I have the circuit below on a tiny SMT factory built wireless Mic PCB, and I would like to replace the mic with a tiny SMC audio oscillator that produces a constant tone.
Note I have used the transistor symbol as shown, but I can not confirm which pin is which or NPN/PNP of the transistor on the board.
Ideally I would like to modify the existing circuit board, using the existing mic amp SMC transistor as a single transistor oscillator, but I don't know how I would go about that circuit wise - any suggestions?
Failing I could add another small pcb with a tone generator circuit on, outputting at mic levels into the existing mic connections (and removing the bias resistor). any ideas smaller / simpler than an SMC 555?
The oscillator amplitude is effectively stabilized at the amplifier's clipping level. It's not easy to set a lower level. The most simple way to attenuate the output level is to use a two resistor voltage divider in place of R1.