This circuit uses a General Electric coupler from the time of the publication in the 1980s. Equivalent SCR can be used.
This circuit was found in a 2006 publication. It uses discrete components and CMOS that are still...
We found this circuit in the November 1992 issue of Radio Electronics magazine. The circuit has...
This simple circuit, from a 2006 documentation, activates a 12 V lamp in the event of a power...