How To Simply Understand The Basic Method of Circuit Diagram

Although the whole machine is very complex, but learn to understand is not a high thing, through continuous learning and practice, you can learn to read. In fact, when looking at the picture, you can use a variety of ways to look at the picture. Finally, it is necessary to complete several basic tasks of reading the diagram and achieve several basic requirements of looking at the diagram. Here we discuss the basic method of reading circuit diagrams.

1. how to read the picture

1.1. Read various circuit diagrams according to the order from large to small, from coarse to fine

As has been mentioned before, the ordinary circuit diagram mainly includes the whole machine or system block diagram, module or system diagram, printed circuit board diagram and module string diagram. These circuit diagrams have their own uses and unique places, but there are external combinations. When reading these circuit diagrams, you can read them in order from large to small and from coarse to fine. This order is in line with the general law of many people's awareness of things, and practice has proved that it is a useful method of action, which can make scholars take many detunities at the beginning.

The "big" and "thick" refer to the overall structure of the whole machine or system, as well as the main processing process of the signal; The "small" and "fine" refer to specific circuits, components and strings, etc., specifically to the various circuit diagrams mentioned above, the basic order should be the whole machine block diagram D→ system block diagram D→ module schematic diagram D→ system schematic diagram D→ printed circuit board diagram D→ the whole machine string diagram, and finally the schematic diagram. First of all, we must learn to look at the block diagram of the whole machine, to understand which parts (modules or systems) the whole machine is composed of, what kind of processing process is implemented for each small batch of signals, and what combination is between the parts. These problems are understood, and we have a general understanding of the whole machine. On this basis, then to read the block diagram of each system, each module. It is necessary to understand which parts of each system and module are mainly composed of, the main utility of each small batch and the disposal process of the signal, and to understand the relationship between the parts. When these problems are solved, it is clear how the signal flows and how it is handled in the system. After mastering the local block diagram, we can read the corresponding schematic diagram. The schematic is made up of symbols and string lines of meta parts. In the schematic diagram, draw what kind of specific circuit each part is composed of, what utility each component has, detailed signal direction and disposal process, how to achieve the preset requirements. When the local schematic diagram is understood, the office principle of the whole machine will be easy to understand. From then on, read the printed circuit board. This diagram is not about the principle of office, but about how to turn the schematic into a practical machine. It mainly considers the problem of how to place the components better, how to make the strings more reasonable, so that the lines are not staggered, and there is no interference between the components. Assembly according to the drawing to start, maintenance according to the drawing to find suspicious components, to test and judge, to find the cause of the fault. The machine string diagram is mainly used for the assembly and maintenance of the machine, which is drawn on the basis of the schematic diagram and the printed circuit board diagram. After reading the wire diagram of the whole machine, you can figure out the wire relationship between the printed circuit board, or the printed circuit board and the display, buttons, input and output jacks. Therefore, the whole machine string diagram can only be understood after knowing the schematic diagram and printed circuit board diagram.

1.2. according to the basic circuit program can read the circuit block diagram (system, module or machine)

There are several types of circuit diagrams in front of the whole machine, which is composed of block diagrams is the basis of other types of circuit diagrams, and it is also the basis of reading circuit diagrams. The block diagram includes the simplified block diagram of the whole machine, the thorough block diagram of the whole machine, the block diagram of the module composition and the block diagram of the system. Sometimes, the reader's information is not complete, there may not be the above mentioned various block diagram, or the type of block diagram is not complete, in order to accurately and deeply read the diagram, the reader should draw a reference composition block diagram.

According to the basic circuit program, the circuit block diagram can be drawn. According to the circuit program of the whole machine diagram, the block diagram of the module system can be drawn according to the circuit program of the module diagram, and the system block diagram can be drawn according to the circuit program of the system circuit diagram. Circuit composition block diagram does not reflect the specific structure of the circuit, mainly reflects the function of the circuit, reflects the transformation process of the signal, reflects the combination of various levels of circuits or system circuits, and reflects the beginning and end of various signals. In fact, one of the tasks of looking at the circuit diagram is to study and analyze the internal substantive meaning, categories, waveforms and their transformation laws of the transmission signals of the ministry. The process of drawing the block diagram is the practice process of the consciousness circuit, is a practical stage of analyzing and discussing the circuit, and can be used to deepen the understanding of the practical circuit diagram is the basis of stable ideas and things. The block diagram can reflect the final result and level of readers' comprehension.

Whether it is the whole machine module or system circuit, it is the integrated circuit as the center, a chip can complete the function of one or several circuit systems, but it often needs to be equipped with a bit of discrete circuit, discrete circuit diagram is a semiconductor triplet or semiconductor diode as the center. When drawing the block diagram, it is based on the integrated circuit as the core, and several integrated circuit blocks can be combined through the signal co-signed line to form the block diagram of the system, module or the whole machine. Sometimes a tube with three electrodes, a diode circuit, and sometimes a network circuit such as an rlc are also drawn in a box. Because the block diagram can be simple and complex, the internal substance meaning can be different, so the block diagram drawing method is not unique.

Analysis of utility diagrams (system, module and machine) according to the principle of signal transformation of the machine

On the basis of reading the block diagram, it is necessary to further read the specific practical circuit schematic. To truly understand the circuit schematic, it is necessary to read the basic principles of the machine, that is, to analyze what specific circuit is used to complete the signal processing process, and why this circuit is used to accomplish this function, rather than using other circuits.

According to the thickness and volume of the circuit function, the practical circuit diagram can be divided into unit circuit diagram, system circuit diagram, module circuit diagram and machine circuit diagram. Because the integration level is increasing day by day, a large number of unit circuits have entered the integrated chip, so far the analysis of practical circuit diagram is mainly to analyze the system circuit diagram and the module circuit diagram. In fact, to read the system circuit and module circuit is mainly to read the integrated circuit, that is, to read the type function of the integrated block, the signal processing process and the function of the lead foot, but also to read the combination between the collector circuit, the combination of the integrated circuit and the peripheral circuit or component.

In order to read the circuit diagram of the video disc without difficulties, the reader should have a certain basic knowledge, with the analog electronic circuit, digital electronic circuit, logo basic knowledge, optics and electrotechnics and other basic knowledge of the main surface, master the basic office principle of the machine and circuit program, signal processing methods and transformation laws; It should also have extensive practical experience, know the name, model, specification, and value of common and typical components, especially understand the basic capability of commonly used integrated circuits. Without these basic conditions, reading the circuit diagram of the whole machine will encounter greater difficulties.

2. look at the module circuit diagram of the method step

In general, a whole machine is composed of how many printed circuit boards, printed circuit boards can be large or small. The circuit contained on each printed board is often drawn on a circuit diagram. Therefore, a whole machine circuit diagram is often composed of how many modules circuit diagram, read each module circuit diagram, you can read the whole machine circuit diagram, each module circuit diagram covers one or several circuit systems, the complexity of large module circuit diagram is almost the same as the usual small and medium-sized screen TV circuit diagram. Although the circuit is more complex, various module circuits complete different functions, but they have rules to follow, can be read in accordance with a certain way.

In order to read the circuit diagram less detours, we should use accurate reading methods and steps. Generally, the method of outer encirclement and from the outside in is adopted. By adopting the method of joining inside and outside, combining before and after, and breaking step by step, all circuit diagrams can be read more easily. The specific methods and steps of looking at the map can be summarized in three sentences and three steps: starting from the periphery and choosing the entrance; Open the gap, combine before and after; Not easy to solve the place of analysis, put in the end.

2.1. intuitive start, choose the entrance

That is to say, first look at the most intuitive and easy-to-read components and circuits at the edge of the circuit as the entrance to the reading diagram. From these peripheral recognisable components, a number of circuits or integrated blocks can be found along the signal line (possibly in the opposite direction of the signal flow).

2.2. open the gap, combined before and after

No matter what kind of circuit diagram there is a little bit of vulnerability to read. The complexity and difficulty of each local circuit are always a little different, or the graphics and symbols of some meta components are not the same as those of ordinary meta components, these places are vulnerable links in the interior of the reading diagram, are easy to read links, and they can be used as the inner break of the reading diagram. These places can be selected as the breaking mouth of the reading diagram, after opening the gap, it can be quickly combined forward, after, left and right, and it is suitable for the first step method, and it can read a lot of circuits.

As long as the reader is in mind, there will always be many links in the circuit diagram that the reader already knows clearly, and the capture of it can quickly open the gap of looking at the diagram and progress to the depth. The most intuitive and easy to read inner link is the integrated circuit, especially some large-scale integrated circuits, their leading feet are more than 40, more than 100, very eye-catching in the diagram, the plotter often put them in the core or surface position of the circuit diagram. Then, with these integrated circuits as the core to expand outward, the heart to find a lot of circuits. There is a prerequisite for the integrated circuit as the internal breaking port demand, be sure to know the specific cell number of these integrated circuits, know the main invitation function of the model integrated circuit, know the name and use of the main extraction foot, otherwise it will bring a lot of inconvenience to the reading of the diagram. Sometimes the reader already knows most integrated circuits clearly, some individual integrated circuits are unfamiliar, and the function of the unknown integrated circuit can be expected according to the composition block diagram and the combination before and after.

There is also a point in the circuit diagram that is easy to read and easy to remember, and it can also be used as a break in the circuit. For example, the Chinese character deed, the outer letter deed or the reduced word shown in the figure, a close and easy-to-read graphic symbol of the meta component, some adjustable resistors or potentiometers, etc. In order to be able to use these breaks easily and without difficulties, the reader should have a clear understanding of the physical meaning of various foreign letters and abbreviations, have a certain foreign language foundation (usually English), the reader should know clearly a few professional terms and abbreviations commonly used in reading and listening facilities; The reader should know clearly the functions, parameters and indicators of these components. A wide range of readers' knowledge is helpful in reading the picture, and the reader should have some useful common sense to remember.

2.3. not easy to solve the analysis of the place, in the end

Through the above two-step reading process, most of the internal essence of the circuit diagram can be understood. However, there will be parts of the circuit that are not yet understood or not well understood. The third step can be used specifically to encircle and suppress places that are not easy to solve. This is not easy to solve the local part of the picture, but also the final step of the picture. The reader can break the circuit that is not easy to solve through various methods or by hand and eye.

On the practical circuit diagram, the places that are not easy to understand are often shown in two places, one is the signal flow disposal process inside some integrated circuits, because these internal substantive meanings are not understood, so the external lead foot function can not be understood; The other is some peripheral discrete component circuit, can not solve the purpose of setting the circuit, do not know the signal processing process. For these local circuits that are not easy to solve, according to the block diagram of the whole machine, according to the function and combination of each local circuit, after thinking law analysis, try to explore the function and signal process analysis methods, you can always understand these local circuits that are not easy to solve.

In fact, there is too much information available to read and use on the circuit diagram, and the synthesis, analysis, and discussion of the appropriate readers will be able to understand the whole diagram. The actual situation of each individual is different, the way of looking at the picture and judging may be slightly different, and the steps of looking at the picture are not ten percent unchanged. Electronic technology advances rapidly, and manufacturers often develop new circuits or circuits with new functions, and even circuit programs are more unusual. You can flexibly complete the drawing office on the basis of the above basic thinking clues.

3. look at the method and requirements of integrated circuit diagram

The general machine uses a variety of models, functions of integrated circuits (ics), and several large-scale or very large scale integrated circuits as the center, suitable for other integrated circuits and discrete parts circuit, composed of the whole machine circuit. These central-utility integrated circuits may include the functions of one or more system circuits. The circuit diagram of the whole machine, the module circuit diagram and the system circuit diagram are all based on the circuit diagram of the integrated circuit. How should I look at the integrated circuit diagram? See what the inside substance means? What requirements should be met? The following is a brief summary.

Look at the method and internal significance of the integrated circuit diagram

Looking at the method of integrated circuit diagram, it can be considered appropriate to use the above three sentences and three steps; It can also be integrated circuit as the core, on the basis of the signal path in the chip, to combine and expand outside the block, and then establish the combination between the integrated blocks, and finally master the whole situation: mind ~ and details; It can also be joined in several ways to look at the map accordingly.

When looking at the integrated circuit diagram, what should be the main internal significance? It can be summarized in the following four sentences: function type, signal flow, internal and external combination, and pin function.