IIRC a carbon mic can be simply thought of as a variable resister, so put a
low current through it and measure the voltage across it, it should
fluctuate with you voice. Try AC coupling to take out the DC bias that is
present, the variations may be very small. TTYL


> -----Original Message-----
> From: pic microcontroller discussion list
> [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Chris Eddy
> Sent: Wednesday, February 20, 2002 16:50
> 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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