Found in an American publication from the 1980s, this circuit can be found in commercial sound equipment of the time. The list with the component values is given next to the diagram.
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...