Whats the ebay part number?

-----Original Message-----
From: psn-l-request@.............. [mailto:psn-l-request@............... On
Behalf Of James Allen
Sent: Wednesday, April 22, 2009 7:54 PM
To: psn-l@..............
Subject: Re: TELEDYNE GEOTECH HELICORDERS

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 ----- 
	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. 
	
	       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,
	
	       Chris Chapman 


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