This 600-ohm output impedance circuit was found in a Radio Electronics from October 1963. The circuit uses PNP transistors of the time and is powered with a voltage of 12 V.
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...