[Milsurplus] SIMPLE Carbon Microphone Substitute.

[AKLDGUY .]

> https://en.wikipedia.org/wiki/Electret_microphone#/media/File:Electret_conde
 nser_microphone_schematic.png
>
> It's a two terminal variable resistance.
> I hadn't realized this feature of the many electrets i've harvested.
> What will remain a puzzlement for me, is why, as Dave reported, his electret
> is entirely polarity dependent.
> The FET should be able to be polarity "rolled", and the electret element is
> permanently polarized, a DC nonconducting device.

It shouldn't be a puzzlement. FET's are polarity conscious, confirmed
by David's finding that the circuit worked with the polarity one way only.

His configuration of the FET as a source follower is actually rather good,
with the FET drain-source current turning on the transistor and the low
impedance output as a source follower driving the base. Probably explains
why the audio quality is good. I intend to use this circuit in my BC-AO-230.

73 de Neil ZL1ANM