This circuit is from a July 1970 Radio Electronics magazine. The sensors are metal probes. The 18 V power source must be isolated from the mains.
We found this junction tester circuit in an old English documentation. The circuit serves to check...
This circuit can generate signals up to 100 kHz. Found in documentation from the 1980s, it makes...
Found in American documentation from the 70s, this circuit uses components of the time, uncommon...