Here is the schematic for an 8 watt audio power amplifier. This amp can be used as a simple booster, the heart of a more complicated amplifier or used as a guitar amp. It is very small and portable ...
TDA2003 is a cheap amplifier that is designed to run on single rail power supplies (unipolar). It provides a high output current capability (up to 3.5A), very low harmonic and cross-over distortion.