Found in an Electronics World of 1966, this circuit makes use of FETs of the time. Modern equivalents can be used. The high voltage supply suggests its use with tube amplifiers.
In the figure we have the way to make the three-phase control of a motor using opto-diacs. The circuit is...
This circuit for testing the voltage gain of a transistor was found in the March 1953 issue of...
This circuit was found in a PE Hobbyst Handbook from 1992. The second oscillator is a VFO. The...