This receiver, whose tuning range depends on L1 and L2, was found in the 1992 special edition of Radio Electronics Experimenter. The circuit is relatively simple and has good sensitivity.
This control circuit or reversible contactor was found in a 1967 General Electric manual. The...
We found this circuit in a 1987 publication. Through a relay, it controls water valve solenoids at several...
The figure shows how to use a varicap in a conventional tuning circuit. The circuit may be an...