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: first, the digits that can display all digits from 0 to 9 are whole digits; The second point is that the numerical value of the fractional digit is based on the highest digit in the maximum displayed value as the numerator. When using full scale, the count value is 2000, indicating that the instrument has three integer digits. 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 3/3 digit multimeter can only display numbers from 0 to 2, so the maximum displayed 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 while others have poor accuracy in the same digit. For example, for the same 41/2 multimeter, some models have an accuracy of up to 0.025% while others only have 0.8%. There are two ways to display the number of digits: counting display and digit display. Count display is the actual expression of the range of digits displayed on a multimeter, but due to people's habit and convenience in traditional terminology, it is generally expressed using digit display.
For example, a 3000 bit count display indicates that the maximum display value of a multimeter can reach 3999, while a 1000 bit count display can only reach 1999. When measuring a 220VAC voltage, it is evident that the 3000 bit display is one decimal place more than the 1000 bit display. This results in a resolution that is one order of magnitude higher. In highly sensitive micro electrical signal debugging and testing, a highly sensitive multimeter will have a greater impact. At the same time, counting display and digit display can be converted: first, calculate how many zeros there are in the counting display digits, then use the preceding number as the denominator of the fraction, and then subtract 1 from that number to become the numerator, becoming the digit display. For example, a 3000 bit count with 32/3 digits. The current product's handheld multimeter has reached 500000 digits for display.
Digital multimeters can be classified into three types based on range conversion methods: 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 instruments, digital/analog dual display meters, and multimeter oscilloscopes (which integrate the kinetic energy of digital multimeters, digital storage oscilloscopes, etc.).
