Saturday, May 21, 2011

Audio Booster Circuit

The following circuit has a maximum gain of around 22 dB (voltage gain). The frequency response of the amplifier is determined mostly by the value of just a couple of components, primarily C1 and R1. The values of the circuit diagram present a response of ±3.0 dB from about 120 Hz to higher than 20,000 Hz.In fact, the frequency response is ruler flat starting from about 170 Hz to more than 20,000 Hz; it's the low end that deviates from a flat frequency response.

Audio Booster Circuit diagram

The low end's roll-off is primarily a function of capacitor C1(since RI's resistive value is fixed). If C1's value is replaced to 0.1 pF, the low end's comer frequency-the frequency at which the low-end roll-off starts-is reduced to about 70 Hz. In the event you want an even deeper low-end roll-off, change C1 to a 1.0 pF capacitor; if it is an electrolytic type, make particular that it is installed into the circuit with the proper polarity, using the positive terminal connected to Q1's base terminal.

Sample circuit design with component value:
Simple Audio Booster

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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