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Lectures 1 and 2:
Welcome to IEE
A practical introduction to Electrical,
Computer and Systems, and Electric
Power Engineering Concepts
Beginning with Voltage, Current,
Resistance, Power, & Diodes
23 May 2017
Introduction to Engineering Electronics
K. A. Connor
1
Prof. K. A. Connor
•
•
•
•
•
•
http://www.rpi.edu/~connor
[email protected]
Office: JEC 6010
Phone: 8552
Secretary: Audrey Hayner in JEC 6003
Info on WebCT – Go to
http://webct.rpi.edu
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Introduction to Engineering Electronics
K. A. Connor
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Course Organization
• Lectures each Monday on a range of topics
involving the use of electronics and other
fundamental concepts in engineering,
particularly in Electrical, Computer and
Systems, and Electric Power Engineering
• 10-11 Labs
• Homework (Not very much)
• All work must be completed in a timely
manner to pass. (S/U grade)
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Introduction to Engineering Electronics
K. A. Connor
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Requirements
• All lectures are mandatory
 Attendance is taken through a variety of activities
 Up to 2 unexcused absences are permitted
• All labs are mandatory
 Make up time is provided should a lab be missed
 Missed labs must be completed promptly. You
cannot be more than one lab behind at any time.
• Signed rules statement is required
 Please read syllabus (online) for policy details
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Introduction to Engineering Electronics
K. A. Connor
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Voltage, Current,
Power and Resistance
• Fundamental concepts




Voltage
Current
Power
Resistance
V
I
W
R
volt
amp
watt
ohm
R1
50
I
V1
R2
V
50
0
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Introduction to Engineering Electronics
K. A. Connor
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Voltage
• Voltage is defined as the amount of work
done or the energy required (in joules) in
moving a unit of positive charge (1 coulomb)
from a lower potential to a higher potential.
Voltage is also called potential difference
(PD). When you measure voltage you must
have two points to compare, one of them
being the reference point. When measuring
the voltage drop for a circuit component it is
sometimes called measuring the potential
across that component.
1 volt = 1 joule/coulomb
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Introduction to Engineering Electronics
K. A. Connor
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Voltage
• Voltage is analogous to pressure. A
battery in an electrical circuit plays the
same role as a pump in a water system.
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Introduction to Engineering Electronics
K. A. Connor
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Current
• Current is the amount of electric charge
(coulombs) flowing past a specific point in a
conductor over an interval of one second.
1 ampere = 1 coulomb/second
• Electron flow is from a lower potential
(voltage) to a higher potential (voltage).
+
e
e
e
e
-
Wire
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Introduction to Engineering Electronics
K. A. Connor
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Current
• For historical reasons, current is
conventionally thought to flow from the
positive to the negative potential in a
circuit.
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Introduction to Engineering Electronics
K. A. Connor
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Power
• Power is the rate at which energy is
generated or dissipated in an electrical
element.
1 watt = 1 joule/sec
Generated
Dissipated
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Introduction to Engineering Electronics
K. A. Connor
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Resistance
• Charges passing through any conducting medium collide with
the material at an extremely high rate and, thus, experience
friction.
R
l
A
• The rate at which energy is lost depends on the wire thickness
(area), length and physical parameters like density and
temperature as reflected through the resistivity

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Introduction to Engineering Electronics
K. A. Connor
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Circuit Diagram
e
Resistor
BA TTERY
Heat
Exchanger
Pump
e
e e e
Current
Water
• Water flow analogy is helpful, if not
totally accurate
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Introduction to Engineering Electronics
K. A. Connor
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Basic Electrical Laws
• Ohm’s Law
V  IR
• Kirchoff’s Voltage Law
V  0
• Kirchoff’s Current Law
I  0
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Introduction to Engineering Electronics
K. A. Connor
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Ohm’s Law
Georg Ohm
• There is a simple linear relationship
between voltage, current and
resistance.
V  IR
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Introduction to Engineering Electronics
K. A. Connor
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Kirchoff’s Voltage Law (KVL)
Gustav Kirchoff
• The sum of the voltage differences
around a circuit is equal to zero.
V  0
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Introduction to Engineering Electronics
K. A. Connor
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Kirchoff’s Current Law (KCL)
Applying
conservation of
current.
• The sum of all the currents entering or
exiting a node is equal to zero.
I  0
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Introduction to Engineering Electronics
K. A. Connor
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Conservation Laws
• Both the KVL and KCL are based on
conservation laws.
 KVL conserves voltage
 KCL conserves current
• Other conservation laws we know about
 Conservation of energy
 Conservation of momentum
• A key to understanding any system is
identifying the relevant conservation laws
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Introduction to Engineering Electronics
K. A. Connor
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Series Combination of Resistors
A
+
Ia
Vr1
+
-
V
+
Vr2
Ib
R1
R2
+
V
+
Req
Vreq
-
-
-
B
• Resistors add in series
REQ  R1  R2 ... RN
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Introduction to Engineering Electronics
K. A. Connor
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Series Combination of Resistors
R1
10Vdc
30ohms
V1
R2
10ohms
0
• The effect of resistors in series is additive.
There is a corresponding voltage drop
across each resistor.
REQ  R1  R2 ... RN
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Introduction to Engineering Electronics
K. A. Connor
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Parallel Combination of Resistors
A
I1
I2
V
Ib
Vr1
+
+
R1
-
I3
+
+
+
R2
-
Vr2
V
Req
Vreq
-
-
I4
B
• The reciprocal or inverse of resistors
add in parallel.
1
1
1
1


...
REQ R1 R2
RN
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Introduction to Engineering Electronics
K. A. Connor
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Parallel Combination of Resistors
10Vdc
V1
R1
R2
30ohms
10ohms
0
• For resistors in parallel, the same voltage occurs
across each resistor and more than one path exists
for the current, which lowers the net resistance.
1
1
1
1


...
REQ R1 R2
RN
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Introduction to Engineering Electronics
K. A. Connor
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Series Combination of Resistors
A
V  Vr1  Vr 2
• KVL:
+
Ia
Vr1
+
R1
-
V
• Ohm’s Law: V  I a R1  I a R2
+
Vr2
R2
-
• Solve for Ia:
B
Ib
+
V
+
Req
Vreq
-
V
V
Ia 

 Ib
R1  R2 REQ
• In General
-
REQ  R1  R2 ... RN
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Introduction to Engineering Electronics
K. A. Connor
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Parallel Combination of Resistors
• KCL:
A
I1
Vr1
+
I2
V
+
R1
I3
-
I4
B
R2
Vr2
• Ohm’s Law:
V
V
V
I1 


R1 R2 REQ
• In General:
Ib
+
V
+
-
-
I1  I 2  I 3
+
Req
Vreq
-
23 May 2017
-
1
1
1
1


...
REQ R1 R2
RN
Introduction to Engineering Electronics
K. A. Connor
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Combination of Resistors
• Series
REQ  R1  R2 ... RN
• Parallel
1
1
1
1


...
REQ R1 R2
RN
• For two resistors, the second
expression can be written as
REQ
23 May 2017
R1 R2

R1  R2
Introduction to Engineering Electronics
K. A. Connor
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Combination of Resistors
• Adding resistors in series always results
in a larger resistance than any of the
individual resistors
• Adding resistors in parallel always
results in a smaller resistance than any
of the individual resistors
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Introduction to Engineering Electronics
K. A. Connor
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Diodes
D1
ANODE
CATHODE
DIODE
• A diode can be considered to be an
electrical one-way valve.
• They are made from a large variety of
materials including silicon, germanium,
gallium arsenide, silicon carbide …
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Introduction to Engineering Electronics
K. A. Connor
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Diodes
• In effect, diodes act like a flapper valve
 Note: this is the simplest possible model of
a diode
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Introduction to Engineering Electronics
K. A. Connor
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Diodes
• For the flapper valve, a small positive
pressure is required to open.
• Likewise, for a diode, a small positive voltage
is required to turn it on. This voltage is like the
voltage required to power some electrical
device. It is used up turning the device on so
the voltages at the two ends of the diode will
differ.
 The voltage required to turn on a diode is typically
around 0.6-0.8 volt for a standard silicon diode
and a few volts for a light emitting diode (LED)
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Introduction to Engineering Electronics
K. A. Connor
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Diodes
D1
D1N4002
VAMPL = 10V
V1
R1
FREQ = 1k
1k
• 10 volt sinusoidal voltage source
0
• Connect to a resistive load through a
diode
 This combination is called a half-wave
rectifier
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Introduction to Engineering Electronics
K. A. Connor
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Diodes
VAMPL = 10V
• Sinusoidal Voltage
V1
FREQ = 1k
10V
5V
0V
-5V
-10V
0s
0.5ms
1.0ms
1.5ms
2.0ms
2.5ms
3.0ms
V(D1:1)
Time
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Introduction to Engineering Electronics
K. A. Connor
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Diodes
D1
VAMPL = 10V
V1
V
D1N4002
V
R1
FREQ = 1k
1k
• Half-wave
rectifier
0
10V
5V
0V
-5V
-10V
0s
0.5ms
V(D1:1)
1.0ms
1.5ms
2.0ms
2.5ms
3.0ms
V(D1:2)
Time
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Introduction to Engineering Electronics
K. A. Connor
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Introduction to Engineering Electronics
K. A. Connor
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Introduction to Engineering Electronics
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At the junction, free electrons from the
N-type material fill holes from the Ptype material. This creates an insulating
layer in the middle of the diode called
the depletion zone.
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Introduction to Engineering Electronics
K. A. Connor
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Introduction to Engineering Electronics
K. A. Connor
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Introduction to Engineering Electronics
K. A. Connor
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Diode V-I Characteristic
• For ideal diode, current flows only one way
• Real diode is close to ideal
Ideal Diode
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Introduction to Engineering Electronics
K. A. Connor
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Introduction to Engineering Electronics
K. A. Connor
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Where Will You See These Concepts Again?
• In later labs in this course
• V, I, R, Kirchoff’s Laws, Combining
Resistors: ECSE-2010 Electric Circuits
• Diode and Transistor Theory and
Electronic Design: ECSE-2050 Analog
Electronics, ECSE-2060 Digital
Electronics and ECSE-2210
Microelectronics Technology
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Introduction to Engineering Electronics
K. A. Connor
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