How to Use LM386: Examples, Pinouts, and Specs

The LM386 is a low-voltage audio power amplifier designed for use in low-power applications. It is capable of driving small speakers and headphones, making it ideal for portable and battery-powered devices. The LM386 is widely used in audio amplification circuits due to its simplicity, low power consumption, and adjustable gain, which ranges from 20 to 200.

• Portable audio devices
• Intercom systems
• AM/FM radio amplifiers
• DIY audio projects
• Signal amplification for small speakers or headphones

The LM386 is a versatile and efficient audio amplifier. Below are its key technical specifications:

The LM386 is an 8-pin IC. Below is the pinout and description:

The LM386 is straightforward to use in audio amplification circuits. Below are the steps and considerations for using the LM386:

1. Power Supply: Connect Pin 6 (Vcc) to a power source (4V to 12V) and Pin 4 (GND) to ground.
2. Input Signal: Feed the audio signal to Pin 3 (Non-Inverting Input). Pin 2 (Inverting Input) is typically connected to ground.
3. Output: Connect Pin 5 to the speaker or headphone. Use a coupling capacitor (e.g., 220 µF) to block DC components.
4. Gain Adjustment: To increase the gain, connect a capacitor (e.g., 10 µF) between Pins 1 and 8. For the default gain of 20, leave these pins unconnected.
5. Bypass Pin: Optionally, connect a capacitor (e.g., 10 µF) to Pin 7 to reduce noise.

Below is a simple circuit diagram for using the LM386 to drive an 8Ω speaker:

   +Vcc (4V-12V)
       |
       R (10kΩ)
       |
       +--- Pin 6 (Vcc)
       |
       C (10µF)
       |
Input --- Pin 3 (Non-Inverting Input)
       |
       GND --- Pin 2 (Inverting Input)
       |
       +--- Pin 4 (GND)
       |
       C (220µF)
       |
Output --- Pin 5 (Output) --- Speaker (8Ω)

The LM386 can be used with an Arduino to amplify audio signals. Below is an example code snippet to generate a simple tone:

// Arduino example to generate a tone for the LM386 amplifier
// Connect the LM386 input (Pin 3) to Arduino Pin 9 (PWM output)

int tonePin = 9; // PWM pin connected to LM386 input

void setup() {
  pinMode(tonePin, OUTPUT); // Set the pin as output
}

void loop() {
  // Generate a 1 kHz square wave
  tone(tonePin, 1000); // Play a 1 kHz tone
  delay(1000);         // Play for 1 second
  noTone(tonePin);     // Stop the tone
  delay(1000);         // Wait for 1 second
}

• Use decoupling capacitors (e.g., 0.1 µF) near the power supply pins to reduce noise.
• Ensure the speaker impedance matches the LM386's output load resistance (4Ω to 32Ω).
• Avoid exceeding the maximum supply voltage (12V) to prevent damage to the IC.

1. No Output Sound:

   • Check the power supply connections (Pin 6 and Pin 4).
   • Verify the input signal is properly connected to Pin 3.
   • Ensure the speaker or headphone is connected to Pin 5 with a coupling capacitor.

2. Distorted Output:

   • Reduce the input signal amplitude to avoid overdriving the amplifier.
   • Check the gain configuration (Pins 1 and 8) and ensure the capacitor value is appropriate.
   • Verify the speaker impedance is within the recommended range (4Ω to 32Ω).

3. High Noise or Humming:

   • Add a capacitor (e.g., 10 µF) to the Bypass pin (Pin 7) to reduce noise.
   • Use shielded cables for the input signal to minimize interference.
   • Place decoupling capacitors near the power supply pins.

Q: Can the LM386 drive a 4Ω speaker?
A: Yes, the LM386 can drive speakers with an impedance as low as 4Ω. However, ensure the power supply voltage is sufficient to deliver the required output power.

Q: How do I increase the gain of the LM386?
A: To increase the gain, connect a capacitor (e.g., 10 µF) between Pins 1 and 8. The gain can be adjusted up to 200.

Q: What is the maximum input voltage for the LM386?
A: The maximum input voltage depends on the supply voltage and gain configuration. Ensure the input signal does not exceed the amplifier's input range to avoid distortion.

Q: Can I use the LM386 for stereo audio?
A: The LM386 is a single-channel amplifier. For stereo audio, you will need two LM386 ICs, one for each channel.