Scratch filter esp. for record player - has interference pulse detector which controls circuit which blanks out interferences by fading delayed signal in or out

摘要

The circuit suppresses impulsive interference in a signal, e.g. scratch noise originating from an audio disc. A delay circuit for the signal and an interference detector are provided. The detector controls a circuit which blanks out the delayed signal when a pulse-like interference is detected. The blanking circuit blanks the delayed signal by fading it out and/or in. The circuit contains a series and a parallel light dependent resistor in a frequency dependent filter configuration.