This circuit was found in a publication in the 1980s. Modern equivalent components can be used. The source must be isolated. The circuit includes an oscillator.
This circuit is from a July 1970 Radio Electronics magazine. The sensors are metal probes. The 18 V...
This commercial medium and short-wave radio was manufactured in Japan in the 60s. The circuit has...
General Electric suggests this circuit in an 80's documentation. The circuit makes use of PUTs...