A multimeter can measure AC with a DC voltage meter.
If you use digital multimeter DC voltage block to measure AC voltage, then it will certainly damage the internal thermistor, voltage divider resistor, limiting protection diode of the multimeter, and seriously may damage the A/D converter, if you use digital multimeter AC voltage block to measure DC voltage, it will show 000. general digital multimeter also uses half-wave rectification, but after half-wave rectification, it has to be sent to the A/D converter after the operational After the half-wave rectification, the DC voltage will be amplified by the operational amplifier and then sent to the A/D converter, so even if you use the AC voltage block of the digital multimeter to measure the DC voltage, the measured signal will be 000.
If you use the DC voltage block of the pointer multimeter to measure the AC voltage, then it will surely damage the voltage divider resistor of the lowest range in the DC voltage block, as well as the fuse, the meter head limiting protection diode, and it may seriously damage the mechanical meter head, and if you use the AC voltage block of the pointer multimeter to measure the DC voltage, then the measured value is twice as much as the actual value. For example, if you use the AC voltage block to measure a 5V voltage, then the displayed voltage is generally 10V-11V or so, because the AC voltage block has a half-wave rectifier circuit, the measured DC voltage after half-wave rectification to the meter head is 0.44 times the Ue reflecting the average value of the AC power, so use the AC voltage block to measure the DC voltage to measure the value of the voltage to be twice as high as the actual value, that is, it is equivalent to the voltage signal out of the half-wave rectifier circuit. voltage signal.
Multimeter voltage, current gear readings estimate the problem.
With a multimeter to measure the direct reading can be why do you need to estimate?
When using a multimeter to measure an unknown voltage or current, first use the largest gear to measure, and then gradually reduce to the appropriate gear, the so-called appropriate is to try to let the needle point in the vicinity of one-third of the dial.
When measuring, try to use the high grade (especially the current grade, the internal resistance into the circuit has the greatest influence), which can reduce the error. Selection of multimeter should try to choose the DC internal resistance of 20000 ohms / volt or more. Of course, the digital meter is more accurate.
