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This audio filter was found in the August 1993 issue of Radio Electronics magazine. It cuts low and high frequencies corresponding to rumble and scratch noises that occur on turntables.
Found in the May 1988 issue of Radio Electronics magazine, this circuit is sensitive to small...
Using a 4046 PLL this circuit recognizes a 1.6 to 1.8 kHz tone by driving an output LED. The...
The circuit is from an 80's publication, but the components are current, only special type diodes...