Hello,

I got this circuit set up only to alarm
when a signal comes in and not to record
anything and it works quite well.

If you just want to know if the earth is really moving
and it is not just your imagination then this circuit
might be for you.

I used OP177G op amps from the Philippines all through
but most probably you can use other types capable of
driving the loads.

Post: [IMG]http://files.photojerk.com/gmvoeth/seisdet1.jpg[/IMG]

The caps were measured using a DMM before designing the circuits.

regards
gmvoeth
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