Friday, March 27, 2015

Mini Audio Amplifier with LM380

This is the very simple circuit of mini audio amplifier single channel / mono using low cost IC LM380. For stereo application, just build the identical circuit.

The circuit shown in Figure 1 is a very simple audio power amplifier. The main component of this circuit is the LM380 audio amplifier. The simplicity of this circuit is made possible by the LM380's minimal requirements for external components, since it is already internally equipped with the necessary biasing, compensation, and gain circuits for audio amplification.

The circuit in Figure 1 uses the LM380 in non-inverting mode, with the inverting input left open (the inverting input may also be tied to ground, either directly or through a resistor or capacitor). C2 is used to decouple Vcc from ground. The optional RC circuit at the output (pin 8) is used for added stability, i.e., to eliminate oscillations in an RF-sensitive application.

Figure 2 shows how the circuit in Figure 1 can have a variable gain simply by connecting a potentiometer across the inputs of the LM380. Rv is varied to adjust the gain of the amplifier.

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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