A, multimeter current measurement method
Selection range: The DC current range of multimeter marked with "mA" has three ranges: 1mA, 1omA and 100mA. The measuring range should be selected according to the large current in the circuit.
1. Selection range: The DC range of multimeter marked with "mA" has three grades: 1 mA, 1mA, 100mA. The measuring range should be selected according to the current in the circuit. If the current is unknown, the maximum range should be selected.
2. Measurement method: The multimeter should be connected in series with the circuit under test. After disconnecting the corresponding part of the circuit, connect the multimeter probes at both ends of the breakpoint. The red stylus should be connected to the breakpoint of the positive pole of the power supply, and the black stylus should be connected to the breakpoint of the negative pole of the power supply.
( 1? )? Connect the circuit to make the LED emit light normally.
(2)? Prepare the multimeter as required before use, and set the selector switch within the mA range of 100mA.
(3)? Disconnect the lead between the middle contact of potentiometer and the negative electrode of LED to form a "breakpoint". At this point, the LED goes out.
(4)? Connect a multimeter in series at the breakpoint. The red contact pin is connected to the negative electrode of the LED, and the black contact pin is connected to the middle contact lead of the potentiometer. At this point, the LED will glow again. The scale value pointed by the multimeter pointer is the current value through the LED.
(5)? Read the current value correctly through LED.
Note: the current through LED is xx mA.
(6)? Turn the handle of potentiometer and observe the change of multimeter pointer and the brightness change of LED. It can be seen that: record: the maximum current through the LED is xx mA. The minimum current is xx mA.
Through the above operations, we can further understand the role of resistance in the circuit.
(7)? After the measurement, disconnect the power supply and put away the multimeter as required.
Second, the principle of measuring current with multimeter
The basic principle of multimeter is to use sensitive magnetoelectric DC ammeter (micro-ammeter) as the meter head.
When there is a small current passing through the meter, there will be a current indication. However, the ammeter cannot pass large current, so it is necessary to shunt or step down some resistors in parallel or series to measure the current, voltage and resistance in the circuit.
In the measurement process of digital multimeter, the measured signal is converted into DC voltage signal by conversion circuit, and then the voltage analog signal is converted into digital signal by analog-to-digital (A/D) converter, and then counted by electronic counter. Finally, the measurement results are directly displayed on the display screen in digital form.
Third, the multimeter brand
Fluke Fluke (a subsidiary of Danaher, a well-known enterprise in the world electronic test tool industry, an excellent supplier of comprehensive measurement solutions, Fluke Test Instrument (Shanghai) Co., Ltd.)
VICTORy Victor (Shenzhen Yisheng Shengli Technology Co., Ltd.) specializes in the production and sales of R&D and digital instruments, and enjoys a high reputation in the industry for developing the Victoria10 series process instrument calibrator.
Unilite UNI-T (founded in 1988, Hongkong, top ten brands of far infrared thermometers, large-scale instrument companies in Asia, high-tech enterprises, Unilite Technology (China) Co., Ltd.).
Bao Gong Pro'skit (a famous professional manufacturer in Taiwan Province Province, tel: 199 1) is committed to developing various tools and testing instruments and selling them to all parts of the world, Shanghai Bao Gong Tools Co., Ltd.).
Huayi MASTECH (top ten brands of multi-purpose meters, world-renowned supplier of electronic measuring tools, main drafting unit of instrument standards, Dongguan Huayi Instrument Technology Co., Ltd.)
Sata Shida (a well-known brand of hand tools under Shida Tools (Shanghai) Co., Ltd., the world's largest manufacturer of industrial hand and pneumatic tools)
HIOKI Kaya Hioki (Kaya Hioki (Shanghai) Trading Co., Ltd., a famous Japanese brand, has an international important position in the research, development and manufacturing of advanced test and measurement technology, the first launch 1935).
Huashengchang CEM (well-known brand, Shenzhen Huashengchang Machinery Industry Co., Ltd., 199 1, is a high-tech enterprise specializing in the development/design/production of various measuring instruments).
Dede Technology is Germany (Germany Technology (China) Co., Ltd., the world's leading test and measurement company and large-scale electronic measurement enterprise, separated from the test and measurement department of Agilent Technology).
FLIR Ferrer (1978 was established in the United States, focusing on thermal imaging technology, a global leader in thermal imaging technology, an innovative sensor solution provider, and avant-garde infrared photoelectric technology (Shanghai) Co., Ltd.)
The principle of multimeter current measurement and test introduced above is hoped to be helpful to you! For more, please continue to pay attention to Tuba Rabbit Decoration Network.
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