Mark,
I think that what you are seeing is about the noise level of Larry,s  16 
bit A/D card. You can check this by operating the A/D card with it's input 
shorted. Check the noise level and see how it compares to the noise when 
your amplifier is connected.

At 08:53 PM 12/22/00 -0600, you wrote:


>Hello Everyone,
>
>
>Recently I finished construction on my first seismometer.  I used
>schematics off of Larry Cochrane's web site to wire wrap the amplifier:
>http://psn.quake.net/sgsumamp.gif and http://psn.quake.net/sgproc.gif
>
>I housed the amplifier in a steel box, grounded to analog ground on the
>amplifier board.
>
>I have the output of the amplifier connected to Larry's 16 bit A to D board
>with about 16 feet of shielded wire.  The shield, around the wire, is
>grounded to the case of my computer.  When viewing the output with SDR I am
>getting about 80 to 100 counts of continuous noise.  I don't know what the
>frequency of the noise is but the period is too short to see on SDR.
>
>Is this noise level abnormally high and does anyone have any suggestions on
>how to reduce the noise.
>
>Thanks for your time!
>
>Mark
>
>

Jim Hannon
http://soli.inav.net/~jmhannon/
42,11.90N,91,39.26W
WB0TXL

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