Methods to reduce errors when measuring resistance with an analog multimeter
1. Detect the accuracy of the resistor level
Before testing the resistance, you should first make a basic assessment of the accuracy of the resistance range of the pointer meter you are using.
First use a straight-edge screwdriver to calibrate the mechanical zero position, then switch to the resistance position to short-circuit the test leads, and adjust the Ω knob to align the pointer with the full-scale zero Ω position. In the next step, you can use a standard resistor or resistance box to conduct a test to have a good idea 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 gear = Ω/Vx full-scale voltage value. for example:
The internal resistance of MF47 at 2.5v level = 20Kⅹ2.5ⅴ = 50KΩ. Other gears can be deduced in the same way.
2. The instrument should be placed flat
The balance of the pointer must be adjusted before leaving the factory to ensure that the meter can be used normally in any posture. However, the error when the multimeter is in different postures is different, and the error is smallest when it is placed flat. Therefore, to obtain the highest accuracy, the meter must be placed flat.
3. Try to eliminate the rotary contact resistance
Due to different working principles, the current flowing through the function switch of the pointer meter is larger than that of the digital meter. Therefore, the same contact resistance can be ignored for digital meters, but may have adverse effects on pointer meters, especially the Rx1 gear. Therefore, it is best to repeatedly rotate the function knob 1 to 2 times before measurement to eliminate contact resistance and ensure accurate measurement.
4. The battery power should be sufficient
The Ω position of the pointer meter has a full-scale zero adjustment knob. Its function is to allow the meter to be used normally when the battery power is in different conditions. Sometimes, although the old battery can still achieve full-scale zero adjustment, the different capacities and internal resistances of the new and old batteries still have an impact on the accuracy of the Ω range. Some multimeters are so small that they can be ignored, while others are more obvious. For example, MF10 will have some impact, while MF47 will have negligible impact.
5. Reduce parallax
When buying an analog watch, it is best to choose one with a reflector on the dial, which can minimize parallax by overlapping the hands in the mirror. Or choose one with a smaller gap between the pointer and the dial, which will also help reduce parallax.
There are also some things to pay attention to: do not measure the resistance with electricity or online; do not touch the resistance being measured with both hands at the same time; do not place the meter in a strong magnetic field; when selecting the gear, try to keep the resistance being measured in the center of the dial.
