CIRCUIT AND METHOD FOR DETECTING LOCALIZED NOISE LEVEL CHANGES AND ESPECIALLY ELECTROMAGNETIC NOISE

摘要

A detection circuit responsive to a localized increase in magnetic noise level such as would be produced by an automobile ignition system. Sensing coils are positioned to detect the presence of such noise and provide an electrical output. The electrical output of the sensing coils is amplified and passed to networks having differing time constants. Both networks feed into a comparator which, in turn, actuates an alarm. The comparator actuates the alarm only when it receives signals of different intensities. Thus the two networks function to provide a threshold for the signaling device which is automatically reset as required.