Apparatus for controlling power to a load such as a fluorescent light

Claim 1

Apparatus connected in series with a load for controlling the power supplied from an AC source to the load such as a fluorescent light, comprising (a) power supply means connected in series with the load for supplying a rectified AC power in a two-wire circuit when the neutral AC power line is not accessible; (b) a start pulse generator connected with said power supply means for producing a start pulse in response to the power output; (c) switching means with said power supply means and with said start pulse generator, said switching means being energized in response to said start pulse to supply power to the load; (d) phase detector means connected with said power supply means for generating a synchronized saw-tooth voltage waveform from said rectified power output, said saw-tooth voltage waveform creating a time delay; (e) power level control means connected with said power supply means for setting a voltage threshold level for controlling the power level supplied to said load; and (f) a run pulse generator connected with said phase detector means and with said level control means for comparing said saw-tooth voltage waveform with said voltage threshold level, said run pulse generator producing a run pulse for energizing said switching means when said saw-tooth voltage waveform exceeds said voltage threshold level, whereby upon operation of said level control means, the run pulses generated by said run pulse generator may be controlled to control the operation of said switching means and for supplying power to load.