Patent ID: 7944198

Claim:
A multimeter comprising: a power control terminal; and a switching circuit comprising a micro control unit (MCU), a first normally-open switch, a second normally-open switch, and an electronic switch; wherein a first terminal of the first normally-open switch couples to a first input terminal of the MCU and couples to a power supply via a first resistor, a first terminal of the second normally-open switch couples to a second input terminal of the MCU and couples to the power supply via a second resistor, a second terminal of the first normally-open switch and a second terminal of the second normally-open switch are grounded; wherein a first terminal of the electronic switch connects to an output terminal of the MCU, a second terminal of the electronic switch is grounded, a third terminal of the electronic switch connects to the power supply via a third resistor and connects to the power control terminal, wherein when the first terminal of the electronic switch is at high voltage level the electronic switch turns on; and wherein the output terminal of the MCU outputs a high voltage in response to the first and second input terminals of the MCU being at low voltage level, thereby the electronic switch turns on, the third terminal of the electronic switch outputs a control signal at low voltage level to power on the multimeter.