Introduction: Simple 20W Audio Amplifier

About: I love science and electronics!

Basically an audio amplifier that works with a linear power supply...

Step 1: About the Circuit...

This simple audio amplifier is composed of two stages.

The first stage is low power voltaje amplifier with an adjustable gain that can be set between 0 and 20.

The second stage is a power current amplifier ( Voltaje gain = 1) that drives a low impedance speaker.

The potenciometer provides the negative feedback needed to remove the crossover distorsion of the output waveform.( When the frequency goes up, the crossover distorsion becomes more and more remarkable).

Ideally this amplifier would provide a peak power of VCC^2/R_speaker = 12^2/8=18W. However the output voltage can not reach 12V peak beacause the 741 is limited to 25mA.

For the linear symmetric voltage source, this circuits needs a 12V 1A transformer( with central tap).