- Here is the circuit diagram of the simplest FM transmitter using a transistor.
- Great performance or range is not guarenteed 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.
NOTES:
- 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.
