When buying a multimeter, consider the following
A. Accuracy
The accuracy of the digital multimeter directly affects the accuracy of the measurement results, get a digital multimeter should be the first to analyse the accuracy of its technical indicators: a look at the table to see whether the accuracy of the table can reach their own requirements, and the second is to analyse the overall performance of the table, do not think that a 4-digit digital multimeter must be higher than the 3.5-digit digital multimeter measurement accuracy, a piece of rough 4.5-digit digital multimeter measurement accuracy may also catch up with a piece of well-made 3.5-digit digital multimeter. The measurement accuracy of a roughly crafted 4.5 digit multimeter may also catch up with a well-made 3.5 digit multimeter. The owner of the shop has encountered such a table: a nameless small factory generates a 4.5 digit multimeter of DT9103 type, and in the process of measurement, the digits jump very much, which is not able to meet the requirements of the technical specifications at all.
B. Precautions
Appearance
A good digital multimeter can be a pleasing craft, no matter from the material, injection moulding process or circuit board, protective cover and other parts, it should be as perfect as possible.
2,Check items
After getting a digital multimeter:
First of all, you should check whether its case is intact, whether the switch and button function normally and feel good.
Whether the toggle switch (measurement function selection) is rotating and flexible, with suitable damping and comfortable hand feeling, and whether the corresponding measurement function is normal.
Whether the liquid crystal display is clear, there is no missing strokes, the digital jump should be as small as possible.
Whether the buzzer can sound.
3,Reference factors
If you can open the 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, the domestic table is generally a double-layer board, and some large foreign manufacturers of the table will be selected multi-layer circuit board layout in order to provide better shielding and electrical performance. The level of selected components determines the measurement accuracy of the digital multimeter, high-end digital multimeter often use SMD components to improve accuracy while also reducing the size of the circuit board, the key parts of the components will even be screened. The level of welding is not much to say, electronic enthusiasts know (talking about the level of welding, you can open a piece of more than ten yuan of digital multimeter to see, handmade workshop products will make you feel miserable).
Purchase should also pay attention to some details, such as safety protection, product warranty, test cables, user manuals, etc. are complete.
4, performance testing
When you buy a digital multimeter, you can measure known quantities with the help of methods (such as resistance, capacitance, battery voltage, AC voltage, etc.) to confirm the measurement function of the digital multimeter, and the conditions can be sent to the appropriate organisations for the technical indicators of the item-by-item inspection and acceptance.
