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A circuit diagram (electrical diagram, elementary diagram, electronic schematic) is a graphical representation of an electrical circuit. A pictorial circuit diagram uses simple images of components, while a schematic diagram shows the components and interconnections of the circuit using standardized symbolic representations. The presentation of the interconnections between circuit components in the schematic diagram does not necessarily correspond to the physical arrangements in the finished device.〔(Circuit diagrams and component layouts )〕 Unlike a block diagram or layout diagram, a circuit diagram shows the actual electrical connections. A drawing meant to depict the physical arrangement of the wires and the components they connect is called ''artwork'' or ''layout'', ''physical design'', or ''wiring diagram''. Circuit diagrams are used for the design (circuit design), construction (such as PCB layout), and maintenance of electrical and electronic equipment. In computer science, circuit diagrams are useful when visualizing expressions using Boolean algebra. ==Symbols== (詳細はcoil. These wirewound resistors are now used only in high-power applications, smaller resistors being cast from ''carbon composition'' (a mixture of carbon and filler) or fabricated as an insulating tube or chip coated with a metal film. The internationally standardized symbol for a resistor is therefore now simplified to an oblong, sometimes with the value in ohms written inside, instead of the zig-zag symbol. A less common symbol is simply a series of peaks on one side of the line representing the conductor, rather than back-and-forth as shown here. The linkages between leads were once simple crossings of lines. With the arrival of computerized drafting, the connection of two intersecting wires was shown by a crossing of wires with a "dot" or "blob" to indicate a connection. At the same time, the crossover was simplified to be the same crossing, but without a "dot". However, there was a danger of confusing the wires that were connected and not connected in this manner, if the dot was drawn too small or accidentally omitted (e.g. the "dot" could disappear after several passes through a copy machine).〔 "It is good practice to never use a + connection with a dot. Why? The dot can disappear when the schematic is copied for the 12th time." -- ("Notes on Reading Schematics" ) 〕 As such, the modern practice for representing a 4-way wire connection is to draw a straight wire and then to draw the other wires staggered along it with "dots" as connections (see diagram), so as to form two separate T-junctions that brook no confusion and are clearly not a crossover.〔 "We recommend against using a 4-way connection point ... To avoid confusion, use only three-way connections." -- ("Design News Gadget Freak Submission Guidelines" ) 〕〔 "Wires connected at 'crossroads' should be staggered slightly to form two T-junctions" -- ("The Electronics Club: Circuit Symbols" ) 〕 For crossing wires that are insulated from one another, a small semi-circle symbol is commonly used to show one wire "jumping over" the other wire〔〔(【引用サイトリンク】url=http://www.circuitstoday.com/electronic-circuit-symbols )〕〔(Electronics Circuit Symbols )〕 (similar to how jumper wires are used). A common, hybrid style of drawing combines the T-junction crossovers with "dot" connections and the wire "jump" semi-circle symbols for insulated crossings. In this manner, a "dot" that is too small to see or that has accidentally disappeared can still be clearly differentiated from a "jump".〔〔 On a circuit diagram, the symbols for components are labelled with a descriptor or reference designator matching that on the list of parts. For example, C1 is the first capacitor, L1 is the first inductor, Q1 is the first transistor, and R1 is the first resistor (note that this is not written as a subscript, as in R1, L1,...). Often the value or type designation of the component is given on the diagram beside the part, but detailed specifications would go on the parts list. Detailed rules for reference designations are provided in the International standard IEC 61346. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Circuit diagram」の詳細全文を読む スポンサード リンク
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