Patent ID: 8350537

Claim:
A power factor correcting power supply, comprising: first and second output terminals for accommodating terminals of an electrical load; a controlled current source for providing electrical power of a regulated current and a regulated voltage to the first output terminal; a voltage comparison current controller; and a control circuit responsive to the current at the first output terminal, the control circuit coacting with the voltage comparison current controller to cause the controlled current source to increase or decrease the current at the first output terminal, the control circuit comprising: a bypass capacitor coupling the first output terminal and the second output terminal; a current sensor measuring the combined current flowing through the bypass capacitor and to the first output terminal; a voltage sensor sensing voltage at the first output terminal or at a point separated from the first output terminal by a resistance; and a derived current calculator operationally coupled to the current sensor and to the voltage sensor, to determine the current at the output terminal exclusive of current flowing in the bypass capacitor.