Found in a Philips publication from the 1970s, this circuit uses a DO040, which is difficult to obtain today. The circuit is powered by 12 V on pins indicated in the diagram.
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...