Found in an Electronic Design from the 90s, this circuit measures the phase difference between two signals using an electronic multimeter. The circuit makes use of components of the time.
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...