This control circuit or reversible contactor was found in a 1967 General Electric manual. The triacs must be in accordance with the power of the controlled load.
The circuit shown is a documentation on 80's tunnel diodes. The frequency depends on the delay line...
This circuit generates excellent sinusoidal signals and has the frequency adjusted by VR1 which is...
This circuit was adapted from an Italian publication that no longer exists. This is “Onda Quadra”...