Things to note when purchasing a digital multimeter
A, accuracy
The accuracy of a digital multimeter directly affects the accuracy of measurement results. To obtain a digital multimeter, the first step is to analyze its accuracy technical indicators: first, to see if the accuracy of the meter can meet one's requirements; second, to analyze the overall performance of the meter. Do not assume that a 4-digit multimeter is necessarily more accurate than a 3.5-digit multimeter. The measurement accuracy of a rough process 4-digit multimeter may be comparable to that of a well crafted 3.5-digit multimeter. The shop owner has encountered such a meter: a DT9103 type 4-digit multimeter produced by an unknown small factory. During the measurement process, the numbers jump very violently, and it can even reach a certain level. Not meeting the requirements of technical specifications.
B, matters needing attention
1. Appearance
A good digital multimeter can become a visually pleasing handicraft, and it should be as perfect as possible in terms of materials, injection molding processes, circuit boards, protective covers, and other components.
2. Inspection items
After receiving a digital multimeter:
Firstly, it is necessary to check whether the case is intact, whether the switches and buttons are functioning properly, and whether the feel is good.
Whether the toggle switch (measurement function selection) rotates flexibly, has appropriate damping, feels comfortable, and whether the corresponding measurement function is normal.
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 produce 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 soldering level, etc. For a good digital multimeter, the design of the circuit board is very important. Domestic watches generally have double-layer boards, while some foreign large factories use multi-layer circuit board layouts to provide better shielding and electrical performance. The level of component selection determines the measurement accuracy of a digital multimeter. High end digital multimeters often use surface mount components to improve accuracy while reducing the size of the circuit board. Components in critical areas may even be screened. I won't talk much about the welding level, as electronic enthusiasts know (when it comes to welding level, you can open a digital multimeter worth more than ten yuan to take a look, the handmade workshop's products are guaranteed to make you feel terrible).
