Additional Description: Theory of operation the FM Mic Kit consists of two stages. The first stage uses a 3.3kohm resistor to bias the microphone. A 0.1 microfarad capacitor isolates the microphone from the base voltage of the transistor allowing only AC signals to pass. The second stage consists of a BC547 transistor a coil a variable capacitor and a 470ohm resistor which form an oscillator circuit. The oscillated frequency can be adjusted by the variable cap from 88 to 108MHz