This 20W amplifier was found in 283 circuits from the 90s. The MOSFET admits equivalents. The power supply must be dual, and the transistors must be mounted on good heat sinks.
For those who like experimental circuits, here is a sequential flasher system with LEDs, which can be...
This circuit was found in an ancient American documentation. The integrated circuit is of the time...
This circuit was found in a 1977 Radio Shack documentation. The circuit is tuned to 1.4 kHz, but...