We found this circuit in the September 1971 Radio Electronics magazine. The SCR can be any of the 106 series and the buzzer can be replaced by a relay according to the supply voltage.
This circuit is from an 80's documentation. The transistor can be any general purpose PNP and the...
This powerful pushbutton uses a power MOSFET. We found it in a Popular Electronics magazine from...
This shield circuit for lamps and other charges was found in a Popular Electronics from the 90's....