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Chapter 5 Electronic Circuit Diagrams Introduction • • • • This chapter covers the following topics: Schematic symbols Schematic diagram Breadboarding Schematic Symbols • Represent electrical devices in a schematic diagram for an electric circuit • International Electrotechnical Commission (IEC) – Responsible for keeping symbols current • Removing old symbols • Adding new ones Schematic Symbols (cont’d.) • Symbols may vary between countries – Much standardization exists • Several international standards • American (MIL/ANSI) symbols used in the text • Symbols may differ based on drawing type Schematic Symbols (cont’d.) • Symbols followed with a reference designator : • Used to identify a component • One or two letters followed by a number • One or two letters followed by a number and a letter – Indicates component with several sections tied to a common point Figure 5-1 Architectural electrical symbols. © 2014 Cengage Learning Figure 5-2 Symbols used for an electronics schematic diagram. © 2014 Cengage Learning Schematic Diagram • Basic reference for a circuit • Gives all necessary specifications • Circuit block diagram – Shows how component blocks are connected • Analog schematics appear different from digital schematics Schematic Diagram (cont’d.) • Tight component grouping of analog components – Important to show in schematic diagram • Digital circuits have many common signals – Common signals are labeled – Not every connection is shown as a line Figure 5-6 Label common signals in digital circuits. © 2014 Cengage Learning. Schematic Diagram (cont’d.) • Show entire circuit in as few drawings as possible • Techniques – Group subcircuit components together – Signal flow proceeds from left to right • Input on the left, output on the right – Highest voltage at the top of the drawing Figure 5-7 Signal flows from left to right; voltage potential has highest potential at top. © 2014 Cengage Learning Schematic Diagram (cont’d.) • Techniques (cont’d.) – Signal lines should cross as little as possible – Label components starting at top left • Move down and back to the top, repeating across schematic – Critical leads should be short or isolated from other signals Figure 5-8 Use signal abbreviations rather than draw a maze of lines. © 2014 Cengage Learning. Figure 5-9 Label components starting at the left side and moving top to bottom repeating across the schematic. © 2014 Cengage Learning. Schematic Diagram (cont’d.) • Techniques (cont’d.) : • Clearly indicate external components and connectors • Label IC pins, including power supply inputs • Tie unused IC logic gates or extra subcircuit inputs to the appropriate power supply level – Include any extra components added during the construction process Schematic Diagram (cont’d.) • Variable components – Include an arrow as part of their symbol • Arrows pointing away from a symbol: – Indicate it is giving off energy • Arrows pointing toward a symbol: – Indicate it is receiving energy • Letter symbols used to identify leads Figure 5-10 Schematic symbols for common electronic components. © 2014 Cengage Learning Schematic Diagram (cont’d.) • Ground symbols • Symbol A: chassis or earth ground • Most common ground symbol • Symbol B: chassis ground only Figure 5-11 Ground symbols. © 2014 Cengage Learning. Schematic Diagram (cont’d.) • Crossing lines does not indicate connection • Dots indicate connection occurs Figure 5-12 Schematic drawing lines © 2014 Cengage Learning Schematic Diagram (cont’d.) • • • • Tools to create schematic diagrams Common drafting tools Computer aided design Electronic circuit simulation programs – Multisim – Circuit Wizard Breadboarding • Breadboard : • Platform for building prototype electronic circuit • Essential step to prove a circuit design works • Solderless breadboards – Developed in 1971 – Allow circuits to be assembled and altered quickly Breadboarding (cont’d.) • Virtual breadboarding – Assembling and testing a circuit using circuit simulation programs