1. Electronic Circuit Diagrams
Chapter 5
Electronic Circuit Diagrams

2. Introduction This chapter covers the following topics:
Schematic symbols
Schematic diagram
Breadboarding

3. 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

4. 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

5. 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

6. Figure 5-1 Architectural electrical symbols. © 2014 Cengage Learning

7. Figure 5-2 Symbols used for an electronics schematic diagram
Figure 5-2 Symbols used for an electronics schematic diagram. © 2014 Cengage Learning

8. 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

9. 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

10. Figure 5-6 Label common signals in digital circuits.
© 2014 Cengage Learning.

11. 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

12. Figure 5-7 Signal flows from left to right; voltage potential has highest potential at top. © 2014 Cengage Learning

13. 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

14. Figure 5-8 Use signal abbreviations rather than draw a maze of lines.
© 2014 Cengage Learning.

15. Figure 5-9 Label components starting at the left side and moving top to bottom repeating across the schematic. © 2014 Cengage Learning.

16. 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

17. 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

18. Figure 5-10 Schematic symbols for common electronic components
Figure 5-10 Schematic symbols for common electronic components. © 2014 Cengage Learning

19. 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.

20. Schematic Diagram (cont’d.)
Crossing lines does not indicate connection
Dots indicate connection occurs
Figure 5-12 Schematic drawing lines © 2014 Cengage Learning

21. Schematic Diagram (cont’d.)
Tools to create schematic diagrams
Common drafting tools
Computer aided design
Electronic circuit simulation programs
Multisim
Circuit Wizard

22. 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 or

23. Breadboarding (cont’d.)
Virtual breadboarding
Assembling and testing a circuit using circuit simulation programs or