Physics
Circuit Schematic
A circuit schematic is a diagram that represents an electrical circuit using symbols to illustrate the components and their connections. It provides a visual representation of the circuit's structure and allows for easy analysis and understanding of its operation. Circuit schematics are commonly used in electronics and electrical engineering to design and troubleshoot circuits.
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7 Key excerpts on "Circuit Schematic"
eBook - PDF- Kevin Robinson(Author)
- 2020(Publication Date)
- Focal Press(Publisher)
Often some amount of creative license is employed by the drafter of a schematic diagram, but once the reader has gained a moderate amount of familiarity with the general conventions, interpreting the intended meaning is usually a straightforward matter. Occasionally a bit of research or experimentation may be needed if a schematic has been drafted without sufficient attention to detail, but on the whole this is rare. The simple circuit introduced in pictographic form in Chapter 2, and reproduced here in Figure 7.2a, can be drawn in a more formal fashion as shown in Figure 7.2b. Once the two symbols used to represent the battery and the bulb are known, this schematic representation of the circuit should be easily interpreted. All the informa-tion needed in order to build the circuit is presented. Notice in particular that some Keyboard VCO VCF Amplifier LFO EG Control signal Audio signal CV CV Gate Envelope RATE SHAPE CUTOFF RESONANCE ATTACK RELEASE LFO : Low Frequency Oscillator VCO : Voltage Controlled Oscillator VCF : Voltage Controlled Filter EG : Envelope Generator CV : Control Voltage Circuit Diagrams 97 components, such as the bulb here, have connection points or terminals which are in-terchangeable. It does not matter which way round such a component is connected into a circuit. In other components (such as the battery here) the terminals must be differentiated. The positive and negative terminals of the battery are not generally in-terchangeable in a circuit. Although in this particular case the battery connections could be flipped without altering the circuit this is not generally the case and the orientation of such components in a circuit must be carefully observed. (a) (b) Figure 7.2 Pictographic versus schematic representation of circuit. Schematic Layout Conventions As the circuits being represented get bigger and more complex it is important to make sure that the schematic diagrams drafted to represent them are as clear and consistent as possible.
- Frank R. Spellman, Nancy E. Whiting(Authors)
- 2013(Publication Date)
- CRC Press(Publisher)
A schematic diagram (usually shortened to “schematic”) is a simplified drawing that represents the electrical, not the physical, situation in a circuit. The symbols used in schematic diagrams are the electrician’s shorthand; they make the diagrams easier to draw and easier to understand. Consider the symbol used to represent a battery power supply (see Figure 11.20). The symbol is rather simple and straightforward but is very important; for example, by convention, the shorter line in the symbol for a battery represents the negative terminal. It is important to remember this, because it is sometimes necessary to note the direction of current flow, which is from negative to positive, when examining a schematic. The battery symbol shown in Figure 11.20 has a single cell, so only one short and one long line are used. The number of lines used to represent a battery vary (and they are not necessarily equivalent to the number of cells), but they are always in pairs, with long and short lines alternating. In the circuit shown in Figure 11.19, the current would flow in a coun-terclockwise direction—that is, opposite the direction that the hands of a clock move. If the long and short lines of the battery symbol (symbol shown in Figure 11.20) were reversed, the current in the circuit shown in Figure 11.19 would flow clockwise —that is, in the direction that the hands of a clock move. Ba ttery + – Resistor (R ) Switch open FIGURE 11.18 Open circuit. Ba ttery + – Fuse Resistor (R) FIGURE 11.19 Simple fused circuit. + – FIGURE 11.20 Schematic symbol for a battery. 259 Fundamental Engineering Concepts Note: In studies of electricity and electronics, many circuits are analyzed that consist mainly of specially designed resistive components. As previously stated, these components are called resistors .
eBook - PDF- Chris Schroeder(Author)
- 1997(Publication Date)
- Newnes(Publisher)
2 Schematic Draftin g Schematic diagrams are used to represent graphically the components an d interconnections of electrical circuits . In the past, schematics were drafted b y means of manual drawing techniques . Up until the late 1970s, the only schemati c drafting aids were plastic drawing templates . Other than the use of templates an d new symbols for solid state devices, little had changed for almost 50 years . Engineers usually drew up a rough schematic by hand . The circuit was the n prototyped on a wire-wrap board . Once the circuit was debugged, the draftin g department redrew the schematic and started the PCB layout . Today mos t engineers do their own schematic drafting using CAD tools . This chapter wil l show you how to draft schematics using AutoCAD . The assumption is made that the reader has some knowledge of electroni c schematics and the use of AutoCAD . This chapter starts with a review o f schematic drafting standards and concludes with a tutorial exercise that shows ho w to use AutoCAD for schematic drafting . Introduction to Electronic Schematic s Electronic schematics consist of symbols that represent the individual electroni c parts used in the circuit . These symbols are interconnected with lines that represen t the actual electrical connections . Figure 2-1 shows symbols for the most commo n of all electronic parts, the resistor . On a typical schematic, each symbol represent s an individual part . The symbols are annotated with text . The basic schemati c symbols are highly standardized, since the most common parts such as resistor s and capacitors have been in use for almost a century . Reference Designator s Each symbol is annotated with text that includes a reference designator, fo r example R1 or R2, and a description of the part . In the case of R1 on Figure 2-1 , the description consists of the value (10K or 10,000 ohms) .
eBook - PDF- Chris Schroeder(Author)
- 1996(Publication Date)
- Newnes(Publisher)
These concepts and constructs must be considered and adhered to in order to obtain all the benefits of schematic capture. The assumption is made that the reader has some knowledge of schematic drafting and the use of PC systems. The orientation of this book is towards automotive, computer, and industrial control electronics. Most of the examples in this and subsequent chapters are taken from real world applications. Using Electronic Symbols Electronic schematics consist of symbols that represent the individual electronic parts used in the circuit. These symbols are interconnected with lines that represent the actual electrical connections. Figure 1-1 shows symbols for the most common of all electronic parts, the resistor. On a typical schematic, each symbol represents an individual part. The symbols are annotated with text. The basic schematic symbols are highly standardized, since the most common parts such as resistors and capacitors have been in use for almost a century. During the last two decades there has been an ever accelerating proliferation of complex integrated circuit devices. An early attempt was made by the IEEE (Institute of Electrical and Electronics Engineers) to standardize the representation of these parts with a complex new symbology. This approach was feasible with decoders, counters, and bus-oriented devices such as latches and drivers. The IEEE symbols did not keep pace with the advent of VLSI devices such as communications controllers, microcontrollers, programmable logic, and other devices that sometimes have hundreds of pins. OrCAD SDT provides support for IEEE symbols, but few companies still use them. For the most part, they have been forgotten. Introduction to Schematic Capture 3 Reference Designators Each symbol is annotated with text that includes a reference designator, for example R1 or R2, and a description of the part.
eBook - PDF- Sparrow Consulting(Author)
- 2014(Publication Date)
- Macmillan(Publisher)
Unit 2.4: Construct a three-phase circuit. Unit 2.5: Evaluate the circuit and installation. Unit 2.6: Complete the task by compiling drawings, operating procedures and specifications of the design. 49 Module 2: Design and construct a three-phase circuit Introduction A circuit diagram is a two-dimensional drawing used to represent an electrical circuit. It shows the different components of a circuit as standard symbols, and it shows how they are connected. Circuit diagrams are used for designing circuits and for the construction and maintenance of electrical equipment. Unit 2.1: Electrical symbols and components Electrical symbols are used to show the components of an electrical circuit, and how they are connected together. Symbols may appear in different designs or colours used by the person or company that produces the circuit diagram. To read, interpret and draw a circuit diagram you must know what each symbol represents. Therefore, this unit shows some common symbols used in electrical systems. These symbols are regulated by standards organisations such as the IEC (International Electrotechnical Commission) and may change from time to time as a result of recommendations by users, manufacturers or other interested parties. The standard used is IEC 60617, Graphical Symbols for Diagrams. The commonly used symbols are those used to represent: • Voltage and current (AC and DC). • Resistance . • Inductance. • Capacitance. Power and power supply symbols Table 2.1: Symbols used for power sources Component Symbol Description Cell or battery A cell or battery supplies electrical energy. The larger terminal (left) is positive and the shorter terminal is negative. A battery consists of more than one cell joined together. DC supply DC stands for direct current. It is electrical energy that always flows in one direction. AC supply AC stands for alternating current. It is electrical energy that continually changes direction.
eBook - PDF- Paul Rosenberg, Robert Gordon Middleton(Authors)
- 2004(Publication Date)
- Audel(Publisher)
Chapter 3 Electric Circuits We have learned that an electric circuit is a closed path for current flow. Electricians are concerned with many types of circuits. It has been noted in the first chapter that a series circuit is a circuit that supplies electricity to one or more loads; all devices in a series circuit are connected end-to-end in a closed path, and the same amount of current flows through each device. We are now ready to consider some more facts about series circuits that are of practical importance to an electrician. Picture Diagrams and Schematic Diagrams Figure 3-1 shows a picture diagram of two electric lamps connected in series with a battery. We occasionally use picture diagrams, but we generally work from schematic diagrams. A schematic diagram shows an electric circuit by means of graphical symbols instead of outline pictures. For example, Figure 3-2 shows two schematic dia-grams. Standard electrical symbols are used to represent a battery, a ELECTRON FLOW ELECTRON FLOW BATTERY LAMP LAMP + + + – – – Figure 3-1 Picture diagram of two electric lamps connected in series with a battery. LAMP LAMP BATTERY BATTERY RESISTANCE RESISTANCE – + – + (A) Lamps connected in series. (B) Resistors connected in series. R 1 R 2 Figure 3-2 Schematic diagram. 59 60 Chapter 3 lamp, and a resistor. Next, let us observe that the schematic diagram in Figure 3-2A can be represented by an equivalent circuit, as seen in Figure 3-2B. An equivalent circuit has the same electrical properties as the original circuit, but an equivalent circuit does not serve the same purpose. Let us see what this means. If R 1 and R 2 in Figure 3-2B have the same amounts of resistance as the lamps in Figure 3-2A, and if the batteries in both circuits have the same voltage, it is clear that each circuit will draw the same amount of current.
- Mark Brown, Jawahar Rawtani, Dinesh Patil(Authors)
- 2004(Publication Date)
- Newnes(Publisher)
2 Devices, symbols, and circuits Objectives 9 To understand basic electrical symbols 9 To understand power and control circuits 9 To read electrical drawings. 2.1 Devices and symbols Any electrical drawing representing an electrical installation or a circuit takes the help of specific symbols to represent various electrical devices in shorthand. This provides a quick idea to the reader about a circuit or installation, and is particularly useful while troubleshooting. Therefore, it is important to familiarize oneself with various symbols. Some of the commonly used device symbols are detailed in the following section and in Figure 2.1. 2.2 Electrical circuits Electrical circuits are circuits used to interconnect different electrical equipments together to enable the working of an electrical device. Electrical schematics are commonly classified into power circuit and control circuit. A power circuit consists of the main power device (a motor, a generator, or other power devices) along with heavy power conductors, contactors, protection devices. A control circuit consists of switches, field device contacts, timers, relay coils, relay contacts, protection devices, and light power conductors. 2.2.1 Power circuits Power circuits are required for carrying power to or from heavy electrical equipments like motors, alternators, or any electrical installation. They carry out the following functions 9 Isolation using devices such as isolators, linked switches and circuit breaks. 9 Circuit control using devices such as contactors, motor circuit breakers, etc. 9 Protection against overload and short-circuits using thermal overload relays, electro-magnetic relays, circuit breakers, with releases, fuses, etc. OR OR -4 f~- / --I z i-- Resistance Variable resistor Impedance Winding, coil or choke Current transformer Devices, symbols, and circuits 25 I1,~ Capacitor I I OR Fuse IF----IF-- Battery Instrument shunt I.
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