Patent ID: 8829921

Claim:
An AC voltage detection circuit comprising: a conversion module, configured for being connecting to an AC power source and converting an AC voltage provided by the AC power source into an AC current, and then converting the AC current into a direct current (DC) voltage reflecting the AC voltage; wherein the conversion module comprises a first resistor, a second resistor, and an optical coupler, the optical coupler comprises a first input terminal, a second input terminal, a first output terminal, and a second output terminal; the first input terminal is connected to one output terminal of the AC power source via the first resistor, the second input terminal is connected to another output terminal of the AC power source via the second resistor, the first output terminal is connected to the comparison module, the second output terminal is grounded; a comparison module connected to the conversion module, configured for comparing the DC voltage with a first predetermined voltage and a second predetermined voltage less than the first predetermined voltage, respectively, and producing a control signal when it determines that the DC voltage is either greater than the first predetermined voltage or less than the second predetermined voltage; and a prompt module, configured for producing a prompt signal when receiving the control signal.