Why is the reading for the pointer multimeter reported as 0?
The ohm file of the pointer multimeter has three key points: 0Ω, ∞ and the center value. Because the ohm gear itself is equipped with a battery, when the short-circuit resistance of the test pen is zero, the current passing through the meter head is the largest. At this time, use the zero-adjusting potentiometer to adjust the pointer to the full-scale value. We artificially define this as zero position. .
After the test leads are separated, we look at the resistance ∞ between the two test leads. At this time, there is no current passing through the meter head, so the pointer does not move, and this position is marked with ∞.
Another important scale of the ohm scale of the pointer multimeter is the center resistance value.
Its ohms center value is 16.5. Multiply the respective coefficients in different gears to represent the resistance value at the center position, for example, Rx1 represents 16.5Ω, Rⅹ10 is 165Ω, Rⅹ100 is 1650Ω, Rx1K is 16.5KΩ, and Rx10K is 165KΩ.
This center scale value is very important, it marks the applicable range of measuring resistance at this gear, for example, Rx1 is most suitable for measuring resistances from several Ω to hundreds of Ω centered on 16.5, and Rx1K is suitable for measuring several K to hundreds of KΩ. When we measure the 100Ω resistance, the Rx1 gear pointer only deflects about 1/6, which is relatively clear. And with 10K file measurement, the pointer basically points to the 0Ω position. It is difficult to observe subtle changes in the pointer. It can be seen that when the same resistance is measured as 0Ω, the pointer deviation range of different gears is different.
At the same time, the center scale of the ohm gear is also the internal resistance of the multimeter for this gear, and interested friends can also measure it by themselves. The specific measurement method is to take out the battery of the pointer multimeter, short the battery clip with a wire, and then find a digital multimeter to measure it directly.
