FM Transmitter Bug: 4 Turns, 1.5 Turns – Build Your Circuit

Circuit diagram

Notes:

This modest radio transmitter employs a Hartley oscillator design. Typically, the capacitor within the resonant circuit would be connected to the base of the transistor, however, at VHF frequencies, the base-emitter capacitance of the transistor functions as a short circuit, thereby maintaining its intended role. The coil is constructed from four turns of 18swg wire wound around a quarter inch former. The aerial tap is positioned approximately one and a half turns from the power supply end. Audio sensitivity is exceptionally high when coupled with an ECM type microphone insert.