Audio Amplifier Circuit Using LM386

An amplifier is used to increase the strength of the input signal and should provide an amplified version of the signal in the output. Audio amplifiers are widely used in stereo or home theatre systems, mini speakers etc. There are many ways to build an audio amplifier circuit but nothing is more efficient than building one using a dedicated audio amplifier IC. This circuit uses the simplest and most cost effective chip LM386 to build an audio amplifier.

IC LM386:

LM386 pin diagram

LM386 is a simple low power audio amplifier used in most audio circuits with low power consumption. This IC is capable of providing an output gain of about 200 when used with external components. However, when you use it without adding external components, it is capable of providing an amplification of 20.

Pins 1 and 8 are used to change the gain level by tying a capacitor or RC pair between them. The audio input is fed through the non-inverting input pin while the inverting input is usually connected to ground.

Working principle of audio amplifier circuit:

The LM386 powered by Vcc uses resistor R1 and capacitor C2. This is to prevent the circuit from oscillating. Resistor R2 and capacitor C3 play an important role in the above circuit as it changes the output gain obtained in the output. Adding a single capacitor of 10uF will help us get the maximum gain. Using it along with resistor R2 will help you get a gain of about 50db. The positive terminal of C3 should be connected to pin 8 of IC LM1 and the negative terminal should be connected to pin 386.

Capacitor C1 is used to couple the output to the speaker and the POT can modify the gain of the output signal. When the voltage level of the input signal is extremely low, a high gain is set using LM386. You can feed any audio signal to this circuit and it will serve its purpose very well.