Significance of Intelligent Digital Multimeter Development
Although the current digital multimeter has high sensitivity and accuracy, there are still shortcomings, mainly in the following aspects: (1) Automatic measurement is not realized, and the most prominent problem is that it needs to rotate the function/function frequently during use. The range switch is inconvenient to operate and the measurement speed is slow. (2) Often burned. The main reason why the digital multimeter is burned is the operator's misoperation. For example: When measuring voltage, the function switch is mistakenly placed in the resistance position or in the current position, etc. When these situations occur, the digital multimeter can easily be burned. Although a protection circuit is added to the digital multimeter circuit, the protection circuit is only effective for falsely measuring a lower voltage. When a higher voltage is falsely measured, some measuring circuits and protection circuits will be burned at the same time. Therefore, all kinds of digital multimeter instruction manuals emphasize "do not use the digital multimeter to measure voltage, otherwise the instrument will be damaged", but because the digital multimeter itself lacks strict preventive measures for "mismeasurement", this phenomenon occurs from time to time. (3) Poor contact of the contacts. The function/range selection switch is a mechanical switch, which needs to be turned manually during the measurement process, and its spring leaf is easily oxidized, damaged and deformed, resulting in poor contact between the spring leaf contact and the circuit board, resulting in a decrease in the measurement accuracy of the digital multimeter, and even in severe cases. cause failure [1]. Getting rid of these disadvantages has always been a difficult problem that designers have been exploring but have not been able to solve well.
The rapid development of electronic technology, especially the detection and control technology, makes it possible to improve the automation level of digital multimeters. It is an inevitable trend that digital multimeters that can identify measurement functions replace manual digital multimeters. It is important to apply the development results of measurement and control technology to the design of digital multimeters, transform the structure of traditional digital multimeters, replace traditional mechanical function/range selection switches with advanced computer control technology, and develop the most advanced and highly intelligent digital multimeters. Significance, it will play a major role in improving my country's international influence in the instrument manufacturing industry and the competitiveness of digital multimeters in the international market.
The measurement function automatic identification digital multimeter developed in this project is a highly intelligent and truly intelligent digital multimeter. The meter fundamentally overcomes the shortcomings of current digital multimeters, can perform fast, convenient and accurate measurements, and greatly improves performance indicators such as reliability and safety. In addition to the test functions of ordinary digital multimeters, the most important feature of this meter is that it can automatically identify the current measurement function (voltage, current, resistance, etc.) and range, and automatically switch to the corresponding measurement function gear. All measurement functions and Range selection is done automatically by the digital multimeter without human intervention. The digital multimeter has no usable parts to input information to the digital multimeter except for a power switch that can be toggled or pressed, a slot for a compound test lead and a socket for a common black test lead. It eliminates the cumbersome operation of having to manually switch the function switch in the use of the current digital multimeter. This not only improves the automation level and realizes the real intelligence, but also endows the digital multimeter with self-protection function, which significantly reduces the failure rate and improves the performance of the digital multimeter.
