Construction principle of digital multimeter
The digital multimeter integrates large-scale integrated circuits (single-chip A/D converters) and digital display technologies. Now we generally believe that the digital multimeter originated from the digital voltmeter. The display of the digital multimeter is shown in Figure 1. The measured voltage, current, resistance and other signals are converted into corresponding digital quantities by the digital-to-analog converter, and then directly sent to the counting circuit for counting and decoding, and the final result is output through the display screen.
Features of digital multimeter
1 Higher accuracy
Compared with other ordinary instruments, digital multimeters have very high accuracy. Taking the DC current measurement of ordinary digital multimeters as an example, the measurement error is generally low-grade DMM<0.5%, mid-range DMM<0.1%, and high-grade DMM<0. .005%. The accuracy of traditional pointer multimeters is generally only about 2.5%.
2 display intuitive
Due to the digital display technology adopted by the digital multimeter, the measurement results can be seen at a glance in all the test processes, which are clearly and intuitively presented in front of the eyes, saving a lot of reading time compared with the pointer multimeter, and now many digital multimeters are in the corresponding The unit can be directly displayed behind the reading of the gear position, making the reading more intuitive and convenient, and greatly shortening the measurement time.
Types of digital multimeters
Digital multimeters have always been widely popular among people, so there are many models of them, which are generally divided into the following two categories:
(1) According to the range conversion method: digital multimeters can be divided into manual range (MANRANGE) and automatic range (AUTORANGE).
(2) According to the purpose and function of the multimeter, it can be divided into: high-end digital multimeter, low-end digital multimeter, intelligent digital multimeter, digital-analog hybrid multimeter, multi-display digital multimeter, digital/analog bar graph dual-display multimeter, special multimeter, etc.
