Found in a 1969 documentation, this circuit for the 20 MHz band does not use a transformer. The circuit is a phase detector that makes use of the transistor of the time.
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...