US 4,906,901 AGranted

Power supply for outdoor lighting systems using high frequency

AssigneeGardenAmerica Corporation

InventorDavid T. Carroll

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Abstract

A power supply for outdoor lighting systems accepts ordinary household alternating current of 120 volts at 60 hertz. The power supply uses a digital switching means to convert this current into a lower voltage at a higher frequency. Typically, these values are 28 volts at 20 kHz. This high frequency signal is then supplied to the lights through a transformer. The use of a higher voltage than that normally used for such systems improves the operating efficiency of the lighting system and allows lights to be placed at a greater distance from the power supply. The higher frequency signal reduces the bulk and cost of the transformer. The voltage and current supplied to the lights can be altered by changing the frequency of the signal entering the transformer. A feedback circuit monitors the signal supplied to the lights and automatically varies the frequency so as to keep the voltage and current within predetermined operating limits.

Claims27

Dependent claims

A power supply for supplying electric current to lighting system, said system having a plurality of lights, comprising:

connector means for accepting electrical power from an external source, said electrical power having a first frequency and a first voltage;
rectifier means coupled to said connector means for converting said electrical current into a DC signal;
switching means connected to said rectifier means for converting the DC signal into a further signal having pulses of alternating polarity;
oscillator means connected to said switching means for operating said switching means at a second frequency;
a first transformer having primary a secondary windings for supplying said further signal to said lights at a second voltage, said primary windings of said first transformer being connected to said switching means and said secondary windings of said first transformer being connected to said lights;
a low voltage power supply means for generating a fourth voltage, said low voltage power supply means being coupled to said rectifier means;
control means for changing said second frequency, said control means having an input and an output connected to said oscillator;
and
current detection means for sensing current drawn by said plurality of lights, said current detection means being coupled to said input of said control means such that when said current is outside of a predetermined range said second frequency is changed.

6 more elements

Dependencies are inferred from the claim text.