This circuit uses common components at the time of its publication in the 1980s. The circuit can be made with modern equivalent transistors. The input signal is sinusoidal.
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...