subject: The Use and Caution of Digital Multimeter [print this page] The Use and Caution of Digital Multimeter
Now, measuring instruments of digital have become a mainstream in our daily life. It is also a trend to replace measuring instruments of analog. Compared with analog multimeters, digital multimeters have many advantages, including a high sensitivity, a high accuracy, strong overload capacity, easy to carry and so on.
(1) Use
a, Before using, we should read the instruction manual carefully, know well the power switch, range switch, jacks, the effect of the special jacks.
b, Transferred the power switch to the "ON" position.
c, The measurement of AC and DC voltage: according to the needs to switch in the appropriate range of DC or AC. Then made the red pen insert V and the black pen insert COM hole. The multimeter should in parallel with the test line. So it can read out automatically.
d, The measurement of AC or DC current: transferred the range switch to the appropriate range of DC or AC. The red pen should insert mA hole ( 200mA), and the black pen insert COM hole. Then the digital multimeter should in series with the test circuit. When testing the DC, digital multimeter will display polarity automatically.
e, The measurements of resistance: transferred the range switch to appropriate position of . The red pen insert V / hole, and the black pen insert COM hole. When tested resistance exceeds the maximum value of the selected range, digital multimeter will display "1", so we should select a higher range. When measuring the resistance, the red pen stands positive and the black stands negative. This is not the same with analog multimeter. Therefore, when we measuring transistors, electrolytic capacitors and other components which are have polarity, we should pay attention to the polarity of meter pen.
(2). Caution
a, If we can't certain the size of the voltage or current, we should set the maximum range. Then we reduce gradually the range to appropriate position. After testing, we should transfer the range switch to the highest voltage profile and turn off the power.
b, when the multimeter display "1", we should choose a higher range.
c, When measuring the voltage, digital multimeter should in parallel with the circuit. When measuring the current, it should in series with the circuit, this time we can ignore the polarity of positive or negative.
d, When we misuse voltage profile of AC to measure DC current, or misuse DC voltage profile to measure AC voltage, the screen will show"000", or low numbers starting to beat.
e, Forbid to change the range when measuring the high voltage (over 220V) or high (over 0.5A), avoid to burning switch contacts which on digital multimeter.
f, When the screen shows "", "BATT" or "LOW BAT", so it shows the voltage of battery is lower than operating voltage.
