Precautions for purchasing a digital multimeter
A digital multimeter is the most basic testing tool for electronics enthusiasts. A good digital multimeter can not only measure various electrical parameters, but also serve as a powerful assistant for electronics enthusiasts to troubleshoot and repair electrical appliances. There are currently many types of digital multimeter products available for selection. How to choose a digital multimeter that is both economical and meets your needs?
Starting from one's actual needs
The classification of digital multimeter is very complex: according to its structure, it can be divided into desktop digital multimeter and handheld digital multimeter. According to whether it has a microprocessor, it can be divided into traditional A/D conversion digital multimeter and intelligent digital multimeter. According to its digits, it can also be divided into 3 and a half digital multimeter, 4 and a half digital multimeter, etc.
The accuracy, structure, brand, and intelligence of digital multimeters determine price differences. Currently, the price range of digital multimeters sold in the market ranges from tens of thousands of yuan to tens of thousands of yuan. Therefore, before choosing a product, it is important to clarify your own needs when buying a digital multimeter. If it is only a general test and does not require high measurement accuracy, then choosing a cheap handheld digital multimeter is sufficient; If you are engaged in precision measurement, repair, or have high requirements for the stability of measurement data, you should choose high-end handheld digital multimeter or desktop digital multimeter.
Precautions when purchasing
A. Accuracy
The accuracy of a digital multimeter directly affects the accuracy of measurement results. To obtain a digital multimeter, one should first analyze its accuracy technical indicators: first, check whether the accuracy of the meter can meet their own requirements; second, analyze the overall performance of the meter. Do not assume that a 4-digit digital multimeter is necessarily higher than a 3-and-a-half digit multimeter in terms of measurement accuracy, A rough craftsmanship 4 and a half digit multimeter may have a measurement accuracy that is not as good as a well crafted 3 and a half digit multimeter. The shop owner has encountered such a meter: a DT9103 type 4 and a half digit multimeter generated by an unknown small factory, during the measurement process, the number jumping is very severe, and it cannot meet the technical requirements at all.
B. Precautions
1. Appearance
A good digital multimeter can become a delightful handicraft, whether it is made of materials, injection molding technology, circuit boards, protective sleeves or other components, it should be as perfect as possible.
2. Inspection items
After receiving a digital multimeter:
Firstly, it is necessary to check whether the watch case is intact, whether the switches and buttons are functioning properly, and whether the touch is good.
Check whether the toggle switch (measurement function selection) rotates flexibly, has appropriate damping, and feels comfortable, and whether the corresponding measurement function is normal.
Check whether the LCD screen is clear, whether there are missing strokes, and whether the number jumping should be as small as possible.
Can the buzzer sound.
3. Reference factors
If you can open the watch case, you can pay attention to the design of the circuit board, the selected components, installation and welding level, etc. A good digital multimeter, the design of the circuit board is very important. Domestic watches usually have a double-layer board, while some large foreign factories choose a multi-layer circuit board layout to provide better shielding and electrical performance. The level of component selection determines the measurement accuracy of digital multimeters. High end digital multimeters often use chip mounted components to improve accuracy while reducing the size of the circuit board. Components in key areas may even be screened. I won't talk much about welding skills, as electronics enthusiasts know (when it comes to welding skills, you can open a digital multimeter worth more than ten yuan to take a look, and the products from the manual workshop are guaranteed to make you feel miserable).
When purchasing, you should also pay attention to some details, such as safety protection, product warranty, testing cables, user manuals, etc., to ensure they are complete.
4. Performance testing
When purchasing a digital multimeter, the measurement function of the digital multimeter can be confirmed by measuring known quantities (such as resistance, capacitance, battery voltage, AC voltage, etc.). If conditions permit, it can be sent to the corresponding organization for itemized inspection and acceptance of technical indicators.
