RST Engineering wrote:

snip
As an extra bonus question, my sensor is going to be an old phonograph
cartridge. Should I use the lightest weight "needle" that I can find?
How
about a tiny little ball of lead at the tip of that needle? Would that
help
the sensor? Or hinder it?

A lot depends on the range of frequencies, any sensor will have its own
fundamental frequency- multiple sensors may be a good idea. Geophones seem
to be good up to a few hundred Hz, cheap but difficult to get qty one. For
the application a speaker may be the clue (as a second sensor).
--

regards

jc

LEGAL - I don't believe what I wrote and neither should you. Sobriety and/or
sanity of the author is not guaranteed

EMAIL - and are not valid email
addresses. news2x at perentie is valid for a while.