Found in a 1980s amateur radio QST magazine, this is the conventional circuit of a medium-wave radio. Coils and transformers are commercial types.
This circuit of a voice-controlled switch, Vox or sonic switch was obtained in a Popular...
This circuit appeared in the July 1969 issue of Radio Electronics magazine. The sensor is an LDR....
This circuit of two transistors was found in a Japanese magazine in 1967. The transistors are made...