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.
Details of the coil of this two-transistor generative receiver were not given. We found it in a...
This very high input impedance circuit is suggested by Texas Instruments. The circuit can be...
This circuit from an 80's publication also features low input capacitance. FET can be a modern...