Found in American documentation from the 90s, this circuit uses a high voltage relay and has no grid isolation. The high values of R1 and R2 prevent the shock when it touches the sensors.
The purpose of this 1985 circuit is to make the sound test of type 106 SCRs (MCR106, TIC106,...
Using the CMOS 4001 we found this circuit in the October 1974 Radio Electronics magazine. The...
We found this circuit in a 1957 Raytheon transistor publication. The circuit can be assembled with...