This telegraphy circuit generates an audio tone from a pure RF carrier. We found it in a publication by Gernsback from 1960.
Using a piezoelectric sensor of the time, this circuit was found in the February 1994 issue of...
I found this circuit in an old English magazine from 1981, but it can still be assembled with some...
Only signals about 1 kHz can pass through this tuned circuit. The main component is a operational...