Control circuit configurable based on characteristics of commercial power source and image forming apparatus using same

An electronic device includes a supply circuit board having a switching power supply circuit for outputting DC voltages in conformity with a type of commercial power, and a control circuit, which is connected to the supply circuit board, for performing control in accordance with the type of the commercial power. The control circuit discriminates the type of commercial power based upon a voltage value that is the result of dividing a DC voltage by the supply circuit board, and changes over control of a fixing heater in dependence upon the type of commercial power discriminated. When the door of an image forming apparatus is opened, the supply circuit board halts the supply of DC to a high-voltage circuit, thereby suppressing the generation of high voltage, and the control circuit is notified of the fact that the door has been opened.