LM386 Low Voltage Audio Amplifier

This Audio Amplifier, or Op Amp (operational amplifier), gives you the ability to amplify an analog signal with ease. Great for beginners looking to build a simple audio amplifier to get started with electronics. As opposed to the TS-349 Op Amp, this is a single amplifier with the internal gain set to 20 by default to keep part count low. With 1 Amplifier inside you can amplify 1 signal with 1 chip. For 2 Amplifiers in a single chip check out the TS-349 Op Amp. This amplifier is most useful for audio applications where you simply want to amplify a single signal. Also used in robotics for amplifying analog sensor readings. Optionally, if you add an additional resistor and/or capacitor between pins 1 and 8, you can increase the gain to any value from 20 to 200.

A little background on Op Amps:

The circuit symbol for an op amp is:

The op amp obeys the input-output relationship:

where v_o is the output voltage, v⁺ and v^- are, respectively, the voltages at the non-inverting and inverting inputs, and A is the amplifier gain.

Quick Getting Started Pin Hookup Explained:

•   2 Input Pins:

• • Pin 3: Non-Inverting Input 1 (V+)
    • This is the pin you will send the signal you want to amplify into.
  • Pin 2: Inverting Input 1 (V-)
    • This is the pin for the signal you want subtracted from Pin 3's value before amplifying. Set this to GND to amplify the full signal on Pin 3.

• 2 Output Pins:

• • Pin 5: Output (Vo)
    • This pin is the amplified difference of Pin 3 and Pin 2. (This will simply be amplified Pin 3 if you've set Pin 2 to GND.)

• Power Pins:

  •  Pin 6: Power (VCC)
    • This pin provides power to the chip. Give it 4V - 12V
  • Pin 4: Ground (GND)
    • This pin is Ground for the chip. Give it 0V

• Other Pins:

• • Pins 1 & 8: Gain 
    • Placing a capacitor across these pins alows you to control the gain (amount of amplification) very easily. Varying the capacitor value will vary the gain.
  • Pin 7: Bypass
    • This pin allows you to access the unamplified input if you'd like to.

Specifications:

• Operating Voltage: 4V - 12V
• Default Gain set to 20 to save on external parts. (Can be varied via capacitor value across pins 1 and 8)
• Voltage Gain Range: 20 - 200
• Output Power:
  • With 8 Ohm Load (such as our 8 Ohm Speaker) @ Vcc = 6V: 325mW
  • With 8 Ohm Load (such as our 8 Ohm Speaker) @ Vcc = 9V: 700mW
• Bandwidth:
  • With Vcc = 6V and nothing attached to pins 1 and 8: 300kHz
• Total Harmonic Distortion: 0.2%
• Rejection Ratio: 50dB
• Input Resistance: 50kΩ
• Number of Pins: 8
• Operating Temperature Range: -20 to 85 C
• Manufacturer Part Number: LM386

Click here to download the Datasheet.