Pointer multimeter resistance measurement method to reduce error
To realize quasi-compact measurement of resistance with a pointer multimeter, the following points should be noted.
Detecting the accuracy of the resistance file
Before testing the resistance, you should first of all do on the self with the pointer meter resistance gear accuracy, there is a basic assessment.
First of all, use a word of rosary knife calibration mechanical zero, and then dial to the resistance file to the pen short circuit, 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.
Meter should be placed flat
Pointer meter in the factory before the balance of the pointer to be adjusted to ensure that the meter is in any posture hibernation can be used normally. But the multimeter is in a different attitude when the error is not the same, flat when the error is the smallest. So to get the highest precision, the meter must be flat.
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 meter can be negligible, while the pointer meter 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.
Sufficient battery power
Pointer meter Ω file are full of zeroing twist, its role is to make the battery power in different conditions, the meter can be used normally. Sometimes, although the old battery can still realize the full zero, but the new and old batteries of different amounts of electricity, different internal resistance to 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.
Reduce parallax
Purchase pointer watch is best to choose the dial with reflector, it can be through and mirror in the pointer coincides with the realization of parallax minimization. Or choose a 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 center of the dial.
