This circuit produces sounds of 6 different notes depending on the keys activated. The circuit is from a Radio Electronics from May 1965. The transistor must be equipped with a heat radiator.
The integrated circuit shown in the figure is nothing more than the LM386 sold by Radio Shack,...
Found in an English publication from the 1980s, this circuit can be built with equivalent...
The transistors of this old circuit from the 60s can be the BC548, in a current version. The...