Thursday, December 2, 2010

325mW Mini Amplifier Circuit based LM386

The following schematic diagram is a mini amplifier circuit based on LM386 with a voltage gain of 200 and power output of 325mW that can be used as a bench amplifier, signal tracer or used to amplify the output from personal computers, MP3 players, MP4 Players, iPods, personal radios or others electronic device with audio support.

325mW Mini Amplifier Circuit based LM386

The IC operates from 4 to 12 V DC, 12 V being the recommended maximum. The internal input impedance of the amplifier is about 50K. This is deflected by a regular 22k potentiometer, input impedance, so this circuit will be less than 15k. The input is DC coupled so be careful not to extend the DC circuit precedent. Otherwise, the speaker may be damaged. A coupling capacitor may included in series with the 22k control to prevent this from happening.

About Audio Amplifier
An audio amplifier is an electronic amplifier that amplifies low-power audio signals (signals composed primarily of frequencies between 20 - 20 000 Hz, the human range of hearing) to a level suitable for driving loudspeakers and is the final stage in a typical audio playback chain.

The preceding stages in such a chain are low power audio amplifiers which perform tasks like pre-amplification, equalization, tone control, mixing/effects, or audio sources like record players, CD players, and cassette players. Most audio amplifiers require these low-level inputs to adhere to line levels.

While the input signal to an audio amplifier may measure only a few hundred microwatts, its output may be tens, hundreds, or thousands of watts. More explanation about power audio amplifier can be found at

This is a video tutorial about how to a very simple audio amplifier based on the LM386 amplifier chip. It can be built for less than $20 (or might be less than $8 in some countries) and used to amplify any low level audio signal including a guitar, bass or mp3 player.

Watch the video:

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