If it is really a carbon mic, you need to provide a voltage. It is just
a "sound-dependent resistor" so to speak. So try putting a voltage and a
resistor in series with it and measure the drop across the mic.

Al Williams
AWC
* Easy RS-232 Prototyping
http://www.al-williams.com/awce/rs1.htm



> -----Original Message-----
> From: pic microcontroller discussion list
> [mailto:PICLIST@MITVMA.MIT.EDU] On Behalf Of Chris Eddy
> Sent: Wednesday, February 20, 2002 3:50 PM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: [EE]: question about carbon microphones..
>
>
> I have a handset, identical to a regular telephone handset.
> It has one of those carbon electret microphones in it. I
> cannot get any sort of signal on my scope when I holler in
> the mic. I am used to the active mics, like the two pin
> device that takes a 1K pullup to power it. Does anyone know
> what sort of amplifier is necessary? Impedance of the mic
> element? Gain that is necessary?
>
> Thanks all
> Chris~
>
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