The circuit shown, with the printed circuit board, was found in an article in the June 1990 issue of Radio Electronics magazine. Integrated circuits must be equipped with heat sinks.
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...