The Display Digits and Precision of a Multimeter
The display digits of a digital multimeter usually range from 3 1/2 digits to 8 1/2 digits. There are two principles for determining the display digits of a digital instrument: First, the digits that can display all numbers from 0 - 9 are full digits. Second, the value of the fractional digit takes the highest - order digit in the maximum display value as the numerator. When the full - scale count value is 2000, it indicates that the instrument has 3 integer digits, and the numerator of the fractional digit is 1 and the denominator is 2. So it is called 3 1/2 digits, pronounced as "three and a half digits", and its highest digit can only display 0 or 1 (0 is usually not displayed). For a 3 2/3 - digit (pronounced as "three and two - thirds digits") digital multimeter, the highest digit can only display numbers from 0 to 2, so the maximum display value is ±2999. In the same situation, its measurement range is 50% higher than that of a 3 1/2 - digit digital multimeter, which is especially valuable when measuring an AC voltage of 380V.
Display digits and precision are two of the most basic and important indicators of a multimeter. They are closely related. Generally speaking, the higher the display digits of a multimeter, the higher its precision, and vice versa. However, due to different measurement principles and quality standards of various manufacturers, for multimeters with the same number of digits, some have high precision while others have poor precision. For example, for 4 1/2 - digit multimeters, the precision of some models can be as high as 0.025%, while that of others is only 0.8%. There are two ways to represent the display digits: count display and digit display. Count display is the actual expression of the display digit range of a multimeter. However, for the convenience of people's habits and traditional naming, digit display is generally used.
For example, a 3000 - count display means that the maximum display value of the multimeter can reach 3999, while a 1000 - count display can only reach 1999. When measuring a 220V AC voltage, it can be clearly seen that the 3000 - count display has one more decimal place than the 1000 - count display. Thus, the resolution is one order of magnitude higher. In the debugging and testing of highly sensitive micro - electrical signals, a high - sensitivity multimeter will play a greater role. At the same time, the count display and digit display can be converted: First, calculate how many zeros there are in the count display digits, then use the number in front as the denominator of the fraction, and subtract 1 from this number to be the numerator, then it becomes the digit display. For example, for a 3000 - count display, the digit is 3 2/3 digits. Currently, the display digits of handheld multimeters on the market have reached 500,000 counts.
Digital multimeters can be classified into three types according to the range conversion method: manual range (MAN RANGZ), auto - range (AUTO RANGZ), and auto/manual range (AUTO/MAN RANGZ).
According to different functions, uses, and prices, digital multimeters can be roughly divided into 9 categories: low - end digital multimeters (also known as popular digital multimeters), mid - range digital multimeters, mid/high - end digital multimeters, digital/analog hybrid instruments, instruments with dual digital/analog graphical displays, and universal oscilloscopes (which integrate the functions of a digital multimeter and a digital storage oscilloscope).
