An electronic circuit that controls an external device. Electronic circuit that controls the operation of an external device
Computer structure Answer the test questions: 1) An electronic circuit that controls the operation of an external device is called: a) Adapter (controller) b) Driver c) Bus d) Hard drive 2) A CD designed for repeated recording of new information is called: a) CD-ROM b) CD-RW c) DVD-ROM d) CD-R 3) The system unit includes: a) motherboard, power supply, controllers, communication equipment b) modulator-demodulator, disk drives, controllers, communications and communications equipment c) power supply, modulator-demodulator, disk drives, communications and communications equipment d) motherboard, power supply, memory, controllers 4) The microprocessor is designed to: a) control the operation of the computer and process data b) input and output of information c) processing of text data 5) The clock frequency of the microprocessor is measured in: a) gigahertz b) gigabits c) character table codes d) megabytes 6) Read-only memory is intended for: a) long-term storage of information b) storage of immutable information c) short-term storage of information at the current moment in time 7) Random access memory is intended for: a) long-term storage of information b) storage of immutable information c) short-term storage of information at the current moment in time 8) External memory is intended for: a) long-term storage of information b) storage of immutable information c) short-term storage of information at the current moment in time 9) A set of metal or ceramic disks (pack of disks) coated with a magnetic layer. a) Hard drive b) DVD-ROM c) Floppy disks d) Magnetic tapes 10) What type of memory is characterized by the following method of reading information: Protrusions reflect the light of a laser beam and are perceived as one (1), depressions absorb the beam and are perceived as zero (0 ). a) Operational b) Flash c) Optical d) Hard disk 11) Devices that burn microscopic depressions on the surface of the disk with a powerful laser. a) DVD-ROM b) Monitor c) Video card d) Scanner 12) Internal memory includes: a) Hard disk, optical disks and flash memory b) RAM and permanent c) RAM, permanent and hard drive d) RAM, hard disk and flash memory 13) A type of memory characterized by high performance and limited capacity. a) Internal b) Floppy disk c) External d) Optical 14) The microprocessor is a very large scale integrated circuit (VLSI). The word “ultra-large” refers to: a) the size of the integrated circuit b) the number of electronic components contained in it c) the ultra-high speed of operation 15) What standard set of devices can be connected to a computer using a sound card? a) display, headphones, printer b) scanner, speakers, headphones c) microphone, headphones, speakers d) headphones, speakers, keyboard Answer additional questions: 1. Explain why a computer needs two types of memory: internal and external . 2. What types of optical disks do you know? 3. Which types of memory are built-in and which are removable? 4. Determine the characteristics of your home computer.
Content:Each electrical circuit consists of many elements, which, in turn, also include various parts in their design. The most striking example is household appliances. Even a regular iron consists of a heating element, temperature regulator, pilot light, fuse, wire and plug. Other electrical appliances have an even more complex design, complemented by various relays, circuit breakers, electric motors, transformers and many other parts. An electrical connection is created between them, ensuring full interaction of all elements and each device fulfilling its purpose.
In this regard, the question very often arises of how to learn to read electrical diagrams, where all components are displayed in the form of conventional graphic symbols. This problem is of great importance for those who regularly deal with electrical installations. Correct reading of diagrams makes it possible to understand how the elements interact with each other and how all work processes proceed.
Types of electrical circuits
In order to correctly use electrical circuits, you need to familiarize yourself in advance with the basic concepts and definitions affecting this area.
Any diagram is made in the form of a graphic image or drawing, on which, together with the equipment, all the connecting links of the electrical circuit are displayed. There are different types of electrical circuits that differ in their intended purpose. Their list includes primary and secondary circuits, alarm systems, protection, control and others. In addition, there are and are widely used principled and fully linear and expanded. Each of them has its own specific features.
Primary circuits include circuits through which the main process voltages are supplied directly from sources to consumers or receivers of electricity. Primary circuits generate, convert, transmit and distribute electrical energy. They consist of a main circuit and circuits that provide their own needs. The main circuit circuits generate, convert and distribute the main flow of electricity. Self-service circuits ensure the operation of essential electrical equipment. Through them, voltage is supplied to the electric motors of the installations, to the lighting system and to other areas.
Secondary circuits are considered to be those in which the applied voltage does not exceed 1 kilowatt. They provide automation, control, protection, and dispatch functions. Through secondary circuits, control, measurement and metering of electricity are carried out. Knowing these properties will help you learn to read electrical circuits.
Full-linear circuits are used in three-phase circuits. They display electrical equipment connected to all three phases. Single-line diagrams show equipment located on only one middle phase. This difference must be indicated on the diagram.
Schematic diagrams do not indicate minor elements that do not perform primary functions. Due to this, the image becomes simpler, allowing you to better understand the principle of operation of all equipment. Installation diagrams, on the contrary, are carried out in more detail, since they are used for the practical installation of all elements of the electrical network. These include single-line diagrams displayed directly on the construction plan of the facility, as well as diagrams of cable routes along with transformer substations and distribution points plotted on a simplified general plan.
During the installation and commissioning process, extensive circuits with secondary circuits have become widespread. They highlight additional functional subgroups of circuits related to switching on and off, individual protection of any section, and others.
Symbols in electrical diagrams
Every electrical circuit contains devices, elements, and parts that together form a path for electrical current. They are distinguished by the presence of electromagnetic processes associated with electromotive force, current and voltage, and described in physical laws.
In electrical circuits, all components can be divided into several groups:
- The first group includes devices that generate electricity or power sources.
- The second group of elements converts electricity into other types of energy. They perform the function of receivers or consumers.
- The components of the third group ensure the transfer of electricity from one element to another, that is, from the power source to electrical receivers. This also includes transformers, stabilizers and other devices that provide the required quality and voltage level.
Each device, element or part corresponds to a symbol used in graphic representations of electrical circuits, called electrical diagrams. In addition to the main symbols, they display the power lines connecting all these elements. The sections of the circuit along which the same currents flow are called branches. The places of their connections are nodes, indicated on electrical diagrams in the form of dots. There are closed current paths that cover several branches at once and are called electrical circuit circuits. The simplest electrical circuit diagram is single-circuit, while complex circuits consist of several circuits.
Most circuits consist of various electrical devices that differ in different operating modes, depending on the value of current and voltage. In idle mode, there is no current in the circuit at all. Sometimes such situations arise when connections are broken. In nominal mode, all elements operate with the current, voltage and power specified in the device passport.
All components and symbols of the elements of the electrical circuit are displayed graphically. The figures show that each element or device has its own symbol. For example, electrical machines may be depicted in a simplified or expanded manner. Depending on this, conditional graphic diagrams are also constructed. Single-line and multi-line images are used to show winding terminals. The number of lines depends on the number of pins, which will be different for different types of machines. In some cases, for ease of reading diagrams, mixed images can be used, when the stator winding is shown in expanded form, and the rotor winding is shown in a simplified form. Others are performed in the same way.
They are also carried out in simplified and expanded, single-line and multi-line methods. The way of displaying the devices themselves, their terminals, winding connections and other components depends on this. For example, in current transformers, a thick line, highlighted with dots, is used to depict the primary winding. For the secondary winding, a circle can be used in the simplified method or two semicircles in the expanded image method.
Graphic representations of other elements:
- Contacts. They are used in switching devices and contact connections, mainly in switches, contactors and relays. They are divided into closing, breaking and switching, each of which has its own graphic design. If necessary, it is allowed to depict the contacts in a mirror-inverted form. The base of the moving part is marked with a special unshaded dot.
- . They can be single-pole or multi-pole. The base of the moving contact is marked with a dot. For circuit breakers, the type of release is indicated in the image. Switches differ in the type of action; they can be push-button or track, with normally open and closed contacts.
- Fuses, resistors, capacitors. Each of them corresponds to certain icons. Fuses are depicted as a rectangle with taps. For permanent resistors, the icon may have taps or no taps. The moving contact of a variable resistor is indicated by an arrow. The pictures of capacitors show constant and variable capacitance. There are separate images for polar and non-polar electrolytic capacitors.
- Semiconductor devices. The simplest of them are pn junction diodes with one-way conduction. Therefore, they are depicted in the form of a triangle and an electrical connection line crossing it. The triangle is the anode, and the dash is the cathode. For other types of semiconductors, there are their own designations defined by the standard. Knowing these graphical drawings makes reading electrical circuits for dummies much easier.
- Sources of light. Available on almost all electrical circuits. Depending on their purpose, they are displayed as lighting and warning lamps with corresponding icons. When depicting signal lamps, it is possible to shade a certain sector, corresponding to low power and low luminous flux. In alarm systems, along with light bulbs, acoustic devices are used - electric sirens, electric bells, electric horns and other similar devices.
How to read electrical diagrams correctly
A schematic diagram is a graphical representation of all the elements, parts and components between which an electronic connection is made using live conductors. It is the basis for the development of any electronic devices and electrical circuits. Therefore, every novice electrician must first master the ability to read a variety of circuit diagrams.
It is the correct reading of electrical diagrams for beginners that allows you to understand well how to connect all the parts to get the expected end result. That is, the device or circuit must fully perform its intended functions. To correctly read a circuit diagram, it is necessary, first of all, to familiarize yourself with the symbols of all its components. Each part is marked with its own graphic designation - UGO. Typically, such symbols reflect the general design, characteristic features and purpose of a particular element. The most striking examples are capacitors, resistors, speakers and other simple parts.
It is much more difficult to work with components represented by transistors, triacs, microcircuits, etc. The complex design of such elements also implies a more complex display of them on electrical circuits.
For example, each bipolar transistor has at least three terminals - base, collector and emitter. Therefore, their conventional representation requires special graphic symbols. This helps distinguish between parts with individual basic properties and characteristics. Each symbol carries certain encrypted information. For example, bipolar transistors may have completely different structures - p-p-p or p-p-p, so the images on the circuits will also be noticeably different. It is recommended that you carefully read all the elements before reading the electrical circuit diagrams.
Conditional images are often supplemented with clarifying information. Upon closer examination, you can see Latin alphabetic symbols next to each icon. This way, this or that detail is designated. This is important to know, especially when we are just learning to read electrical diagrams. There are also numbers next to the letter designations. They indicate the corresponding numbering or technical characteristics of the elements.
Hello, friends! Today we will look at one of the stages of designing electrical devices - drawing up electrical diagrams. However, we will consider them very superficially, since much of what is necessary for design is still unknown to us, and minimal knowledge is already necessary. However, this basic knowledge will help us in the future when reading and drawing electrical diagrams. The topic is quite boring, but rules are rules and must be followed. So…
What is an electrical circuit? What are they? Why are they needed? How to compose them and how to read them? Let's start with what kind of schemes exist in general. In order to unify the preparation of technical documentation (and diagrams are nothing more than part of this documentation) in our country, by Decree of the USSR State Committee for Standards dated August 29, 1984 No. 3038, the State Standard (GOST) “Unified Design System” was introduced documentation. Scheme. Types and types. General requirements for implementation”, otherwise known as GOST 2.701-84, which must comply with any manual or automated diagrams of products from all industries, as well as electrical diagrams of energy structures (power plants, electrical equipment of industrial enterprises, etc.). This document defines the following types of schemes:
- electrical;
- hydraulic;
- pneumatic;
- gas (except pneumatic);
- kinematic;
- vacuum;
- optical;
- energy;
- divisions;
- combined.
We will be primarily interested in the very first point - electrical diagrams that are drawn up for electrical devices. However, GOST also defines several types of circuits depending on the main purpose:
- structural;
- functional;
- fundamental (complete);
- connections (installation);
- connections;
- are common;
- location;
- united.
Today we will look at electrical circuit diagrams and the basic rules for their compilation. It makes sense to consider the remaining types of circuits after the electrical components have been studied, and the training approaches the stage of designing complex devices and systems, then other types of circuits will make sense. What is an electrical circuit diagram and why is it needed? According to GOST 2.701-84, a schematic diagram is a diagram that defines the complete composition of elements and connections between them and, as a rule, gives a detailed idea of the operating principles of the product (installation). Such circuits, for example, were supplied in the documentation for old Soviet televisions. These were huge sheets of paper in A2 or even A1 format, on which absolutely all the components of the TV were indicated. The presence of such a scheme greatly facilitated the repair process. Now such circuits are practically not supplied with electronic devices, because the seller hopes that it will be easier for the user to throw away the device than to repair it. What a marketing ploy! But this is a topic for another discussion. So, a schematic diagram of the device is necessary, firstly, in order to have an idea of what elements are included in the device, secondly, how these elements are connected to each other and, thirdly, what characteristics these elements have. Also, according to GOST 2.701-84, the circuit diagram should provide an understanding of the principles of operation of the device. Here is an example of such a scheme:
Figure 7.1 – An amplification stage based on a bipolar transistor, connected according to a common emitter circuit, with thermal stabilization of the operating point. Electrical circuit diagram
However, we are faced with a small problem: we actually don’t know any electronic elements... What, for example, are the rectangles or parallel lines drawn in Figure 7.1? What do the inscriptions C2, R4, +Epit mean? We will begin our examination of electronic components through the lesson and gradually learn the main characteristics of each of them. And we will definitely study the principle of operation of this device with such a terrible name according to its circuit diagram. Now we will study the basic rules for drawing electrical circuit diagrams. In general, there are a lot of rules, but they are mainly aimed at increasing the clarity and understandability of the diagram, so they will be remembered over time. We will get to know them as needed, so as not to immediately fill our heads with unnecessary information that is not yet necessary. Let's start with the fact that each electrical component on the electrical diagram is indicated by the corresponding conventional graphic symbol (UGO). We will consider the UGO of the elements in parallel with the elements themselves, or you can immediately look at them in GOST 2.721 - 2.768.
Rule 1. Serial numbers for elements (devices) should be assigned, starting with one, within a group of elements (devices) that are assigned the same letter position designation in the diagram, for example, R1, R2, R3, etc., C1, C2, C3, etc. .d. Skipping one or more serial numbers on the diagram is not allowed.
Rule 2. Serial numbers must be assigned in accordance with the sequence of arrangement of elements or devices on the diagram from top to bottom in the direction from left to right. If necessary, it is possible to change the sequence of assigning serial numbers depending on the placement of elements in the product, the direction of signal flow or the functional sequence of the process.
Rule 3. Positional designations are placed on the diagram next to the symbolic graphic designations of elements and (or) devices on the right side or above them. In addition, the intersection of the position designation with communication lines, UGO element or any other inscriptions and lines is not allowed. 
Figure 7.2 – To rule 3
Rule 4. Communication lines should consist of horizontal and vertical segments and have the least number of kinks and mutual intersections. In some cases, it is allowed to use inclined sections of communication lines, the length of which should be limited as much as possible. Intersection of communication lines that cannot be avoided is performed at an angle of 90°.
Rule 5. The thickness of the communication lines depends on the format of the diagram and the size of the graphic symbols and is selected from the range of 0.2 - 1.0 mm. The recommended thickness of communication lines is 0.3 – 0.4mm. Within the diagram, all communication lines must be depicted with the same thickness. It is allowed to use several (no more than three) communication lines of different thicknesses to identify functional groups within the product.
Rule 6. Symbolic graphic symbols of elements are shown on the diagram in the position in which they are given in the relevant standards, or rotated by an angle multiple of 90°, if there are no special instructions in the relevant standards. It is allowed to rotate conventional graphic symbols by an angle that is a multiple of 45°, or depict them as mirror images.
Rule 7. When indicating the nominal values of elements (resistors, capacitors) near the symbolic graphic symbols, it is allowed to use a simplified method of designating units of measurement: 
Figure 7.3 – To rule 7
Rule 8. The distance between the communication lines, between the communication line and the UGO element, as well as the edge of the sheet must be at least 5 mm.
To begin with, these eight rules are enough to learn how to correctly draw simple electrical circuit diagrams. In we looked at power sources for electrical circuits, in particular, “dry” cells and batteries, and in Lesson 6 we looked at an incandescent lamp as a consumer of electrical energy. Let's, based on the rules described above, try to create a simple circuit diagram consisting of three elements: a source (battery), a receiver (incandescent lamp) and a switch. But first, let’s give the UGO of these elements: 
Now let’s connect these elements in series, assembling an electrical circuit: 
Figure 7.4 – First circuit diagram
Contact SA1 is called a normally open contact because in its initial position it is open and no current flows through it. When SA1 is closed (for example, this could be the switch we all use to turn on the lights at home), the HL1 lamp will light up, powered by the energy of the GB1 battery, and it will burn until the SA1 key opens or the battery power runs out.
This diagram absolutely accurately and clearly shows the sequence of connecting elements and the type of these elements, which eliminates errors when assembling the device in practice.
That's probably all for today, another terribly boring lesson is over. See you soon!
2. Electronic key management schemes
2.1. General information about control schemes
In power electronic devices and other devices, it is customary to distinguish between the power part and the control system. The power part includes electrical circuits and elements that are directly involved in the transfer of electrical energy from the primary source to the consumer. The power part of the apparatus is essentially a power executive body that determines the main functions of the apparatus.
For the operation of the power elements of the circuit - transistors, thyristors and other devices - it is necessary to apply appropriate control signals to them. These signals are generated by another component of the device - the control system (CS). Unlike the power part, the control system receives, processes and issues information. Therefore, the control system consists mainly of elements and functional units associated with information flows.
The control system of the power electronic device performs the following functions:
generates control signals for power elements of the power unit;
regulates the output parameters of the power unit;
turns on and off the main power units according to a given algorithm;
exchanges information with the external environment.
The structure presented in Figure 2.1 is generalized, including characteristic enlarged functional blocks. In a real device, a significant part of them may be absent or present in an implicit structural or functional form.
Current monitoring and diagnostics of the device is carried out by a unit, the input of which receives signals from sensors of controlled parameters.
The diagnostic monitoring results are sent to the information processing unit (IPU) and then from its output to the memory protective devices. The information processing unit INF can generally connect the entire device with the external environment. For example, it can receive command signals from a microprocessor controller to turn on, turn off and change the operating mode. Typically, these signals are processed or transmitted directly to the spacecraft switching equipment unit. From the information processing unit, signals about the state of the device, its operating modes, reasons for shutting down or tripping protections, etc. can be sent to the microprocessor controller or to the display system.
Exchange with the external environment can be carried out through toggle switches or buttons, and information about the state of the device will be provided by ordinary incandescent signal lamps. However, in order to understand the operating principle of the device, its functions and capabilities, it is necessary to be able to imagine the structure of the control system and its functional units. Moreover, the functional completeness of a node or block does not necessarily have a separate design in the form of a separate board, module, etc.
Since power electronic devices are usually made on electronic keys, according to the principle of their operation, their control systems are discrete. Accordingly, the element base of the control system combines elements of digital and analog technology, which processes continuous signals, such as current or voltage. These signals can then be converted back to pulse signals.
At the same time, they usually try to minimize the level of energy consumption as much as possible. The control system also includes elements and assemblies that provide ongoing monitoring of the state of the device as a whole, diagnostics of failures and control of protective devices.
In Fig. 2.1 in the generalized block diagram some functional blocks are highlighted.
Rice. 2.1. Generalized block diagram of the control system
Sensor block D contains sensors for adjustable and controlled parameters. Since the output parameters are usually regulated, some of the sensors directly enter into the feedback of the control channel. Signals from these sensors are sent to the REG regulator, whose functions include the formation of a law for controlling the elements of the power section. The PFI control pulse generator is a matching device between the inputs of power devices and the output of the regulator. The PFI unit generates control pulses that are directly supplied to the power elements. The regulator signals are low-power signals and do not meet the requirements for control pulses of power devices (thyristors, transistors, etc.). The control pulse generator, a functionally and often structurally complete device, is also called a “driver” (drive). The operation of drivers will be discussed in Chapter 2.3.
Control system components are made of discrete and integrated electronic components, electromagnetic relays, etc. The operation of these elements requires power sources with various parameters. Therefore, the structure contains a block of secondary power supplies for its own needs, also called operational power supplies (IOP), or secondary power supplies (SPS).
To improve weight and size parameters, an IOP structure with a transformerless input is used. In this structure, the alternating voltage of the power circuit is supplied to a rectifier, the output voltage of which is converted by the inverter into an alternating voltage of higher frequency (usually at least 20 kHz). This voltage is then transformed, straightened again and filtered. Transformation and filtering at higher frequencies can significantly reduce the weight and overall dimensions of the IOP.
When powering the IOP from DC power circuits, the DC voltage is also inverted at a higher frequency into an AC voltage, then transformed, rectified and filtered.
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