CA2226512A1 - Ballast circuit - Google Patents

Abstract

A lighting control circuit that controls the lighting of particular lamps in response to the toggling of the power switch. The circuit a) connects only with the high (output) side of a lighting system's ballast, b) is completely contained on the high side, and c) with regard to toggling, is dependent upon only a single time period. The circuit can be used with any ballast which makes use of an output tranformer and no change need be made to the original ballast circuitry. Users will find operation of the circuit to be straightforward. A
triac driven by a flip-flop via a driver transistor is used to control the high frequency AC power that is used to drive the lamps. A Schmitt trigger sharpens the signal generated by the ballast output transformer in response to the toggling of the light switch which is employed to change the output state of the flip-flop. Operationally, all the lamps driven by the ballast are lit when the power switch is initially turned on. Toggling the power switch once while all of the lamps are lit causes only a predetermined number of the lamps to remain lit.
Toggling the power switch while only a portion of the lamps are lit causes all of the lamps to light again. Leaving the power switch off causes all of the lamps to be turned off. The toggling may be performed quickly or leisurely, so long as the entire toggle cycle is completed within a predetermined amount of time.