Patent ID: 8614583

Claim:
A voltage detection circuit to determine whether a voltage provided by a voltage source is within a required voltage range, the voltage detection circuit comprising: a Zener diode comprising an anode and a cathode, wherein the cathode of the Zener diode is connected to the voltage source; a thyristor comprising a control terminal, an anode, and a cathode; a first resistor and a second resistor, wherein the anode of the Zener diode is connected to the control terminal of the thyristor through the first resistor, the anode of the thyristor is connected to the voltage source through the second resistor; a first light-emitting diode (LED) comprising an anode and a cathode, wherein the anode of the thyristor is connected to the anode of the first LED, the cathode of the thyristor is connected to the cathode of the first LED; and a second LED comprising an anode and a cathode, wherein the cathode of the thyristor is connected to the anode of the second LED, the cathode of the second LED is grounded; wherein when the voltage of the voltage source is greater than a breakdown voltage of the Zener diode, the thyristor is turned on, the second LED is turned on, and the first LED is turned off, to indicate the voltage of the voltage source exceeds a maximum value of the required voltage range.