is one of the few simple FM transmitter circuits you can find on the
internet that transmits in the 88 to 108 MHz fm band. It uses a single
transistor and few passive components and this fm transmitter circuit can deliver
signals up to 50 meters. Transistor Q1 serves as the modulator as well
as oscillator. Capacitor C2 and inductor L1 forms the necessary tank
circuit for oscillation.
The voice transmitted is coupled to the base of Q1 using an electret microphone. The FM signal available at the collector of Q1 is radiated using the antenna. Use a 3V battery for powering the circuit. Coil L1 is 5 turns of 24 AWG wire on a 1cm plastic former or by air winding the coil on a drill bit a notch above 1/4 inch. Adjustments in the transmission frequency can be made by compressing or relaxing the coil. Antenna can be a 25cm long or around 11 inches of 18AWG wire. A small diameter flex wire can be used. Credit for this circuit gos to: Circuitstoday.Com. I just did the Layouts for you. John