Feature: The measurement range of the voltmeter is 0-30V. This voltage is only a measurement signal and cannot be used as the working power supply of the voltmeter. Therefore, the voltmeter needs to provide 5-30V DC voltage from the outside as the working power supply. Among the three wires, the black wire is the common negative pole, the white wire is connected to the positive pole of the measurement voltage, the red wire is connected to the positive pole of the working power supply, and the total negative pole in the meter Measuring range 0V-30V / 0-100V Two wires =DC30.0V Note: Input voltage higher than 30V may be permanently damaged! Three wires = 0-100V, but can not use a large current, otherwise it will damage the product Allowable error1% When it is greater than or equal to 10V, the error is 0.3V; Error 0.10 when less than 10V Input impedance