This circuit was originally intended for reading movie soundtracks. The circuit is from 1967 and was found in an English publication. The sensor is semiconductor type.
This circuit is from Radio Electronics magazine from June 1958. The tuned range at the time was...
Found in Popular Electronics from the 90's, this tuned to infrared modulated receiver uses a PLL....
This circuit was found in the March 1979 issue of Radio Electronics magazine. Integrated circuits must...