Transcript BCD Clock - SUNY Broome Community College

BCD Clock
Charles Burger, Nick Hiatt, Setrak Kerjilian, Tom
Neish
Broome Community College
Binghamton, New York
EET 252 Design & Fabrication
Spring 2001
Project Goals
Computer Driven Binary Clock
 Marketable
 Small, Attractive Product
 Low Cost Production

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Heart of the Circuit - 74LS595 IC
8 Bit Shift Register with Output
Latches
• 8 Shift Registers
• 8 Latches
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Heart of the Circuit - 74LS595 IC
Shift Registers
– Row of cascaded flip-flops (21 bits
required)
– Serial Input
– Parallel Output to Latches
– Shifted by Clock
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Heart of the Circuit - 74LS595 IC
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Latches
– Sustains high or low value from Shift
Register
– Triggered by RCK Input
– Outputs and Drives LED’s
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Other Electrical Components

Resistors
– Purpose: To act as Current Limiting
Device

Light Emitting Diodes
– Visual Output Display
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Circuit Design

Circuit Design
– One Chip for each digit (hrs., min., sec.)
– Off-board Connector Location
– Minimize Traces
– Minimize PCB size
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Circuit Design

Breadboard Circuit Check
Why Breadboard First?
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Printed Circuit Board Design

Design Rules
– Trace and Pad
Spacing
– Dead Space
– Component
Spacing
– Placement of
Components
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1
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2
Pre-Fabrication Requirements
Circuit Check
 Parts List
 Jumper Pin-Out
 Drill Plan
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Pre-Fabrication Requirements
Circuit Check

Why do a Circuit Check?
– Ensure that Schematic and PCB Design match
electrically.
– Future Troubleshooting Aid
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Pre-Fabrication Requirements
Parts List
Cost Assessment
Manufacture Preparation
 Repair Information
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Pre-Fabrication Requirements
Jumper Pin-Out
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Assembly Aid
Troubleshooting Aid
Pre-Fabrication Requirements
Drill Plan
Assembly Aid

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Necessary Hardware
 Drilling Location
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Fabrication

Fabrication of Printed Circuit Board
 Fabrication of Chassis
 Fabrication of Cover
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Fabrication of PCB

Mylar
 PhotoResist
 Mylar and Copper
Exposed to UV
Light
 Heat Treatment
 Removal of
Exposed Photo
Resist
00:27Etching of PCB
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Removed
Remaining
PhotoResist
Drilled Holes
Tinned Traces
Trimmed PCB
Filed Edges
LED Spacer
Fabrication of PCB

Insertion and Fitting of Components
 Lead Soldering
 De-Fluxing
 Functionality Test
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Fabrication of Chassis
•Chose Appropriate Size Aluminum Box
•Drilled Holes for DB-9, PBC Mounts, and Cover
•Applied Paint
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Fabrication of Cover

Choice of Cover
– Aesthetically Pleasing
– Colorful
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Testing of Cover
Manufacture
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Cut plexiglass to size
Drilled holes for LEDs
Drilled Mounting Holes
Engraved Lettering
Finally…
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Special Thanks To:
Don McCarty
Mr. Antanakos
and of course,
Mr. DiGiacomo
Mr. De Voe
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