Friday, February 11, 2011

Low Cost Mixer Circuit

The following circuit is an easy, simple and cheap mixer circuit.
Low Cost Mixer Circuit diagram

A simple mixer circuit suitable for mixing microphones or effects outputs. The overall gain from input to output is one if the pot related towards the input is full up. You'll be able to generate this a net gain of ten (or any other reasonable gain) by lowering the input resistor towards the second op amp. 10K in this position provides a gain of 10db, or 20db. If you are mixing effects outputs which have an output level control built into them, it is possible to dispense using the input level controls, or make some have level controls, some not. Audio taper pots are most likely better, but linear will be work.

For the op amps, pick a JFET input dual or singles, such as from the National Semi LF3xx series, or something such as the TL072 or TL082.

Download this Low Cost Mixer Circuit in PDF file:
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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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