Found in old American documentation, this circuit is intended for the control of heating elements. The SCR must have current according to the controlled load. Transistors are from the time.
The integrated circuit used in this filter is not very common today, but the configuration can be implemented...
In fact, this is the circuit also known as “vox”, that is, a relay triggered by sound. This...
This circuit makes it possible to reverse the direction of a DC motor through a relay controlled by a...