[Milsurplus] SIMPLE Carbon Microphone Substitute.

[AKLDGUY .]

A couple of readers have said that a FET stage ought to be used
to drive the 2N3569 transistor in David's circuit, shown here:

https://goo.gl/photos/26HUmzVuqhZKWrNZ7

I strongly suspect that the mike he's using already has a built-in
FET stage that in this circuit is configured as a source follower
whose low impedance output drives the base-emitter junction of
the transistor.

73 de Neil ZL1ANM