How can I tell (test) that the multimeter's AC voltage setting (ACV) is good?
Household testing sources, AC adapter, household outlets (two-phase 220V kind, it is best not to measure the three-phase 380V kind, because this voltage is more dangerous to the instrument (at least CAT III 600V or more multimeter) and the use of people are demanding), for safety reasons, it is recommended that the first measurement of a smaller voltage, such as AC adapter, and then measure the voltage of the household socket, the specific security! Please refer to the product manual for details of the operation method.
How to judge the resistance gear (OHM Ω) good or bad?
A: Note that, please do not use the resistance file to measure the voltage, online measurement, the equipment should be powered off, there are capacitors or batteries in the line, it should also be fully discharged, before you can measure. This is a better test, generally engaged in electronic maintenance, have some resistance components on hand, direct measurement of resistance can be.
How to determine the good or bad of the DC current gear (DCA)?
A: If there is a known current source, directly in the current file input, if not, it does not matter, casually in the current file input voltage can be, if out of 1, to the lower range gear to dial a gear, until the effective value appears, please note the following points:
A, please do not input too high a voltage, so as not to current is too large, and damage to the instrument, commonly used can be input source of ordinary batteries, such as No. 5, No. 7 and so on;
B, in the input voltage to see the measurement of its current, because the instrument resistance (load) is very small, the input is too long, if there is damage to the source, so a single input try not to exceed 5 seconds;
C, each high and low ranges, adjacent ranges, generally 10 times the relationship.
How to determine the capacitance file (CAP) good or bad?
A: Generally find a known value of capacitance, directly inserted into the measurement, the range display value should be 10 times than the relationship; detection is best to use a good metal goods capacitors, its capacity is stable, high precision. It is not recommended to use electrolytic capacitor to test, because electrolytic capacitor stability and accuracy are poor.
What is the basic working principle of digital multimeter?
A: The basic circuit of digital multimeter is a header circuit, the basic function it accomplishes is to quantize the input DC voltage (analog) and output; other functions generally need to increase the external circuitry. ps: the chip of multimeter nowadays has a higher and higher degree of integration, and fewer and fewer peripheral circuits, which is both good and bad. Advantages: high integration, simple external circuitry, component quality problems caused by quality failures will be much less; disadvantages: chip a bad, high replacement cost and trouble, sometimes replace a chip money, can buy a meter, so the general bad have to scrap.
