This circuit is from a Radio Electronics from February 1966. The circuit is of a type that was found in many applications at the time as output from radios, televisions and other equipment.
This circuit was published in a January 1971 issue of Radio Electronics to check television...
Found in Popular Electronics from the 90's, this tuned to infrared modulated receiver uses a PLL....
This 1967 General Electric circuit makes use of an array of 3 (integrated) transistors for an...