Methods for reducing errors in measuring resistance with a pointer multimeter
1, Check the accuracy of the resistance level
Before testing the resistance, the first thing to do is to have a basic evaluation of the accuracy of the resistance range of the pointer meter you are using.
First, calibrate the mechanical zero position with a straight Rose knife, then switch to the resistance mode and short-circuit the probe. Adjust the Ω knob to align the pointer with the full zero Ω position. The next step is to use standard resistors or resistance boxes 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 multimeter and use its DC voltage range to act as a resistance box. The resistance value of each level is Ω/V x the full voltage value. For example:
The internal resistance of MF47 in the 2.5v range is 20K ⅹ 2.5 ⅴ=50K Ω. The rest of the gears follow suit.
2, The instrument should be placed flat
Before leaving the factory, the balance of the pointer of the pointer gauge must be calibrated to ensure that the instrument can be used normally in any posture. But the error of the multimeter varies when it is in different positions, and the error is minimized when it is placed flat. So to achieve the highest accuracy, the instrument must be placed flat.
3, Try to eliminate the contact resistance caused by twisting and turning
Due to different working principles, the current flowing through the pointer meter function switch is greater than that of the digital meter. Therefore, the same contact resistance can be ignored for digital meters, but it may have adverse effects on pointer meters, especially in the Rx1 range. So it is best to repeatedly rotate the function by 1-2 turns before measurement to eliminate contact resistance and ensure measurement accuracy.
4, The battery power should be sufficient
The Ω position of the pointer meter has a full zeroing knob, which is used to ensure that the instrument can be used normally when the battery level is in different conditions. Sometimes, although old batteries can achieve full zeroing, the different levels of charge and internal resistance between new and old batteries still have an impact on the accuracy of the Ω range. Some multimeters may be so small that they are negligible, while others may be more noticeable. For example, MF10 may have some impact, while MF47 can be ignored.
5, Reduce disparity
It is best to choose a dial with a reflective mirror when purchasing a pointer watch, as it can minimize parallax by overlapping with the pointer in the mirror. Alternatively, choosing a smaller gap between the pointer and the dial can also help reduce parallax.
Additionally, there are some things to note: do not use live or online measurement of resistance; Do not touch the measured resistor with both hands at the same time; Do not place the instrument in a strong magnetic field; When selecting gears, try to position the measured resistance value at the center of the dial as much as possible.
