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.

Here is the 22 watt stereo audio power amplifier circuit diagram based on TDA1554 and integrated circuit from NXP semiconductors (formerly PHILIPS semiconductors). It is very simple and useful circuit ...