This circuit is from an American documentation from 1975. The circuit uses components of the time which can be replaced by modern equivalents. The coupler is homemade with a lamp and a photocell.
June 2017 - New Honeywell MT MICROSWITCH Series can be ordered from Mouser Electronics for...
This two-transistor circuit was found in the January 1994 issue of Electronics Now. The circuit can...
This circuit is from American documentation from the 70s. Transistors are not common today, but...