FM transmitter microphone

An op-amp IC (741) amplifies the audio signal from MIC1, and R12 controls its gain. Audio is fed to the oscillator circuit Q1 and related components. D2 is a varactor diode. Audio fed to D2 causes FM of the oscillator signal.
FM transmitter microphone - schematic

L1 is 3 turns of #18 wire. The antenna is a 12` whip.