easy fm bug transmitter circuit

500m FM transmitter circuit

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Easy, Simple and best FM transmitter circuit for homemade mini radio station


 Homemade FM Transmitter circuit diagram

easy fm bug transmitter circuit


Transistor- 2N3904-2

Resistor-1M-1, 470Ω-1, 22k to 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

Condenser mic-1

This simple and easy FM transmitter circuit can transmit the input signal gets from the microphone up to the 500-meter range area. Two NPN transistors and some discrete components are used in the circuit.

You can use 3v to 12v DC power supply for this circuit. At low voltage, the range of this transmitter will be shorter. At high voltage range will also be increased. 

In this FM transmitter, there is no variable capacitor are used for tunning by the change of capacitance, So the frequency will remain constant if the input power supply does not fluctuate. This is a simple circuit and can easily construct at any general-purpose Vero board or PCB board. For more stability of frequency don’t use ac adaptor, use the only battery and all connections should be insulated from external touch. Use only the Battery to give the power supply to stable operation of the circuit. Condenser mic hs polarity so check the polarity before connection.

Also read

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4 thoughts on “500m FM transmitter circuit”

  1. Hello,
    I was looking for a simple and easy to build FM transmitter which uses accessible parts and came across your design which seems very great! But I have one Question. What kind of values should the two Capacitors C5 and C6 have, in order for the transmitter to transmit at a frequency of 87.5mhz? As this is the only legal FM frequency to use in the country I live in.
    Thank you.

  2. Hello,
    If I may ask another Question, what is the current draw of this Fm Transmitter under normal use
    Thank you.

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