Patent ID: 7684223

Claim:
An automatic power supply converting circuit, the automatic power supply converting circuit comprising: a live input terminal and a neutral input terminal configured for receiving a first AC voltage; a relay; a regulator configured for filtering and steadying the first AC voltage and outputting a regulated voltage; a voltage divider circuit configured for sampling the first AC voltage and outputting a divided voltage, wherein the voltage divider circuit comprises a first resistor, a second resistor, and a variable resistor comprising a first terminal connected to the live input terminal via the first resistor, a second terminal connected to the neutral input terminal via the second resistor, and a sliding terminal acting as an output of the divider circuit to output the divided voltage; an identifying circuit comprising a comparator for receiving the divided voltage and comparing the divided voltage with a reference voltage, and outputting a control signal according to the comparison result; a switch circuit configured for controlling the relay to be conductive or not according to the control signal; and a voltage doubling circuit capable of being controlled by the relay and outputting a doubled voltage.