We found this circuit in a 90s Popular Electronics. The circuit can be implemented with modern components. The power MOSFET is according to the controlled load.
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...