Hi Kareem
    This maybe a little to involved but I made a long period horizontal ( ~10" long ) from information read from Sean Thomas Morrissey's web site  http://www.eas.slu.edu/People/STMorrissey/index.html. I built the vertical he described first then tried a horizontal next. It looks like the W.F. Sprengnether figure at the "PSN info" location.It's natural period was about 5 sec without the feedback circuitry. I used his circuitry with his description of the speaker coil and the VRDT construction for the feedback. I think the period was increased to about 20-30 sec but I haven't been able to check the base frequency vs response yet. the construction was not expensive but it was time consuming. I chose the component values from his Mcad equations but I'm not sure they are optimum (part of the required input was the coil output G and the sensors natural frequency) . I'm still working on a few bugs in the external amplifier/filter  and balancing motor circuitry. It did record the recent
 Mozambique event but so did my simple Lehman ( pretty large event). 
         I have wanted to try a horizontal lehman type sensor but with two long springs (one on each side) meeting at a heavy weight and slightly apart at the base of the boom. For a vertical like John Lahr showed previously, if the spring angle is brought more horizontal (parallel with the boom ) my understanding is the period is increased. I thought the same might apply with the horizontal  and one would not have to worry as much about the drift the Lehman can produce as the boom assemble approaches the non returning position ( ie trying to increase the lehman period). 
   
  Sorry I got so wordy
   
  Regards
  Barry.

Kareem at HeyJooJoo  wrote:
  Hi Steve,

Are there any simple plans for building a horizontal, long period
seismograph? (I know that there are tons of places online but figured you or
the others may know of some real-time plans.)


Kareem 

-----Original Message-----
From: psn-l-request@.............. [mailto:psn-l-request@............... On
Behalf Of Steve Hammond
Sent: Wednesday, February 22, 2006 9:02 AM
To: psn-l@............... PSN-L@..............
Subject: RE: two home-made vertical seismometers

If you want to build a simple seismograph, here is a URL of a very simple
vertical seismograph that was designed by a fellow in Pasadena in the early
1990's.
http://pw2.netcom.com/~shammon1/compressed/VERTICAL.GIF
It uses a screen door spring and cost under $20. It is made from common
parts in a local hardware store and produces good results. It does lack the
electronics however, so if you check the same site,
http://pw2.netcom.com/~shammon1/equip.htm#Electronics
you will find a pre-amp using OP-07's that can be used with this. The coil
can be built from #44 wire on a plastic frame. You can get the frame from
Radio Shack if you just purchase a spool of their red/black/green #22
construction wire. Hand wind about 4,000 turns of the #44 wire onto a frame.
Warp the coil in black electrical tape to protect it. The magnet is a cow
magnet sold in an animal feed stores but other magnets will also work. I
used these plans to build a system for a 5th grade classroom and the
students were able to locate local events with it.

Regards, Steve Hammond PSN San Jose, Aptos California

-----Original Message-----
From: psn-l-request@..............
[mailto:psn-l-request@................. Behalf Of Gerencher, Joseph J
Sent: Tuesday, February 21, 2006 12:09 PM
To: PSN-L@..............
Subject: two home-made vertical seismometers



I have photographs of two vertical seismometers that were made by
Jim Lehman and given to me. Both have been in continuous operation for
several years and both have a natural period of about one second. The
smaller unit is in my classroom and the larger one is in the basement
beneath the classroom. I modified the damping of the smaller unit using
copper plumbing fittings, which makes it both easier to construct and easier
to operate than the larger one. The web address for going directly to the
photographs is too long to post on an e-mail, so if you want to see images
of both these seismometers go to my opening web page at 

http://home.moravian.edu/users/phys/mejjg01/

then click "homemade seismographs," click "Illustrated history of
the seismometer system, 1991 to 1998" and click the links on that page.
Additional detailed photographs of the construction design of the smaller
home-made seismometer can be found at the following web site:
http://www.netquake.org/seismometers/vertical.htm Unfortunately, I have not
yet gotten around to annotating these photographs, but intend to do so in
the next several days.



Joe Gerencher






__________________________________________________________

Public Seismic Network Mailing List (PSN-L)

  

Hi Kareem
  
  This maybe a little to involved but I made a long period horizontal ( ~10" long ) from information read from Sean Thomas Morrissey's web site  http://www.eas.slu.edu/People/STMorrissey/index.html. I built the vertical he described first then tried a horizontal next. It looks like the W.F. Sprengnether figure at the "PSN info" location.It's natural period was about 5 sec without the feedback circuitry. I used his circuitry with his description of the speaker coil and the VRDT construction for the feedback. I think the period was increased to about 20-30 sec but I haven't been able to check the base frequency vs response yet. the construction was not expensive but it was time consuming. I chose the component values from his Mcad equations but I'm not sure they are optimum (part of the required input was the coil output G and the sensors
 natural frequency) . I'm still working on a few bugs in the external amplifier/filter  and balancing motor circuitry. It did record the recent Mozambique event but so did my simple Lehman ( pretty large event). 
  
       I have wanted to try a horizontal lehman type sensor but with two long springs (one on each side) meeting at a heavy weight and slightly apart at the base of the boom. For a vertical like John Lahr showed previously, if the spring angle is brought more horizontal (parallel with the boom ) my understanding is the period is increased. I thought the same might apply with the horizontal  and one would not have to worry as much about the drift the Lehman can produce as the boom assemble approaches the non returning position ( ie trying to increase the lehman period). 
  
 
  
Sorry I got so wordy
  
 
  
Regards
 
 
Barry.

Kareem at HeyJooJoo <system98765@.............> wrote:
  
Hi Steve,

Are there any simple plans for building a horizontal, long period
seismograph? (I know that there are tons of places online but figured you or
the others may know of some real-time plans.)


Kareem 

-----Original Message-----
From: psn-l-request@.............. [mailto:psn-l-request@............... On
Behalf Of Steve Hammond
Sent: Wednesday, February 22, 2006 9:02 AM
To: psn-l@............... PSN-L@..............
Subject: RE: two home-made vertical seismometers

If you want to build a simple seismograph, here is a URL of a very simple
vertical seismograph that was designed by a fellow in Pasadena in the early
1990's.
http://pw2.netcom.com/~shammon1/compressed/VERTICAL.GIF
It uses a screen door spring and cost under
 $20. It is made from common
parts in a local hardware store and produces good results. It does lack the
electronics however, so if you check the same site,
http://pw2.netcom.com/~shammon1/equip.htm#Electronics
you will find a pre-amp using OP-07's that can be used with this. The coil
can be built from #44 wire on a plastic frame. You can get the frame from
Radio Shack if you just purchase a spool of their red/black/green #22
construction wire. Hand wind about 4,000 turns of the #44 wire onto a frame.
Warp the coil in black electrical tape to protect it. The magnet is a cow
magnet sold in an animal feed stores but other magnets will also work. I
used these plans to build a system for a 5th grade classroom and the
students were able to locate local events with it.

Regards, Steve Hammond PSN San Jose, Aptos California

-----Original Message-----
From: psn-l-request@..............
[mailto:psn-l-request@................. Behalf Of
 Gerencher, Joseph J
Sent: Tuesday, February 21, 2006 12:09 PM
To: PSN-L@..............
Subject: two home-made vertical seismometers



I have photographs of two vertical seismometers that were made by
Jim Lehman and given to me. Both have been in continuous operation for
several years and both have a natural period of about one second. The
smaller unit is in my classroom and the larger one is in the basement
beneath the classroom. I modified the damping of the smaller unit using
copper plumbing fittings, which makes it both easier to construct and easier
to operate than the larger one. The web address for going directly to the
photographs is too long to post on an e-mail, so if you want to see images
of both these seismometers go to my opening web page at 

http://home.moravian.edu/users/phys/mejjg01/

then click "homemade seismographs," click "Illustrated history of
the seismometer system, 1991 to 1998" and click the links