FM Circuit to Transmit Audio signal

The FM transmitter uses FM waves to transmit sound and data; it is a low-power transmitter that employs frequency modulation to transport data by changing the frequency of carrier waves. This transmitter transmits audio signals through the carrier wave by changing the frequency. Using two NPN transistors and a few inexpensive components, we create a simple, versatile FM transmitter circuit. Here we design a simple FM circuit to transmit audio signals easily.

FM Circuit to Transmit Audio signal

FM-circuit-transmitter-using-transistor-50-300-meter range
FM transmitter Circuit

An important role in wireless communication is played by the FM circuit. This circuit employs a single transistor to send an FM signal without any noise from 50 to 300 meters away. A straightforward receiver circuit with FM capabilities can be used to receive the transmitter’s signal.


The above circuit is quite basic and only requires 9V and a microphone to supply audio input to the transmitter circuit. For ease of comprehension, the circuit can be broken down into three components: oscillator, modulator, and amplifier.

The Q1 boosts the audio signal coming from the microphone and serves as an amplifier. R2-R4 is used in the circuit to control the transistor’s operating point. Only the AC signal can pass through the blocking capacitors C1 and C2 in the circuit.

The Oscillator portion of the circuit is made up of the Tank circuit with the transistors Q2, C5, C6, and L1.

The resistors around Transistor Q2 establish Q2’s operating point and serve to prevent modulation in the FM band, which ranges from 80 to 130 MHz.

Efficient transmission and the ability for the receiver to receive a signal free of noise require a long antenna.


I hope all of you understand how to design an FM Circuit to Transmit Audio signals. We MATHA ELECTRONIC will be back soon with more informative blogs.

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