instructions for making contact mics

[anechoic <kim@xxxxxxxxxxxxxxxxx>]

with a little research online you might find some schematics but it is very
simple to make as contact mic but it does require a deft hand at soldering:

- buy a piezo element (typically used in those little black plastic encased
buzzer/speakers found at Radio Shack)
- remove the plastic case *very* carefully (so as to not crack or bend the
piezo element)
- take a thin coaxial cable (much thinner than a guitar cable), strip,
twist and tin the center stranded cable with a little solder
- separate the ground shield cable and poke the center lead thru the side
of it...sorta complicated to explain without a diagram but in essence make
it neat so you can solder both leads to the piezo without there being any
strain on the element
- solder the center lead to the inner part of the piezo element...do NOT
apply too much heat to the piezo element or else you will crack it...this
is where soldering experince comes in handy...
- tin the ground shield and solder it to the outer gold part of the element
- make sure you don't have cold solder joints on either the element or the
ground
- put a plug of your liking on the other end (1/4", RCA, mini, etc)
- be sure to solder both the center lead and ground shield at the plugs end
- plug into an amp and test by tapping the underside of the piezo element
with a small screwdriver or something hard...if the amp has enough gain you
will hear loud precussive tapping
- I would then often use epoxy glue to cover the soldered parts on the
piezo element so as to make them more durable...I'd pour a bubble of the
epoxy when it was just starting to harden and carefully let it dry...when I
was working as a electronic technician in the audio industry I would take
epoxy used for creating potted modules and use that...this made for some
really professional looking shiny black mics...
- in the mid 80's I was selling these for $20 a piece and was making a
couple of hundred bucks a month for while as most of the industrial and
noise musicians wanted them very badly...

another suggestion is to find an electronic supply mail order house that
sells the piezo in bulk...this way if you break one during soldering you'll
have another handy...
good luck!
KIM