2023-12-09
How to choose handheld digital multimeters by their resolutions and digits?
With the development of electronic technology, digital multimeters are becoming more and more commonly used in our daily lives and work due to their advantages such as convenient and intuitive display and reading.
A good digital multimeter can not only measure various electrical parameters but is also a powerful assistant for electronic enthusiasts to troubleshoot and repair electrical appliances.
There are currently many types of digital multimeter products to choose from. How do you choose a digital multimeter that is both economical and affordable and can meet your needs?
You can consider the following aspects when purchasing
1. Resolution
Resolution refers to the multimeter's ability to resolve small signals when measuring. Knowing the resolution of the multimeter, you can determine whether it can observe small changes in the signal being measured.
For example, if you have to measure a minimum length of 1 mm, then you wouldn't buy a ruler with a minimum graduation of 1 cm.
If the resolution of the digital multimeter in the 4V range is 1mV, then when measuring a 1V signal,
You can see a tiny change of 1mV (1/1000V volt).
If the normal voltage is 100.11V, then the digital multimeter UT61A with a resolution of 0.1V can only test one digit after the decimal point (100.1V)
, unable to distinguish the number to the second decimal place. You need a multimeter with a resolution of 0.01V such as UT171A.
2. Number of words and number of digits
The so-called three-and-a-half three digits refer to the ten numbers that can display 0-9, which are called full digits. The maximum display of thousands of digits is 1 (blanking when less than 1),
In theory, this can display a maximum of 2. For example, in the 2V gear, the maximum display should be 2000, but the actual display is 1999.
If there is still one difference from the theoretical value, then the theoretical value of this bit should display a maximum of 2, but in reality, it can only display 1, which is called a 1/2 position.
The theoretical value is the denominator, and the actual displayed maximum value is the numerator. The same goes for 4 and a half digits and 5 and a half-digits.
The terms "number of digits" and "number of words" are used to describe the resolution of a multimeter, grouping digital multimeters by the number of words and/or digits they display.
In a three-and-a-half-digit or four-digit digital display, the maximum number of displayed words is 1999, and the resolution is 1/2000 of the measuring range.
Nowadays, the resolution of three-and-a-half-digit digital multimeters can be divided into 3 1/2 digits, 3 3/4 digits, and 3 5/6 digits.
Four-and-a-half-digit or five-digit digital display, the maximum number of displayed words is 19999, and the resolution is 1/20000 of the measuring range.
Currently, the resolution of four-and-a-half-digit digital multimeters can be divided into: 4 1/2 digits, 4 3/4 digits, and 4 5/6 digits.
Compared with "number of digits", "number of words" can more accurately describe the resolution of a multimeter. For some measurements, a 3999-digit multimeter can provide higher resolution.
For example, when measuring voltages of 200V or higher, a 1999-digit multimeter cannot measure 0.1V.
A 3999-digit multimeter can measure voltages up to 399V and display it down to 0.1V. This resolution is the same as that of a 19,999-digit multimeter until the voltage exceeds 400V.
3. Accuracy
Accuracy refers to the maximum error between the measured value and the true value under specific conditions. In other words, accuracy indicates how close the multimeter’s measurement is to the actual value of the signal being measured.
The accuracy of a digital multimeter is usually expressed as a percentage of the reading. The accuracy is expressed as 1% of the reading. If the measured value is 100V,
The actual displayed value may be any value between 99V and 101V. Specifications also include a range of bits (last digit) added to the basic accuracy parameter.
For example, the accuracy is expressed as: ±(1%+2), so if the test voltage is 100V, the actual displayed value will be between 98.8 and 101.2V.
HINT:
When purchasing a multimeter, you should first start with your actual needs.
The accuracy, structure, brand and intelligence of a digital multimeter determine the price difference. The price range of digital multimeters currently on the market
They range from a dozen yuan to tens of thousands of yuan. Therefore, when buying a digital multimeter for what purpose, you must clearly understand your needs before choosing a product.
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