We found this circuit that triggers an SCR in the Encyclopedia of Electronic Circuits volume 5 of 1995. The circuit is powered by voltage according to the warning load.
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...