PSN-L Email List Message

Subject: Re: Homade Geophone
From: "Geoff" gmvoeth@...........
Date: Fri, 5 Aug 2005 20:25:22 -0700

1. It seems to me that a cylindrical magnet inserted into the center a coil
   dangling freely might be the best way to go 
   but it needs to be a very powerful magnet and have no more
   then 1mm of slop in any direction. The question is what dampening device to use is best
   I have found silicon oil of about 50WT should do nicely
   but trying to get your hands on silicon oil is like impossible
   in small quantities.

2. I have found most noise sources do not look anything like a seismic signal
   if the noise is infrequent you can filter out such things
   with your own human judgment.
   This is saying though that people are not out there
   intentionally trying to induce an EQ signal using noise
   into your particular system.

3.  I am interested in knowing the cheapest way possible to
    build your own Geophone that consistently receives
    teleseismic signals over a long period of time
    The Geophone companies want like $3000 for a single
    vertical 1Hz Geophone...surely us amateurs can build a simple one
    for a Lab setting < opposed to a field setting > for
    much less like $20.



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