This circuit was obtained in a 90s 73 magazine for radio amateurs. The power transistor must have a heat sink. The input voltage is 13.6 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...