Infrared inductive light switch using triac trigger-control and early-charging-peak current limiter with adjustable power consumption

Abstract

An electronic switch can replace a standard mechanical light switch for 110-240 volt alternating-current (A.C.) devices. A triac switches the A.C. current to an A.C. device such as a light. A rectifier bridge generates a direct-current (D.C.) voltage that is applied to a special current limiter. The special current limiter generates a large current peak at low voltages, but limits current at high voltages. The large current peak from the special current limiter charges a capacitor when voltage is low at the beginning of each A.C. half-cycle, before the triac turns on. The capacitor has enough charge to supply D.C. current to an Infrared detector and trigger control logic for the rest of the A.C. half-cycle. When the detector detects a person nearby, it signals the trigger control logic. The D.C. voltage from the rectifier bridge is filtered to generate a sync pulse to the trigger control logic when adds a phase delay to the sync pulse which triggers the triac.