PSN-L Email List Message

Subject: Re: TELEDYNE GEOTECH HELICORDERS
From: "James Allen" jcallen1@...........
Date: Wed, 22 Apr 2009 19:54:20 -0700


There is a large lot of Teledyne Geotech Helicorders just listed on Ebay =
today.  Problem is, it is a very large "lot auction"  that would entail =
shipping cost for hundreds of pounds of equipment.
James Allen
  ----- Original Message -----=20
  From: ChrisAtUpw@..........
  To: psn-l@.................
  Sent: Thursday, October 02, 2008 4:33 PM
  Subject: Re: Torsion Seismometer


  In a message dated 2008/10/02, tchannel1@............ writes:


    I have seen something similar somewhere on the web, but I can't find =
it.   This is all I could find.   If someone has tried this please email =
me.   Thanks, Ted
    Torsion Seismometer Wood Anderson
    http://www.data.scec.org/Module/s3inset3.html


  Hi Ted,

         The Wood-Anderson was a horizontal system with a torsion =
suspension, magnetic damping, optical + photographic recording and a =
period of about a second. There is no reason why you could not fit a =
dual Si photocell readout system.=20

         To increase the period you can reduce the wire diameter / =
increase the wire length / mount the mass on an extended side boom to =
increase the inertia.

         Check out
         http://doga.ogs.trieste.it/doga/risk/woodanderson/index.html
         http://www.eas.slu.edu/Earthquake_Center/Instruments/

         Randall Peters has a vertical torsion device on this website.
         http://physics.mercer.edu/hpage/peters.html

         Regards,








There is a large lot of Teledyne = Geotech=20 Helicorders just listed on Ebay today.  Problem is, it is a very = large "lot=20 auction"  that would entail shipping cost for hundreds of pounds of = equipment.
James Allen
----- Original Message -----
From:=20 ChrisAtUpw@.......
To: psn-l@..............
Sent: Thursday, October 02, = 2008 4:33=20 PM
Subject: Re: Torsion = Seismometer

In a=20 message dated 2008/10/02, tchannel1@............=20 writes:

I have seen something similar somewhere on the web, but = I can't=20 find it.   This is all I could find.   If = someone has=20 tried this please email me.   Thanks, Ted

Torsion = Seismometer Wood=20 Anderson
http://www.data.sc= ec.org/Module/s3inset3.html

Hi=20 Ted,

       The Wood-Anderson was = a=20 horizontal system with a torsion suspension, magnetic damping, optical = +=20 photographic recording and a period of about a second. There is no = reason why=20 you could not fit a dual Si photocell readout system.=20

       To increase the period = you can=20 reduce the wire diameter / increase the wire length / mount the mass = on an=20 extended side boom to increase the=20 inertia.

       Check=20 out
      =20 = http://doga.ogs.trieste.it/doga/risk/woodanderson/index.html
 &nb= sp;    =20 = http://www.eas.slu.edu/Earthquake_Center/Instruments/

  =     =20 Randall Peters has a vertical torsion device on this=20 website.
      =20 = http://physics.mercer.edu/hpage/peters.html

   &nbs= p;  =20 Regards,

       Chris = Chapman=20

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