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Phase controlled dimming system with active filter for preventing flickering and undesired intensity changes

  • US 6,091,205 A
  • Filed: 10/02/1997
  • Issued: 07/18/2000
  • Est. Priority Date: 10/02/1997
  • Status: Expired due to Term
First Claim
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1. A load control system for controlling power delivered from an AC line to a load, wherein the AC line has a fundamental component with a fundamental frequency, comprising:

  • a) a first circuit comprising a filter that attenuates frequency components of the AC line that are substantially equal to third order harmonics and greater of the fundamental frequency, and that provides a filtered signal substantially free of noise and distortion present on the AC line;

    b) a second circuit receiving the filtered signal and providing an indication of zero crossings thereof;

    c) a third circuit that provides control signals in response to the zero crossing indications; and

    ,d) a controllably conductive device for controllably applying the AC line to the load in response to the control signals.

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