| 摘要 |
A circuit including bridge rectifier, switches across one or more of the diodes of the bridge rectifier, and a comparator providing control signals to the switch or switches can be constructed to apply a constant polarity voltage to an electrical load, regardless of the polarity of the input power applied to the circuit. The comparator produces a control signal depending upon a comparison of the input power voltages, and the control signal activates one or more of the switches to allow current flow through an appropriate path in the circuit to yield the constant polarity across the electrical load. Thus, the circuit can protect the electrical load from an inappropriately applied voltage by switching the applied voltage's polarity. Because an activated switch can short a diode in the bridge rectifier, power loss associated with current flow through the diode is reduced. Additionally, the circuit can provide constant polarity across the electrical load with either AC or DC input power.
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