Medium power FM transmitter circuit

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This is the circuit diagram of a moderate power FM transmitter circuit employing two transistors.The voice signals picked by the microphone will be amplified by the transistor Q1.The second transistor is wired as an oscillator operating in the FM band.The output of T1 is given to the base of T2.T2 performs the modulation also.The tank circuit comprising of components L1 and C6 determines the frequency of the signal, and can be varied by adjusting C6.The capacitor C7 couples the FM signal to the antenna.

Circuit diagram with Parts list.



  • You can assemble the circuit on a general purpose PCB.
  • The circuit can be powered from a9V PP3 battery.
  • The Antenna A1 can be a 1M long wire.
  • The inductor L1 can be made by making 6 turns of 0.8mm enameled copper wire on a 5.5mm diameter/4.5mm length plastic former.
  • With a matching antenna and proper tuning this transmitter can have range upto 100meters.