Common items of equipment and principles for selecting a multimeter
A digital multimeter is currently the most commonly used type of digital instrument. Its main characteristics are high accuracy, strong resolution, complete testing functions, fast measurement speed, intuitive display, strong filtering ability, low power consumption, and easy portability. Since the 1990s, digital multimeters have been rapidly popularized and widely used in China, becoming an essential instrument for modern electronic measurement and maintenance work, and gradually replacing traditional analog (i.e. pointer) multimeters.
Digital multimeter, also known as Digital Multimeter (DMM), has a wide variety of types and models. Every electronic worker hopes to have an ideal digital multimeter. There are many principles for choosing a digital multimeter, and sometimes it may even vary from person to person. But for handheld (pocket) digital multimeters, they should generally have the following characteristics: clear display, high accuracy, strong resolution, wide testing range, complete testing functions, strong anti-interference ability, relatively complete protection circuit, beautiful appearance, generous appearance, easy operation, flexibility, good reliability, low power consumption, easy portability, moderate price, and so on.
The main indicators, display digits, and display characteristics of a digital multimeter
The display digits of a digital multimeter are usually 3 1/2 to 8 1/2 digits. There are two principles for determining the display digits of a digital instrument: first, the digits that can display all digits from 0 to 9 are whole digits; The second point is that the numerical value of the fractional digit is based on the highest digit in the maximum displayed value as the numerator. When using full scale, the count value is 2000, indicating that the instrument has three integer digits. The numerator of the decimal digit is 1, and the denominator is 2, so it is called 3 1/2 digits, pronounced as "three and a half digits". Its highest digit can only display 0 or 1 (0 is usually not displayed). The highest digit of a 3/3 digit multimeter can only display numbers from 0 to 2, so the maximum displayed value is ± 2999. In the same situation, it is 50% higher than the limit of a 3 1/2 digit digital multimeter, especially valuable for measuring 380V AC voltage.
Popular digital multimeters generally belong to handheld multimeters with a 3 1/2 digit display. Digital multimeters with 4 1/2 and 5 1/2 digits (less than 6 digits) are divided into handheld and desktop types. More than 6 1/2 digits mostly belong to desktop digital multimeters.
The digital multimeter adopts advanced digital display technology, which displays clearly and intuitively, and reads accurately. It not only ensures the objectivity of the reading, but also conforms to people's reading habits, and can shorten the reading or recording time. These advantages are not possessed by traditional analog (i.e. pointer) multimeters.
