Patent ID: 7772812

Claim:
A DC (direct current) power supply for a power meter comprising: a transformer, the transformer having an input and an output, the input receiving a first AC (alternating current) voltage waveform and converting the first AC voltage to a second AC voltage, the transformer also having an inductive portion, the output of the transformer coupled to; a diode bridge, the diode bridge rectifying the second ac voltage into a rectified AC voltage, the diode bridge coupled to; a first switching transistor circuit biased to turn on when the rectified AC voltage is greater than a first voltage threshold and turn off when the rectified AC voltage is less than the first voltage threshold; a second switching transistor circuit, the second switching transistor circuit biased to turn off when the rectified AC voltage is above the first voltage threshold and turn on when the rectified AC voltage is below the first voltage threshold; and, a switching regulator circuit, the switching regulator circuit providing a DC power source, the switching regulator circuit receiving energy from the inductive portion when the rectified AC voltage is below the first voltage threshold and the second transistor circuit is on.