We found this circuit in documentation from the 1980s. The transformer is of the low voltage type with a 1: 3 turn ratio and the transistors can be of general-purpose types.
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...