This grounding test circuit was found in an American 80's documentation. The circuit is for the 110 V power grid but can be changed to the 220 V power grid.
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...