If the AC/DC voltage gear of the multimeter and the AC/DC type of the voltage to be measured are correct, the digital multimeter will display the sign "-" when measuring the DC voltage, and the pointer of the pointer multimeter will swing in the positive direction.
The DC voltage range of the digital multimeter measures the AC voltage reading will be very small or basically zero, and the DC voltage range of the pointer multimeter measures the AC voltage swing is also very small or no swing. The same is true for the AC voltage range of the multimeter to measure the DC voltage. At this time, it should be noticed that the type of voltage being measured is incorrect, and the correct AC and DC voltage type gear of the multimeter should be re-selected.
In addition, when the voltage level of the power supply to be measured is unclear, the high-voltage gear 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 with an AC voltage of 750V, look at the displayed value, if it is very small or not displayed at all, you can test it with a DC voltage gear!
First, use the maximum AC voltage to measure, 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 reading.
Use the maximum AC voltage range to measure the positive and negative 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 for the correct use of a multimeter. When measuring the voltage of an unknown power supply, turn the multimeter to the maximum AC voltage, and then adjust the gear to the appropriate gear according to the approximate measurement results for accurate measurement.
It's very simple, use a mechanical multimeter, start from the maximum gear, and measure with AC gear and DC gear respectively. If the AC gear cannot be measured, the DC gear can measure direct current, and vice versa. In fact, it can be judged whether it is AC or DC through the pins of the device structure.
