FM Transmitter Circuit

FM Transmitter Circuit


FM Transmitter Circuit


Here is the circuit diagram of the simple FM transmitter using a transistor. Great performance or range is not guaranteed here, because this is an elementary design. General purpose radio frequency transistor BF 494 (Q1) is used here for obtaining FM modulation. A condenser mic is used here to pickup the sound.The condenser mic converts the sound to electrical variations and this variations are fed to the base of Q1 , which performs the amplification as well as modulation.The capacitor C2 and L1 determines the frequency of transmission.The circuit can be powered from a 9V transistor radio battery.


The coil L1 can be made by winding 8 turns of 1mm thick enamel coated copper wire on a ball pen refill. The coil should be tapped at the center for connecting the antenna.

A 30 cm wire can be used as an antenna.

Remember! This circuit is an elementary circuit.No good performance or range is not guaranteed.Ideal for demo applications only.I got only 8 meter range with some decent sound quality.

Battery is strictly recommended because mains powered supply may induce additional noise.

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