Download Ch 5 Notes ppt

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