Error reducing pointer multimeter resistance measurement method
I. Detecting the accuracy of the resistance file
Before testing the resistance, first of all, you should have a basic assessment of the accuracy of the resistance of the pointer meter used by you.
First of all, use a word of rosary knife calibration mechanical zero, and then dial to the resistance file to the short circuit of the pen, adjust the Ω twist to the pointer to the satisfaction of the zero Ω position. The next step can be used standard resistance or resistance box for a test, to do on the instrument's quasi 硧 degree of chest. If you do not have these conditions, you can also find another pointer multimeter, with its DC voltage gear to act as a resistance box. The resistance value of each file = Ω / V x satisfaction voltage value. For example.
MF47 2.5v gear internal resistance = 20K x 2.5 v = 50KΩ. other gears and so on.
II. Meter should be placed flat
The pointer meter should be adjusted to the balance of the pointer before delivery to ensure that the meter is in any posture can be used normally. But the multimeter is in a different posture when the error is not the same, flat when the error is the smallest. So to get the highest precision, the meter must be placed flat.
III. Try to eliminate the twist contact resistance
Due to different working principles, the current flowing through the function switch of pointer meter is larger than that of digital meter. Therefore, the same contact resistance for the digital table can be negligible, while the pointer gauge may constitute an adverse effect, especially the Rx1 file is particularly obvious. Therefore, it is best to repeatedly rotate the function switch 1 to 2 turns before measurement to eliminate the contact resistance and ensure that the measurement is accurate.
Four. Sufficient battery power
Pointer meter Ω file are full of zero adjustment twist, its role is to make the battery power in different conditions, the instrument can be used normally. Sometimes, although the old battery can still achieve full zero, but the new and old batteries of different amounts of electricity, different internal resistance of the Ω file accuracy still has an impact. Some multimeters can be as small as negligible, some will be more obvious. For example, MF10 will have some effect, while MF47 is negligible.
V. Reduce parallax
Purchase pointer watch is best to choose the dial with a reflector, it can be achieved through the mirror and the pointer coincides with the minimum parallax. Or choose the one with smaller gap between the hands and the dial, which is also conducive to reducing parallax.
In addition there are some need to pay attention to: do not carry electricity or online resistance measurement; do not use both hands at the same time contact with the measured resistance; do not make the instrument placed in a strong magnetic field; select the gear as far as possible so that the measured resistance value is located in the centre of the dial.
