This circuit was suggested by Texas Instruments in a 1968 publication. The transistors are of the time, and modern equivalents can be used.
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...