Simple Audio Power Amplifier Circuit

The circuit illustrated here is probably the simplest form of an audio power amplifier. Though the circuit is very crude by its specs yetis able to amplify an audio input up to a powerful 4 watts in a 8 Ohm speaker.The transistor is a 2N3055 is used as a switch for inducing voltages in response to the input signals into one half winding of the transformer. The back emf generated across the winding of the transformer is effectively dumped over the speaker generating the required amplifications. The transistor needs to be mounted on a suitable heat sink.

Circuit Diagram :