PCB News - teach you to understand circuit diagrams

teach you to understand circuit diagrams

The circuit board factory needs the circuit diagram under the premise of producing the circuit board. The circuit diagram refers to the diagram that uses the circuit component symbols to indicate the circuit connection. Circuit diagram is a kind of principle layout diagram that shows the composition of various components and the relationship between components drawn by physical and electrical standardized symbols for the needs of people for research and engineering planning. From the circuit diagram, you can know the working principle of the components, and provide planning solutions for analyzing performance, installing electronic and electrical products. In the design of the circuit, the engineer can calmly carry out on paper or computer, confirm the perfection before proceeding to the actual installation. Improve through debugging, fix errors, until success. The use of circuit simulation software for circuit-aided design and virtual circuit experiments can improve the work efficiency of engineers, save learning time, and make physical diagrams more intuitive.

1. Read various circuit diagrams according to the order from big to small, from coarse to fine

General circuit diagrams mainly include complete machine or system block diagrams, board or system circuit schematic diagrams, printed circuit board diagrams, and board connection diagrams. These circuit diagrams have their own uses and characteristics, but they also have internal connections. When reading these circuit diagrams, you can read them in the order from large to small, from coarse to fine. This sequence conforms to the general law of people's understanding of things, and practice has proved to be an effective method, which can make beginners avoid many detours.

2, according to the basic circuit program can read the circuit block diagram (system, board or complete machine)

There are several types of circuit diagrams of the whole machine, among which the composition block diagram is the basis of other types of circuit diagrams and also the basis for reading circuit diagrams. The block diagram also includes the simplified block diagram of the whole machine, the detailed block diagram of the whole machine, the block diagram of the block composition, and the system block diagram. Sometimes, the reader may not have complete information at hand, or the various block diagrams mentioned above, or the types of block diagrams are not complete. In order to read the diagram correctly and in-depth, 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 circuit diagram of the whole machine, the block diagram of the whole machine can be drawn. According to the circuit program of the block circuit diagram, the block diagram of the block system can be drawn. According to the circuit program of the system circuit diagram, the system block diagram can be drawn. The circuit composition block diagram does not reflect the specific structure of the circuit, but mainly reflects the function of the circuit, reflects the transformation process of the signal, reflects the connection between the circuits of various levels or systems, and reflects the ins and outs of various signals. In fact, one of the important tasks of looking at circuit diagrams is to study and analyze the content, types, waveforms and their transformation laws of transmitted signals. The process of drawing a block diagram is a practical process of understanding the circuit and a practical stage of analyzing and researching the circuit. It can lay the ideological and material foundation for in-depth understanding of practical circuit diagrams. The block diagram drawn can reflect the reading results and level of readers.

3. Analyze the practical circuit schematic diagram (system, board and complete machine) according to the principle of signal conversion of the whole machine

On the basis of reading the block diagram, it is necessary to further read the specific practical circuit schematic diagram. To truly understand the circuit diagram, you must read it in conjunction with the basic principles of the whole machine, that is to say, analyze what specific circuit is used to complete the signal processing process, and why this circuit is used to complete this function instead of other circuits. .

According to the thickness and size of the circuit function, practical circuit diagrams can be divided into unit circuit diagrams, system circuit diagrams, block circuit diagrams and complete machine circuit diagrams, etc. Due to the increasing level of integration, a large number of unit circuits have entered the integrated chip, so the current analysis of practical circuit diagrams is mainly to analyze system circuit diagrams and block circuit diagrams. In fact, the reading system circuit and the board circuit are mainly reading the integrated circuit, that is, reading the type function of the integrated block, the signal processing process and the function of the lead pin, and the connection between the collector circuits and the integrated circuit. Connection with peripheral circuits or components, etc.

1, determine the direction of the signal processing flow

According to the overall function of the circuit diagram, find out the total input end and total output end of the entire circuit circle, and then the signal processing flow direction of the circuit diagram can be judged. The function of the wireless microphone is to modulate the voice signal to the high-frequency signal and send it out. In the circuit diagram of Figure 1, the microphone BM is the total input terminal, and the antenna W is the total output terminal. From the total input end to the total output end is the direction of the signal processing flow.

2, dividing unit circuit

Generally speaking, transistors, integrated circuits, etc. are the core components of each unit circuit. Therefore, we can decompose the circuit diagram into several unit circuits according to the direction of the signal processing flow with the main components such as transistors or integrated circuits as a sign, and draw a block diagram of the circuit principle based on this. The block diagram helps us to grasp and analyze the circuit diagram.

3. Analyze the DC power supply circuit

The power supply is usually arranged on the right side in the circuit diagram, and the DC power supply circuit is arranged from right to left.