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.
An oscillator that can be frequency controlled by a resistive sensor is shown in the figure. The...
The idea of this circuit from a 1960 publication is simple: we can switch the transistor being...
This circuit was found in a Radio Electronics from February 1966. With it it is possible to trace...