Patent ID: 8314697

Claim:
An alarm device, comprising: a first detecting unit for receiving an input signal and outputting a first detecting signal according to the input signal; and a controlling unit electrically connected to the first detecting unit for receiving the first detecting signal and outputting a control signal according to the first detecting signal, wherein the control signal controls an electronic device to operate under a standby mode when the first detecting signal refers to an abnormal status; wherein the first detecting unit comprises: an isolating circuit for receiving the input signal and generating an adjusting signal according to the input signal; a first enabling circuit electrically connected to the isolating circuit for receiving the adjusting signal and generating a first enabling signal according to the adjusting signal; a second enabling circuit electrically connected to the first enabling circuit for receiving the first enabling signal and generating a second enabling signal according to the first enabling signal; and an output circuit electrically connected to the second enabling circuit for receiving the second enabling signal and outputting the first detecting signal according to the second enabling signal; and wherein the first enabling circuit comprises: a first resistor having a first terminal for receiving a power supply voltage; a first transistor having a gate electrically connected to the isolating circuit to receive the adjusting signal, a drain electrically connected to a second terminal of the first resistor, and a source electrically connected to a ground; a second resistor having a first terminal electrically connected to the gate of the first transistor, and a second terminal electrically connected to the ground; a third resistor having a first terminal for receiving the power supply voltage; and a second transistor having a base electrically connected to the second terminal of the first resistor and the drain of the first transistor, an emitter electrically connected to the ground, and a collector electrically connected to a second terminal of the third resistor for outputting the first enabling signal.