Power supply for low-voltage load
First Claim
1. A current-regulating power supply for energizing a load at a voltage magnitude less than the voltage magnitude provided by an A.C. source, comprising:
- an autotransformer having a tapped winding, said load being connected solely between a first end and the tap of said winding;
switching means connected to said autotransformer only at a remaining end of said winding for enabling a flow of current from said source through said winding during the duration of a control signal;
means for providing a sampling signal of magnitude responsive to the instantaneous current flowing through said switching means; and
control circuit means for providing said control signal at an operating frequency at least an order of magnitude greater than the frequency of said A.C. source and for adjusting, responsive to said sampling signal magnitude, the proportion of time during each of a successive plurality of operating frequency cycles during which said switching means conducts current, to mainain the current through said load at a substantially constant value.
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Accused Products
Abstract
A power supply operating at high frequencies for energizing a low-voltage lamp and the like loads, utilizes an autotransformer in series with a switching device. The series combination receives a voltage, greater than the voltage required for load operation, from commercial power mains. The load is tapped down upon the autotransformer, with the load current magnitude being controlled by variation of the percentage of time during which the switching device is in the conductive condition, during a power supply cycle interval; the conductive time is adjusted responsive to the current sensed to be flowing through the transformer and hence through the load.
25 Citations
22 Claims
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1. A current-regulating power supply for energizing a load at a voltage magnitude less than the voltage magnitude provided by an A.C. source, comprising:
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an autotransformer having a tapped winding, said load being connected solely between a first end and the tap of said winding; switching means connected to said autotransformer only at a remaining end of said winding for enabling a flow of current from said source through said winding during the duration of a control signal; means for providing a sampling signal of magnitude responsive to the instantaneous current flowing through said switching means; and control circuit means for providing said control signal at an operating frequency at least an order of magnitude greater than the frequency of said A.C. source and for adjusting, responsive to said sampling signal magnitude, the proportion of time during each of a successive plurality of operating frequency cycles during which said switching means conducts current, to mainain the current through said load at a substantially constant value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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- 10. The power supply of calim 8, further comprising means coupled to said circuit control means for protecting said switching means from damage in the event that said load is not connected to said power supply.
Specification