Introduction

This tutorial will guide you through building a simple FM receiver circuit that utilizes the LM386 amplifier to amplify the audio output. This project is suitable for beginners and provides a foundation for understanding FM reception and audio amplification.

Materials Required

• LM386 Audio Amplifier IC
• FM Radio Receiver Module (e.g., TEA5767)
• Speaker or audio output device
• Resistors (R1, R2)
• Capacitors (C1, C2, C3)
• Potentiometer (10kΩ for volume control)
• Breadboard and jumper wires
• Power supply (5V to 12V)

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Circuit Diagram

The following circuit diagram illustrates how to connect the LM386 amplifier with an FM receiver module:

Pin Configuration of the LM386

• Pin 1: Gain (default is 20, connect a resistor to increase gain)
• Pin 2: Inverting input
• Pin 3: Non-inverting input
• Pin 4: Ground
• Pin 5: Output
• Pin 6: VCC (supply voltage)

Steps for the Experiment

1. Place the LM386 IC and FM radio receiver module on the breadboard.
2. Connect VCC (Pin 6) of the LM386 to the positive terminal of the power supply (5V to 12V) and GND (Pin 4) to ground.
3. Connect the output of the FM radio module to Pin 3 (IN+) of the LM386.
4. Connect Pin 2 (IN-) to ground through a resistor (R1).
5. Connect a capacitor (C1) between Pin 5 (OUT) and ground to stabilize the output.
6. Connect the speaker to Pin 5 (OUT) and ground to output the amplified audio signal.
7. Optionally, connect a potentiometer to adjust the volume between the FM module output and the LM386 input.

Explanation

In this setup, the FM receiver module receives FM signals, and the audio output is sent to the LM386 for amplification. The amplified audio is then delivered to the speaker, allowing you to hear the received FM signals clearly.

Results and Observations

Once the circuit is completed and powered, tune the FM receiver module to a station of your choice. You should observe:

• Clear audio output from the speaker.
• The volume can be adjusted using the potentiometer.

Applications of the LM386 in FM Receivers

The LM386 amplifier can be used in various FM receiver applications, including:

• Simple FM radios
• Wireless audio transmission systems
• DIY audio projects
• Educational projects demonstrating radio frequency concepts

Conclusion

In this experiment, we successfully built an FM receiver circuit using the LM386 operational amplifier. This circuit can effectively amplify audio signals received from FM stations, demonstrating the practical application of amplifiers in communication systems.