True carbon type elements are just nothing but carbon granules in a
chamber attached to a diaphragm(sp?). Sound waves vibrate the granules and
create a variable "resistance" representing the wave form hitting it. A
bias such as what you have in a conventional electret microphone will
provide sufficient "audio" to drive your application. A 1k bias "pullup"
resistor will work. (1k mic impedance)

Rick


Chris Eddy wrote:

> 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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