Voltmeter and using method thereof

Provided in the invention is a voltmeter comprising a universal meter having a positive probe and a negative probe. In addition, the voltmeter also includes a first selection switch, a second selection switch, a control module, and an adjustable power supply. The first selection switch has gears S1 and S2 and a joint T1; the second selection switch has gears S3 and S4 and a joint T2; the positiveprobe is connected with the joint T1 of the first selection switch; and the negative probe is connected with the joint T2 of the second selection switch. 种电压表，包括万用表，所述万用表具有正探头和负探头，所述电压表还包括有第选择开关、第二选择开关、控制模组、以及可调电源，所述第选择开关具有档位S1、S2和接头T1，所述第二选择开关具有档位S3、S4和接头T2，所述正探头连接所述第选择开关的接头T1，所述负探头连接所述第二选择开关的接头T2。