This power stage with two transistors was found in Radio Electronics magazine from October 1963. The transistors must be equipped with heatsinks and the supply voltage is 12 V.
The circuit shown is from an old European publication. In it we have the way to activate a relay...
We found this circuit in a European publication from the 1990s. Transistors are still common types...
This circuit was found in an American documentation and can be added to common amplifiers of any...