Circuit Diagram Recognition 2-Diagram Recognition Methods for Analog Circuits

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Circuit Diagram Recognition 2-Diagram Recognition Methods for Analog Circuits [Copy link]

(Special note: The pictures in this article are only analog circuit diagrams. There is no corresponding relationship between the picture position and the text in the corresponding position. Please understand!)

1. Key points for reading pictures1. Circuit composition

Analog circuit diagrams are made of various graphic symbols and text symbols of components, such as resistors, capacitors, inductors, transistors, integrated circuits and other components. To understand the electronic circuit diagram of an electrical device, you must first understand what electronic components are used in the diagram, and what are the structures, functions and characteristics of these components. Transistors and integrated circuits are the most commonly used in circuit diagrams, so you must understand the input and output characteristics of transistors, as well as the conditions for working in the amplification area, cutoff area and saturation area, the pins and functions of integrated circuit chips, etc. You should also understand the functions and characteristics of some sensitive components (such as thermal components, humidity components, gas components, photosensitive components, etc.). Master the working characteristics and working conditions of all components in the diagram to provide convenient conditions for reading circuit diagrams.

2. The principle of "easy first, difficult later, local first, overall later, and gradual deepening"

Diagram reading should start with relatively simple local circuit analysis, and then proceed to overall circuit analysis. In the process of reading diagrams, attention should be paid to the application of comprehensive knowledge, and gradual deepening. The deeper the understanding of basic circuits and the more solid the mastery, the easier it will be to understand complex circuit diagrams. Through repeated training and practice, and gaining certain experience, the ability to read diagrams will gradually improve.

2. Methods of Recognizing Drawings1. Compare drawings and objects

Before looking at the analog circuit diagram, read the manual of the electrical equipment first to understand the purpose and safety precautions of the equipment, and the functions of various switches, knobs, indicator lights, and instruments in the equipment. Then, find the corresponding graphic symbol positions in the circuit diagram in combination with the actual objects, so as to understand which part of the circuit they belong to, what their functions are, and what control functions they have. In this way, you can roughly understand the overall situation of the circuit and prepare for further detailed and in-depth reading of the diagram. Some manuals provide block diagrams. By reading the block diagram, you can roughly understand what parts the entire circuit is composed of and the relationship between the parts, so that you can roughly know the composition, function and purpose of the circuit. 2. Break the whole into parts and analyze step by step. No matter how complex the analog circuit is, it can be decomposed into several unit circuits. In analog circuits, it can generally be divided into several parts such as input circuit, intermediate circuit, output circuit, power supply circuit, auxiliary circuit, etc. Each part can be decomposed into several basic unit circuits, and the unit circuit is composed of various components. You can also use the method of drawing a block diagram to decompose the whole circuit, divide the circuit into several unit circuits according to their functions, find out the connection between them, clarify the role of the components in each unit, and thus figure out the function of each unit circuit, and then figure out what kind of relationship exists between the unit circuits, so as to have a complete understanding of the entire circuit.

3. From static to dynamic

In analog circuits, various transistors and integrated circuits are the core of the circuit, and they need to establish a static working point in their work to achieve the amplification of AC signals. In order to further understand the working principle of the circuit, the DC equivalent circuit method and the AC equivalent circuit method can be used when analyzing the diagram to perform static and dynamic analysis of the circuit.

The DC equivalent circuit method is to determine the working state of each level of the amplifier circuit under the action of the DC power supply when the input signal is zero. In fact, it is to find the DC path and determine the bias current and voltage of each level of the circuit in static state.

The AC equivalent circuit method is to determine the AC signal path and working state of the circuit when the input signal is not zero.

It should be noted that when using the equivalent circuit analysis method, special treatment should be given according to the properties of the components. For example, when the circuit contains capacitors and inductors, the capacitor has the function of "isolating DC and passing AC", and the inductor has the function of "isolating AC and DC". When performing DC equivalent circuit analysis, DC signals cannot pass through capacitors, and the capacitor is equivalent to an open circuit. However, DC signals can pass through inductors, and the inductor is equivalent to a short circuit (it only acts as a conductor), which simplifies the circuit and facilitates the analysis of the circuit.

When using the AC equivalent method for analysis, the frequency of the input signal should be considered. When the signal frequency is different, the capacitive reactance and inductive reactance presented when the signal passes through the capacitor and inductor will be different, that is, the blocking effect on the AC signal will also be different, and the characteristics and functions of the circuit will also be different. When the input signal contains multiple frequency components, some components allow high-frequency signals to pass through, but prevent low-frequency signals from passing; some are just the opposite. This depends on the specific parameters of each component in the circuit. Some circuits are similar in form, but have completely different functions and characteristics. The important reason is that the circuit parameters are different. Therefore, when reading the diagram, we should not only look at the position of the components in the diagram, but also their parameters. Different parameters have different functions and effects.

4. Comprehensive analysis and comprehensive understanding

Finally, each unit circuit should be connected according to its function and signal flow for comprehensive analysis. Start from the input end of the circuit diagram and gradually connect it to the output end, clarify the signal transmission process and changes that occur, and analyze the relationship between the output and input of the front and back stages of the circuit, so as to have a complete, comprehensive and correct understanding of the principle and function of the entire circuit.

zhao5901830

Sofa, great, thanks for sharing.