Patent ID: 7936576

Claim:
A power controller for controlling the power supplied from power supplies of different voltage ratings to a load having an input voltage threshold, comprising a controller operable to control a trigger circuit to have a triggering phase angle greater when the power supply voltage received by the controller exceeds a first threshold dependent on the input voltage threshold of the load than when the first threshold is not exceeded, the controller being configured to include a circuit operable to produce a step signal change, for effecting the change in the resistance of the resistive circuit when the voltage of the input power supply exceeds the input voltage threshold of the load, and configured to effect change in the resistance of a resistive circuit forming part of the trigger circuit to control the triggering phase angle at a high phase angle in response to the power supply voltage input being at least as high as the voltage threshold, to provide power to the load at a reduced voltage, relative to the input voltage, and control the triggering phase angle at a low phase angle in response to the power supply voltage input being less than the voltage threshold, to provide power to the load at a voltage that is substantially the same as the voltage of the input voltage.