Through the study of this chapter, you will become familiar with and understand the model naming and marking methods of electronic components. Generally, the names of electronic components reflect their types, materials, characteristics, models, production serial numbers, and distinguishing codes, and can indicate the main electrical parameters. The names of electronic components are composed of letters and numbers. And their models and various parameters should be marked on the surface of the components as much as possible. There are three commonly used marking methods:
- Direct Marking Method: Directly printing the main parameters of the component on its surface is called the direct marking method. This method is intuitive and can only be used for components with a relatively large volume. For example, the surface of a resistor is printed with "RXYC-50-T-1K5-+10%(-10%)", which indicates that its type is a moisture-resistant glazed wire-wound adjustable resistor, the rated power is 50W, the resistance value is 1.5 kilohms, and the allowable deviation is ±10%.
- Text Symbol Method: It is mainly used for marking semiconductor devices, and the text symbols used to represent their types and relevant parameters should comply with national standards. For example, "3DG6C" represents a domestic small-power NPN-type silicon triode. The model is 6, and "C" indicates the voltage withstand specification. 1. In this method, the symbol "R" or "Ω" is used to represent ohms, "K" represents kilohms, and "M" represents megohms. The integer part of the resistance value (in Arabic numerals) is written before the symbol, and the decimal part is written after the symbol. 2.Digital Representation Method: The method of using three digits to represent the resistance value of a resistor and using corresponding letters to represent the allowable deviation is called the digital representation method. Among them, in the order from left to right, the first and second digits are the effective values of the resistance, and the third digit is the number of zeros. The unit of the resistance is ohms. For example, the nominal resistance value of "102J" is 10×10² = 1KΩ, and "J" indicates that the allowable error of this resistor is ±5%.
- Color Coding Method: It is a marking method that uses color rings of different colors to represent the nominal resistance value and allowable deviation of a resistor. This representation method is commonly used for small resistors. There are two commonly used color coding methods: the four-color coding method and the five-color coding method.
