First, the significance of electronic circuits
It is a circuit diagram for the needs of research and engineering, a graph showing a circuit configuration of a symbol in a drawing convention. It can be known by actual circuit diagram of the circuit. In this way, when we analyze the circuit, you do not have the kind of pondering over and over again, as long as holding a drawing on it. In the design of the circuit, it could easily be on paper or on the computer, and then confirm the actual sound installation, through commissioning, improvement, until successful. We can use more advanced computer-aided design software to the circuit, and even virtual circuit experiment, greatly improving efficiency.
Second, the electronic circuit diagram of classification
Electronic circuit diagram of a commonly encountered are schematic block diagrams, assembly drawings, and printing layout and the like.
1, schematics
It is used to reflect a schematic circuit diagram of the electronic circuit works, also called the "electrical schematics." Such a map because it directly reflects the structure and operating principle of the electronic circuit, it is generally used in the design, analysis circuit. When analyzing circuit, by drawing the identification of the various circuit elements drawn symbols and connections between them, you can understand the actual operation of the circuit. The figure is shown a schematic diagram of a radio circuit.
2, a block diagram (block diagram)
It is a block diagram showing a connection block and configured to represent the working principle and circuit diagram of an overview. Fundamentally, this is a schematic. However, in this drawing, in addition to the connection box and almost no other sign up. And its main difference lies above the schematic diagram drawn in detail all of the circuit components and their connections, while the circuit block diagram simply install function is divided into several parts, each part will be depicted as a block, combined with simple text description in the box, the relationship between the respective blocks with wires (sometimes arrowed connection) between the block. Therefore, a block diagram of the working principle can only be used substantially embodied circuit diagram and shows that in addition to the circuit works in detail, but also can be used as the basis for collecting element, making the circuit. Is a block diagram of the above-described radio circuit shown in FIG.
(C) the assembly of FIG.
It is a circuit for drawing to assemble and use, and often the symbols on the physical shape of FIG circuit elements of FIG. We just follow the drawing on Fig way, some of the suit to be able to connect the circuit components to complete the assembly of the circuit. This is a general circuit diagram for beginners to use.
Depending on the mounting assembly view of the template not the same, most electronic products as occasion, are used in the printed wiring board to be described below, it is the main form of FIG printing plate of the assembly of FIG.
In the beginner electronic knowledge, in order to earlier contact with the electronic technology, we chose the basic installation screw plate as a template, so the installation diagram it into another mode. As shown below:
(Iv) the plate of FIG.
FIG printing plate full name is "printed circuit board map" or "printed wiring board map", which actually belong to the assembly drawing and a circuit diagram of the same class, are used for the actual circuit assembly.
The printed circuit board in a first insulating plate covered with a layer of metal foil, and then the circuit does not require a metal foil etched, the remaining portion of the metal foil as the connecting line between the circuit components, then the circuit element this device is mounted on the insulating plate, the remaining board using a conductive metal foil as the wiring between the components, circuit connection is completed. Since such a circuit board coated on one or both surfaces of a metal is copper, the printed circuit board so called "CCL." Distribution element and the plate of FIG schematic often quite different. This is mainly because, in the design of printed circuit boards, the main consideration of the distribution and connection of all elements is reasonable to consider a volume element, cooling, anti-jamming, anti-coupled and many other factors, the combination of these factors designed printed circuit board , from the outside and is difficult to exactly the same schematics; in fact able to better achieve the functional circuit.
With advances in technology, now printed circuit board production technology has been greatly developed; in addition to the single-sided, double-sided, and multi-panel, has been applied to a large number of daily life, industrial production, national defense, and so many space industry field.
In the circuit diagram of four forms described above, the electrical schematic is the most common and most important, can be read schematics, will grasp the basic principle of the circuit, create diagrams, FIG assembly design, a printing plate that are relatively FIG. easy. Mastered schematics, electrical repairs carried out, the design is also very convenient. Therefore, the key is to master schematic.
Third, the composition of the circuit diagram
A circuit diagram of the main elements of symbols, connection nodes, comment four major components.
Element symbols represent actual circuit elements, and its shape is not necessarily similar to the actual element, or even completely different. However, it generally shows the characteristics of the element, and the actual number of pins of elements are consistent.
It represents the connection wires in the actual circuit, while in the schematic is a line, but in a conventional printed circuit board copper foil but is often not block the line of various shapes, as many radio schematics connecting the printed circuit board are not necessarily in FIG linear, a copper film may be a certain shape.
Nodes represent the mutual connection relationships between several elements or several lead wire. And all nodes connected to the pin element, the wire, no matter how much the number are turned on.
Comments are very important in the schematic, circuit diagram all of the text can be classified as a comment - class. FIG scan will find the above, there are various parts of the circuit diagram comments, which are used to illustrate elements of the model name and the like.
If the role of the circuit do not know, it can first analyze the relationship between the input and output signals of the circuits. The variation signal and the relationship between them, the phase problem is in phase or anti-phase. Circuit form and composition, is an amplifier circuit, oscillation circuit, the pulse circuit or demodulation circuit. Electrical repairs, the staff are to circuit design by analyzing the circuit diagram to understand the function and electrical works, can be handy to carry out the work. As we engaged in the work of the technical staff, first of all have strong basic skills, to be able to carry out an overview of the technical specifications, circuit schematics, and can be divided into functional modules to identify the signal flow, determining element role. To learn to repair electrical equipment and circuit design, each unit circuit to master the principles must be familiar with. May divide functions blocks the whole circuit elements are grouped according to different functions, each function block is formed so that a particular combination of functional elements, such as the basic amplifying circuit, a switching circuit, the waveform converting circuit.
Analysis of the circuit used to grasp several methods, each method suitable circuitry familiar type and analysis steps.
1. First Method AC equivalent circuit shown in an AC equivalent circuit, and then the state of the AC circuit analysis, namely: when the signal input circuit, each link circuit voltage and current is changed according to the law of the input signal, is amplified, oscillation, or clipping limiter, shaping, Kam equal.
2. Method DC equivalent circuit shown an equivalent circuit diagram of DC, DC analysis system parameters of the circuit, the transistor find out the nature of the quiescent point bias and interstage coupling methods. Component analysis of the circuit and the state in which the role. For example: the transistor operation state, such as saturation amplification, the cutoff region, the diode is turned off, or the like.
3. The frequency characteristic of the spectrum analysis mainly to see if the circuit itself has a frequency which it is adapted to process the signal. Rough estimate about its center frequency, the lower frequency band width and the like, for example: various filtering, notch, the resonance frequency selective circuit.
4. The time constant of the primary analysis by the analysis circuit R, L, C, and diodes, properties. The time constant is a parameter reflecting the energy consumption and the accumulation speed of the storage element. If the time constant is different, although it is similar in form and connection, but the role is different, a common coupling circuit, a differentiating circuit, the integrating circuit, the decoupling circuit, peak detector circuit.
Finally, the basic principle of the actual control circuit, according to the active element in the circuit, a step by step manner according to the above analysis, it is not difficult to understand. Of course, to really digest also need to persevere in learning, with a theoretical analysis of the circuit diagram is not laborious.
Circuit diagram definition:
A circuit diagram, is drawn by the electronic device to connect to circuit elements of FIG symbol, which depicts in detail to the various elements and wiring, description of each pin, and a number of detected data.
Schematics, also called the "electrical schematics." Such a map, since it directly reflects the structure and operating principle of the electronic circuit, it is generally used in the design, analysis circuit. When analyzing circuit, by drawing the identification of the various circuit elements drawn symbols, and the connection between them, you can understand the actual operation of the circuit. Schematic A circuit is used to reflect the situation of the working principle of the electronic circuit.
FIG PCB, the circuit board is a map drawing, which details the location of the circuit board traces, and other elements.
See circuit diagram of a first look at the power supply portion, in the case where the circuit is understood what power, AC or DC, single or multiple power supplies and power supply voltage level. After seeing the clear division circuit, the first difference is a digital circuit or an analog circuit, an analog circuit signal acquisition see, clear signal source, radio frequency, audio, various types of sensors, or other instrumentation circuits, signals are AC analysis, DC or pulse, is a current or a voltage-type. Subsequent analysis of the circuit, is demodulated to ascertain the role of amplification, shaping or compensation. See last output circuit, or a modulation drive. Digital circuits mainly functions and effects analysis logic circuit.
To understand the circuit board, it is best to first be able to read its electrical schematic diagram (circuit diagram), to grasp the electronic component and marked way it works, the normal control parameters of some common components and in normal circuit in the role of knowledge and so on, and then on the circuit board (called a printed circuit board) are analyzed to understand the faster it works, and in some cases a need to know.
Molecular circuit module sub-circuit to find the core element (of course, be familiar with this element) to find the amount of electrical contact between the sub-circuit module, and finally the entire input and output circuit or a function.
Whole circuit is a certain function, is composed of each unit circuit, the signal processing branch circuit unit having a certain function, then these circuit branches whole circuit. Look first to find out what the role of the circuit diagram, belongs to the kind of circuit, audio, video, digital, or hybrid circuit, then the corresponding unit circuit knowledge to interpret these circuits, while from the AC signal level DC level analysis, is the basis of the DC link part of the circuit to work, after the AC signal is in the DC circuit in order to give the corresponding normal processing circuit is not good DC state, it is not working properly. Should be analyzed from a frequency level, the gain level of amplifier, signals of different frequencies through the circuit at the time of treatment, due to the non-linear circuit elements, different frequencies have different processing results for different frequencies of the signal amplifier is also different amplification capability, the frequency signal circuit design will require purposeful processing, so as to achieve the desired function on the machine. There is also to analyze the relationship between the relationship between the unit circuit, and a unit circuit input and output. After the AC signal generating circuit and so what changes. In the understanding of the working principle of the leg pieces, to analyze the working principle of the machine, it may also be present between each branch circuit signal cross-linked, for example, line flyback pulse output circuit of the row was used in color television decoding circuit, the presence of horizontal output circuit and the color signal decoding circuit associated with each other, then these branches may be understood to another unit circuit, and then to analyze them.
I think that there are a sequence of questions: for example, high-frequency circuit, should first master the functions and input circuits, output relationship, with the overall grasp, like a caught a bid, because although different circuit, different devices, but their input, output spectrum of relations will not change. Then analyze the basic principles and methods of such transformation functions, specific to the analysis section.
Circuit design is to start by analyzing the circuit schematic, but must first understand the fundamental role required pins and chips, this will help to better understand the working principle of the circuit, so as to apply to its own circuit, it is conducive to cutting and expansion circuit. During the circuit analysis, first a general overview of the circuit diagram, divided into various functional modules, such as power modules, the controller module, the memory module, an audio module, GPRS module. Each module one by one analysis, you can look at last unify a general understanding of the function of the circuit to be achieved. When designing a circuit, preferably the common master unit circuit or the common principle, power module, voltage regulator modules, memory modules, etc., commonly used in the chip, such as: 7805,7812 like.
When the circuit design, to own the circuit to be designed is divided into several modules, which were designed in a different schematics, and finally integration. When the circuit has an input signal, the voltage of the respective basic point is how much, how much current, to have a rough estimate. For an amplifier circuit, R, L, C, and depends on whether the oscillation circuit, an amplifier circuit, shaping circuit or the like.
Analysis of the quiescent operating point of the transistor, the state analysis and the like, the filter capacitor interstage coupling, high-frequency, low frequency circuit. We generally use the low frequency circuit, a high frequency is generally used more communications.
After self-analysis and self-design, it will be on the basic principles of how to understand the circuit and master of their own accumulated experience in designing and debugging the design in the future. Of course, the real proficiency needed to hone ah!
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