> The AS1 works amazingly well for such a simple mechanical system with 
> moving magnet.
> I've posted information here on the system:  http://jclahr.com/science/psn/as1/


That actually looks like a very nice little
machine but they could improve the magnet
by having two opposing magnets facing
each other with alternate poles on each side of the coil
then the strength of the
magnetic field alone should be good enough
for the damping given a load resistor
of about 2.414 of the coil resistance.

If the filter were reduced to between 2Hz and 20 seconds
you would have an ideal standard system for any Amateur out there.
Such a filter would need to block all frequencies
over about 10 HZ to prevent problems using
slower sample rates like the tic rate of an
IBM style computer of 65536/3600 samples per hour.

It is a shame though that the pros do not make a
cheaper geophone for amateurs to use. They do not
need to be made to the same specs the pros use
only need to have a free period between 2 seconds and
one hertz. Amateurs do not need ruggedized equipment
like military or industry.

gmvoeth
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