This circuit interrupts the power supply when grounding is missing. The circuit is from an old documentation (from the 80's) using current transformers and other components of the time.
This is actually an automatic dimmer we find in an American 1980s documentation. The triac must be...
With the presented circuit it is possible to detect signals from transmitters in a frequency range...
This tester for common unijunction transistors is nothing more than a low frequency oscillator...