This shield circuit is from an American documentation from 1969. The components can be modified according to the relay and power, and the coupler can be of a modern type.
This detector uses an unusual sensor today. The circuit is from an 80s documentation. Its...
This circuit was found in the December 1976 issue of Radio Electronics magazine. The circuit...
For inductive loads we have the configuration shown in the figure. Note that the opto-coupler...