This circuit is from 1973 documentation. The transformer has 500 mA of current and the transistor can be the TIP32 mounted on a heat radiator.
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...