This is tiny and compact digital voltmeter with a LED Display. The 0.36inch 0-32V Three Wire DC Voltmeter Panel requires only a few minutes of configuration and is as simple as directly connecting wires to the source you want to measure and seeing the LED blink!!!!
The red wire is to connect to the positive pole, the black wire is to connect to negative pole and the yellow/white wire is to connect to the positive pole of that source or another source across which we meant to measure the voltage. While measuring the supply voltage of another source make sure that negative pole is joined common. No need to worry even if there is any connection mismatch of the wires, the electric circuit won’t be a boom because it features reverse polarity protection.