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.
With frequency control and active cycle, this circuit was found in General Electric documentation from the...
This circuit includes a battery charging system and an inverter for operating a fluorescent lamp....
This circuit is from an American documentation from the 90's. The SCR can be of any type and the...