2x6W audio amplifier
A long time ago I disassembled the stereo power amplifier BA5406 from a old radio. With the datasheet from the internet I built a small amplifier out of it.
Schematic and pinout from the datasheet:
Unfortunately after some time one channel got distorted, which I might have shorted by mistake. Therefore the TDA2030 is recommended for new designs, because it has appropriate protection circuits.