Electronics Design Laboratory
Lecture #2 Fall 2014
ECEN 2270
Electronics Design Laboratory
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Lab 1: Introduction
• Objectives
– Develop laboratory and circuit design skills and techniques,
perform simulations, prototyping, testing and debugging
• Part A: Laboratory equipment
– Become familiar with electronic laboratory equipment
• Part B: Reverse engineering:
circuit schematics and prototypes
– Gain experience working with
electronic components, circuit
schematics, prototyping boards,
and simulation
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Electronics Design Laboratory
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Proto-board
• Prototype boards are useful for quickly implementing ‘simple’ circuits
• Provides a stable foundation for constructing circuits
• Middle divide is spaced correctly for many common integrated circuits
Example Proto-Board
Internal Connections
• Vertical side columns for power/ground
• Integrated Circuits fit across middle gap
GOOD! clean and
simple. No long
loops and a clean
layout.
BAD! Stray wires,
long loops, messy
setup. This would
be a struggle to
debug!
A badly implemented protoboard circuit can take days to debug.
Spend the time to do things well initially… it will save you time in the long run!
ECEN 2270
Electronics Design Laboratory
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Components, Schematics, and Breadboard Wiring
• A circuit is a collection of interconnected electrical components (devices)
– Circuits are loops, such that charge (electrons) can flow continuously without
beginning or end
• To specify and document electrical circuits, standardized symbols are used for the
devices and the wires that interconnect them.
• Components typically encountered in electronic circuits include
– Batteries
– Resistors
– Capacitors
– Inductors
– Diodes
– Transistors
– Op-Amps
– Various integrated circuits, etc.
Symbols vary, sometimes describe physical shape and
sometimes describe IC function
– Ideal Sources and Sinks
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Electronics Design Laboratory
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Resistors
Characteristics:
• Resistance
• Linear relationship between
voltage and current
• Tolerance
• 1%, 5%, and 10% are Common
• Power rating
• ¼ and ½ most common. Larger
‘power resistors’ available for kW
and higher ratings.
• Other: temperature dependence, …
Example:
( 4 7 ) * 100k = 4.7 MW, +/-5%
ECEN 2270
Electronics Design Laboratory
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Capacitors
Characteristics:
• Capacitance
𝒅𝒗(𝒕)
• 𝒊 𝒕 =𝑪
𝒅𝒕
• Integrates currents
• Types:
• electrolytic
• ceramic, film, …
• Important Parameters
• Voltage rating
• Tolerance
• Equivalent series
resistance (ESR)
Ceramic and Other Caps:
- Two digits assumes pF (x10-12)
22 (assume x10-12) = 22pF
-
Three digits assumes pF with
an additional multiplier
Electrolytic Caps:
- Polarity Sensitive devices!
- Value Written on Side
- Long lead/Color
Stripe/Minus Sign denotes
the negative terminal
47 mF, 35VMAX
negative lead
is on the left
10 x 103 (assume x10-12) = 10nF
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Electronics Design Laboratory
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Diodes
Integrated Circuits (ICs)
Characteristics:
• Voltage, current and power ratings
• V(I) characteristic, forward voltage drop
• Many other: long data sheets
C
C
A
A
ECEN 2270
For most Integrated Circuits…
• A dot/divot/chip/etc indicates pin 1.
• Most ICs number pins top to bottom left then right.
Not all do this! Check with every chip!
• Part number may or may not be on top of chip
• Questions about a particular IC can almost always be
answered by reading the datasheet.
• Googling for the part number, or using a site like
digikey.com are good ways to find data sheets.
• If you know the part number, you can find the
datasheet and answer any questions yourself.
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Rules of Drawing Circuit Diagrams (aka Schematics)
• Diagram must be complete and informative:
– All components and all connections must be shown
– Components
•
•
•
•
Use standard, commonly accepted component symbols
Must have names, use standard naming conventions (e.g. R1, C1, …)
Show values using appropriate units (e.g. W, kW, MW, mF, nF, pF), or part numbers
Placement: horizontal or vertical
– Input and output ports, and connecting wires
• Straight horizontal or vertical lines, do not cross components or text labels
• Connections
Not
Good
Good
good
Connected wires
Better
Wires that cross, but are not connected
(use as few of these as possible)
• All inputs, outputs, and other relevant voltages and currents must have
names (use standard naming conventions, e.g., V1, I1, vout, iout)
– Other miscellaneous info, e.g. comments, author, date, revision, …
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Electronics Design Laboratory
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Rules of Drawing Circuit Diagrams (aka Schematics)
• Follow standard layout
– Power supply wires
• Positive supply voltage (e.g. +VCC, +VDD) is a horizontal line on top
• Ground is a horizontal line at the bottom, or use the ground symbol
• Negative supply voltage (e.g. –VEE, -VSS) is a bottom horizontal line
– Logical direction of signal flow, e.g. inputs on the left, outputs on the right
+VCC
+
+
vin
vout
_
_
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Electronics Design Laboratory
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Example 1: op-amp amplifier
Task: draw circuit diagram of an op-amp amplifier with a gain A = vout/vin = +2.
The amplifier has a single dc supply voltage VCC = 12 V
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Electronics Design Laboratory
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Incomplete: missing supplies
Weird op-amp orientation
Incomplete: input & output not
labeled, components not labeled,
values unknown
?
Non-standard
R1 value
Incomplete:
R2 value?
Not
straight
Where is ground?
Wrong circuit
Upside-down ground and supply
Weird placement of R1, R2
Op-amp not labeled
C1 value?
Unnecessary wire crossings
Some do not like these R symbols
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Electronics Design Laboratory
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Example 1: op-amp amplifier
Inputs on the left
Text labels used to help
group components
Voltage Supply near the top
All components
have names and
values
Wire routed with
as few overlaps
as possible
Outputs on the right
Ground on the bottom
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Electronics Design Laboratory
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Example 1: simulation results
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Electronics Design Laboratory
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Simulating Circuits - LTSpice
•
•
•
LTSpice is on of many ‘Simulation Programs with Integrated Circuit Emphasis’ (SPICE)
Useful for complex circuit simulation. Test before you build!
Many manufacturers pride spice models for their devices
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Electronics Design Laboratory
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