White LED Night Light Circuit

Published:2013/9/3 20:02:00 Author:lynne | Keyword: White LED Night Light Circuit | From:SeekIC

White Light Emitting Diodes recently available can be used as a powerful alternative to incandescent lamps in lighting applications. Today’s White LEDs are less expensive, draw much less current, and project a fairly well focused beam. Described here is a simple circuit of an efficient White LED Night Light which can be directly powered from AC230V supply. First of all, note that a “capacitive transformerless power supply” is used in this circuit. When a capacitor and resistor are connected in series to an AC source, as shown here, a constant current can be maintained through the resistor, so long as the reactance of the capacitors is much greater than the resistance. The current flow is dependent upon the value of the capacitor and assuming that V1 is much greater than V2, the value of the current can be assumed to be: IRMS = V1/XC where XC is the reactance of the capacitor. According to this, if we are using a 1uF capacitor , the current value is near 70mA at 230VAC/50Hz input. In order to get a DC voltage using this method, as usual, rectifiers and filter capacitors should be added.



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