This circuit with three transistors was suggested in a Radio Electronics magazine from February 1963. The transistors are types of the time. Power comes from a 12 V battery.
This circuit was found in volume 5 of the 1995 Encyclopedia of Electronic Circuits. The circuit is based...
This control circuit was found in a Radio Electronics from May 1965. The circuit switches a...
The TDA2040 is not a common IC these days, but if you find one you can build this high quality...