Multimeter Readouts and Accuracy
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 numbers from 0-9 are integer digits; The second point is that the value of the fractional digit is based on the highest digit in the maximum displayed value as the numerator. When measured at full range, the value is 2000, indicating that the instrument has 3 integer digits. The numerator of the fractional digit is 1, and the denominator is 2, so it is called 3 1/2 digit, which is read as "three and a half digits". The highest digit can only display 0 or 1 (0 is usually not displayed). The highest digit of the 3 2/3 digit (pronounced as "3 and 2/3 digits") digital multimeter can only display numbers from 0 to 2, so the maximum displayed value is ± 2999. In the same situation, it has a 50% higher limit than a 3 1/2 digit digital multimeter, especially valuable for measuring 380V AC voltage.
The display digit and accuracy are the two most basic and important indicators of a multimeter. The relationship between the two is 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 at the same digit. For example, for the same 41/2 multimeter, some models have an accuracy as high as 0.025% while others have only 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 digit range displayed on a multimeter, but due to people's habits 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 220VAC voltage, it is evident that the 3000 bit display has one decimal place more than the 1000 bit display. This increases the resolution by an order of magnitude, and in high-sensitivity micro electrical signal debugging and testing, a high-sensitivity multimeter will have a greater impact. 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 preceding digits as the denominator of the fraction, and subtract 1 from that number to become the numerator, which becomes the digit display. For example, for a 3000 bit count, the number of bits is 32/3. The current product handheld multimeter displays 500000 digits.
Digital multimeters can be classified into three types based on range conversion: manual range (MAN RANGZ), automatic range (AUTO RANGZ), and automatic/manual range (AUTO/MAN RANGZ).
According to their 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, digital/analog dual display instruments, and multimeters (combining digital multimeters, digital storage oscilloscopes, and other kinetic energy into one).
