The display digits and accuracy of a multimeter
The display digits of a digital multimeter are usually 3 1/2 to 8 1/2 digits. There are two principles for determining the display digits of a digital instrument: firstly, the digits that can display all digits from 0 to 9 are integer digits; The second is that the numerical value of the fractional digit is based on the highest digit in the maximum displayed value as the numerator, and when measuring at full scale, the value is 2000. This indicates that the instrument has 3 integer digits, while the numerator of the decimal digit is 1 and the denominator is 2, so it is called 3 1/2 digits, pronounced as "three and a half digits". Its highest digit can only display 0 or 1 (0 is usually not displayed). The highest digit of a 32/3 digit (pronounced as "three and two-thirds digits") digital multimeter can only display numbers ranging from 0 to 2, so the maximum display value is ± 2999. In the same situation, it is 50% higher than the limit of a 3 1/2 digit digital multimeter, especially valuable for measuring 380V AC voltage.
The display digits and accuracy are the two most basic and important indicators of a multimeter. The two are closely related, generally speaking, the higher the number of digits displayed on a multimeter, the higher the accuracy, and vice versa. However, due to the different measurement principles and quality standards of various manufacturers, some multimeters have high accuracy in the same digit, while others have poor accuracy. For example, for the same 41/2 multimeter, some models have an accuracy of up to 0.025% while others have only 0.8%. There are two ways to display the number of digits: counting display and digit display. Counting display is the actual expression of the range of digits displayed on a multimeter, but due to the convenience of people's habits and traditional nomenclature, it is generally expressed using digit display.
For example, a 3000 bit count display indicates that the highest display value of the multimeter can reach 3999, while a 1000 bit count display can only reach 1999. When measuring 220VAC voltage, it is evident that the 3000 bit display is one decimal place more than the display after 1000 bits: this resolution is one order of magnitude higher, which will have a greater impact on highly sensitive micro electrical signal debugging and testing. At the same time, counting display and digit display can be converted: first, calculate how many zeros there are in the counting display digit, then use the previous number as the denominator of the fraction, and then subtract 1 from this number to become the numerator to become the digit display. For example, with a 3000 bit count, the number of digits is 32/3. The current product's handheld multimeter has reached 500000 digits for display.
Digital multimeter is classified according to the range conversion method and can be divided into three types: manual range (MAN RANGZ), automatic range (AUTO RANGZ), and automatic/manual range (AUTO/MAN RANGZ).
According to different functions, purposes, 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, medium/high-end digital multimeters, digital/analog hybrid meters, digital/analog dual display meters, and multimeter oscilloscopes (which integrate the kinetic energy of digital multimeters, digital storage oscilloscopes, and other devices).
