Found in old American documentation, this circuit can use crystals between 27.5 and 33 MHz operating on the third harmonic. The transistor admits equivalent.
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...