This power supply protection circuit was found in the December 1978 Radio Electronics magazine. The SCR is triggered by shortening the power supply and quickly blowing the protection fuse.
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...