Transcript Drawings

Drawings
The Drawing Set
Design Drawings
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System Block Diagram
Circuit Design Sketch
Packaging Plan
Working Schematic
Breadboard Drawing
PC Board Design Layout
PC Board Artwork
Electronic Project Design and Fabrication 4th edition, Ronald Reis ( page 76)
The Drawing Set
(Continued)
PC Board Fabrication Drawing
PC Assembly Drawing
Sheet Metal Drawing
Wiring Diagram
Final Packaging Drawing
Electronic Project Design and Fabrication 4th edition, Ronald Reis ( page 76)
The Design Drawings
System Block Diagram
Electronic Project Design and Fabrication 4th edition, Ronald Reis ( page 60)
Circuit Design Sketch
Electronic Project Design and Fabrication 4th edition, Ronald Reis ( page 61)
Packing Plan
Electronic Project Design and Fabrication 4th edition, Ronald Reis ( page 61)
Introduction to Schematics
ANSI and IEEE
Define accepted practices and symbols
for schematic and electrical diagrams.
Most CAD program conform to these
standards.
Schematic symbols are covered by
(ANSI Y32.2)
Standard Symbols
Designators
Resistor - R
Switch - S
Transformer – T
Transistor - Q
IC – U
Crystal – Y
Capacitor – C
Diode – D
Fuse – F
Relay – K
Coil/Inductor – L
Microphone – MK
Protel places the proper designator on all parts for you.
Layout Considerations
If a schematic is large, split the
schematic into functional sections, each
on a separate page, making sure to
properly label connection ports.
Layout should be arrange to develop
from the top to bottom and from left to
right as the signal flows
Layout Considerations
(continued)
Voltages should be clearly marked.
Ground symbols should always be
drawn below the line.
Proper Signal Flow Example
INPUTS
Outputs
Higher Potential
Lower Potential
Layout Considerations
(continued)
All connecting lines are either vertical or
horizontal.
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There are a few exceptions:
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Bus connections
Flip flops
Bridge Rectifiers
Layout Considerations
(continued)
Similar circuits should be drawn
uniformly.
Common circuits should be drawn
according to accepted conventions.
Example
Non-Standard Schematic
Example
Non-Standard Schematic
Standard Schematic
Layout Considerations
(continued)
When identifying values of resistors,
capacitors or inductors:
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Use proper unit prefixes
 p for Pico
 u for Micro
 m for milli
 K for Kilo
 M for Mega
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For resistors, ohms is implied and should not be
used.
Layout Considerations
(continued)
Parts should be numbered starting from
the upper left hand side of the
schematic to the lower right hand side.
This method makes it very easy to
locate parts on the schematic.
Part Numbering Example
Layout Considerations
(continued)
Short dashed lines indicate mechanical
interconnects.
Each schematic should have a filled in
title block.
Layout Considerations
(continued)
Lines should be drawn with the minimum of
crossovers and joggles.
Junctions of 3 or more wires should be
marked with a dot to indicate a connection.
No dot, no connection.
Lines between components should take the
shortest path.
Example of Crossover and
Joggles
Connections and Dots
What’s Wrong With This
Picture?
Improved Schematic