Scratch is the scratching noise that occurs mainly with old records. This high frequency noise is eliminated by the filter found in the February 1990 issue of Radio Electronics magazine.
In the figure we have a typical detector stage for a radio receiver. The circuit is from 1963,...
Found in a 1968 Texas Instruments documentation this circuit uses an SCR from that time. Modern...
This circuit was obtained from an American publication of the 80's. The integrated circuit is of the...