertical sensor. One design I've been > considering would use a bowed leaf spring similar to the Sean-Thomas > Morisssey design, combined with the differential capacitor sensor using > Larry's SG electronics board. I'd be interested in hearing whether anyone > else has tried this or if anyone has any thoughts regarding the viability of > this approach. > > Larry Conklin > Liverpool, NY > lconklin@............ . . __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Subject: Vertical sensors From: allan egleston allane@......... Date: Mon, 23 Dec 2002 10:12:30 -0800 hi My name is Allan Egleston, and am new to the list. Am currently building a horizontal lehman sensor at this time. Have been reading the mail about Vertical sensors and it seems that there is a number to choose from. A question for the group, can there be a way to record events with out having to tie up a computer, as this seems to be the accepted norm? Thanks, Allan Egleston, kf6uxj __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: yes you need a computer From: "a.rodriguez" stuff@................. Date: Mon, 23 Dec 2002 15:26:57 -0500 Hello Allan, Yes, you will need a computer to read and store the data from the A/D, but it can be a very old (cheap) computer and if you have it on a network you will not have to tie up monitor/kbd/mouse. You can also run many systems on one computer (also with no monitor/kbd/mouse) I have one computer reading three seismographs, a weather station and web cam and soon hope to have nine seismographs on one computer. regards, angel Monday, December 23, 2002, 1:12:30 PM, you wrote: ae> hi My name is Allan Egleston, and am new to the list. Am currently ae> building a horizontal lehman sensor at this time. Have been reading the ae> mail about Vertical sensors and it seems that there is a number to ae> choose from. A question for the group, can there be a way to record ae> events with out having to tie up a computer, as this seems to be the ae> accepted norm? Thanks, Allan Egleston, kf6uxj __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: yes you need a computer From: ACole65464@....... Date: Mon, 23 Dec 2002 15:56:19 -0500 In a message dated 12/23/2002 3:26:57 PM Eastern Standard Time, "a.rodriguez" writes: >Hello Allan, > >Yes, you will need a computer to read and store the data from the A/D, >but it can be a very old (cheap) computer and if you have it on a >network you will not have to tie up monitor/kbd/mouse.  You can also >run many systems on one computer (also with no monitor/kbd/mouse) I >have one computer reading three seismographs, a weather station and web >cam and soon hope to have nine seismographs on one computer. > >regards, > >angel > >Monday, December 23, 2002, 1:12:30 PM, you wrote: > >ae> hi My name is Allan Egleston, and am new to the list. Am currently >ae> building a horizontal lehman sensor at this time. Have been reading the >ae> mail about Vertical sensors and it seems that there is a number to >ae> choose from.  A question for the group, can there be a way to record >ae> events with out having to tie up a computer, as this seems to be the >ae> accepted norm?  Thanks, Allan Egleston, kf6uxj > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. > Hello Angel, Sorry to say that you replied to the wrong Allan. How was your vaction? Debra and I (including son Mitchell and Debra's mother) will be leaving at the end of this week for a 2 week vaction ourselves. While I am typing to you I want to let you know that I spoke to your friend Larry 3 days after you left my house. I would think that you have been in contact with him several times since I last talked to you. Note: A couple of months ago, after I spoke to Larry, I emailed you to tell what he and I discussed, but my message kept being bounced back to me, so I have waited to make sure that you were back home to recieve messages again. Larry said he was going to mark up my sketches and then fax them to me, some 2-3 days later. He never responded. I thought we had a good discussion. What happened? Some of his ideas panned out, a couple of others didn't whereby I couldn't see any improvement in the system performance. But there was a net gain after our 2 hour phone conversation. I have made a new horizontal instrument and made some new tweaks to the displacement transducer circuit. It appears to have helped the sensitivity slightly. Only into my second day of testing with the instrument operating on my desk in my office at home. It picked up the 5.5 mag event near Honduras today nicely. I will send you a paper describing it when I get time, hopefully in January or perhaps February, to write it. I see that you have put up a copy of my MkXV on your web site. I have since made some tweaks to the circuit and have already revised the paper accordingly. With the changes I found necessary to do to the latest device on the bench, I will need to revise the earlier paper yet again. Anyway, enough for now. May you and your wife have a very Merry Christmas, Regards, Allan __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: yes you need a computer From: ChrisAtUpw@....... Date: Mon, 23 Dec 2002 16:34:01 EST In a message dated 23/12/2002, stuff@................. writes: > Yes, you will need a computer to read and store the data from the A/D, but > it can be a very old (cheap) computer and if you have it on a network you > will not have to tie up monitor/kbd/mouse. Hi Allan, You need quite a lot of storage, so do check on the size of the hard drive. At 10 samples / sec on a single channel, this is a bit under 2 Mb / day if you record everything. Some older computers had drives of less than 40 Mb and can not address very large drives even if you can change them eg 386 and lower number processors. Regards, Chris Chapman In a message dated 23/12/2002, stuff@................. writes:

Yes, you will need a computer to read and store the data from the A/D, but it can be a very old (cheap) computer and if you have it on a network you will not have to tie up monitor/kbd/mouse. 


Hi Allan,

     You need quite a lot of storage, so do check on the size of the hard drive. At 10 samples / sec on a single channel, this is a bit under 2 Mb / day if you record everything. Some older computers had drives of less than 40 Mb and can not address very large drives even if you can change them eg 386 and lower number processors.

     Regards,

     Chris Chapman
Subject: Graphite levitation seismometers and/or setups From: meredithlamb meredithlamb@............. Date: Mon, 23 Dec 2002 21:58:47 -0700 Holiday greetings to all! I've recently completed a brief and general non-technical web page/s relating to the past and current history of basic mechanical graphite levitated mass setups that could or have been used for seismometer purposes. The article is actually the abbreviated work results from several generious contributing individuals involved in the R&D subject over acouple of years now. http://geocities.com/meredithlamb/page060.html Take care, Meredith Lamb __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Subject: Vertical sensors From: BOB BARNS royb1@........... Date: Tue, 24 Dec 2002 10:30:26 -0500 Allan, Windows could probably run the recording program in the background. This requires that the computer be left running 24/7 which, even without the monitor takes a fair amount of AC power. I looked around in ebay.com and discovered that there are many laptops (requiring less power) for $125 or less. A few bucks more will get a considerably better machine. I looked for laptops which had at least Windows, 96K of RAM and some means of reloading Windows (3.1 is good enough) and programs-either a floppy drive or CD-ROM drive (if only one, a floppy drive). A monochrome screen is good enough (although I'm not sure that Windows is useable with monochrome). A working hard-drive is not necessary as a lot of 'quake data can be stored on a floppy if the sampling rate is kept low. A laptop will not accept Cochrane's excellant A/D board so an external A/D and some program other that SDR) would be necessary. If you go this way, be sure to get the computer's manual. Bob Barns allan egleston wrote: > > hi My name is Allan Egleston, and am new to the list. Am currently > building a horizontal lehman sensor at this time. Have been reading the > mail about Vertical sensors and it seems that there is a number to > choose from. A question for the group, can there be a way to record > events with out having to tie up a computer, as this seems to be the > accepted norm? Thanks, Allan Egleston, kf6uxj > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Digest from 12/23/2002 00:00:37 From: "Roger Sparks" rsparks@........... Date: Tue, 24 Dec 2002 07:50:04 -0800 Hi Allan, No, you do not have to run a dedicated computer for a seismic station. I am running mine on the same computer that I use for the Internet and every other computer use including games. At the present time, I am limited to only one channel meaning only one sensor running at a time I am using Amaseis written by Alan Jones. It is available at no cost from http://www.geol.binghamton.edu/faculty/jones/as1.html It is designed for a serial connection to the computer so it does tie up one serial port. I am using Microsoft Millennium as a computer operating system but I had to make some software changes to make it perform acceptably on my system. Alan says that Amaseis operates better on Windows 95 or 98. Mauro Mariotti also has a software package that operates with other programs but I have no experience with that program except to say that it will handle Dave Saum's amplifier board. It can be found at http://www.infoeq.it/index_e.htm. Merry Christmas, Roger ------ ------ ------ ------ ------ ------ ------. > | Message 2 | > '------ ------ ------ ------ ------ ------ ------ ------ ------ ------' > Subject: Subject: Vertical sensors > From: allan egleston > Date: Mon, 23 Dec 2002 10:12:30 -0800 > > hi My name is Allan Egleston, and am new to the list. Am currently > building a horizontal lehman sensor at this time. Have been reading the > mail about Vertical sensors and it seems that there is a number to > choose from. A question for the group, can there be a way to record > events with out having to tie up a computer, as this seems to be the > accepted norm? Thanks, Allan Egleston, kf6uxj > > > .------ ------ ------ ------ ------ ------ ------ ------ ------ ------. information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Dedicated computer? From: "Larry Conklin" lconklin@............ Date: Tue, 24 Dec 2002 11:10:50 -0500 I second the thought that a dedicated data logging computer need not be an expensive proposition. I just bought a very nice 350 mhz machine, complete with monitor, for $25. I'm already using a much older, much slower machine for data collection (dedicated to the application), with absolutely no problem. I would probably run it under MSDOS, but it is so handy to have it hanging on my home network so I run Windows 98 to get the networking functions. Larry Conklin lconklin@............ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Subject: Vertical sensors From: "Mauro Mariotti" mariotti@......... Date: Tue, 24 Dec 2002 17:10:44 +0100 Hi, you can use Larry's serial board with the laptop. If you need something more little you can give a look to http://www.infoeq.it/doc04_e.htm it is a 4 channels board but it requires 10V dc power supply and a preamplifier. This board runs with SEISMOWIN. Or, you can use the David Saum's board that can be used with SEISMOWIN or AMASEIS. Regards Mauro ----- Original Message ----- From: "BOB BARNS" To: Sent: Tuesday, December 24, 2002 4:30 PM Subject: Re: Subject: Vertical sensors > Allan, > Windows could probably run the recording program in the background. > This requires that the computer be left running 24/7 which, even without > the monitor takes a fair amount of AC power. > I looked around in ebay.com and discovered that there are many laptops > (requiring less power) for $125 or less. A few bucks more will get a > considerably better machine. > I looked for laptops which had at least Windows, 96K of RAM and some > means of reloading Windows (3.1 is good enough) and programs-either a > floppy drive or CD-ROM drive (if only one, a floppy drive). A > monochrome screen is good enough (although I'm not sure that Windows is > useable with monochrome). > A working hard-drive is not necessary as a lot of 'quake data can be > stored on a floppy if the sampling rate is kept low. A laptop will not > accept Cochrane's excellant A/D board so an external A/D and some > program other that SDR) would be necessary. > If you go this way, be sure to get the computer's manual. > Bob Barns > > allan egleston wrote: > > > > hi My name is Allan Egleston, and am new to the list. Am currently > > building a horizontal lehman sensor at this time. Have been reading the > > mail about Vertical sensors and it seems that there is a number to > > choose from. A question for the group, can there be a way to record > > events with out having to tie up a computer, as this seems to be the > > accepted norm? Thanks, Allan Egleston, kf6uxj > > __________________________________________________________ > > > > Public Seismic Network Mailing List (PSN-L) > > > > To leave this list email PSN-L-REQUEST@.............. with > > the body of the message (first line only): unsubscribe > > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: re: vertical sensors From: allan egleston allane@......... Date: Tue, 24 Dec 2002 08:41:14 -0800 Thanks for your time and replys. I now have to sit down and digest this information. Allan Egleston kf6uxj. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: old computer From: "a.rodriguez" stuff@................. Date: Tue, 24 Dec 2002 15:09:06 -0500 Hello Everyone, Even here in Panama old and cheap means a Pentium II with 64K and a 4 gig disk, at least. :) angel Tuesday, December 24, 2002, 11:10:50 AM, you wrote: LC> I second the thought that a dedicated data logging computer need not be an LC> expensive proposition. I just bought a very nice 350 mhz machine, complete LC> with monitor, for $25. I'm already using a much older, much slower machine LC> for data collection (dedicated to the application), with absolutely no LC> problem. I would probably run it under MSDOS, but it is so handy to have it LC> hanging on my home network so I run Windows 98 to get the networking LC> functions. LC> Larry Conklin LC> lconklin@............ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Update to all on my array project From: "a.rodriguez" stuff@................. Date: Tue, 24 Dec 2002 15:12:24 -0500 Hello psn-l, I am getting ready to install my array and have some photos. All comments welcome. http://www.volcanbaru.com/array/array.html I hope to have it working by late February early March. -- Merry Christmas to all, a.rodriguez mailto:stuff@................. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: RE: Dedicated computer? From: steve hammond shammon1@............. Date: Tue, 24 Dec 2002 22:28:40 -0800 I'm still using IBM AT 286 class machines with the very old IBM D/A 12-bit cards. I've lost a few power supplies over the years and a CGA monitor or two. The real issue is that the 12-bit cards I have will not work on a 386 machine or above... I plan on moving to Larry's setup next year. Regards, Steve Hammond PSN San Jose -----Original Message----- From: Larry Conklin [SMTP:lconklin@............. Sent: Tuesday, December 24, 2002 8:11 AM To: PSN List Subject: Dedicated computer? I second the thought that a dedicated data logging computer need not be an expensive proposition. I just bought a very nice 350 mhz machine, complete with monitor, for $25. I'm already using a much older, much slower machine for data collection (dedicated to the application), with absolutely no problem. I would probably run it under MSDOS, but it is so handy to have it hanging on my home network so I run Windows 98 to get the networking functions. Larry Conklin lconklin@............ __________________________________________________________ Public Seismic Network Mailing List (PSN-L) __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Earthquake Conversations From: "Bob Hancock" robert.hancock@........... Date: Wed, 25 Dec 2002 18:57:20 -0500 On pages 72 - 79, in the January 2003 edition of Scientific American, there is an article on earthquakes, and some insight into earthquake prediction, titled Earthquake Conversations. Copied below is the teaser contained on their web site. The author is a PhD geophysicist with the USGS Hazards Team in Menlo Park, CA. You can download the article from the archives of the Scientific American web site for a fee, or buy the magazine. www.sciam.com * * * * * * * * * Earthquake Conversations Contrary to prevailing wisdom, large earthquakes can interact in unexpected ways. This exciting discovery could dramatically improve scientists' ability to pinpoint future shocks By Ross S. Stein For decades, earthquake experts dreamed of being able to divine the time and place of the world's next disastrous shock. But by the early 1990s the behavior of quake-prone faults had proved so complex that they were forced to conclude that the planet's largest tremors are isolated, random and utterly unpredictable. Most seismologists now assume that once a major earthquake and its expected aftershocks do their damage, the fault will remain quiet until stresses in the earth's crust have time to rebuild, typically over hundreds or thousands of years. A recent discovery-that earthquakes interact in ways never before imagined-- is beginning to overturn that assumption. This insight corroborates the idea that a major shock relieves stress-and thus the likelihood of a second major tremor-- in some areas. But it also suggests that the probability of a succeeding earthquake elsewhere along the fault or on a nearby fault can actually jump by as much as a factor of three. To the people who must stand ready to provide emergency services or to those who set prices for insurance premiums, these refined predictions can be critical in determining which of their constituents are most vulnerable....continued at the Scientific American Archive __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Earthquake Conversations From: David A Nelson davenn@............... Date: Thu, 26 Dec 2002 12:10:19 +1100 just a note ..... articles from the archives cost US$5.00 / article to download you have to signup with sci am and give credit card details etc searching the archive is free but u CANNOT read an article till u pay and download it in PDF format Dave Nelson At 06:57 PM 25-12-02 -0500, you wrote: >On pages 72 - 79, in the January 2003 edition of Scientific American, there >is an article on earthquakes, and some insight into earthquake prediction, >titled Earthquake Conversations. Copied below is the teaser contained on >their web site. The author is a PhD geophysicist with the USGS Hazards Team >in Menlo Park, CA. You can download the article from the archives of the >Scientific American web site for a fee, or buy the magazine. > > www.sciam.com __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Winsdr under Linux From: Karl Cunningham karlc@.......... Date: Fri, 27 Dec 2002 10:32:33 -0800 Hi -- This may be old hat to some, but it's new to me and something I've wanted to try for a while now. The last few days I have been running Larry Cochrane's Winsdr under Linux using Wine (http://www.winehq.com), a system that allows Windows-based programs to be run under Linux. To move Winsdr to the Linux box, the entire winsdr directory and everything under it on the Windows machine were copied (including the daily record files) to a subdirectory created for the purpose on the Linux box. After a bit of editing of the Wine configuration file, it worked. This machine is a Celeron 466 with 256MB of ram. Wine and Winsdr are only using about 1.2% of the CPU cycles and 3% of the RAM, so I'm sure it would work fine on a much less capable computer. Screen redraw speed is comparable to the Pentium II 350MHz Windows NT machine it was running on before. The operating system is Mandrake 9.0 Linux, and I imagine it would work under Redhat linux as well. Wine is seeing a lot of development these days, with new versions coming out on a daily basis. I downloaded and installed one as of 12/23/02 for this test. If anyone is interested, I'd be happy to supply more details. And for anyone who want to try, my wine configuration file is at http://www.keckec.com/wine_config . There are probably more optimizations that can be made, but a least it works. The next challenge is to replace the serial connection between the A/D and Winsdr with a TCP/IP connection. This should remove the limitation of serial line length and reduce ground noise since ethernet cards are transformer isolated whereas the serial connections are not. Regards, and happy new year to all. Karl Cunningham __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Winsdr under Linux From: Ian Smith ian@........... Date: Fri, 27 Dec 2002 22:02:18 +0000 if you acquire a "terminal server" you can plug your rs232 based A/D into it and talk to the terminal server with a tcp/ip socket connection from linux. Terminal servers can probably be found on ebay... Older units providing LAT services are no use, they must provide telnet services Ian Smith Karl Cunningham wrote: >Hi -- > >This may be old hat to some, but it's new to me and something I've wanted >to try for a while now. The last few days I have been running Larry >Cochrane's Winsdr under Linux using Wine (http://www.winehq.com), a system >that allows Windows-based programs to be run under Linux. > >To move Winsdr to the Linux box, the entire winsdr directory and everything >under it on the Windows machine were copied (including the daily record >files) to a subdirectory created for the purpose on the Linux box. After a >bit of editing of the Wine configuration file, it worked. This machine is >a Celeron 466 with 256MB of ram. Wine and Winsdr are only using about 1.2% >of the CPU cycles and 3% of the RAM, so I'm sure it would work fine on a >much less capable computer. Screen redraw speed is comparable to the >Pentium II 350MHz Windows NT machine it was running on before. The >operating system is Mandrake 9.0 Linux, and I imagine it would work under >Redhat linux as well. > >Wine is seeing a lot of development these days, with new versions coming >out on a daily basis. I downloaded and installed one as of 12/23/02 for >this test. > >If anyone is interested, I'd be happy to supply more details. And for >anyone who want to try, my wine configuration file is at >http://www.keckec.com/wine_config . There are probably more optimizations >that can be made, but a least it works. > >The next challenge is to replace the serial connection between the A/D and >Winsdr with a TCP/IP connection. This should remove the limitation of >serial line length and reduce ground noise since ethernet cards are >transformer isolated whereas the serial connections are not. > >Regards, and happy new year to all. > >Karl Cunningham > >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Winsdr under Linux From: "Larry Cochrane" cochrane@.............. Date: Fri, 27 Dec 2002 16:43:41 -0800 Karl, Thanks for the report. Have you tried WinQuake under Wine? Regards, Larry Cochrane Redwood City, PSN ----- Original Message ----- From: "Karl Cunningham" To: Sent: Friday, December 27, 2002 10:32 AM Subject: Winsdr under Linux > Hi -- > > This may be old hat to some, but it's new to me and something I've wanted > to try for a while now. The last few days I have been running Larry > Cochrane's Winsdr under Linux using Wine (http://www.winehq.com), a system > that allows Windows-based programs to be run under Linux. > > To move Winsdr to the Linux box, the entire winsdr directory and everything > under it on the Windows machine were copied (including the daily record > files) to a subdirectory created for the purpose on the Linux box. After a > bit of editing of the Wine configuration file, it worked. This machine is > a Celeron 466 with 256MB of ram. Wine and Winsdr are only using about 1.2% > of the CPU cycles and 3% of the RAM, so I'm sure it would work fine on a > much less capable computer. Screen redraw speed is comparable to the > Pentium II 350MHz Windows NT machine it was running on before. The > operating system is Mandrake 9.0 Linux, and I imagine it would work under > Redhat linux as well. > > Wine is seeing a lot of development these days, with new versions coming > out on a daily basis. I downloaded and installed one as of 12/23/02 for > this test. > > If anyone is interested, I'd be happy to supply more details. And for > anyone who want to try, my wine configuration file is at > http://www.keckec.com/wine_config . There are probably more optimizations > that can be made, but a least it works. > > The next challenge is to replace the serial connection between the A/D and > Winsdr with a TCP/IP connection. This should remove the limitation of > serial line length and reduce ground noise since ethernet cards are > transformer isolated whereas the serial connections are not. > > Regards, and happy new year to all. > > Karl Cunningham __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Re Notes to UK? From: "Nick Caporossi" capnick2k2@............. Date: Sat, 28 Dec 2002 11:28:23 -0500 Hi: I Would be glad to send you my Email address. I don't recall corresponding with you Was there a special reason why = you are asking for my Email Id? ----- Original Message -----=20 From: Connie and Jim Lehman=20 To: psn-l@................. Sent: Saturday, December 21, 2002 2:11 PM Subject: Re Notes to UK? Nick--all I need is an address--no problem, Frank Cooper if you are tuned in, no need to send postage.. ----Jim
Hi:
 I Would be glad to send you = my Email=20 address.
 I don't recall corresponding with = you =20 Was there a special reason why you are asking for my Email = Id?
----- Original Message -----
From:=20 Connie and=20 Jim Lehman
Sent: Saturday, December 21, = 2002 2:11=20 PM
Subject: Re Notes to UK?

Nick--all I need is = an=20 address--no problem,
 
  Frank Cooper = if you are=20 tuned in, no need to send postage..
          &nbs= p;            = ;            = =20 ----Jim
Subject: Notes to UK--Nick From: "Connie and Jim Lehman" lehmancj@........... Date: Sat, 28 Dec 2002 14:15:04 -0500 Nick--I do not need an e-mail address. I only needed your mailing = address to send the "Short Period" design plans. The plans were mailed airmail to U.K. 2 days before Christmas. A good New Year to you and all the PSN group. J. Lehman.
Nick--I do not need = an e-mail=20 address.  I only needed your mailing address to send the "Short = Period"=20 design plans.
   The = plans were=20 mailed airmail  to U.K. 2 days before Christmas.
   A good = New Year to=20 you and all the PSN group.
          &nbs= p;            = ;      =20 J. Lehman.
Subject: Re: Update to all on my array project From: meredithlamb meredithlamb@............. Date: Sat, 28 Dec 2002 21:43:03 -0700 Hi Angel, Wow! What a huge undertaking you have taken on, and are accomplishing there in Panama! Most impressive indeed from examining your web site!!! Meredith Lamb "a.rodriguez" wrote: > Hello psn-l, > > I am getting ready to install my array and have some photos. All > comments welcome. > > http://www.volcanbaru.com/array/array.html > > I hope to have it working by late February early March. > > -- > Merry Christmas to all, > a.rodriguez mailto:stuff@................. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Seismometer Distance Transducer Type LX1358 From: ChrisAtUpw@....... Date: Sun, 29 Dec 2002 16:26:03 EST Hi all seis builders / modifiers! I have built, tested and now use the Type LX1358 Linear Variable Differential Transformer Seismometer Sensor sold as a Kit by Nuova Elettronica in Italy. Their Website is at http://www.nuovaelettronica.it/ The price of the Kit is E 51.65, ~US $52 + Carriage, which looks like quite good value. The net weight of the Kit is about 12 oz. The sensor is described in their Magazine No:195 June-July 1998, which is on sale, but it is in Italian. If you call up their Website, just type 1358 in slot labelled 'Ricerca'. If, like me, you have difficulty reading Italian, call up http://babelfish.altavista.com/tr, enter Italian ---> English translation and type in the website, but I have experienced a slow response. A picture of the NE 1.4 sec short period pendulum seismometer is shown at http://www.nuovaelettronica.it/it/pop/index.cfm?fb=scheda_kit&w.kit_id=1849 NE sell the complete pendulum seismometer Kit, with the LX1358 detector included, but it weighs about 22 lb. They also sell a microprocessor monitoring system with a 12 bit A/D converter, a paper printout and have a new 16 bit PC computer interface kit. The LX1358 sensor board can be seen in the bottom of the vertical steel case with the ferrite rod positioned horizontally between the two white coils. The rod is suspended from the pendulum bob on two strips of glass circuit board, which also dip into the oil tub beneath the board to provide damping. The LX1358 Kit includes the circuit board, four integrated circuits, resistors, capacitors, diodes, an analogue meter, a plastic tub for oil damping, two sensor coils and the ferrite sensing rod to make up a full working sensor. It will work well with simple pendulums and also with Lehmans. Basically, the sensor does just what it is supposed to do! The principle of operation is quite simple. A ferrite rod is threaded through two identical transformer windings, with it's ends about half way into each former. The formers are of the type used for double insulated mains transformers with two equal width coils, side by side. The two magnetising windings are nearest the centre of the rod and the secondary sense windings are on the outside. A precisely controlled sinusoidal voltage is applied to the primary windings, which are connected in series so that their magnetic fields add and magnetise the ferrite rod. The secondary windings are connected in opposition so that their signals subtract. With the rod central, there is no net secondary output. If the rod is moved axially, a bit further into one coil and out of the other; the induced voltage is increased in one secondary coil and reduced in the other, giving a net output. This is passed to a direct / invert switch running in phase with the oscillator, which rectifies the signal. The chopped output is fed into a two pole low pass filter to smooth it. This intermediate level signal is a frequency limited DC voltage level giving about 0.3 V out per mm of rod movement. This sensitivity allows for the full 15 mm travel of the ferrite rod without reaching the saturation levels of the amplifier. For setup and monitoring purposes the signal is displayed on a small centre zero volt meter. The AC component passes through a high pass filter and it is then amplified by a factor of x213 to give the final output. This allows the rod to slowly drift in position over +/-12 mm, while maintaining a very high sensitivity for the much faster seismic signals. The double sided NE circuit board is 14.5 cm long by 12.5 cm wide by 1.8 mm thick and is of excellent quality. The component positions / number references are printed on the board. The sensor and electronics form a single unit and both are mounted on the board with the electronics on the front long side. The two sensor coils are mounted at either end of the rear long side of the board. The ferrite rod is threaded through the coils and it should be set up to move along an axis roughly parallel to the long axis of the circuit board. A small plastic tub can be attached underneath the circuit board in between the coils, to hold oil for a damping vane, allowing +/-15mm travel. An 'on board' 12 V DC Regulator is provided which needs an absolute minimum supply input of 14.5 V DC at about 50 mA (42.5 mA measured). NE recommend a 24 V DC unregulated supply. I use a 15 V 100 mA 'double insulated' miniature transformer, two diodes and a 1000 micro farad capacitor, which gives me ~20 V DC unregulated and allows for occasional voltage reductions in the Mains Supply. I also fitted components to protect against mains and lightning surges. These components, a fuse, a LED and a switch should be mounted in a separate screened case away from the seismometer rig. You need some transient protection and a good earth to reject switching surges from domestic appliances like refrigerators, etc. The circuit is designed around the Phillips NE5521 LVDT chip. The electronics consists of the LVDT section which produces a smoothed linear response calibrated at approximately 300 mV per mm of travel. This is followed by a high pass filter and an amplifier with a gain of x213, giving a final sensitivity of about 65 mV per micron. The output noise level of my final circuit is below +/- 0.5 mV, which corresponds to about +/- 7 nanometres. The zero reference level is at 1/2 the regulated supply voltage, about 6 V. For more information on Philips LVDT circuits, go to http://www.semiconductors.philips.com/search/ and type NE5521. This should bring up the download links for the data sheet and for applications note AN1182. To obtain the large linear range, the sensor itself needs to be physically quite large. A 99 mm (4") long by 9.6 mm dia (3/8") ferrite rod and two square section transformer type windings, each ~3.5 cm cube, are used. The rod weighs approx. 35 gm. Quite chunky stuff! But it allows a comfortable +/- 3 mm gap inside the formers for variations in the lateral and vertical position of the ferrite rod, which I found to be very useful indeed! This makes it easy to set up and align and allows the rod to swing in an arc. The output voltage is linear for sensor movements of up to +/- 6 mm and the output is only 10% down at +/- 12 mm. It is 'usable' to beyond +/- 15 mm. This large range allows the sensor to also be used with seismometers of the 'garden-gate' Lehman type, but if your Lehman is set up with a long natural time constant giving it a high intrinsic sensitivity, you might wish to reduce the gain. Putting it another way, your seismometer arm can drift 1/2", but you still get 90% of the central position seismic response. The high pass output filter has an RC time constant of 1 second (0.15 Hz), which is fine for a short period pendulum, but may be rather low for a 'garden-gate' seismometer. I found that by changing the coupling capacitor and one resistor, I could extend the time constant up to 47 sec without any problems. The existing output circuit can ALSO be configured to differentiate the displacement output to give a velocity plot. This may be the preferred option for longer period Lehman systems. To assist in setting up the balance / zero point and for checking for drift, a small 36 mm moving coil 'tuning' meter is provided. This is driven directly off the LVDT output. The meter is nominally +/- 200 micro A at 740 Ohm. As designed, the calibration marks on the meter correspond to about +/- 0.2 mm and +/- 1.2 mm off centre. If you are planning to use this sensor with a Lehman, you might find it helpful to increase the full scale range to +/- 12 mm or more. This will give you a remote readout of the sensor position. It can be most useful to have a visible check, which does not disturb the seismometer, against any tilt / drift problems. Since I live in a place which has intermittent high traffic / environmental noise and this gave serious interference on the seismic recordings, I decided to investigate the characteristics of the LVDT filter. The LVDT detection circuit uses a two pole Sallen and Key low pass filter design with gain, which gave a 3 dB point at 33 Hz and a 20 dB point at 250 Hz on my board. It seems to be a copy of the circuit in the Philips data sheet and is better suited to commercial LVDT applications. I changed three resistors and a capacitor to improve the noise rejection above 10 Hz and to give a three pole response with a much sharper cut-off. I measured the new 3 dB point at 10 Hz and the 20 dB point at a bit under 20 Hz. The cut-off frequency may be lowered still further if desired, to below 3 Hz, but two additional capacitor changes are needed. Miniature polyester capacitors with a 0.2" pin spacing are used. My sensor is housed inside a steel container and is well screened from external magnetic fields. However, ferrite rods were designed for the efficient reception of radio signals and the oscillator frequency is approx. 15 KHz, so interactions are possible between an unshielded sensor and the 15 KHz scanning fields produced by TVs and computer monitors and also with some VLF radio signals. I checked the sensor output for interference with low magnetic fields of ~15 KHz and it is quite sensitive, but the bandwidth is very narrow. If you use an unshielded sensor, I suggest that you do check for any pickup problems. The oscillator frequency is set by a capacitor and a resistor, so it may easily be changed. The actual frequency in not critical to within a KHz or so, but the frequency stability needs to be good. The frequency calculations are given on the Philips data sheet. The magnetic field from the coils extends to about seven cm beyond the end of the board. The commercial free armature LVDTs that I have used had only 1/2 mm difference between the outer diameter of the armature and the inner diameter of the coil. I found these seriously difficult to set up and maintain in alignment. However, Schaevitz do produce LVDTs with a 1/16" clearance. An introductory article is given at http://www.msiusa.com/schaevitz/pdf/lvdt/LVDT_Intro.pdf The 050 HR has a free armature with a +/- 1.27 mm stroke is 28.7 mm long, the 100 HR has a free armature with a +/-2.54 mm stroke and is 46 mm long - see http://www.msiusa.com/schaevitz/pdf/lvdt/HR-Series.pdf Schaevitz have a technical article including some details of the design of LVDT sensors and systems at http://www.msiusa.com/schaevitz/products/LVDT/signal.pdf You may have to 'sign on' to download from their Website. Another description of LVDTs complete with a Java Applet showing the operation of AC transducers is at http://www.rdpe.com/displacement/lvdt/lvdt-principles.htm I will be happy to pass on information on the filter and other minor design changes that I found by experiment to significantly lower the noise and on the modifications to increase the time constant of the output of my LX1358 for periods of up to 47 seconds. This information, which I believe to be correct, will be supplied in good faith but without any warranty or liability, either direct or implied. The suggestions are the result of my personal experiments and I have not discussed the circuit changes with Nuova Elettronica. I have no connection with Nuova Elettronica other than being a satisfied customer. The suggestions should not in any way be interpreted as a criticism of Nuova Elettronica equipment or designers. The original Kit worked OK as supplied - but it worked even better with a few component changes. Regards, Chris Chapman Hi all seis builders / modifiers!

      I have built, tested and now use the Type LX1358 Linear Variable Differential Transformer Seismometer Sensor sold as a Kit by Nuova Elettronica in Italy. Their Website is at http://www.nuovaelettronica.it/ The price of the Kit is E 51.65, ~US $52 + Carriage, which looks like quite good value. The net weight of the Kit is about 12 oz. The sensor is described in their Magazine No:195 June-July 1998, which is on sale, but it is in Italian. If you call up their Website, just type 1358 in slot labelled 'Ricerca'. If, like me, you have difficulty reading Italian, call up http://babelfish.altavista.com/tr, enter Italian ---> English translation and type in the website, but I have experienced a slow response. A picture of the NE 1.4 sec short period pendulum seismometer is shown at http://www.nuovaelettron ica.it/it/pop/index.cfm?fb=scheda_kit&w.kit_id=1849 NE sell the complete pendulum seismometer Kit, with the LX1358 detector included, but it weighs about 22 lb. They also sell a microprocessor monitoring system with a 12 bit A/D converter, a paper printout and have a new 16 bit PC computer interface kit.

      The LX1358 sensor board can be seen in the bottom of the vertical steel case with the ferrite rod positioned horizontally between the two white coils. The rod is suspended from the pendulum bob on two strips of glass circuit board, which also dip into the oil tub beneath the board to provide damping. The LX1358 Kit includes the circuit board, four integrated circuits, resistors, capacitors, diodes, an analogue meter, a plastic tub for oil damping, two sensor coils and the ferrite sensing rod to make up a full working sensor. It will work well with simple pendulums and also with Lehmans. Basically, the sensor does just what it is supposed to do!

     The principle of operation is quite simple. A ferrite rod is threaded through two identical transformer windings, with it's ends about half way into each former. The formers are of the type used for double insulated mains transformers with two equal width coils, side by side. The two magnetising windings are nearest the centre of the rod and the secondary sense windings are on the outside. A precisely controlled sinusoidal voltage is applied to the primary windings, which are connected in series so that their magnetic fields add and magnetise the ferrite rod. The secondary windings are connected in opposition so that their signals subtract. With the rod central, there is no net secondary output. If the rod is moved axially, a bit further into one coil and out of the other; the induced voltage is increased in one secondary coil and reduced in the other, giving a net output. This is passed to a direct / invert switch running in phase with the oscillator, which rectifies the signal. The chopped output is fed into a two pole low pass filter to smooth it.     

      This intermediate level signal is a frequency limited DC voltage level giving about 0.3 V out per mm of rod movement. This sensitivity allows for the full 15 mm travel of the ferrite rod without reaching the saturation levels of the amplifier. For setup and monitoring purposes the signal is displayed on a small centre zero volt meter. The AC component passes through a high pass filter and it is then amplified by a factor of x213 to give the final output. This allows the rod to slowly drift in position over +/-12 mm, while maintaining a very high sensitivity for the much faster seismic signals.

      The double sided NE circuit board is 14.5 cm long by 12.5 cm wide by 1.8 mm thick and is of excellent quality. The component positions / number references are printed on the board. The sensor and electronics form a single unit and both are mounted on the board with the electronics on the front long side. The two sensor coils are mounted at either end of the rear long side of the board. The ferrite rod is threaded through the coils and it should be set up to move along an axis roughly parallel to the long axis of the circuit board. A small plastic tub can be attached underneath the circuit board in between the coils, to hold oil for a damping vane, allowing +/-15mm travel.

    An 'on board' 12 V DC Regulator is provided which needs an absolute minimum supply input of 14.5 V DC at about 50 mA (42.5 mA measured). NE recommend a 24 V DC unregulated supply. I use a 15 V 100 mA 'double insulated' miniature transformer, two diodes and a 1000 micro farad capacitor, which gives me ~20 V DC unregulated and allows for occasional voltage reductions in the Mains Supply. I also fitted components to protect against mains and lightning surges. These components, a fuse, a LED and a switch should be mounted in a separate screened case away from the seismometer rig. You need some transient protection and a good earth to reject switching surges from domestic appliances like refrigerators, etc.

     The circuit is designed around the Phillips NE5521 LVDT chip. The electronics consists of the LVDT section which produces a smoothed linear response calibrated at approximately 300 mV per mm of travel. This is followed by a high pass filter and an amplifier with a gain of x213, giving a final sensitivity of about 65 mV per micron. The output noise level of my final circuit is below +/- 0.5 mV, which corresponds to about +/- 7 nanometres. The zero reference level is at 1/2 the regulated supply voltage, about 6 V. For more information on Philips LVDT circuits, go to http://www.semiconductors.philips.com/search/ and type NE5521. This should bring up the download links for the data sheet and for applications note AN1182.

     To obtain the large linear range, the sensor itself needs to be physically quite large. A 99 mm (4") long by 9.6 mm dia (3/8") ferrite rod and two square section transformer type windings, each ~3.5 cm cube, are used. The rod weighs approx. 35 gm. Quite chunky stuff! But it allows a comfortable +/- 3 mm gap inside the formers for variations in the lateral and vertical position of the ferrite rod, which I found to be very useful indeed! This makes it easy to set up and align and allows the rod to swing in an arc.

      The output voltage is linear for sensor movements of up to +/- 6 mm and the

output is only 10% down at +/- 12 mm. It is 'usable' to beyond +/- 15 mm. This large range allows the sensor to also be used with seismometers of the 'garden-gate' Lehman type, but if your Lehman is set up with a long natural time constant giving it a high intrinsic sensitivity, you might wish to reduce the gain. Putting it another way, your seismometer arm can drift 1/2", but you still get 90% of the central position seismic response.

      The high pass output filter has an RC time constant of 1 second (0.15 Hz), which is fine for a short period pendulum, but may be rather low for a 'garden-gate' seismometer. I found that by changing the coupling capacitor and one resistor, I could extend the time constant up to 47 sec without any problems. The existing output circuit can ALSO be configured to differentiate the displacement output to give a velocity plot. This may be the preferred option for longer period Lehman systems.

      To assist in setting up the balance / zero point and for checking for drift, a small 36 mm moving coil 'tuning' meter is provided. This is driven directly off the LVDT output. The meter is nominally +/- 200 micro A at 740 Ohm. As designed, the calibration marks on the meter correspond to about +/- 0.2 mm and +/- 1.2 mm off centre. If you are planning to use this sensor with a Lehman, you might find it helpful to increase the full scale range to +/- 12 mm or more. This will give you a remote readout of the sensor position. It can be most useful to have a visible check, which does not disturb the seismometer, against any tilt / drift problems.

      Since I live in a place which has intermittent high traffic / environmental noise and this gave serious interference on the seismic recordings, I decided to investigate the characteristics of the LVDT filter. The LVDT detection circuit uses a two pole Sallen and Key low pass filter design with gain, which gave a 3 dB point at 33 Hz and a 20 dB point at 250 Hz on my board. It seems to be a copy of the circuit in the Philips data sheet and is better suited to commercial LVDT applications. I changed three resistors and a capacitor to improve the noise rejection above 10 Hz and to give a three pole response with a much sharper cut-off. I measured the new 3 dB point at 10 Hz and the 20 dB point at a bit under 20 Hz. The cut-off frequency may be lowered still further if desired, to below 3 Hz, but two additional capacitor changes are needed. Miniature polyester capacitors with a 0.2" pin spacing are used.

 
      My sensor is housed inside a steel container and is well screened from external magnetic fields. However, ferrite rods were designed for the efficient reception of radio signals and the oscillator frequency is approx. 15 KHz, so interactions are possible between an unshielded sensor and the 15 KHz scanning fields produced by TVs and computer monitors and also with some VLF radio signals. I checked the sensor output for interference with low magnetic fields of ~15 KHz and it is quite sensitive, but the bandwidth is very narrow. If you use an unshielded sensor, I suggest that you do check for any pickup problems. The oscillator frequency is set by a capacitor and a resistor, so it may easily be changed. The actual frequency in not critical to within a KH z or so, but the frequency stability needs to be good. The frequency calculations are given on the Philips data sheet. The magnetic field from the coils extends to about seven cm beyond the end of the board.

      The commercial free armature LVDTs that I have used had only 1/2 mm difference between the outer diameter of the armature and the inner diameter of the coil. I found these seriously difficult to set up and maintain in alignment. However, Schaevitz do produce LVDTs with a 1/16" clearance. An introductory article is given at http://www.msiusa.com/schaevitz/pdf/lvdt/LVDT_Intro.pdf The 050 HR has a free armature with a +/- 1.27 mm stroke is 28.7 mm long, the 100 HR has a free armature with a +/-2.54 mm stroke and is 46 mm long - see http://www.msiusa.com/schaevitz/pdf/lvdt/HR-Series.pdf
      Schaevitz have a technical article including some details of the design of LVDT sensors and systems at http://www.msiusa.com/schaevitz/products/LVDT/signal.pdf You may have to 'sign on' to download from their Website.
      Another description of LVDTs complete with a Java Applet showing the operation of AC transducers is at http://www.rdpe.com/displacement/lvdt/lvdt-principles.htm


      I will be happy to pass on information on the filter and other minor design changes that I found by experiment to significantly lower the noise and on the modifications to increase the time constant of the output of my LX1358 for periods of up to 47 seconds. This information, which I believe to be correct, will be supplied in good faith but without any warranty or liability, either direct or implied. The suggestions are the result of my personal experiments and I have not discussed the circuit changes with Nuova Elettronica. I have no connection with Nuova Elettronica other than being a satisfied customer. The suggestions should not in any way be interpreted as a criticism of Nuova Elettronica equipment or designers. The original Kit worked OK as supplied - but it worked even better with a few component changes.

      Regards,

      Chris Chapman     


Subject: Re: Notes to UK--Nick From: John & Jan Lahr johnjan@........ Date: Mon, 30 Dec 2002 10:47:26 -0700 I've scanned Jim's Short Period design plans and put a copy on my web site here:
http://jjlahr.com/science/psn/lehman/
This will save on postage and make the plans available to more people.  They
are a good example of how to document a seismic sensor design.

Happy New Year,
John



At 12:15 PM 12/28/2002, you wrote:
Nick--I do not need an e-mail address.  I only needed your mailing address to send the "Short Period" design plans.
   The plans were mailed airmail  to U.K. 2 days before Christmas.
   A good New Year to you and all the PSN group.
                              J. Lehman.
Subject: Re: Notes to UK--Nick From: "Mauro Mariotti" mariotti@......... Date: Mon, 30 Dec 2002 20:00:45 +0100 Hi all, I suggest a different approach for homemade vertical sensors. The sensor in the link you propose is VERY sensitive to axial movements (horizontal movements) if you give a look to=20 http://www.infoeq.it/doc02v_e.htm and scroll the page until you reach: Lacoste suspension sensor=20 you can see a good approach to a sensitive=20 long period seismometer. There are also sofisticated tecniques to=20 have a virtually infinite response for that kind of seismometer using a "zero length spring". Mr Lacoste writed a lot of paper on it. Chris Chapman is better documented on this point. I hope to have the time to publish an abstract on these tecnmiques but any clever mind can understand how the Lacoste suspension is great and simple to build. Regards Mauro ----- Original Message -----=20 From: John & Jan Lahr=20 To: psn-l@................. Sent: Monday, December 30, 2002 6:47 PM Subject: Re: Notes to UK--Nick I've scanned Jim's Short Period design plans and put a copy on my web = site here: http://jjlahr.com/science/psn/lehman/ This will save on postage and make the plans available to more people. = They are a good example of how to document a seismic sensor design. Happy New Year, John At 12:15 PM 12/28/2002, you wrote: Nick--I do not need an e-mail address. I only needed your mailing = address to send the "Short Period" design plans. The plans were mailed airmail to U.K. 2 days before Christmas. A good New Year to you and all the PSN group. J. Lehman.
Hi all,
I suggest a different approach for = homemade=20 vertical sensors.
The sensor in the link you propose is = VERY=20 sensitive to axial movements
(horizontal movements)
if you give a look = to=20
 
http://www.infoeq.it/doc02v_e.= htm
 
and scroll the page until you = reach:
 
Lacoste suspension = sensor=20
 
you can see a good approach to a = sensitive=20
long period seismometer.
 
There are also sofisticated tecniques = to=20
have a virtually infinite response = for that=20 kind
of seismometer using a "zero length=20 spring".
 
Mr Lacoste writed a lot of paper on=20 it.
Chris Chapman is better documented on = this=20 point.
I hope to have the time to publish an = abstract on=20 these tecnmiques
but any clever mind can understand = how the=20 Lacoste suspension
is great and simple to = build.
 
Regards
Mauro
 
 
 
----- Original Message -----
From:=20 John = & Jan=20 Lahr
Sent: Monday, December 30, 2002 = 6:47=20 PM
Subject: Re: Notes to = UK--Nick

I've scanned Jim's Short Period design plans and put a = copy on=20 my web site here:
http://jjlahr.com/science/psn/lehman/
This = will save=20 on postage and make the plans available to more people.  = They
are a=20 good example of how to document a seismic sensor design.

Happy = New=20 Year,
John



At 12:15 PM 12/28/2002, you wrote:
Nick--I do not need=20 an e-mail address.  I only needed your mailing address to send = the=20 "Short Period" design plans.
   = The plans=20 were mailed airmail  to U.K. 2 days before = Christmas.
   A good New Year to you and all the PSN=20 group.

          &nbs= p;            = ;      =20 J. Lehman.
Subject: Italian tsunami From: "Mauro Mariotti" mariotti@......... Date: Mon, 30 Dec 2002 20:04:08 +0100 Hi All, Today the stromboli volcano erupted and caused a tsunami wave of 20meters on coast when a side of the island collapsed in the sea. IESN provide a special page (in italian, sorry) at: http://www.iesn.org/eolie/main.htm Maybe further news will come. Regards Mauro http://www.infoeq.it http://mariottim.interfree.it/index.htm __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: echolink From: BOB BARNS royb1@........... Date: Mon, 30 Dec 2002 15:19:34 -0500 Hi gang, I know some of the members of this list are hams. Just last week, I became aware of a facility for hams to contact many others worldwide either direct or thru repeaters (AM and FM). Licensed hams can hold half duplex voice contacts via the internet (of course that's free). Dialup service works fine. The program, avail. at www.echolink.org, is free. It appears to be quite sophisticated and convenient. When connected, the prog. shows a complete list of all others who are connected. There is no hardware to buy if your computer has a sound card-NO RADIO EQUIP. NEED BE INVOLVED. To be called by someone (licensed hams only), your computer must be running the program either on top or in the background. I got this running with no problems. When the prog. is started, a list of all repeaters, links and people who are currently connected is shown. So far this has been about ~1,000 worldwide, I often start the prog. whenever I have the computer running and put it into the background (it's running while I type this). When someone calls me, a beep sounds and I can look to see who is calling and then start the QSO. One constraint is that your computer must be online. I have cable internet service so that is no problem. Bob Barns KB2IKC __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: Winsdr under Linux From: Karl Cunningham karlc@.......... Date: Mon, 30 Dec 2002 14:30:11 -0800 Larry and others -- More news about Winsdr, Winquake, and Wine. Some of Winquake seems to run under wine, but it crashes when I click on "event report" from the replay window. Haven't really worked on that one yet. Also, wine doesn't seem to yet support a Windows function called findfirstchangenotificationa, which Winsdr apparently uses to detect if a replay request file is present. The result is that Winsdr ignores replay requests from Winquake. Too bad. There is someone supposedly working on the findfirstchangenotification set of functions for wine, and I'm going to check the status of that. At this point it seems that Winsdr & Winquake are marginally useful under wine. But wine is being worked on and is bound to get better as time goes on. I'll post reports of any successes here. Karl --On Friday, December 27, 2002 4:43 PM -0800 Larry Cochrane wrote: > Karl, > > Thanks for the report. Have you tried WinQuake under Wine? > > Regards, > Larry Cochrane > Redwood City, PSN > > ----- Original Message ----- > From: "Karl Cunningham" > To: > Sent: Friday, December 27, 2002 10:32 AM > Subject: Winsdr under Linux > > >> Hi -- >> >> This may be old hat to some, but it's new to me and something I've wanted >> to try for a while now. The last few days I have been running Larry >> Cochrane's Winsdr under Linux using Wine (http://www.winehq.com), a >> system that allows Windows-based programs to be run under Linux. >> >> To move Winsdr to the Linux box, the entire winsdr directory and > everything >> under it on the Windows machine were copied (including the daily record >> files) to a subdirectory created for the purpose on the Linux box. After > a >> bit of editing of the Wine configuration file, it worked. This machine >> is a Celeron 466 with 256MB of ram. Wine and Winsdr are only using about > 1.2% >> of the CPU cycles and 3% of the RAM, so I'm sure it would work fine on a >> much less capable computer. Screen redraw speed is comparable to the >> Pentium II 350MHz Windows NT machine it was running on before. The >> operating system is Mandrake 9.0 Linux, and I imagine it would work under >> Redhat linux as well. >> >> Wine is seeing a lot of development these days, with new versions coming >> out on a daily basis. I downloaded and installed one as of 12/23/02 for >> this test. >> >> If anyone is interested, I'd be happy to supply more details. And for >> anyone who want to try, my wine configuration file is at >> http://www.keckec.com/wine_config . There are probably more >> optimizations that can be made, but a least it works. >> >> The next challenge is to replace the serial connection between the A/D >> and Winsdr with a TCP/IP connection. This should remove the limitation >> of serial line length and reduce ground noise since ethernet cards are >> transformer isolated whereas the serial connections are not. >> >> Regards, and happy new year to all. >> >> Karl Cunningham > > > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: Re: echolink From: David A Nelson davenn@............... Date: Tue, 31 Dec 2002 13:11:20 +1100 hi Bob and all, further to that system is another one for amatuers... called IRLP Internet Radio Linking Project http://www.irlp.net/ this is a great one i have been making regular contacts with amateurs in the USA and Canada over the last 5-8 weeks. amateur 2 metre (146.xxx MHZ) and 70cm (438.xxx MHz) repeaters are connected to the internet via the appropriate modems and using a well known voice chat program called Speak Freely. each repeater (Node) connected to the system has a 4 digi number assigned to it that # is dialld up using a DTMF keypad on the radio's microphone or by another DTMF source held up to the microphone. the # 73 is used to close the link after u have finished ur conversation. maybe some of u amateur operaters out there can find a link close to ur home and we can try to contact. the node # for my repeater is 6010 (for greater Sydney, OZ, region) there is a complete list of active nodes and their status at http://status.irlp.net/statuspage.html last sunday nite had a great chat to an amateur in Tacoma, WA who also has as i discovered a keen interest in earthquakes. happy new year all Dave Nelson VK2TDN / ZL4TBN At 03:19 PM 30-12-02 -0500, you wrote: >Hi gang, > I know some of the members of this list are hams. Just last week, >I became aware of a facility for hams to contact many others worldwide >either direct or thru repeaters (AM and FM). > Licensed hams can hold half duplex voice contacts via the internet (of >course that's free). Dialup service works fine. > The program, avail. at www.echolink.org, is free. It appears to be >quite sophisticated and convenient. When connected, the prog. shows a >complete list of all others who are connected. > There is no hardware to buy if your computer has a sound >card-NO RADIO EQUIP. NEED BE INVOLVED. > To be called by someone (licensed hams only), your computer must be >running the program either on top or in the background. > I got this running with no problems. When the prog. is started, a list >of all repeaters, links and people who are currently connected is shown. >So far this has been about ~1,000 worldwide, > I often start the prog. whenever I have the computer running and put >it >into the background (it's running while I type this). When someone >calls me, a beep sounds and I can look to see who is calling and then >start the QSO. > One constraint is that your computer must be online. I have cable >internet service so that is no problem. > >Bob Barns >KB2IKC >__________________________________________________________ > >Public Seismic Network Mailing List (PSN-L) > >To leave this list email PSN-L-REQUEST@.............. with >the body of the message (first line only): unsubscribe >See http://www.seismicnet.com/maillist.html for more information. > __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: re: echolink From: allan egleston allane@......... Date: Mon, 30 Dec 2002 18:55:51 -0800 Hi, Echolink runs on wintel platforms and irlp is for linux/unix boxes. 73's Allan Egleston kf6uxj __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: re: echolink From: David A Nelson davenn@............... Date: Tue, 31 Dec 2002 17:56:27 +1100 fortunately thats not an important factor as the amateur radio operator doesnt use his computer jst his VHF or UHF tranceiver in the normal way to access the local repeater that has IRLP capabilities :) cheers Dave At 06:55 PM 30-12-02 -0800, you wrote: >Hi, Echolink runs on wintel platforms and irlp is for linux/unix boxes. >73's Allan Egleston kf6uxj __________________________________________________________ Public Seismic Network Mailing List (PSN-L) Subject: irlp From: allan egleston allane@......... Date: Tue, 31 Dec 2002 07:25:25 -0800 To Mr. David A. Nelson Hi. I have just started seriously getting into seismology. Am rather new to the list, but have been "into" quakes since i was little. I started with a pendulum Seismomoter and an currently with the help of some "handy"friends building a lehman. Have scrapped sevral designs before settling on the current design that I like. We have eight 2 m and 1 70 cm repeaters in the area, no the machines are not irlp/echolink equipped at this time. Our Ham club has been talking about taking the step. Im in a little town in the sierra nevada mountain foothills, (california Gold Rush Country)(roughly 3 hours from Mammoth Mountain volcano, California) 3 Hours From Sanfransico California, 8 hours from Los Angles California and 8 hours from the Oregon border. Hope this helps. 73's de Allan Egleston kf6uxj __________________________________________________________ Public Seismic Network Mailing List (PSN-L)