Analysis of the principle and method of measuring voltage with a multimeter

The method of measuring voltage with a multimeter is to first align the range switch with the five gears marked with V (to test AC voltage, align it with the AC voltage gear, and to test DC voltage, align it with the DC voltage gear). When measuring voltage, connect the meter probes to the circuit to be measured. Select a suitable range position according to the approximate value of the circuit to be measured. The maximum value of each dry cell is 1.5V, so it can be placed in the 5V range. At this time, the full-scale reading of the needle on the panel should be read as 5 for 500. That is, it is reduced by 100 times. If the needle is at the 300 scale, it will read 3V. Note that the value indicated by the tip of the range switch is the corresponding value of the full-scale reading of the needle on the meter head. When reading the meter, you only need to convert it according to this to read the actual value. Except for the resistance gear, all gears of the range switch read the measurement results in this way. In actual measurement, when you encounter an unsure approximate value of the measured voltage, you can first turn the switch to the maximum range, and then reduce the range to the appropriate position step by step. When measuring DC voltage, you should pay attention to the positive and negative polarity. If the test leads are connected in reverse, the needle will move in the opposite direction. If you don't know the positive and negative polarity of the circuit, you can set the range of the Mantan meter to the maximum range and quickly test it on the circuit to be tested. By observing how the pen needle deflects, you can determine the positive and negative polarity.

Measure 220V AC. Turn the range switch to AC 500V. The full scale is 500V, and the reading is read according to the scale of 1:1. Insert the two test leads into the power socket, and the scale where the needle points is the measured voltage value. When measuring AC voltage, the test leads have no positive or negative distinction.

Principle of voltage measurement by multimeter
1. DC voltage conversion circuit

2. AC voltage conversion circuit