I don't know whether it is AC or DC voltage, how to measure it with an electrician's multimeter、
If the AC/DC voltage range of the multimeter and the AC/DC type of the measured voltage are correct, the digital multimeter will display a - sign when measuring DC voltage, and the pointer of the pointer multimeter will swing in the positive direction.
The DC voltage reading of the digital multimeter will be very small or basically zero when measuring the AC voltage, and the DC voltage reading of the pointer multimeter will also be very small or no swing when measuring the AC voltage. The same is true for measuring DC voltage with the AC voltage file of the multimeter. At this time, you should find that the type of voltage to be measured is incorrect, and you should re-select the correct AC/DC voltage type gear of the multimeter.
In addition, when the voltage level of the power supply to be tested is not clear, the high-voltage gear should be switched to the low-voltage gear first, and then the low-voltage gear should be gradually switched to the gear with the most suitable reading resolution and the most accurate reflection of the measured value to ensure safety.
You can first measure it with an AC voltage of 750V, and look at the displayed value. If it is very small or basically not displayed, you can test it with a DC voltage file!
First use the maximum AC voltage for measurement, and then use the appropriate range for accurate measurement after determining the range. If there is no stable value in reality, it is DC. Change to the highest level of DC voltage to measure the approximate value. After determining the range, change to the appropriate range for accurate readings.
Use the maximum AC voltage file to measure the positive and negative sides first. If the two voltages are consistent, it is AC, otherwise it is DC~
Alternating current has no positive and negative poles; direct current has positive and negative poles.
This is a common sense to use the multimeter correctly. When measuring the voltage of an unknown power supply, turn the multimeter to the maximum AC voltage level, and then adjust the gear to the appropriate gear according to the rough measurement results to make accurate measurements.
It's very simple, use a mechanical multimeter, start from the maximum gear to measure, use AC gear and DC gear to measure, and if the AC gear can't be measured, the DC gear can measure it is direct current, and vice versa. In fact, the AC or DC can be judged through the device structure pins.
