From: Larry Cochrane Subject: Amateur Seismologist needs comradeship Date: Sun, 31 Dec 1995 19:51:40 Hi All, I thought I would send out the first official psn-l mailing list message with a e-mail I got from Allan Coleman. I sent him a message back letting him know that he's not alone. I also added him to our list. That's it for now. Regards, Larry >>From acolem@............ Thu, 14 Sep 1995 14:04:12 >Date: Thu, 14 Sep 1995 13:34:31 -0700 >From: Allan Coleman >To: System Root >Subject: Amateur Seismologist needs comradeship > > > >Larry, >I got your name via an E-mail from Ken Navarre today. I am a amateur >seismologist operating home built equipment at my house just north of >Seattle. With help from a friend who used to work for the University of >Washington I am able to receive signals from 20 different seismometers >(1Hz verticals) in weatern Washington that are a part of their radio >telemetry network. A radio scanner, a home built discriminator circuit and >a simple recorder I can easily monitor seismic activitives from the tip of >the Olympic pennisular to the NE flank of Mt Rainier. I used to receive >more signals but the UW have changed some of their networks over to >microwave. I used to to operate a horizontal long period seismometer that >was built after the design of Dr Lehmans and that was OK for 6 years. >Starting last year I got the bug to develop a 10 second plus vertical long >period and I am starting to have some limited success using electronic >feed-back. I made two verticals with acceleration feed-back, one has >about a 10 sec period and the second instrument has what appears to >be greater than 20 seconds. The last 6 months I have been working on a >simple horizontal displacement force-balance seismo that if it works out >OK I will utilize in a vertical, but it needs more work. Please note that >none of the instruments I have described are of professional quality and >could make good amateur type projects. For the last couple of months a >retired engineer from Kinemetrics is acting as my mentor, we >communicate by letter as he llives in California, east of San Francisco. He >has given me some good tips but has taken upon himself to do the >number crunching to help analize the designs. I think I am keeping him >amused with my contraptions. That is basically where I am at for now >and I would be most interested in contacting other instrument builders. >Are there some clubs in your state that I could contact? If you or any one >else would care to contact me please do so. > >Allan Coleman >7111-165th Place SW >Edmonds Wa 98026 >(206) 742-2951 > > > From: Larry Cochrane Subject: LVDT FOR A DISPLACEMENT TRANSDUCER Date: Sun, 31 Dec 1995 19:58:54 In reply to Jim Hannon's proposal to utilizing an LVDT as a displacement transducer on a seismometer: Some months ago I made a simple shake table to do some experimental work with. As it turned out this project needs more time to develop and hopefully will provide some satisfactory results. It is a crude, light duty, kind of thing driven by a 3" speaker. An adjustable sine wave of .10 to 5 Hz powered the speaker. Designing and building a shaker table is as much fun as designing and building a seismometer. To compare the motion of the seismometer (output signal) as shaken on the table with the actual motion of the table itself I made a LVDT and coupled it to the table surface. The LVDT's output signal was displayed on a scope. On one channel of the scope was the seismometer's signal and on the second, lower trace was the LVDT's signal, and surprise surprise, there was a difference in motion, the seismometer did not follow the same path as the table. The LVDT showed that the table was not driven with a pure sine wave and that the seismometer needed more work! At the time of using the table (that is now in moth balls) it was obvious that using an LVDT on a seismometer was worth considering. I observed some signal drift with time but that may have been due to coil heating effects etc. I have not gone back to establish as to where the problem occurs. I machined a piece of nylon for the bobbins, a piece of 1/4" dia x 1" long mild steel for the plunger, an excitation frequency of 1000 Hz to the center coil and the outer coils signals rectified with diodes. It was easy to build and I would recommend that someone should put an LVDT on a seismometer. If any one would like further details please contact me. All the best, Allan From cochrane@.............. Sun, 31 Dec 1995 20:09:25 To: psnarchive From: Larry Cochrane Subject: LVDT Chip Date: Sun, 31 Dec 1995 20:09:25 -- [ From: Jim Hannon * EMC.Ver #2.5.02 ] -- I finally remembered to bring home the info on the Analog Devices LVDT chip. The chip most suited to my application is the AD698. It has an oscillator for the primary drive and the sync detectors to convert the output into a dc voltage. It costs around $14. Jim Hannon From: Larry Cochrane Subject: New Sensor Date: Sun, 31 Dec 1995 20:24:11 Hi Everyone, After talking to Burl Updyke a few weeks ago I made a new seismometer based on the Sept. 1975 Scientific American article. This new sensor will produce *.lc3 files and is currently using the channel normally used by my short period sensor located at my house (*.lc2 files). I'll get my vertical sensor going again as soon as I run another wire from my data logging system to my sensor room. The new sensor is a short period vertical pendulum made to look like a long period sensor with electronics. The sensor is sensitive to horizontal movement and I currently have it oriented N-S like my Lehman so I can compare the two. So far I've received one teleseismic (distant quake) with the sensor. I was able to get the 6.3 in central Chile on 11/1/95 (I've attached the file 951101a.lc3 with this email). My Lehman did not pick up anything from this event. The event was 9100km from me and it normally takes a 7+ to get anything that far away on my Lehman. So it looks like the new sensor is about 10 times more sensitive to the low frequences of teleseismic events. I think this is because the sensor measures displacement rather then velocity like the coil/magnet method. On the other hand there was a ~3.0 near Gilroy (about 87 km from me) and my Lehman was able to show a good P and S wave but the new sensor was unable to pick up the higher frequencies. The new sensor is less sensitive to the local ground noise but has some very low waves showing up a lot of the time. I'm not sure what is causing this problem. Rather then trying to describe the sensor I would like to know if anyone has original copy of the Scientific American article I could barrow. I would like to scan in the article and make it available on the PSN Web page. I used some poor quality copes from the article to build my sensor and it wouldn't scan in very well. That's it for now. Regards, Larry From: Allan Coleman (by way of Larry Cochrane ) Subject: Long Period Seismograph Date: Sun, 31 Dec 1995 20:33:12 Message-Id: <19951231203312.04dc0683.in@.............> Hello Larry, This weekend I finished documenting how my 10 second period, horizontal, velocity seismometer had its period extended out to 35 seconds using electronic feedback. I will mail you a copy of the article, and if it looks OK it may be worthwhile to put it up on the network for others in the group to access. At the weekend I stopped at a library and got a photocopy of the Sept 1975 Scientific American article that described the design of a displacement seismometer, which this group is discussing at the moment. This is a good design, I think I will need to make one too. The photocopy was taken off micro-film and the image was not real clear, but the copy was readable. I hope you can find a magazine to copy directly from. I have been developing a long period displacement seismometer over the last few months using simple low tech components, and so far the results are encouraging. It will be a couple of months before I get around to documenting it, as I would like be sure that everything is working fine before I publish it. Best regards to you and the group, Allan. From: Ken Navarre (by way of Larry Cochrane ) Subject: Re: A-D boards Date: Sun, 31 Dec 1995 20:42:15 On Wed, 6 Dec 1995, Peter Styles asked: > Can anyone help me to find a supplier for the PC-LABS PC-112 A-D > board which is required for SDR/EMON. I believe that Halted Specialties in Sunnyvale, Ca. carries them. I'll check tomorrow and will advise the listmembers. If they do still carry them I'll get and address and phone number and pass it along. Just in time for the Xmas stocking... :) Wonder if my girlfriend has thought about including *another* one in MY stocking ??? Larry, wanna offer her a hint for me??? :) > Is this better than other > boards from MICROSTAR, METRABYTE et al or is it just because the > software is written specifically for it?. I'll defer to Larry for this one. Ken From: Larry Cochrane (by way of Larry Cochrane ) Subject: Re: A-D boards Date: Sun, 31 Dec 1995 20:43:15 At 01:58 PM 12/6/95 GMT, you wrote: > >Dear PSN-readers > >Can anyone help me to find a supplier for the PC-LABS PC-112 A-D >board which is required for SDR/EMON.>Is this better than other >boards from MICROSTAR, METRABYTE et al or is it just because the >software is written specifically for it?. SDR is designed to work with a PC-Labs 711s, not sure if the PC-112 will work. If you can wait until January or February I will have a 12 or 16 bit AtoD card designed for SDR and EMON. I hope to sell the 12 bit version for about 1/2 the cost of a PC-711s. This board, when used with SDR, will have several options like time correction to WWV using a shortwave receiver, and a temperature stabilize crystal oven for keeping the time correct between WWV locks. If you can't receive WWV in the UK, SDR can use a serial port connected to some type of time server to keep the time correct. > >We already have a station recording in N.Wales and telemetring to >Liverpool to a Helicorder but Id like to put it online in the very near >future. > >Peter Styles >Department of Earth Sciences >University of Liverpool >Liverpool >UK Regards, Larry From: Larry Cochrane Subject: New WinQuake Date: Sun, 31 Dec 1995 00:34:59 Hi, I have just finished the next release of both 16 and 32 bit versions of WinQuake. You can download them using your Web browser at http://psn.quake.net/software or using ftp to psn.quake.net in directory /software. The 16 bit version, for Window 3.1, is in file winqk191.zip and the 32 bit version, for Windows 95 or NT, is in file wq32v21.zip. This version allows you to save your P and S wave picks so when you re-open the event file the P and S markers will be set to that location on the seismogram. This version also works better with the Windows File Manager (Explorer on Win95) or a Web browser when using WinQuake as a Helper Application. For 16 bit WinQuake a new program call WqStart is now included in the ZIP file. This is from the WqStart doc file: > WqStart is a program used to interface between the Windows File Manager, >or a Web browser, and the 16 bit version of WinQuake. This program is not >needed if you are using the 32 bit WinQuake (version 2.1 and higher) that runs >under Windows 95 or NT. >This program was written because only one copy of the 16 bit version of >WinQuake can run at a time. If you set up your Web browser to run WinQuake >as a Helper App it was necessary to close WinQuake every time you wanted to >view another event file. If you did not close WinQuake first, the Netscape Web >browser would hang. If WinQuake was used through the File Manager, and you >tried to open another event file with WinQuake already running, you would get >an error message. If you set up your Web browser or the File Manager to run >wqstart.exe this problem is fixed. >Here's how it works: When wqstart.exe is started it checks to see if WinQuake >is already running, if it isn't, it will start up WinQuake with the event file >name to open. If WinQuake is already running, it sends a message (using DDE) >with a open file command. After starting WinQuake, or sending the DDE message, >WqStart exits. WqStart is a Windows program but has no windows or dialog >boxes of it's own. For 32 bit users (Windows 95 or NT) you do not need to use WqStart. When the 32 bit version of WinQuake is started by the File Manager or a Web browser it checks to see if there is another copy of WinQuake running. If there is, it sends an open message with the file to open and exits. I also found a major bug when running under Windows 95 with the 32 bit beta version of WinQuake. The Directory button in the File Open dialog box would not open an another dialog box to change the path to your event files. That's it for now, happy new years to all... Larry