I'm trying to figure out if a crystal microphone that was provided with a wire recorder is any good after some 60+ years, though I have yet to complete my restoration of the recorder itself, I have been trying to test the mic. At this point, I am thinking that it is dead based on simply plugging it into several tape players, computers, etc, I am not sure if crystal microphones take siginificantly more voltage to read properly, or if it actually is DOA. Anyone here have much experience with these old tin cans?

 

A crystal mic was a very high impedance, piezo type. It needs a preamp with a very high input impedance, maybe an electric guitar amp. Modern mics and preamps have a fairly low impedance.

 

I figured that much, though I didn't measure anything with my guitar amp. Have yet to put it on a scope though. I'm sure that will tell me for sure.

 

Hello,

You could try the following preamp:
http://fet-project.blogspot.com/2010/07/crystal-microphone-preamplifier.html

Bertus