Patent ID: 7518316

Claim:
An LED string circuit comprising: a plug that is adapted to fit in a standard household electrical socket; a half-wave rectification and low-pass filter circuit disposed in said plug comprising: a resistor having a resistance (R) that is connected to a first lead of an alternating current power source having a frequency (f o ); a diode connected in series with said resistor; a capacitor connected between an output node of said diode and a second lead of said alternating current power source; an LED string, having a resistance (R LED ) that is connected to said output node of said diode and said second lead of said alternating current power source, said LED string having an effective resistance (R LED ); said capacitor having a capacitance (C) selected in accordance with: C = R + R LED 2 ⁢ π ⁢ ⁢ RR LED ⁢ f c , and f c = 2 ⁢ η ⁢ ⁢ f o π , and where f c <<f o and η is the change in voltage that is applied to the LED string divided by the average voltage that is applied to the LED string.