Method and apparatus for controlling a load
Abstract:
A method and apparatus for switching AC power to a lamp (or other load) via a two terminal switch device. The switch device comprises a first electrically controlled switch, such as a triac or relay, and a second electrically controlled resistance or switch connected in series to the first switch. A diode is connected in parallel to the second switch. When the first switch is open, only a leakage current is flowing through the switch device, supplied to an AC/DC converter for producing a low DC voltage to the switch device logic and other low-voltage circuits and for charging a capacitor. When the first switch is closed, the second switch is controlled to be conductive for allowing powering the lamp from the AC power. During part of a positive half-cycle of the AC voltage, a closed loop regulates a DC voltage over the second switch terminals for providing a low DC voltage for charging a capacitor. At least during a negative half-cycle of the AC voltage, the low DC voltage is provided from the capacitor.
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