This small regulated power supply was found in a 1963 General Electric documentation. The special zener diode transistor can be replaced with an equivalent discrete configuration.
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...