I found this circuit in a documentation for radio amateurs from 1975. The FET could be the BF245. The circuit works in the range of 40, 80 and 160 meters of radio amateurs.
This simple circuit was found in an English magazine that no longer exists, January 1970 issue. It is...
This circuit, suggested by a 1975 documentation, detects an electrical discharge in a storm by...
This circuit for timing small loads was found in a 1964 General Electric documentation....