Display digits and accuracy of multimeter
The display digits of a digital multimeter are usually 3 1/2 to 8 1/2 digits. There are two principles for judging the display digits of digital instruments: one is that the digits that can display all numbers from 0 to 9 are integer digits; The numerator is the numerator, and the count value is 2000 when the full scale is used, which 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, read as "three and a half digits ", the highest bit can only display 0 or 1 (0 is usually not displayed). 3 2/3 digits (pronounced "three and two-thirds digit"), the highest digit of the digital multimeter can only display numbers from 0 to 2, so the maximum display value is ±2999. Under the same conditions, it is 50% higher than the limit of a 3 1/2 digit digital multimeter, which is especially valuable when measuring 380V AC voltage.
Display digits and accuracy are the two most basic and most important indicators of the multimeter. The two are closely related. Generally speaking, the higher the number of digits displayed by the multimeter, the higher the accuracy, and vice versa. However, due to the different measurement principles and the quality standards of various manufacturers, some multimeters have high precision while others have poor accuracy in the same digit. For example: it is also a 41/2 multimeter, some models have an accuracy as high as 0.025% and some have only 0.8%. There are two ways to display digits: count display and digit display. The counting display is the actual expression of the range of digits displayed by the multimeter, but due to people's habits and the convenience of the traditional name, it is generally expressed in digits.
For example: 3000-digit counting display means that the highest display value of the multimeter can reach 3999, while the 1000-digit counting display can only reach 1999. When measuring 220VAC voltage, it can be clearly seen that the 3000-digit display has one more decimal place than the 1000-digit display: this The resolution is an order of magnitude higher, which will play a greater role in the debugging and testing of high-sensitivity micro-electrical signals. At the same time, the count display and digit display can be converted: first calculate how many 0s there are in the count display digit, then use the previous number as the denominator of the fraction, and then subtract 1 from the number to become the numerator, which becomes the digit show. For example: 3000-digit count, the number of digits is 32/3 digits. The number of digits of the existing product handheld multimeter has reached 500,000 digits.
Digital multimeters are 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, 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, medium/high-end digital multimeters, digital/analog hybrid instruments, digital Instrument with dual display of /analog diagram, multi-purpose oscilloscope (integrating digital multi-meter, digital storage oscilloscope and other kinetic energy into one body).
