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.
This amplifier was found in a Japanese publication in 1972. Transistors are uncommon today, and...
The current of this source is 200 mA at the most, and the output depends on the zener that may...
Found in Mallory documentation from 1968 this circuit uses an integrated circuit from that time. The...