How to Use LM386 audio amplifier module: Examples, Pinouts, and Specs

The LM386 is a popular low-voltage audio power amplifier integrated circuit (IC) designed for battery-powered devices. It is capable of delivering up to 325 mW of continuous average power to an 8-ohm load with a 5V power supply, making it an ideal choice for small audio amplification projects. Common applications include portable speakers, radio receivers, and as a driver for low-power headphones.

• Supply Voltage (Vcc): 4V to 12V
• Output Power: Up to 325 mW (when connected to an 8-ohm load and powered by a 5V supply)
• Load Impedance: 4Ω to 32Ω
• Quiescent Current: 4mA (typical)
• Total Harmonic Distortion (THD): 0.2% (typical at 1kHz)
• Gain: Adjustable from 20 to 200

1. Power Supply: Connect pin 3 (Vs) to your power supply (4V to 12V) and pin 1 (GND) to the ground.
2. Audio Input: Connect your audio source to pin 2 (IN+), with the source ground connected to the LM386 ground.
3. Audio Output: Connect pin 4 (OUT) to the speaker, and ensure the speaker's other terminal is connected to ground.
4. Gain Control: Pins 7 and 8 can be used to set the gain. For the default gain of 20, leave these pins open. To increase the gain, connect a capacitor between these pins.

• Use a decoupling capacitor (typically 0.1µF) between Vs and GND close to the IC to filter out noise.
• For higher gain settings, a capacitor and resistor in series between pins 1 and 8 can be used.
• Keep audio input lines as short as possible to minimize noise pickup.
• Use a heat sink if operating near the maximum power output to prevent overheating.

// Connect LM386 pin 2 to Arduino pin 9 (PWM output)
// Connect LM386 pin 3 to 5V and pin 1 to GND
// Connect a speaker between LM386 pin 4 and pin 5

int speakerPin = 9; // PWM output for audio signal

void setup() {
  pinMode(speakerPin, OUTPUT);
}

void loop() {
  // Generate a 1kHz tone for 1 second
  tone(speakerPin, 1000, 1000);
  delay(1500); // Wait for 1.5 seconds
}

• No Sound: Check power supply, ensure audio input is connected properly, and verify speaker connections.
• Low Volume: Increase the gain by adjusting the gain control pins or check if the input signal is too low.
• Distortion: Ensure the power supply is within the specified range and that the speaker impedance matches the IC's requirements.

• Power Supply Issues: Use a regulated power supply to prevent voltage fluctuations that can cause noise or distortion.
• Input Signal: Use a preamplifier if the input signal level is too low.
• Heat Dissipation: Attach a heat sink to the LM386 if it gets too hot during operation.

Q: Can I use a 16-ohm speaker with the LM386? A: Yes, the LM386 can drive speakers with impedances ranging from 4Ω to 32Ω.

Q: How can I increase the gain above the default value? A: Connect a 10µF capacitor between pins 1 and 8 for a gain of 200.

Q: What is the maximum supply voltage for the LM386? A: The maximum supply voltage is 12V. Exceeding this voltage can damage the IC.

Remember to always consult the LM386 datasheet for detailed specifications and application notes.