Resistor-1M-1, 470Ω-1, 47kΩ-2, 10kΩ-1
Capacitor-1nf-1, 0.1uf-3, 10pf-2, 33pf-2
Inductor- 4-5 Turn of 4 mm dia air core coil of copper wire
This simple and easy FM transmitter circuit can transmits the input signal get from the microphone upto 500 meter range area. Two npn transistor and some discrete components are used in the circuit.
You can use 3v to 12v DC power supply for this circuit. At low voltage , range of this transmitter will shorter. At high voltage range will also increased.
In this FM transmitter there is no any variable capacitor are used for tunning by the change of capacitance, So the frequency will remain constant, if input power supply is no fluctuate. This is simple circuit and can easily construct at any general purpose vero board or pcb board. For more stability of frequency dont use ac adaptor, use only battery and all connection should insulated from external touch.