1. FAEN 108: Basic Electronics
ROBERT A. SOWAH, PhD
COMPUTER ENGINEERING DEPARTMENT
UNIVERSITY OF GHANA

2. FAEN 108 Basic Electronics
Introduction
Kirchhoff’s laws
Measurements of voltages, currents and resistances
Resistors, Capacitors and inductors
History of Electronics and impact of electronics in everyday life.
Signals and systems
Modern Technological Advancements: Communications with fiber optics

3. What is Electricity? Everything is made of atoms
There are 118 elements, an atom is a single part of an element
Atom consists of electrons, protons, and neutrons

4. Electrons (- charge) are attracted to protons (+ charge), this holds the atom together
Some materials have strong attraction and refuse to loss electrons, these are called insulators (air, glass, rubber, most plastics)
Some materials have weak attractions and allow electrons to be lost, these are called conductors (copper, silver, gold, aluminum)
Electrons can be made to move from one atom to another, this is called a current of electricity.

5. Surplus of electrons is called a negative charge (-)
Surplus of electrons is called a negative charge (-). A shortage of electrons is called a positive charge (+).
A battery provides a surplus of electrons by chemical reaction.
By connecting a conductor from the positive terminal to negative terminal electrons will flow.

6. Voltage
A battery positive terminal (+) and a negative terminal (-). The difference in charge between each terminal is the potential energy the battery can provide. This is labeled in units of volts.
Water Analogy

7. Voltage Sources:

8. Voltage is like differential pressure,
always measure between two points.
Measure voltage between two points
or across a component in a circuit.
When measuring DC voltage make
sure polarity of meter is correct,
positive (+) red, negative (-) black.

9. Ground

10. Current Uniform flow of electrons thru a circuit is called current.
WILL USE CONVENTIONAL FLOW NOTATION ON ALL SCHEMATICS

11. Measurement is imperfect because of voltage drop created by meter.
To measure current, must break circuit and install meter in line.
Measurement is imperfect because of voltage drop created by meter.

12. Resistance
All materials have a resistance that is dependent on cross-sectional area, material type and temperature.
A resistor dissipates power in the form of heat

13. Various resistors types

14. When measuring resistance, remove
component from the circuit.

17. Resistor Color Code

18. Color code Color black brown red orange yellow green blue violet gray
Resistor values determined by color
Three main bands
1st = 1st digit
2nd = 2nd digit
3rd = # of trailing zeros
Examples
red, brown, black
no zeros = 21 Ohms
yellow, brown, green
= 4.1 Mohm
purple, gray, orange
= 78 kOhms
Capacitors can have 3 numbers
use like three colors
Color
black
brown
red
orange
yellow
green
blue
violet
gray
white
Number 1 2 3 4 5 6 7 8 9

19. Ohm’s Law

20. Prototyping Board Example of how components are
Inserted in the protoboard

21. Capacitance
A capacitor is used to store charge for a short amount of time
Capacitor
Battery
Unit = Farad
Pico Farad - pF = 10-12F
Micro Farad - uF = 10-6F

23. Capacitor Charging

24. Capacitor Discharge

25. Inductance

27. History of Electronics
The history of electronics is a story of the twentieth century and three key components namely:
vacuum tube, (2) transistor, and (3) integrated circuit.
In 1883, Thomas Alva Edison discovered that electrons will flow from one metal conductor to another through a vacuum.
This discovery of conduction became known as the Edison effect.

28. In 1904, John Fleming applied the Edison effect in inventing a two-element electron tube called a diode.
Lee De Forest followed in 1906 with the three-element tube, the triode. These vacuum tubes were the devices that made manipulation of electrical energy possible so it could be amplified and transmitted.

29. History of Electronics
The early history of electronics is closely tied to experimentation of vacuum tube developed by Sir William Crookes.
Wilhelm Konrad Roentgen, discovered X rays in 1895.
In 1897, Ferdinand Braun, a German physicist modified the Crookes tube to make the first oscilloscope, an instrument that produces a visual image of an electric signal.

30. Interest in improving the reception of radio waves led to the invention of the vacuum-tube diode in 1904 by Sir John Fleming, an English electrical engineer, and to the invention of the vacuum-tube triode in 1907 by Lee De Forest, a United States inventor.
The invention of the triode was a key event in the history of electronics, since it was the first electronic amplifier.

31. Vacuum-tube Technology
During World War I there was an increased interest in developing radio and electronics, and by 1920 the development of vacuum tubes and circuits employing them had advanced to the point where their superiority over all other devices used in radio transmitters and receivers was apparent.
Regular commercial radio broadcasting in the United States began in 1920, and the demand for household receivers soon made electronics an important industry.

32. Certain technical limitations in the operation of electron tubes were overcome with the development of the pentode in 1929.
The advances being made at this time helped lead to the development of television; the first regular television broadcasting began in 1936, in London.

33. During World War II, emphasis was placed on the development of electronics for military use.
Radar was greatly improved due to the mathematical contributions from Norbert Wiener and in 1944 the first large electronic digital computer, ENIAC, was built.
The main purpose of the computer was to speed up the calculation of tables of data for aiming artillery.

34. The electronics industry emerged from the war as a major industry.
Its growth following the war continued as television manufacturing entered a boom period and military programs demanded more advanced electronic technology.

35. Transistor Technology
In 1948 William Shockley, John Bardeen, and Walter H. Brattain of Bell Telephone Laboratories developed the first transistor, a forerunner of the bipolar junction transistor.
During the early 1950's the technology was developed to mass-produce transistors. The advantage of semiconductor devices over electron tubes created a demand for techniques to further reduce the amount of space required for electronic components.

36. An important step toward miniaturizing electronic components was the introduction of the integrated circuit in the early 1960's.
The techniques necessary to fabricate such circuits were pioneered by Jack Kirby of Texas Instruments in 1959.

37. Microelectronics
During the 1970's and 1980's the size of the components of integrated circuits continued to be reduced and the number of components that could be produced on each chip grew rapidly.
With increasing miniaturization, the capabilities of the electronic circuits and the speed at which they could perform their functions greatly increased thus reducing the cost of production.

38. Through the 1980's and into the 1990's, the variety of products being built with electronic components increased, and the use of electronic control devices led to greater automation.

39. Microelectronics led to the development of new technologies, such as digital audio recording; to the introduction of new products, such as personal computers; and to the reduction in the size of portable telephones and many other electronic products.

42. History of Electronics

53. Transistor counts

54. The transistor count is the number of transistors on an integrated circuit chip. Transistor count is the most common measure of semiconductor integrated circuit complexity.
As of 2015, the highest transistor count in a commercially available CPU (in one chip) is over 5.5 billion transistors, in Intel's 18-core Xeon Haswell-EP.

55. Moore's Law
According to Moore's Law, the transistor count of the integrated circuits doubles approximately every two years.

56. On most modern microprocessors, the majority of transistors are contained in caches.
In fact, IBM's Storage Controller at 7.1 billion transistors with 480 MB L4 cache in 2015, is bigger than any microprocessor before, on both counts; it is however not a CPU until combined with one (or more) of its companion IBM z13 microprocessor chip.

57. That chip holds the rest of the cache, 64 MB L3 (and the other smaller levels) and processor logic, and while having the same dimensions has only 3.9 billion transistors (near record breaking for a microprocessor on its own).

61. Integrated Electronics (Intel)
Intel Core is Intel's brand name for various mid-range to high-end home and business microprocessors.
These processors displaced the existing mid-to-high end Pentium processors of the time, moving the Pentium to the entry level, and bumping the Celeron series of processors to low end.

62. Identical or more capable versions of Core processors are also sold as Xeon processors for the server and workstation market.
As of 2015 the current lineup of Core processors included the Intel Core i7, Intel Core i5, Intel Core i3, and Core M.

63. Features of Intel Core i7
The 6th generation Intel® Core™ i7 processors deliver a new class of computing with a host of new features to power the next generation of desktops, laptops, and 2 in 1 PCs.

64. Expect lighting fast speeds and peak performance through even the toughest of tasks and games.
The built-in revolutionary Intel® Hyper-Threading Technology allows each processor core to work on two tasks at the same time for smoother multitasking

65. Intel® Iris™ graphics delivers stunning 3D visuals and faster, more advanced video and photo editing.
The ultimate in peak performance for video games with overclocking for your most demanding gaming needs. 

68. Electronic Devices and Systems
Electronics may be defined as the science and technology of electronic devices and systems.
Electronic devices are primarily non-linear devices such as diodes and transistors and in general integrated circuits (ICs) in which small signals (voltages and currents) are applied to them.

69. Circuit Elements
Resistors, capacitors and inductors existed long ago before the advent of semiconductor diodes and transistors, these devices are thought of as electrical devices and the systems that consist of these devices are generally said to be electrical rather than electronic systems.
With today’s technology, ICs are getting smaller and smaller and thus the modern IC technology is referred to as microelectronics.

70. Signals and Signal Classifications
A signal is any waveform that serves as a means of communication. It represents a fluctuating electric quantity, such as voltage, current, electric or magnetic field strength, sound, image, or any message transmitted or received in telegraphy, telephony, radio, television, or radar.

71. Amplifiers
An amplifier is an electronic circuit which increases the magnitude of the input signal. The symbol of a typical amplifier is a triangle as shown below:

72. Amplification
An amplifier can be classified as a voltage, current or power amplifier. The gain of an amplifier is the ratio of the output to the input. Thus, for a voltage amplifier

73. Voltage Amplifier Equivalent Circuit
Amplifiers are often represented by equivalent circuits* also known as circuit models. The equivalent circuit of a voltage amplifier is shown. The ideal characteristics for the circuit of

74. Current Amplifier Equivalent Circuit

75. Ohm’s law V1 I R V2 Current = voltage / resistance I = V / R V = I x R
Definitions
Voltage = potential energy / unit charge, units = Volts
Current = charge flow rate, units = Amps
Resistance = friction, units = Ohms
Example
Voltage drop when current flows through resistor
V1 - V2 = I R V1 R I V2

76. Schematics Symbols represent circuit elements Lines are wires Battery+
Battery
Sample circuit V + I R
Resistor
Ground
Ground voltage
defined = 0

77. Parallel and series resistors
same current flows through all
Parallel
save voltage across all
Series circuit
V = R1 I + R2 I = Reff I
Reff = R1 + R2 +
Note: these points are
connected together I V R1 R2
Parallel circuit
I = V/R1 + V/R2 = V/Reff
1/Reff = 1/R1 + 1/R2 + V R1 R2 I1 I2 I

78. Resistive voltage divider
Series resistor circuit
Reduce input voltage to desired level
Advantages:
simple and accurate
complex circuit can use single voltage source
Disadvantage:
dissipates power
easy to overload
need Rload << R2
Resistive divider
I = Vin/Reff = Vout/R2
Vout = Vin (R2 / (R1 + R2) ) +
Vin R1 R2 I
Vout
New schematic symbol:
external connection

79. Variable voltage divider
Use potentiometer (= variable resistor)
Most common: constant output resistance
Variable voltage divider
Vout = Vin (Rout / (Rvar + Rout) )
New schematic symbol:
potentiometer I
Vout
Vin
Rvar +
Rout I

80. Capacitors Charge = voltage x capacitance Q = C V Definitions
Charge = integrated current flow , units = Coloumbs = Amp - seconds
I = dQ/dt
Capacitance = storage capacity, units = Farads
Example
Capacitor charging circuit
Time constant = RC = t
Vout t
Vin
t = RC
Capacitor charging curve
time constant = RC
New schematic
symbol:
capacitor + V R C I
Vout Q
Capacitor charging circuit
V = VR + VC = R dQ/dt + Q/C
dQ/dt + Q/RC = V/R
Q = C V (1 - exp(-t/RC))
Vout = Vin (1 - exp(-t/RC))

81. AC circuits C R Replace battery with sine (cosine) wave source
V = V0 cos(2 p f t)
Definitions
Frequency f = cosine wave frequency, units = Hertz
Examples
Resistor response: I = (V0/R) cos(2 p f t)
Capacitor response: Q = CV0 cos(2 p f t)
I = - 2 p f CV0 sin(2 p f t)
Current depends on frequency
negative sine wave replaces cosine wave
- 90 degree phase shift = lag
Capacitive ac circuit
90 degree phase lag
V0 cos(2 p f t) R
I =
(V0/R) cos(2 p f t)
Resistive ac circuit
New schematic
symbol:
AC voltage source
V0 cos(2 p f t) C
I =
- 2 p f CV0 sin(2 p f t)

82. Simplified notation: ac-circuits
V = V0 cos(2 p f t) = V0 [exp(2 p j f t) + c.c.]/2
Drop c.c. part and factor of 1/2
V = V0 exp(2 p j f t)
Revisit resistive and capacitive circuits
Resistor response: I = (V0/R) exp(2 p j f t) = V / R = V/ ZR
Capacitor response: I = 2 p j f CV0 exp(2 p j f t) = (2 p j f C) V = V/ ZC
Definition: Impedance, Z = effective resistance, units Ohms
Capacitor impedance ZC = 1 / (2 p j f C)
Resistor impedance ZR = R
Impedance makes it look like Ohms law applies to capacitive circuits also
Capacitor response I = V / ZC

83. Explore capacitor circuits
Impedance ZC = 1/ (2 p j f C)
Limit of low frequency f ~ 0
ZC --> infinity
Capacitor is open circuit at low frequency
Limit of low frequency f ~ infinity
ZC --> 0
Capacitor is short circuit at low frequency
Capacitive ac circuit
V0 cos(2 p f t) C
I = V/ZC

84. Revisit capacitor charging circuit
Replace C with impedance ZC
Charging circuit looks like voltage divider
Vout = Vin (ZC / (ZR + ZC) ) = Vin / (1 + 2 p j f R C )
Low-pass filter
Crossover when f = 1 / 2 p R C = 1 / 2 p t , t is time constant
lower frequencies Vout ~ Vin = pass band
higher frequencies Vout ~ Vin / (2 p j f R C ) = attenuated
Capacitor charging circuit
= Low-pass filter
Vin = V0 cos(2 p f t) R C I
Vout
Low-pass filter response
time constant = RC = t
logVin
Single-pole rolloff
6 dB/octave
= 10 dB/decade
knee
log(Vout)
f = 1 / 2 p t
log( f )

85. Capacitor charging circuit
Inductors
Voltage = rate of voltage change x inductance
V = L dI/dt
Definitions
Inductance L = resistance to current change, units = Henrys
Impedance of inductor: ZL = (2 p j f L)
Low frequency = short circuit
High frequency = open circuit
Inductors rarely used
Capacitor charging circuit
= Low-pass filter
High-pass filter response
Vin = V0 cos(2 p f t) R L I
New schematic
symbol:
Inductor
Vout
logVin
log(Vout)
f = R / 2 p j L
log( f )

86. Capacitor filters circuits
Can make both low and high pass filters
Low-pass filter
Vin = V0 cos(2 p f t) R C I
Vout
High-pass filter
Vin = V0 cos(2 p f t) C R I
Vout
log(Vout)
log( f )
logVin
f = 1 / 2 p t
Gain response
knee
log(Vout)
log( f )
logVin
f = 1 / 2 p t
Gain response
phase
log( f )
f = 1 / 2 p t
Phase response
-90 degrees
phase
log( f )
f = 1 / 2 p t
Phase response
-90 degrees
0 degrees
0 degrees

87. Summary of schematic symbols
Potentiometer
Resistor +
Battery
Potentiometer
2-inputs plus
center tap
Capacitor
AC voltage
source
Inductor
Diode
Ground
Non-connecting
wires
External
connection - +
Op amp

88. Exercise Measure DC voltage from power supply using multimeter
Measure DC voltage from power supply using oscilloscope
Measure DC voltage from battery using multimeter
Measure AC voltage from wall outlet using a multimeter
Measure AC voltage from wall outlet using an oscilloscope
Effective or Root Mean Square Voltage
(Measured with multimeter)
ERMS=0.707xEA E

89. Exercise
Determine the resistance of various resistors of unknown value using the resistor color code
Using the multimeter, compare the specified resistance and measured resistance
Using the multimeter to examine the characteristics of various potentiometers

90. Exercise
Calculate the total current and voltage drop across each resistor shown in Figure 1
Build the circuit in Figure 1 on the prototype board
Measure the total circuit current and voltage drops across each resistor and compare
the calculated and measured values

91. SERIES ELEMENTS
KCL tells us that all of the elements in a single branch carry the same current.
We say these elements are in series.
Current entering node = Current leaving node
i1 = i2

92. Thus, equivalent resistance of resistors in series is the sum
Circuit with several resistors in series:
Find “equivalent resistance” R 2 1
VSS I 3 4  +
KCL tells us same current flows through every resistor
KVL tells us
Clearly,
Thus, equivalent resistance of resistors in series is the sum

93. VOLTAGE DIVIDER
Circuit with several resistors in series
We know I  + V1 R 1
Thus, R 2  +
VSS  + V3 R 3 R 4
and
etc…

94. WHEN IS VOLTAGE DIVIDER FORMULA CORRECT?2 1 V SS I 3 4 - + I R 2 1 3 4 - + V2 + 2 V - + - V I SS 3 R 5 SS 4 3 2 1 V R × + = SS 4 3 2 1 V R × + ≠
Correct if nothing else
connected to nodes
because R
removes condition of 5
resistors in series I 3

95. MEASURING CURRENT
To measure current in a circuit, insert DMM (in current mode) into circuit, in series with measured element.
But ammeters change the circuit. Ammeters are characterized by their “ammeter input resistance,” Rin. Ideally this should be very low. Typical value 1W.
Ideal Ammeter
Real Ammeter ?
Rin

96. Example: V = 1 V: R1= R2 = 500 W, Rin = 1W
MEASURING CURRENT
Potential measurement error due to non-zero input resistance: I I
meas
ammeter R R 1 1 R in _ + _ + V V R R 2 2
undisturbed circuit
with ammeter
Example: V = 1 V: R1= R2 = 500 W, Rin = 1W

97. PARALLEL ELEMENTS Va = Vb
KVL tells us that any set of elements which are connected at both ends carry the same voltage.
We say these elements are in parallel.
KVL clockwise,
start at top:
Vb – Va = 0
Va = Vb

98. Resistors in parallel can be made into one equivalent resistorx
KCL tells us
Iss = I1 + I2 I I 1 2
ISS R R 1 2
The two resistors are in parallel; they have the same voltage
VX = I1 R1 = I2 R2
ground
Iss = VX / R1 + VX / R VX = Iss R1 R2 / (R1+R2)
Generally, Req = (R1-1 + R2-1 + R3-1 + …)-1

99. For resistors in series:
IMPORTANT FACTS
For resistors in series:
Current through Req is equal to the current through each of the original resistors (all have same current)
Voltage over Req is the sum of the voltages over the original resistors
For resistors in parallel:
Current through Req is equal to the sum of the currents through each of the original resistors
Voltage over Req is equal to the voltage over the original resistors (all have same voltage)

100. CURRENT DIVIDER
There is a simple equation for the way current splits between two parallel resistors: x
Remember
VX = I1 R1 = ISS Req I I 1 2
ISS R R 1 2
ground

101. REAL VOLTMETERS
How is voltage measured? Digital multimeter (DMM) in parallel with measured element.
Connecting a real voltmeter across two nodes changes the circuit. The voltmeter may be modeled by an ideal voltmeter (open circuit) in parallel with a resistance: “voltmeter input resistance,” Rin. Typical value: 10 MW
Ideal Voltmeter
Real Voltmeter
Rin

102. Computation of voltage (uses ideal voltmeter)
REAL VOLTMETERS
Computation of voltage (uses ideal voltmeter)
Measurement of voltage (with loading by real voltmeter) R R 1 1 +  - + + - +
VSS
VSS R V R 2 2 2 R in - -
Example:
But if
a 1% error

103. Fiber optics communications

104. Fiber optics
Fiber optic (or "optical fiber") refers to the medium and the technology associated with the transmission of information as light impulses along a glass or plastic wire or fiber.
Fiber optic wire carries much more information than conventional copper wire and is far less subject to electromagnetic interference.

105. Applications of Fiber optics
Optical fiber is used by many telecommunications companies to transmit telephone signals, Internet communication, and cable television signals.
Due to much lower attenuation and interference, optical fiber has large advantages over existing copper wire in long-distance and high-demand applications.

106. Infrastructural development within cities was relatively difficult and time-consuming, and fiber-optic systems were complex and expensive to install and operate.
Fiber-optic communication systems have primarily been installed in long-distance applications and serve communication system backbone, where they can be used to their full transmission capacity, offsetting the increased cost.

107. Since 2000, the prices for fiber-optic communications have dropped considerably.
The price for rolling out fiber to the home has currently become more cost-effective than that of rolling out a copper based network.

108. Since 1990, when optical-amplification systems became commercially available, the telecommunications industry has laid a vast network of intercity and transoceanic fiber communication lines.

109. By 2002, an intercontinental network of 250,000 km of submarine communications cable with a capacity of 2.56 Tb/s was completed.
Though specific network capacities are privileged information, telecommunications investment reports indicate that network capacity has increased dramatically since 2004.