[Boatanchors] Motorola carbon-mike-replacement schematic

[Dave Maples]

All: Here is a link to a Motorola mike that "looks" like an old carbon mike.
I can't say that it's an equivalent, for example, to a T-17; however, it's a
starting point.

This particular mike uses an electret element rather than a dynamic element.
For a dynamic element there would have to be some isolating capacitor
between the mike element and the rest of the circuit.

Does anyone have the normal operating points (i.e. bias voltage and load
resistance) for a typical WWII carbon mike?  Having that info should allow
someone to design a transistor circuit to replace the carbon mike with an
equivalent.

Here's the link:

http://www.repeater-builder.com/motorola/pix/hmn1052a.jpg

Thanks,
Dave WB4FUR