The method of reducing errors in measuring resistance with a pointer multimeter
Check the accuracy of the resistance level
Before testing the resistance, the first step is to ensure the accuracy of the resistance range of the pointer meter used, and to have a basic evaluation.
First, use a flat screwdriver to calibrate the mechanical zero position, then turn it to the resistance position to short-circuit the probe, adjust the Ω knob to align the pointer with the zero Ω position of the full scale. The next step is to use a standard resistor or resistance box for testing, so as to have a clear understanding of the accuracy of the instrument. If these conditions are not met, you can also find another pointer type multimeter and use its DC voltage range to act as a resistance box. The resistance value of each gear=Ω/V x full scale voltage value.
The instrument should be placed flat
Before leaving the factory, the balance of the pointer should be adjusted to ensure that the instrument can be used normally in any position. But the error of a multimeter varies when it is in different postures, with the smallest error when placed flat. So to achieve the highest accuracy, the instrument must be placed flat.
Try to eliminate the contact resistance between the rotating and twisting parts
Due to different working principles, the current flowing through the function switch of the pointer meter is greater than that of the digital meter. Therefore, the same contact resistance can be ignored for a digital meter, while it may have a negative impact on a pointer meter, especially in the Rx1 range. So it is best to repeatedly rotate the function knob 1-2 turns before measurement to eliminate contact resistance and ensure accurate measurement.
The battery should be fully charged
The Ω gear of the pointer meter has a full scale zero adjustment knob, which is used to ensure that the instrument can function normally when the battery level is in different conditions. Sometimes, although old batteries can still achieve zero to full capacity adjustment, the different levels and internal resistances of new and old batteries still have an impact on the accuracy of the Ω range. Some multimeters can be so small that they are negligible, while others can be more noticeable. For example, MF10 may have some impact, while MF47 can be ignored.
Reduce parallax
It is best to choose a dial with a reflective mirror when purchasing a pointer watch, which can achieve minimum parallax by overlapping with the pointer in the mirror. Alternatively, choosing a smaller gap between the pointer and dial can also help reduce parallax.
Additionally, there are some things to note: do not charge or measure resistance online; Do not touch the measured resistance with both hands simultaneously; Do not place the instrument in a strong magnetic field; When selecting a gear, try to keep the measured resistance value at the center of the dial as much as possible.
