A diagram showing circuit connections with circuit element symbols is called a circuit diagram. Circuit diagram is a kind of principle layout diagram drawn with physical and electrical standardized symbols for the needs of research and engineering planning, which shows the relationship between components. The working principle between components can be known from the circuit diagram, which provides a planning scheme for analyzing performance and installing electronic and electrical products. When designing the circuit, engineers can finish it on paper or computer calmly, and then install it after confirming it is perfect. Improve and fix errors through debugging until success. Using circuit simulation software to carry out circuit aided design and virtual circuit experiment can improve engineers' work efficiency, save learning time and make physical drawings more intuitive.
Classification:
The circuit diagram includes schematic diagram, block diagram, assembly diagram and printed board diagram.
(1) schematic diagram, also known as "electrical schematic diagram". This diagram directly reflects the structure and working principle of electronic circuits, so it is generally used for circuit design and analysis. When analyzing the circuit, we can understand the principle of the actual operation of the circuit by identifying the symbols of various circuit elements drawn on the drawings and their connection methods. Schematic diagram is a tool to reflect the working principle of electronic circuits.
② Block diagram (block diagram). Block diagram is a kind of circuit diagram which uses blocks and lines to represent the working principle and composition of the circuit. Fundamentally speaking, this is also a schematic diagram, but in this kind of diagram, there are almost no symbols except boxes and wires. The main difference between it and the schematic diagram above is that all the components of the circuit and their connection modes are drawn in detail in the schematic diagram, while the block diagram simply divides the circuit into several parts according to the function, depicts each part as a box, adds simple words to the box, and illustrates the relationship between the boxes with connecting lines (sometimes arrows). Therefore, the block diagram can only be used to reflect the general working principle of the circuit, while the schematic diagram can not only show the working principle of the circuit in detail, but also be used as the basis for collecting components and making circuits.
(3) Assembly drawing. It is a kind of drawing used for circuit assembly, and the symbols on the drawing are often the physical outline drawings of circuit elements. As long as we connect some circuit components according to the picture, we can complete the assembly of the circuit. This kind of circuit diagram is generally for beginners. According to the different assembly templates, the assembly drawings are also different. The printed circuit board to be introduced below is used in most electronic products, so the printed circuit board is the main form of assembly drawing. When learning electronic knowledge, in order to get in touch with electronic technology earlier, we choose screw orifice as the basic installation template, so the installation drawing becomes another mode.
(4) PCB drawing. The full name of the printed circuit board diagram is "printed circuit board diagram" or "printed circuit board diagram", which belongs to the same kind of circuit diagram as the assembly diagram and is used to assemble the actual circuit. The manufacturing method of printed circuit board is to cover an insulating board with a layer of metal foil, then etch away the unnecessary metal foil, and use the remaining metal foil as the connecting line between circuit components, and then install the components in the circuit on this insulating board, and use the remaining metal foil as the conductive connecting line between components to complete the circuit connection. Because one or both sides of this circuit board are covered with copper skin, the printed circuit board is also called "copper clad laminate". The component distribution of printed circuit board diagram is often very different from that of schematic diagram. This is mainly because in the design of printed circuit board, whether the distribution and connection of all components are reasonable depends on many factors such as component volume, heat dissipation, anti-interference and anti-coupling. The printed circuit board designed by combining these factors is difficult to be completely consistent with the schematic diagram in appearance; In fact, it can better realize the function of the circuit. With the development of science and technology, the manufacturing technology of printed circuit board has made great progress. In addition to single and double panels, there are many panels, which have been widely used in daily life, industrial production, national defense construction, aerospace and many other fields. Among the four circuit diagram forms introduced above, the electrical schematic diagram is the most commonly used and the most important. If you can understand the schematic diagram, you can basically master the circuit principle, draw the block diagram, design the assembly diagram and print the board diagram, which is relatively easy. It is also very convenient to master the schematic diagram and carry out the maintenance and design of electrical appliances. Therefore, the key is to master the schematic diagram.