Dynamic Microphone Preamp - These are often found inside old 2way radio microphones. HOME

Notice how the transistor bias current flows through the microphone. A similar circuit can be used with an 8 ohm speaker but in that case you would put it in place of the emitter resistor. This circuit works as a carbon microphone replacement.
Circuit Diagram aka Schematic reverse engineered from circuit board

I do not gaurantee the accuracy or safety of any information herein.
This is only a graphic due to spam      HOME     Valid HTML 3.2!
Do not experiment with or build any of the above circuits.