Simple FM Transmitter Circuit Diagram and Connection

Hey, in this article we are going to see the Circuit Diagram of FM Transmitter. The FM transmitter is an electronic circuit that generally converts the electronic signal such as an audio signal into a radio wave so we can transmit the signal wirelessly. Here, the FM transmitter circuit we have shown is applicable for a very short range. So it can be suitable for wireless portable MP3 players. Its input can be connected through an aux or headphone jack. The signal can be picked up by nearby FM radios up to a 30-100 meter range. It is a very compact and low-power-consuming circuit built with very few electronic components. It can be operated with 3.3V to 6V DC power supplies. So you just need a small battery. The frequency band for the transmission varies between 87.5 MHz to 108.0 MHz.

**Here we have used a microphone as the input device, but you can connect an audio player using an aux or headphone jack**

Components Required

• Transistor BC547 - 2 PCs
• Trimmer Capacitor 60pF - 1 PCs
• Inductor 0.1uH - 1 PCs
• Resistor 22K - 1 PCs, 10K - 1 PCs, 43K - 1 PCs, 1 Mega ohm - 1 PCs, 330 ohm - 1 PCs
• Ceramic Capacitor 1uF - 1 PCs, 27pF - 1 PCs, 1nF - 1 PCs, 100nF - 1 PCs, 22nF - 2 PCs
• Condensor microphone or other audio sources (aux or headphone jack)
• 3.3V to 6V DC power supply

Circuit Diagram

Here, you can see a Simple FM Transmitter Circuit Diagram and the Connection between each component.

Connection Procedure

1. Connect the Condensor microphone across the positive and negative terminal of the power supply in series with a 22 Kilo Ohm resistor.
2. Connect the Emitter terminal of the first BC547 Transistor to the negative terminal of the power source.
3. Connect the collector terminal of the first BC547 Transistor to the positive terminal of the power source in series with a 10 10 Kilo Ohm resistor.
4. Connect a 1 Mega Ohm resistor between the Collector and Base terminals of the first BC547 Transistor.
5. Connect the Base terminal of the first BC547 Transistor to the positive terminal of the microphone in series with a 22nF ceramic capacitor.
6. Connect the Base terminal of the second BC547 Transistor to the collector terminal of the first BC547 Transistor in series with a 100nF ceramic capacitor.
7. Connect a 43 Kilo Ohm resistor between the positive terminal of the power source and the Base terminals of the second BC547 Transistor.
8. Connect a 1nF Ceramic Capacitor between the negative terminal of the power source and the Base terminals of the second BC547 Transistor.
9. Connect the Emitter terminal of the second BC547 Transistor to the negative terminal of the power source in series with a 330-ohm resistor.
10. Connect the collector terminal of the second BC547 Transistor to the positive terminal of the power source in series with a 60pF Trimer Capacitor.
11. Connect a 0.1uH inductor in parallel with the Trimmer Capacitor.
12. Connect a 1uF ceramic capacitor between the emitter and collector of the second BC547 Transistor.
13. Connect the antenna with the collector terminal of the second BC547 Transistor in series with a 27pF ceramic capacitor.
14. Connect a 22nF Ceramic Capacitor between the positive and negative terminals of the power supply terminal.

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