Found in a 90’s Popular Electronics, this circuit uses a component that can be difficult to obtain today. It achieves a 10 dB noise reduction with the indicated components.
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...