Patent ID: 8154371

Claim:
A method, comprising: calculating a first number of turns of a shield winding included in an energy transfer element of a power supply, wherein the first number of turns of the shield winding is greater than zero and is calculated for the power supply to have a low noise current in an input conductor of the power supply; increasing the first number of turns for the shield winding to a second number of turns, wherein the second number of turns is greater than the first number of turns; operating the power supply; and adjusting a value of an impedance coupled between the shield winding and an input conductor of the power supply to substantially reduce the noise current in the input conductor, wherein adjusting the value of the impedance includes adjusting the value of the impedance until a voltage waveform between the input conductor and an output conductor of the power supply reverses polarity in response to the adjusting of the value of the impedance.