•
ELECTRONICS ENGINEERING
-Basic Electricity, Magnetism and Circuits
•
•
•
An invisible force that can produce heat,
light, and motion.
The force for _________ is an attraction or
repulsion between electric charges.
•
The basic form for a quantity of electricity.
•
The closed path for the movement of
charges.
•
Two basic particles of electric charge.
•
_______ is the smallest amount of electric
charge having the characteristic called
negative polarity.
•
•
•
The proton is a basic particle with
________.
Is it true or false that the neutral condition
means equal positive and negative
charges?
The smallest particle of the basic
elements that form solid, liquids, gases
we know as physical substances.
•
Central mass of an atom
•
Proton is _______ times heavier than
an electron.
Electrons that can move freely from one
atom to the next.
Electrons that can move easily from
atom to atom in a material.
•
•
•
The best conductor.
•
A material with atoms in which the
electrons tend to stay in their own
orbits.
An insulating material and also can
store electric charges.
A material that conducts less than the
metal conductors but more than the
insulators.
Practically all transistors are made of
_________.
•
•
•
Electricity
Motion
Electric
Charge
Circuit
Electron and
Proton
Electron
Positive
Polarity
•
•
•
A group of two or more elements.
•
The smallest unit of a compound with
the same chemical characteristics.
•
Atomic number of oxygen.
•
In 1913, ________ proposed our
present planetary model of the atom
A new idea of nuclear atom was
developed by _________.
•
True
•
Atom
•
•
1840
Free electrons
Conductor
Silver
Insulator
Dielectric
This gives the number of protons or
electrons required in the atom for
each element.
Atomic number of hydrogen is
______.
The planetary electrons are in
successive shells.
Maximum electrons in Q shell.
•
____ Shell is the closest to the
nucleus.
The number of electrons in an
incomplete outermost shell.
A completed outer shell has a valence
of _______.
•
•
Carbon has a valence of __.
•
The number of outer electrons is
considered __________, as these
electrons are in addition to the stable
shells.
__________ indicate magnetic
properties of atom.
_________ is electrically neutral
without any net charge.
Semiconductors
•
Silicon
The quantum theory of radiation was
developed by ________.
•
•
•
Elements
•
•
Atom
Neutron has a mass same as a
_______.
_________ has a positive charge of a
hydrogen nucleus.
Proton
Proton
Charge of electron, in orbital shells
0.16 x 10-18 C,
negative
•
Charge of proton, in nucleus.
0.16 x 10-18 C,
positive
Compound
•
Charge of neutron, in nucleus.
Molecule
•
Mass of electron, orbital shells.
8
•
Mass of proton, in nucleus.
•
Mass of neutron, in nucleus.
•
Mechanical force of attraction or
repulsion between charges is the
fundamental method by which
electricity makes itself evident.
4
•
8
Molecule
A group of two or more atoms.
•
•
Nucleus
Defined as a substance that cannot be
decomposed any further by chemical
action.
Greek word that means a particle too
small to be subdivided.
Semiconductors have _____ electrons
in the outermost ring.
____ Electrons in the outside ring is a
stable structure.
Niels Bohr
Lord Rutherford
Max Planck and
Albert Einstein
•
Value of a coulomb.
Atomic Number
•
The analysis of static charges and
their forces.
1
•
The symbol of electric charge.
K, L, M, N, O, P, Q
•
A French physicist who measured the
force between charges
8
•
A dielectric with positive electric
charge of 2C has 12.5 x 1018 electrons
added. What is its charge then?
An American physicist who measured
the extremely small force of electron
and proton.
One coulomb is equivalent to
__________ electrons.
__________ refers to the possibility of
doing work.
The result of work done in separating
electrons and protons.
A measure of work needed to move
an electric charge.
K
•
Electron Valence
Zero
•
4
•
•
Positive Valence
•
Subshells
Neutron
•
One volt equals to ___________
None
9.108 x 10-28 g
1.672 x 10-24 g
1.675 x 10-24 g
Static Electricity
6.25 x 1018 C
Electrostatics
Q or q
Charles A.
Coulomb
0
Robert A. Millikan
6.25 x 1018
Potential
Charge
Volt
1 joule of work per
coulomb of
charge
•
•
•
•
•
•
The potential difference between two
charges forces a third charge to
move.
The value of the charge moves at the
rate of 6.25 x 1018 electrons flowing
past a given point per second.
The ampere unit of current was
named after __________.
A measure of how intense or
concentrated the electron flow is.
Current multiplied by time is
equivalent to a ________.
The charge of 5 C moves past a given
point in 1s. How much the current?
•
The most common charge.
•
Vacant space where an electron is
missing.
•
Type of current of Ion.
•
•
An atom that has either lost or gained
one or more valence electrons to
become electrically charged.
The opposition which limits the
amount of current that can be
produced by the applied voltage.
•
The practical unit of resistance.
•
The opposite of resistance.
•
A German physicist who named after
the unit of resistance
•
A European inventor who named after
the unit of conductance.
•
The current that flow through the load
resistance.
The motion of positive charges in the
opposite direction from the electron
flow.
Similar characteristic of a Direct
Current and Alternating Current
•
•
•
Unit for cycle per second.
•
Frequency used in most homes.
•
Is it true when the polarity of the
applied voltage reverses, the direction
of current flow also reverses?
Electric Current
•
One Ampere
•
Andre M. Ampere
_______ Produces voltage by means
of a conductor rotating in a magnetic
field.
An element that is often used as a
source of photoelectrons.
Current/Amperage
•
The emitting electrode.
Charge
•
It is used to collect emitted electrons.
•
The quantity unit of electrons or
protons
Potential difference between two
unlike charges.
Opposition that reduces amount of
current
5A
•
Electron
•
Hole charge
Ion current
•
•
Material that attracts pieces of iron.
Space between magnets
Ion
•
Permanent magnet used in speakers
Resistance
•
Temperature where materials loss
their magnetism
Ohm
•
Magnetic lines of force
Conductance
•
Magnetic lines per unit area.
George Simon
Ohm
•
Property that concentrates the
magnetic flux
Ernst Van
Siemens
•
It is the reciprocal of permeance
Magnetic Units Conversion
Generator
Cesium
Cathode
Anode
Coulomb
Quantity
SI
cgs
Relation
Flux
(ø)
Flux Density
(β)
Magnetomotive
force (mmf)
Field Strength
(H)
Weber
(Wb)
Tesla
T(Wb/m2)
Ampere-turn
(A-t)
Ampereturn/meter
Maxwell
(Mx)
Gauss
G(Mx/cm2)
Gilbert
(Gb)
Oersted
Oe(Gb/cm)
1 Wb =108 Mx
1A-t=1.2157 Gb
1A-t/m=0.01257
Gb/cm
Voltage
Resistance
Materials According to Permeability
Ferromagnetic
magnets
▪
Air gap
▪
Alnico
With very high relative permeability from 50 to
5000
Examples: alnico, cobalt, iron, nickel, steel, ferrites
Paramagnetic
▪
▪
Curie Temperature
flux
With relative permeability slightly greater than 1
Examples: aluminum, chromium, manganese,
platinum
Non- Magnetic
Magnetic flux
density
▪
Permeance
Reluctance
▪
With permeability equals to space or vacuum
permeability which is equals to 4π x 10-7 H/m
With relative permeability equals to 1
Diamagnetic
▪
▪
Load Current
with relative permeability slightly less than 1
examples: antimony, bismuth, copper, gold,
mercury, silver, zinc
ELECTONIC CIRCUITS
Conventional
Current
Heating Effect
•
He discovered the Ohm’s Law.
Hertz
•
60 hertz
•
It is used to determine the amount of
electric power in the circuit.
True or false: Ohm’s law applies to both
DC and AC circuits.
True
1T= 104 G
Georg Simon
Ohm
Ohm’s Law
True
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
The ohm’s law is equal to
__________________.
In Ohm’s law, increase in voltage is
_________ in current.
The current is _______________ to volts
and ______________ to the resistance.
The voltage is ______________ to current
and resistance.
The resistance is ______________ to
current and _____________ to the
voltage.
It is the amount of current through a oneohm resistance that has one volt of
potential difference applied across it.
It is the potential difference across a oneohm resistance that has one ampere of
current through it.
It is the amount of opposition in a
resistance that has a V/I ratio of 1,
allowing one ampere of current with one
volt applied.
1 milli-ampere multiply by 1 kilo ohms is
equal to __________.
1 micro-ampere multiply by 1 mega-ohm is
equal to _________.
1 milli ampere is equal to
_______________.
The formula which states that V and I are
directly proportional for any value of R.
In ohm’s law, increases of volts will
__________ the current.
It shows how much current the resistor
allows for different voltages.
In a volt-ampere characteristic graph, the
value in y axis or ordinate is
_______________.
In a volt-ampere characteristic graph, the
value in x axis or abscissa is
_____________.
In ohm’s law, voltage and current are
__________.
V=IR
Decrease
Directly
proportional;
inversely
proportional
•
•
This type has a nonlinear volt-ampere
characteristic.
Whether the resistor is linear is not, the
current is ________ for more resistance,
with applied voltage constant.
•
The unit of electric power.
•
He discovers the unit of electric power.
Inversely
proportional;
proportional
•
It equals the work done in one second by
one volt of potential difference in moving
one coulomb of charge.
One ampere
•
Direct
proportional
must produce heat in order to do its job.
proportional
•
One volt
It is the time rate of doing work.
It is the time rate at which charges is
forced to move by voltage.
•
1 horse power is equal to____________.
•
One horse power is approximately equal to
____________.
It is the power used during a period of
time.
Nonlinear
resistance
1 volt
•
•
One joule is equal to ________
•
One watt is equal to ___________.
•
One joule is equal to ________ coulomb
•
This is a unit commonly for large amounts
of electrical work or energy.
The amount is calculated simply as the
product of the power in kilowatts multiplied
by the time in hours during which the
power is used.
It is produced when current flows in a
resistance because friction between the
moving free electrons and the atoms
obstructs the path of electron flow.
It is generated by the source of applied
voltage and consumed in the resistance in
the form of heat.
It is desirable because the component
1000 µA
Ohm’s Law
Increase
Volt-ampere
characteristic
graph
Current
values
Voltage
values
•
•
•
Directly
•
0.24 calorie of
heat energy
•
1 watt during the time of 1sec is equivalent
to __________.
•
Power is equivalent to __________.
Watt
•
The calculations that can be used for just
about all types of circuits.
Ohm’s Law
James Watt
(1736-1819)
•
Zero
One watt of
power
•
The algebraic sum of the voltage sources
and IR voltage drops in any closed path
must total ________.
At any point in a circuit the algebraic sum
of the currents directed in and out must
total ________.
•
Creator of Kirchoff’s Law
•
The algebraic sum of the currents entering
and leaving any point in a circuit must
equal the algebraic sum of the currents out
of that point.
Kirchoff’s
Current Law
(KCL)
•
Consider all currents into a branch point as
__________ and all current directed away
from that point as ____________.
Positive;
Negative
1watt second
•
1
joule/second
It is really the basis for the practical rule in
parallel circuits that the total line current
must equal the sum of the branch currents.
•
Go around any closed path and consider
any voltage whose negative terminal is
reached first as a negative term and any
voltage whose positive terminal is reached
first as a positive term.
•
Any closed path is called __________.
•
The Greek letter which means “sum of”.
•
When a loop does not have any voltage
source, the algebraic sum of the IR voltage
drops alone must total ________.
Using the Kirchoff’s law, first indicate the
___________ and mark the voltage
polarity across each resistor.
Less
Power
Electric
power
764 Watts or
550 ft lb/s
One ohm
1 volt
Power
Dissipation
¾ kW
Work
6.25 x 1018 eV
Kilowatt-hour
Kilowatt-hour
Heat
•
Power
•
Electric
It is a branch point where currents divide
or combine.
VI; I2R; V2/R
Zero
Gustav R.
Kirchoff
Kirchoff’s
Current Law
(KCL)
Kirchoff’s
Voltage Law
(KVL)
Loop
Sigma “Σ”
Zero
Current
Directions
Principal
Node
•
These currents are used for specifying the
voltage drops around the loops.
•
A branch point in which the voltage drops
specify the currents.
•
Solving the __________, we can calculate
the unknown branch currents.
•
It is the simplest possible closed path.
•
•
•
•
•
•
•
•
•
It is assumed to flow around a mesh
without dividing.
The number of meshes equals the number
of _________, which is the number of
equations required.
In each mesh equations, the algebraic
sum of the voltage drops equals the
____________.
The advantage of mesh currents is the
______, without the need for tracing any
branching currents.
The only positive IR voltage in a mesh is
for the ____ of each mesh current in its
own mesh.
It is just a combination of components,
such as resistances interconnected in a
way to achieve a particular end result.
It usually provides shorter methods of
solving the circuit than the Kirchoff’s law.
This theorem is very useful because it
extends the use of Ohm’s Law to circuits
that have more than one source.
In a network with two or more sources, the
current or voltage for any components is
the algebraic sum of the effects produced
by each source acting separately.
•
Each __________ can have any number
of series resistances.
•
It means that current is proportional to the
applied voltage
It means that the current is the same
amount for opposite polarities of the
source voltage.
There are components that doesn’t
•
•
Branch
Current
amplify or rectify.
•
Node
Loop
Equations
Mesh
•
•
Mesh Current
Mesh
currents
Applied
voltage
Pattern of
algebraic
signs for the
voltages
Total
Resistance
•
•
•
•
•
•
Network
•
Network
Theorems
•
Superposition
•
Superposition
Theorems
•
Voltage
Divider
Linear
•
Bilateral
•
Passive
These are components such as
transistors, semiconductors diodes, and
electron tubes in which are never bilateral
and often are not linear.
Named after M. L. Thevenin, a French
engineer, this theorem is very useful in
simplifying the voltages in a network.
It states that the entire network connected
to two terminals can be replaced by a
single voltage source VTH in series with a
single resistance RTH.
To calculate VTH, find ______ across the
open terminals.
To calculate RTH, ____________ the
sources V1 and V2.
To calculate VTH, find ______ across the
open terminals.
To calculate RTH, ____________ the
sources V1 and V2.
Named after E. L. Norton, a scientist with
Bell Telephone Laboratories, this theorem
is used for simplifying a network in terms
of currents instead of voltages.
It states that the entire network connected
to two terminals can be replaced by a
single current source IN in parallel with a
single resistance RN.
Any components directly across the two
terminals are also short-circuited by the
_________.
It says that any network can be
represented by a voltage source and
series resistance.
It says that any network can be
represented by a current source and shunt
resistance.
It is a specific example of the general
principle that any voltage source with its
series resistance can be converted to an
equivalent current source with the same
resistance in parallel.
This theorem provides a shortcut for
finding the common voltage across any
number of parallel branches with different
voltage sources.
In the Y-to-Δ conversion, each side of the
delta is found by first taking all possible
_____ of the arms of the wye, using two
components
•
Active
Components
•
Thevenin’s
Theorem
arms at a time.
In the Δ-to-Y conversion, each arm of the
wye is found by taking the ________ of the
two adjacent sides in the delta and dividing
by the sum of the three sides of the delta.
When all the resistor values are equal in a
network, it is _________.
Product
balanced
•
When it is desired to concentrate magnetic
lines within a magnet, however, the
magnet can be formed as ___________.
Closed
Magnetic
Loop
•
It is made in the form of a doughnut.
Toroid or
Ring Magnet
•
It is often used for the core.
•
This type of electromagnet has maximum
strength in the iron ring, with little flux
outside.
Norton’s
Theorem
•
The small part of the field in the air.
Norton’s
Theorem
•
The principle of the closed magnetic ring is
used to ______.
•
It maintains the strength of the permanent
magnet as it becomes magnetized by
induction to form a closed loop.
In terms of molecular structure, iron atoms
are grouped in microscopically small
arrangements called ____.
Thevenin’s
Theorem
Voltage
Short-circuit
Voltage
Short-circuit
Wire Jumper
Thevenin’s
Theorem
•
Norton’s
Theorem
•
Each domain is an elementary ________,
with two opposite poles.
•
In crystal form, the iron atoms have
domains that are _______ to the axes of
the crystal.
Norton
Conversion
Millman’s
Theorem
Cross
Products
Iron
Ring Magnet
Leakage Flux
Protect
permanent
magnet in
storage.
Keeper
Domains
Dipole
magnet
Parallel
REVIEW QUESTIONS
1. One of the earlier capacitor constructions is the leydan jar for storing
electrical charges for a long period of time. So called leydan because it was
developed in the University of Leiden in 1746 by whom?
a. Pieter van Musschenbroek
b. Cleve Antoine Marraf
c. Jaime Licuanan
d. Charles Coulomb
2. Protons are about____ heavier than electrons.
a. 1800 times
b. Less than thrice
c. Less
d. Twice
3. In the periodic table, all elements are arranged in the order according to
their
a. Atomic number
b. Valence
c. Nucleus
d. Characteristics
4. What do you call the subatomic particle that has a mass approximately
equal to that of the proton, but it has no electrical charge? (April, 2004)
a. Atom
b. Proton
c. Electron
d. Neutron
5. The nucleus of an atom is made up of_____ (April, 2004)
a. Protons and electrons
b. Electrons only
c. Electrons and neutrons
d. Protons and neutrons
6. Refers to the atom that losses an electron (November, 2003)
a. Positive ion
b. Negative ion
c. Emf
d. Neutron
7. What is the symbol for carbon dioxide? (November, 2005)
a. CO
b. C2O
c. CO2
d. Co2
8. The definite discrete amount of energy required to move an electron from
lower shell to another shell (November, 1999)
a. Negative energy
b. Positive energy
c. Quantum
d. Quanta
9. The force between two magnetic poles in relation to their pole strength
is________ (November, 1999)
a. Not related
b. Inversely proportional
c. Directly proportional
d. Independent
10. How are static charges created? (November, 2003)
a. By motion
b. By friction
c. By immersion
d. By conduction
11. Very few metals are now used in their pure state. A mixture of two or more
metals or a mixture of metal and another material is called? (November, 2003)
a. Alloy
b. Colloid
c. Compound
d. Amalgam
12. Which of the following statement is true for metals? (November, 2003)
a. An increase in the temperature does not affect the resistance
b. An increase in temperature lowers the resistance
c. An increase in temperature increases the resistance
d. An increase in temperature doubles the resistance
13. It exhibits positive temperature coefficient (April, 2004)
a. Conductor
b. Glass
c. Semiconductor
d. Superconductor
14. Which material has more free electrons? (November, 1999)
a. Mica
b. Dielectric
c. Insulators
d. Conductor
15. Which of the following is not a good conductor of electricity (April, 2004)
a. Silver
b. Copper
c. Aluminum
d. Mica
16. An insulator is a substance that
a. Offers a resistance to current flow
b. Offers a low resistance to current flow
c. Absorbs electricity
d. Forms a condenser
17. The total resistance of two similar wire conductors connected in parallel is
_____. (November, 1999)
a. Same resistance of 1 wire
b. Double the resistance of 1 wire
c. One half the resistance of 1 wire
d. Resistance of 1 wire multiplied by 4
18. A rheostat is a device that regulates the strength of an electric current by
(November, 2003)
a. Increasing the magnetic field in the circuit
b. Varying the voltage in the circuit
c. Varying the resistance in the circuit
d. Varying the current in the circuit
19. The reciprocal of capacitance is called________(November,1995)
a. Elastance
b. Permitivitty
c. Permeability
d. Conductance
20. Which of the following describes the action of capacitor (April, 1998)
a. Converts AC to DC
b. Creates a DC resistance
c. Stores electrical energy
d. Opposes change in current flow
21. The following are the factors that affect the inductance of a coil (April,
2004)
1. The number of turns in a coil
2. The diameter of a coil
3. The coil length
4. The number of layers of windings in the coil
5. The type of core material
a. 1,2,3 and 4 only
b. 1,2,3 and 5 only
c. 1,2,3,4 and 5
d. 1,2,4 and 5 only
22. Inserting a soft iron core into a coil has what effect on the inductance of
the coil? (November, 2003)
a. Increase inductance
b. Decrease inductance
c. Does not affect the inductance
d. None of these
23. Which of the following characterizes inductance? (April, 1998)
a. Tends to oppose DC
b. Tends to oppose change in current
c. Tends to oppose change in voltage
d. Opposes all frequencies equally
24. What law in electronics where an induced current will be in such a
direction that its own magnetic field will oppose the magnetic field that
produces the same?
a. Electromagnetic law
b. Norton’s law
c. Lenz’s law
d. Maxwell’s law
25. What is the unit of magnetic flux in SI system?
a. Weber
b. Maxwell
c. Tesla
d. Gauss
26. Materials with permeabilities slightly less than that of free space are
referred to as
a. Diamagnetic
b. Ferromagnetic
c. Non-magnetic
d. Paramagnetic
27. Solve for flux density (in gauss) from a magnetic flux of 5,000 Mx through
a perpendicular area of 2 cm x 5 cm.
a. 5,000 G
b. 500 G
c. 10,000 G
d. 50 G
28. What is the law that determines polarity of an induced voltage?
a. Norton’s law
b. Thevenin’s law
c. Lenz’s law
d. Faraday’s law
29. The natural magnet refers to (November, 1999)
a. Steel
b. Soft iron
c. Magnesia
d. Lodestone
30. It is the air space between poles of magnet .
a. Air gap
b. Vacuum
c. Free zone
d. Free space
ELECTRONICS ENGINEERING
-Energy Conversion, Resonance and Filters-
Armature Reaction
- When the generator is loaded, the armature conductor carries
current and hence current carrying conductors produce a magnetic
flux of its own which affects the flux created by the main poles
I. GENERATORS
- are rotating electrical machines that convert mechanical energy
input to usable electrical energy.
Main Parts
a. Yoke
- It is cylindrical in shape to which even number of poles is bolted.
b. Pole and Pole Shoe
- Support the field coil and spread the flux over large area.
c. Field Winding
- The source of flux
- The current flowing through this winding can be controlled to control
the flux passing through the machine.
d. Armature
- A cylindrical core
- Made of sheet steel laminations and insulated from each other by a
thin layer of paper and varnish to reduce iron losses.
e. Commutator
- Cylindrical in shape and consists of segments of hard drawn copper.
A mica strip insulates each segment from each other. Windings of
armature and terminated on it.
- Commutator is responsible in converting the generated AC voltage
in the armature to DC
- Commutation is the reversal of current in the coil when the coil
passes through the brush position
f. Brushes
- Used to connect the external circuit to the armature.
Losses in DC Generator
1. Copper Loss
- Losses due to current in the various windings of the machine.
i. Armature copper loss
ii. Field copper loss
iii. Brush contact loss
2. Iron Loss.
- Magnetic or core losses.
i. Hysteresis loss
ii. Eddy Current loss.
3. Mechanical Losses.
i. air friction of rotating armature
ii. bearing friction
iii. brush friction
where: Eg – generated voltage/induced voltage
P - no. of poles(always even number)
 - flux per pole, lines or maxwells
N – speed of roration of the armature,rpm
Z – total number of active conductor
a- no. of parallel paths

- flux per pole, maxwells
kd – distribution factor
kp – pitch factor
note:
for full pitch winding, kp = 1
for concentric winding, kd = 1
III.MOTORS
▪
▪
are rotating electrical machines that convert electrical
energy into mechanical energy
it has a reverse operation with generators
Counter EMF of Motors
Ec =
- Machines designed to generate alternating currents.
Operating Principle
When the rotor rotates, the stator conductors are cut by the
magnetic flux, hence they have induced emf produced in them.
Because of the magnetic poles are alternately N and S poles, they
induced an emf and hence current in the armature conductors, which
first flow in one direction and then in the other. Hence, an alternating
emf is produced in the stator conductors whose frequency depends
on the number of poles moving past in a conductor in one second and
whose direction is given by Fleming’s right-hand rule.
f=
P rpm
hertz
120
where: f – frequency, hertz
P – no. of poles , rpm – speed of rotation
Generated Voltage of an Alternator
P N Z
 10 - 8
60 a
where: Ec – back emf or counter emf, volts
P – no. of poles (always an even no.)

- flux per pole, lines or maxwells
N - speed of rotation of the armature, rpm
Z - total number of active conductors
a - no. of parallel paths
Mechanical Power Output
HP =
Frequency of the Generated Voltage
volts
where: E – total generated voltage, volts
N – no. of turns per coil
II. ALTERNATORS
Generated Voltage of a DC Generator (EMF)
- This is the voltage generated across the armature of the DC
generator
PNZ
Eg =
 10 - 8
60 a
E = 4.44 f N  k d k p  10 - 8
2  NT
33,000
HP =
2  NT
44760
Where: HP – horsepower
N- no. of turns,rpm
T-torque,N-m
Speed Regulation
▪
percentage rise in the speed of the motor when the
mechanical load is removed
%NR =
N NL − N FL
 100%
N FL
where: NNL – no-load speed
NFL – full-load speed
IV. APPLICATIONS OF GENERATORS AND MOTORS
a. Amplidyne
- Trade name for rotating amplifiers
- It is a quick response dc generator, the output of which is controlled
by a very small field power
- From the name itself, rotating amplifier, it is a power amplifier; it is
most suitable for use as an exciter in a closed loop control system.
b. Brushless Generator
- A generator employing silicon rectifiers as static commutation
devices
- It is of particular value as aircraft generator, difficulties having been
experienced with sliding contacts under conditions of high running
speed, dry rarefied air and wide temperature range.
c. Dyna-motor
- another name for rotary transformer
- A composite machine having a single magnet frame but two
separate armature windings, one acting as a generator and the other
as a motor, and independent commutators.
d. Rototrol
- a single-stage rotating amplifier relying on the use of positive
feedback.
e. Magnicon
- trade name for rotating amplifiers with cross field excitation
f. Magnetohydrodynamic Generator
- a device for converting thermal energy into electric by breaking a
stream of hot ionized gas
- It is also known as plasma hydrodynamic generator.
g. Electrohydrodynamic Generator
- a generation device in which a stream of gas is ionized, the positive
ions being carried away by the stream while the electrons are
collected by an electrode ring causing a current to flow through a wire
between the ring and a collecting grid.
h. Metadyne Generator
- trade name for rotating amplifier
- It is similar to the nature of amplidyne.
i. Metadyne Converter
- a machine similar to metadyne generator with the supplementary set
of brushes connected to an external dc supply so that the output
power does not require any appreciable mechanical power input to
the transformer.
j. Motor Converter
- an induction motor and a synchronous converter mechanically and
electrically coupled
- Converts ac to dc.
k. Motor Generator
- a converter consisting of an ac motor directly coupled to a dc
generator
l. Static Converter
- a converter based on electronic devices of the semiconductor,
mercury arc or gaseous type, usually in combination with a
transformer.
V. BATTERY
- An assembly of voltaic primary or secondary cell.
2. Normal Charge
3. Equalizing Charge
4. Floating Charge
5. Fast Charge
Most Commonly Used Cells
Primary Cells
Type
Carbon -Zinc
Voltage(V)
1.5
Zinc – Chloride
Manganese
Alkaline
Silver Oxide
Lithium
1.5
1.5
1.5
2.8
Remarks
Used for flashlights and
toys; low cost and low
current capacity
Higher current capacity
Hydroxide Electrolyte and
high current capacity
Hydroxide electrolyte
Long life, high cost
Primary cells
- Chemical action is not reversible.
Secondary cells
- Also known as accumulators or storage batteries.
VI. RESONANCE
a. Acid cells
- Uses acid as an electrolyte.
b. Alkali cells
- Uses alkali as an electrolyte
- Resonance occurs at a particular frequency when the inductive
reactance and the capacitive reactance are of equal magnitude
- it is a condition where the current is in phase with the voltage
- during resonance, the circuit power factor is unity
Local Action
- The continuous dissolution of the zinc rod even when the cell is not
connected to the external circuit
- This is due to impurities present in commercial zinc. The impurities
form small tiny cells, which are short circuited by the main body of the
zinc rod
- Can be minimized by using amalgamated zinc.
Resonant conditions:
1. The current I is in phase with the applied voltage in an RLC circuit.
This implies that
Imag[Zeq] = Imag[Yeq] = 0
Polarization
- The collection of hydrogen bubbles on the surface of the copper
plate
Effects of Polarization:
a. The bubbles act as insulators and hence increase the internal
resistance of the cell.
b. Sticking H2 ions on the +ve plate exert a repulsive force on the
other H2 ions coming towards the Cu plate. Minimized by
surrounding the cathode by depolarizers, which oxidizes H2
bubbles as soon as they are produced
Charging the Battery
- Process of reversing the current flow through the battery to restore
the battery to its original position
- There are five types of charges
1. Initial Charge
2. The magnitude of the equivalent impedance (or admittance) is
either
a. MINIMUM – for series resonance or
b. MAXIMUM – for parallel or anti-resonance
1. SERIES Resonance
- at resonance the circuit acts as a low impedance and frequency
selective network
Resonant Frequency, fr (Hz) =
where: L – inductance(H)
1
2 LC
C – capacitance (F)
▪
Characteristics of Series Resonance
▪
▪
XL =XC
Circuit impedance(Z) is minimum
▪
Current (I) is maximum
At resonance, the circuit acts as a high impedance and
a frequency selective network
Resonant Frequency,fr (Hz)=
1
2 LC
where: L – inductance(H)
C – capacitance (F)
Characteristics of a Theoretical Parallel Resonant Circuit
▪
▪
C=
Circuit impedance(Z) is maximum
Z=R
Total Current (I) is minimum
L
R 2 + (2fr L )2
Tuning capacitance (C)
fr =
2
1
1
R
−   Resonant Frequency,fr (Hz)
2 LC  L 
Z=
L
Dynamic Impedance (Z), 
RC
VII. FILTER
- It is a circuit designed to pass desired frequencies and reject or
attenuate undesired frequencies
Classifications According to Design
a. Butterworth Filter
▪
A filter with a very flat amplitude response in the
passband
▪
Butterworth approximation is maximally flat
approximation because the passband attenuation is
zero
▪
▪
▪
Z is resistive
At freq>fr, Z is inductive
At freq < fr, Z is capacitive
Roll-off rate = 20n dB/decade
Roll-off rate = 6n dB/octave
Where n – order of filter
▪
▪
▪
Z is resistive
At freq>fr, Z is capacitive
At freq < fr, Z is inductive
Quality factor/ Figure of Merit (Q)
▪
▪
it refers to the “goodness” of a reactive component.
In series circuit: the voltage magnification factor at the
time of resonance
Q = Reactive Power/Active Power
Q=
XL
XC
=
R
R
Q=
PARALLEL Resonance
1
R
L
C
b. Chebyshev Filter
▪
Rolls off faster in the transition region than a
Butterworth filter
▪
Ripples and overshoot appear in the passband of the
frequency response
n
Number of Ripples = 2
Practical Parallel Resonant Circuit
c. Inverse Chebyshev Filter
▪
Need for flat passband response as well as fast roll-off
▪
It has a flat passband response and rippled stopband
response
▪
Roll-off rate in the transition region is comparable to the
roll off rate of Chebyshev filter
▪
Monotonic means that the stopband has no ripples
d. Elliptic Filter
▪
Need for the fastest possible roll-off in the transition
region
▪
▪
Also known as the CAUER filter
Optimizes the transition region at the expense of the
passband and stopband
e. Bessel Filter
▪
A filter that has a linear phase characteristics and no
overshoot on the output with a pulse input
▪
It has a flat passband and Monotonic stop band similar
to Butterworth approximation
Type
Butterworth
Chebyshev
Inverse
Chebyshev
Elliptic
Bessel
Passband
Stopband
Roll-Off
Step
response
Flat
Monotonic
Good
Good
Rippled
Monotonic
Very
Good
Poor
Flat
Rippled
Very
Good
Good
Rippled
Rippled
Best
Poor
Flat
Monotonic
Poor
Best
Filter Approximations
Order of Filter (n)
▪
Order of a passive filter (symbolizes by n) equals the
number of inductors and capacitors in the filter
▪
If a passive filter has two inductors and two capacitors,
n =4
The order of an active filter depends on the number of
RC circuits (called poles) it contains, n = number of
capacitors
REVIEW QUESTIONS
1. A 4-pole DC generator with duplex lap winding has 48 slots and
four elements per slot. The flux per pole is 2.5 x 106 Maxwells and it
runs at 1500 rpm. What is the output voltage?
a. 60
b. 360
c. 225
d. 120
2. Find the frequency in kilocycles per second in the armature of a 10
pole, 1200 rpm generator?
a. 100
b. 1000
c. 10
d. 0.1
3. What is the voltage regulation when the full load voltage is the
same as no-load voltage assuming a perfect voltage source?(Nov.
1999)
a.
100%
b.
10%
c.
1%
d.
0%
4. In dc motors, the emf developed which opposes to the supplied
voltage.
a.
Residual emf
b.
Coercive emf
c.
Induced emf
d.
Counter emf
5. What will happen to a dc series motor when its load is removed?
a.
the motor will stop
b. the motor speed remains the same
c. the torque remains the same
d. the motor will over speed
6. The armature of a DC generator is laminated to ____________.
a. Reduce the bulk
b. Provide passage for cooling air
c. Reduce eddy current losses
d. Insulate the core
7. The loss in DC generator that varies with the load is ___________.
a. Copper loss
b. Eddy current loss
c. Hysteresis loss
d. Windage loss
8. In DC generator, the cause of rapid brush wears maybe
_____________.
1. Severe sparking
2. Rough commutation surface
3. Imperfect contact
4. slots disorientation
a. 1, 2 and 3 only
b. 1, 2 and 4 only
c. 2, 3 and 4 only
d. 1, 2, 3 and 4
9. Which of the following components of a DC generator plays vital
role for providing direct current of a DC generator?
a. Dummy coils
b. Commutator
c. Eye bolt
d. Equalizer ring
10. Find the voltage regulation of a generator when full load voltage is
110V and the no load voltage is 120V.
a. 1%
b. 9.09%
c. 90.9%
d. 10%
11. Where does voltage generated in a dc generator depend?
1.Field resistance
2. speed
3. flux
4. Field current
5. Armature resistance
a.
1, 2 and 3 only
b.
2 and 3 only
c.
2, 3, and 4 only
d.
1, 3 and 5 only
12. Generators are often preferred to be run in parallel because of
________.
1.Great reliability
2.Meeting greater load demands
3.Higher efficiency
a. 1,2 and 3
b. 1 and 2 only
c. 1 and 3 only
d. 2 and 3 only
13. DC generator preferred for charging automobile batteries is
_______.
a. Shunt generator
b. Long shunt compound gen.
c. Series generator
d. Any of these
14. The purpose of providing dummy coils in a generator is
________.
a. To reduce eddy current losses
b. To enhance flux density
c. To amplify voltage
d. To provide mechanical balance for the rotor
ELECTRONICS ENGINEERING
-SEMICONDUCTORS, DIODES and TRANSISTORSELECTRON TUBES
THERMIONIC EMISSION is caused when metallic substances are heated to
high temperatures. Electrons liberated by thermonic emission provide the
conduction currents of vacuum tubes.
A DIODE VACUUM TUBE is composed of two elements: the cathode and the
plate.
BEAM-POWER TUBES are also used as power amplifiers. In addition to the
in-line grid arrangement, beam-power tubes use a set of negatively charged
beam-forming plates.
PLANAR TUBES have their plates and grids mounted parallel to each other.
Because of their planar construction, they can handle large amounts of power
at uhf frequencies.
GAS-FILLED TUBES contain a small amount of gas that ionizes and reduces
the internal resistance of the tubes. Because of this, gas-filled tubes can
handle relatively large amounts of power while maintaining a constant voltage
drop across the tube.
COLD-CATHODE TUBES lack heaters or filaments and, therefore, do not use
thermionic emission. Instead, a voltage potential applied across the tube
causes the internal gas to ionize. Once ionization has occurred, the voltage
drop across the tube remains constant, regardless of increased conduction.
The CRT is a special-purpose tube that has the unique ability to visually
display electronic signals
METALLIC RECTIFIER or dry-disc rectifier is a metal-to-semiconductor
device that acts just like a diode in that it permits current to flow more readily
in one direction than the other.
DIODE RATINGS are the limiting value of operating conditions of a diode.
Operation of the diode outside of its operating limits could damage the diode.
Diodes are generally rated for: MAXIMUM AVERAGE FORWARD CURRENT,
PEAK RECURRENT FORWARD CURRENT, MAXIMUM SURGE CURRENT,
and PEAK REVERSE VOLTAGE.
II. SPECIAL PURPOSE DIODES
1. ZENER DIODE
▪ Diode designed to operate in the reverse breakdown region
a. Zener Breakdown
▪ When the breakdown voltage is below 5 volts
b. Avalanche Breakdown
▪ When the breakdown voltage is above 5 volts
2. POINT CONTACT DIODE
SEMICONDUCTOR DIODES
DOPING is the process by which small amounts of selected additives, called
impurities, are added to semiconductors to increase their current flow.
Semiconductors that undergo this treatment are referred to as EXTRINSIC
SEMICONDUCTORS.
The CATHODE is the electron-emitting element of a tube. Cathodes are
usually composed of special materials that are heated either directly or
indirectly.
A TRIODE is basically a diode with a control grid mounted between the plate
and the cathode. The control grid gives the triode the ability to amplify signals.
TRANSIT TIME is the time required for electrons emitted by the cathode to
reach the plate. Because transit time in a vacuum tube is considerably less
than the speed of light, vacuum tube operation is affected at high frequencies.
TETRODES were developed to compensate for the effects of interelectrode
capacitance. Placing a positively charged screen grid between the control grid
and plate has the effect of adding a capacitor in series with the capacitance
that exists between the control grid and plate.
SECONDARY EMISSION of electrons from the plate is caused by the
acceleration of electrons by the screen grid. This causes the performance of a
tetrode to be degraded. In addition to reduced amplitude, the output signals
become noisy.
PENTODES do not suffer from the effects of secondary emission. This is
because a negatively charged suppression grid placed between the screen
grid and plate forces any electrons emitted back to the plate.
An N-TYPE SEMICONDUCTOR is one that is doped with an N-TYPE or donor
impurity (an impurity that easily loses its extra electron to the semiconductor
causing it to have an excess number of free electrons).
A P-TYPE SEMICONDUCTOR is one which is doped with a P-TYPE or
acceptor impurity (an impurity that reduces the number of free electrons
causing more holes).
The SEMICONDUCTOR DIODE, also known as a PN JUNCTION DIODE, is a
two-element semiconductor device that makes use of the rectifying properties
of a PN junction to convert alternating current into direct current by permitting
current flow in only one direction.
JUNCTION BARRIER is an electrostatic field that has been created by the
joining of a section of N material with a section of P material. Since holes and
electrons must overcome this field to cross the junction, the electrostatic field
is commonly called a BARRIER. Because there is a lack or depletion of free
electrons and holes in the area around the barrier, this area has become
known as the DEPLETION REGION.
FORWARD BIAS is an external voltage that is applied to a PN junction to
reduce its barrier and, therefore, aid current flow through the junction
REVERSE BIAS is an external voltage that is connected across a PN junction
so that its voltage aids the junction and, thereby, offers a high resistance to the
current flow through the junction.
▪ Semiconductor diode having fine wire whose point is permanent
contact with the surface of a wafer of a semiconductor material such
as Silicon, Germanium or Gallium Arsenide
▪ The fine wire is called cat-whisker
3. SCHOTTKY DIODE
▪ Also known as Surface Barrier Diode
▪ Also known as hot-carrier diodes
▪ This type of diode has no depletion layer which eliminates the
stored charges in the junction
▪ A rectifying metal semiconductor junction such as gold, silver and
platinum.
▪ Typical forward voltage drop is typically around 0.25 V to 0.3 V
▪ ESBAR(Epitaxial Schottky Barrier)
4. VARACTOR (varicap)
▪ Voltage-variable capacitor
▪ When this diode is reversed bias, the width of the depletion layer
increases with the reverse voltage
▪ The key idea is that the capacitances is controlled by voltage
▪ Used foe electronic tuning, harmonic generator and parametric
amplifier
Symbol:
5. TUNNEL DIODE
▪ Also known as Esaki diode
▪ Type of diode that exhibit the phenomenon known as negative
resistance
▪ Negative resistance implies that an increase in forward voltage
produces a decrease in forward current for a certain part.
▪ Utilizes a heavily doped material and therefore have so many
electrons.
If
Negative
Resistance
region
Tuneling
Current
▪ Operated in reverse bias condition
▪ A window let light to pass through the package of the junction.
The incoming light produces free electrons and holes producing
larger reverse current
▪ Dark current is the reverse current flowing through the photodiode
when there is no incident light
TRANSISTORS
Vf
0
A TRANSISTOR is a three or more element solid-state device that amplifies
by controlling the flow of current carriers through its semiconductor materials
Tunnel Diode Charactristics Curve
6. BACK DIODE
▪ Conducts better in the reverse (-0.1 V) than in the forward (+0.7
V) direction
▪ Designed such that its high current flow takes place when the
junction is reversed bias
7. PIN Diode
▪ Positive –Intrinsic-Negative Diode
▪ The intrinsic material between the P and N layer offers
impedance at microwave frequencies being controlled by low
frequency signals
▪ Used in microwave switches
8. LIGHT EMITTING DIODE
▪ In a forward biased LED, free electrons cross the junction and fall
into holes. As these electrons fall from higher to a lower energy
level, they radiate energy goes off in the form of heat. But in a
LED, the energy is being radiated as a light
▪ Commonly used Gallium Arsenide, Gallium Arsenide Phosphide
and Gallium Phosphide
▪ GaAs LEDs emit infrared (IR) radiation which is non invisible,
GaAsP produces either red or yellow visible light and GaP emits
red or green visible light.
▪ Red is the most common color of LEDs
▪ Electroluminescense is the process involved when large surface
area on one layer of one semiconductive material permits the
photons to be emitted as visible light
▪ Irradiance is the power per unit area at a given distance from a
LED source expressed in mW/ cm2.
9. LASER DIODE
▪ Term laser stands for light amplification by stimulated emission of
radiation
▪ Laser light is monochromatic meaning it consists of a single color
and not a mixture of colors
▪ Laser light is also a coherent light meaning single wavelength
▪ Laser diode pn junction is formed by two layers of doped gallium
arsenide
10. PHOTODIODE
The THREE ELEMENTS OF A TRANSISTOR are (1) the EMITTER, which
gives off current carriers, (2) the BASE, which controls the carriers, and (3) the
COLLECTOR, which collects the carriers
The COMMON-EMITTER CONFIGURATION (CE) is the most frequently used
configuration in practical amplifier circuits, since it provides good voltage,
current, and power gain.
The COMMON-BASE CONFIGURATION (CB) is mainly used for impedance
matching, since it has a low input resistance and a high output resistance. It
also has a current gain of less than 1. In the CB, the input is applied to the
emitter, the output is taken from the collector, and the base is the element
common to both input and output.
The COMMON-COLLECTOR CONFIGURATION (CC) is used as a current
driver for impedance matching and is particularly useful in switching circuits.
The CC is also referred to as an emitter-follower and is equivalent to the
electron-tube cathode follower. Both have high input impedance and low
output impedance.
THE CLASS OF AMPLIFIER OPERATION is determined by the portion of the
input signal for which there is an output.
Amplifier Type
Common
Base
Common
Emitter
Common
Collector
There are four classes of amplifier operations: class A, class AB, class B, and
class C.
Input-output
relationship
0º
180º
0º
Voltage Gain
high
medium
low
Current Gain
low
medium
high
Power Gain
low
high
medium
Input Resistance
low
medium
high
Output
Resistance
high
medium
low
θ
TRANSISTORS ARE IDENTIFIED by a Joint Army-Navy (JAN) designation
printed directly on the case of the transistor. If in doubt about a transistor's
markings, always replace a transistor with one having identical markings, or
consult an equipment or transistor manual to ensure that an identical
replacement or substitute is used.
CUTOFF occurs when the base-to-emitter bias prevents current from flowing
in the emitter circuit.
For example, in the PNP transistor, if the base becomes positive with respect
to the emitter, holes are repelled at the emitter-base junction. This prevents
current from flowing in the collector circuit.
SATURATION occurs in a PNP transistor when the base becomes so
negative, with respect to the emitter, that changes in the signal are not
reflected in collector-current flow.
2 N 130 A
First modification
Identification number
Semiconductor
Number of junctions (Transistor)
An AMPLIFIER is a device that enables an input signal to control an output
signal. The output signal will have some (or all) of the characteristics of the
input signal but will generally be larger than the input signal in terms of
voltage, current, or power
COUPLING is used to transfer a signal from one stage to another.
DIRECT COUPLING is the connection of the output of one stage directly to
the input of the next stage. This method is not used very often due to the
complex power supply requirements and impedance-matching problems.
RC COUPLING is the most common method of coupling and uses a coupling
capacitor and signal-developing resistors.
IMPEDANCE COUPLING uses a coil as a load for the first stage but
otherwise functions just as RC coupling. Impedance coupling is used at high
frequencies
TRANSFORMER COUPLING uses a transformer to couple the signal from
one stage to the next. Transformer coupling is very efficient and the
transformer can aid in impedance matching.
NEUTRALIZATION in an RF amplifier provides feedback (usually positive) to
overcome the effects caused by the base-to-collector interelectrode
capacitance
A DIFFERENCE AMPLIFIER is any amplifier with an output signal dependent
upon the difference between the input signals. A two-input, single-output
difference amplifier can be made by combining the common-emitter and
common-base configurations in a single transistor
A DIFFERENTIAL AMPLIFIER has two possible inputs and two possible
outputs. The combined output signal is dependent upon the difference
between the input signals.
FIELD EFFECT TRANSISTOR (FET)
▪ Unipolar device because they operate only with one type of
charge carrier
▪ Voltage controlled device where the voltage between two of the
terminals (gate and source) controls the current through the
device.
▪ Major feature is very high input resistance
a. Junction Field Effect Transistor (JFET)
▪ Operates with a reverse-biased PN junction to control current in
the channel
▪ Square law device because of the relation of ID and VGS
ID
=

VGS
IDSS  1 −

VGS(off)





JFET/D-MOSFET
VIDEO AMPLIFIERS must have a frequency response of 10 hertz to 6
megahertz (10 Hz
6 MHz). To provide this frequency response, both highand low-frequency compensation must be used.
PEAKING COILS are used in video amplifiers to overcome the high-frequency
limitations caused by the capacitance of the circuit.
SERIES PEAKING is accomplished by a peaking coil in series with the outputsignal path.
p
transfer
Source
Gate
Enhancement MOSFET (E-MOSFET)
▪
▪
▪
▪
▪
▪
▪
▪
Drain
p
▪ The drain and source are diffused into the substrate material and
connected by a narrow channel adjacent to the insulated gate
▪ It can be operated in two modes-the depletion mode or the
enhancement mode and sometimes called
depletion/enhancement mode MOSFET
▪ It can be operated with a zero, positive or negative gate-source
voltage
▪ Normally operated in the depletion mode
▪
n
P-channel
A PUSH-PULL AMPLIFIER uses two transistors whose output signals are
added together to provide a larger gain (usually a power gain) than a single
transistor could provide. Push-pull amplifiers can be operated class A, class
AB
Gate
N-channel
Drain
Depletion MOSFET (D-MOSFET)
▪
2
characteristics
▪ Can be n-channel or p-channel
A PHASE SPLITTER provides two output signals that are equal in amplitude
but different in phase from a single input signal. Phase splitters are often used
to provide input signals to a push-pull amplifier.
▪ because of the presence of an insulated gate then it is sometimes
called IGFETs
▪ MOSFETS differs from JFET in that it has no PN junction
structure
▪ It has two basic types, D –MOSFET and E – MOSFET
n
Source
Types of JFET, Its
Structure and Parts
Operation of JFET
▪ JFET is always operated with the gate-source PN junction
reversed biased
Reverse biasing of the gate-source junction with negative voltage produces a
depletion region along the PN junction which extends into the n-channel and
thus increases its resistance by restricting the channel width
b. Metal Oxide Semiconductor Field Effect Transistor (MOSFET)
▪ second category of the field effect transistor
operates only in the enhancement mode
has no depletion mode
it has no structural channel
it has no IDSS parameter
for an n-channel type of this device, a positive gate voltage above
threshold induces a channel by creating a layer of negative
charges (inversion layer) in the substrate portion that is adjacent
to the SiO2 layer.
An n-channel E-MOSFET has a positive VGS while a p-channel EMOSFET has a negative VGS
The conductivity of its channel is enhanced by increasing the gate
to source voltage
For gate voltage below the threshold, there is no channel to be
formed
If configured as a switch, this device is normally off
LD MOSEFT, VMOSFET and TMOSFET are EMOSFET
technologies developed for higher power dissipation
ELECTRONICS ENGINEERING
-FEEDBACKS, OSCILLATORS and MICROELECTRONICS-
b. Voltage Shunt Feedback
Input Impedance (Zif)
Z if
I. FEEDBACK
▪ A method of returning a portion of the output signal into the input
end using a feedback network
▪ Usually applied in control systems
▪ One in which a fraction of the amplifier output is fed back to the
input
1. POSITIVE FEEDBACK
▪ Regenerative feedback or regeneration
▪ The feedback signal taken from the output is in phase with the
input signal
▪ If the feedback voltage or current is so applied to increase the
input voltage or current
▪ Application: oscillators
Vi
+
+
A
Af =
1 − A
Vf

2. NEGATIVE FEEDBACK
▪ Degenerative
▪ If the feedback signal is combined 180 degrees out of phase with
the input signal
▪ If the feedback voltage or current is so applied to reduce amplifier
input
▪ Application: amplifier circuits
Vi
+
Z of =
Zo
1 + A
c. Current Series Feedback
Input Impedance (Zif)
Z if = Z i (1 + A)
Af =
Vf
Types Of Oscillators
1. RC OSCILLATORS
▪ Oscillators whose feedback is an RC network
a. Phase Shift Oscillator
▪ An RC oscillator that makes use of 3 RC circuit as feedback
network
▪ Each of the three RC circuits in the feedback loop can provide a
maximum phase shift approaching 90 degrees.
▪ Oscillation occurs at the frequency where the total phase shift
through the three RC circuits is 180˚
▪ Resonant frequency =
1
2RC 6
Z of = Zo(1 + A)
▪ Resonant Frequency =
Z if =
Zi
1 + A
Output Impedance (Zof)
Z of = Zo(1 + A)
II. OSCILLATORS
▪ circuit that generates repetitive waveform at a certain frequency
which maybe sinusoidal or non-sinusoidal with only a DC supply
at the input.
▪ Using a positive feedback with a transistor, electron tube,
magnetic amplifier or other amplifying device produce the
oscillations
Vout
Z if = Z i (1 + A)
Z of =
Zo
1 + A
Criteria to Sustain Oscillation
1. Positive Feedback must be employed
2. Barkhausen Criterion must be satisfied
▪ The loop gain must be equal to unity (βA = 1)
2 L t C
b. Colpitts Oscillator
▪ Uses a tapped capacitor in its feedback
▪ Approximate frequency of oscillation is established by the values
of C1,C2 and L
3. AMPLIFIER FEEDBACK TOPOLOGIES
oscillator
1
▪ Where Lt = L1 +L2
▪ Resonant Frequency =
DC
1
2RC
2. LC OSCILLATORS
▪ Oscillator whose feedback is an LC network
▪
a. Hartley Oscillator
▪ An oscillator with a tapped inductor
▪ Resonant Frequency =

Output Impedance (Zof)
0.41
2RC
b. Wien Bridge Oscillator
▪ An RC oscillator that uses a Wien Bridge circuit as its feedback
network
d. Current Shunt Feedback
Input Impedance (Zif)
A
1 + A
a. Voltage Series Feedback
Input Impedance (Zif)
=
Output Impedance (Zof)
Vo
A
Vs
Output Impedance (Zof)
Vo
A
Vs
Zi
=
1 + A
1
2 LC t
c. Clapp Oscillator
▪ An improvement of Colpitts oscillator and
designed for a more stable oscillation
Resonant Frequency
3. Other LC Oscillators
=
1
2 LC t
a. Armstrong Oscillator
▪ Type of LC feedback oscillator that uses transformer coupling to
fed back a portion of the signal voltage
▪ It is sometimes called a “tickler” oscillator in reference to the
transformer secondary
b. Pierce Oscillator
▪ Crystal-controlled oscillator
▪ The most stable and accurate type of feedback oscillator that uses
piezoelectric crystal in the feedback loop to control the frequency
▪ Crystal can be quartz, rochelle salt and tourmaline
▪ Operates in the principle of piezoelectric effect
▪ Piezoelectric effect is a crystal property that is when a changing
mechanical stress is applied across the crystal to cause it to
vibrate, a voltage develops at the frequency of mechanical
vibration
Ls
Cm
Cs
Rs
Symbol
b. Thick and Thin Film IC’s
▪ Only passive components are formed through the thick and thin
film techniques on the insulating surface
Thin Film IC’s
▪ Resistors and conductors are formed by varying the width and
thickness of the film and by using materials of different resistivity
▪ Capacitors are produced by sandwiching an insulating oxide film
between two conducting films
Thick Film IC’s
▪ Printed thin film circuits
▪ Silk screen printing techniques are employed to create the desired
circuit pattern on the surface of a substrate
c. Hybrid or Multichip IC’s
▪ Are formed by either interconnecting a number of individual chips
or by combination of thin film or monolithic IC techniques
3. MONOLITHIC IC’s PREPARATION
a. Wafer Preparation
▪ A P-type Si bar (ingot) is taken and cut into thin slices called
wafers
▪ Czochralski Method is one of the most popular process in ingot
growth
Electrical Equivalent
b. Epitaxial Growth
▪ An N-type Si layer is grown on the P-type substrate by the
introduction of a gas containing phosphorus at 1200°C temperature
III. INTEGRATED CIRCUITS (IC)
▪ A complete electronic circuit in which both the active and passive
components are fabricated on an extremely tiny single chip of a
silicon
▪ First developed by Jack S. Kilby in 1958
1. SCALE of INTEGRATION
a. Small Scale Integration (SSI)
▪ The no. of circuits contained in an IC package is less than 30
b. Medium Scale Integration (MSI)
▪ The no. of circuits per package is between 30-100
c. Large Scale Integration (LSI)
▪ Circuit density is between 100-100 000
d. Very Large Scale Integration (VLSI)
▪ Circuit density is in excess of 100 000 – 10 000 000
e. Ultra Large Scale Integration (ULSI)
▪ No. of circuits per package is between 10 million to 1 billion
f. Super Large Scale Integration (SLSI)
▪ No. of circuits per package is in excess of 1 billion
Epitaxial Layer
P
N
P
N
P
P substrate
f. Base and Emitter Diffusion
▪ P-type base is diffused into the N-type layer which itself acts as a
collector
g. Pre-Ohmic Etch
▪ For good metal contact with diffused layers, N+ regions are
diffused into the structure
h. Metallization
▪ Process involve in making interconnections and providing bonding
pads around the circumference of the chip
i. Circuit probing
▪ Each IC on the wafer is checked electrically for proper
performance by placing probes on the bonding pads
j. Scribing and Separating into Chips
▪ Wafers are first scribed with a diamond tipped tool
▪ Wafer is broken down into individual chips containing the
integrated circuits
Substrate
c. Oxidization
▪ a thin layer of SiO2 is grown over the N type layer by exposing the
wafer to an oxygen atmosphere at 1000°C temperature
d. Photolithographic Process
▪ involves the selective etching of SiO2 with the help of
photolithographic mask, photo-resist and etching solution
Two Types of Etching
1. Wet Etching – use of nitric (hydrofluoric acid)
2. Dry etching – use of hot plasma gas
Si02
N layer
2. CLASSIFICATION of IC’s by STRUCTURE
a. Monolithic Integrated Circuits
▪ Monolithic means single stone
▪ All circuit components are fabricated inseparably within a single
continuous piece of Si crystalline material
e. Isolation Diffusion
▪ wafer is subjected to a P-type diffusion process by which N-type
layer is isolated into islands on which components are fabricated
Si02
P substrate
k. Mounting and Packing
▪ IC’s are cemented or soldered to a gold-plated header through
which leads have already been connected
l. Encapsulation
▪ A cap is placed over the circuit and sealing is done in an inert
atmosphere
IV. OPERATIONAL AMPLIFIERS (OP-AMPS)
▪ A very high gain differential amplifier that has very high input
impedance and very low output impedance
▪ The very first op-amp was developed by Fairchild Co.
▪ Ideal operational amplifier has infinite input impedance, zero
output impedance and infinite gain
▪ Term describing the change in output voltage resulting from
change in temperature
h. Roll-Off
▪ It is the reduction of op-amps gain due to increasing operating
frequency
i. Rise time, Rt
▪ An alternate parameter used to specify the bandwidth
+V
Inverting
input
Output
+
Non-inverting
input
-V
BW (MHz) =
OP-AMP Symbol
▪ Virtual Ground Principle sates that the differential input voltage
is zero meaning V+ = V-. Simply shows that two inputs are shorted
but actually not.
Pin Assignments
1 – offset null
2 – inverting input
3 – non inverting input
4 – negative supply
5 – offset null
6 – output
7 – positive supply
8 – no connection
1
350
Rt ns
j. Gain Bandwidth Product
▪ A constant parameter which is always equal to the frequency at
which the op-amps open loop gain is unity
8
2. OP-AMP APPLICATION TIMER CIRCUIT
2
-
3
+
7
6
5
4
OP-AMP Integrated Circuit
1. OP- AMP SPECIFICATIONS
a. Input Offset Voltage
▪ It is the difference in the DC voltages that must be applied to the
input terminals to obtain equal quiescent operating voltage at the
output terminals
b. Input Offset Current
▪ The difference in the current at the 2 input terminals
c. Common Mode Voltage Gain(Ac)
▪ The ratio of the signal voltages developed at either of the two
output terminals to the common signal voltage applied to 2 input
terminals
d. Differential Voltage Gain (Ad)
▪ Ratio of the change in output voltage at either output terminal with
respect to the ground to the difference in the input voltages
e. Common Mode Rejection Ratio (CMRR)
▪ The ratio of the full differential voltage gain to the common mode
voltage gain
CMRR = 20 log
Ad
Ac
f. Slew Rate
▪ Device parameter indicating how fast the output voltage changes
with time
g. Drift
▪ Used in generation of pulse signals that are triggered by an input
signals
▪ Generation of a clock signal that operates at a frequency set by
external resistor and capacitor
555 Timer
▪ Made of combination of linear comparators and digital flipflops
▪ The entire circuit is housed in an 8-pin DIP package
8-Vcc
6-Threshold
5Kilo ohms
+
5-Control Voltage
3-Output
5Kilo ohms
Output
stage
F/F
+
5Kilo ohms
-
7-Discharge
4-Reset
1-ground
2-Trigger input
Vref
555 Timer Internal Circuitry
Applications:
1. Astable Multivibrator or Clock Circuit
▪ Also term as “free-running”
▪ It has no stable state and has 2 quasi-stable states
▪ Its period To = 1.38RC
2. Bistable Multivibrator
▪ Basically the Flipflop
▪ Eccles Jordan Circuit
▪ Has two stable states and no quasi-stable state
3. Mono-Stable Multivibrator
▪ One shot
▪ Has one stable state and 1 quasi-stable state
▪ Its period To = 0.69 RC
ELECTRONICS ENGINEERING
-ROBOTICS, MEDICAL ELECTRONICS and INDUSTRIAL
ELECTRONICS-
I. HISTORICAL OVERVIEW OF ROBOT DEVELOPMENT
1801
▪ Joseph Jacquard invents a textile machine that is operated by
punch cards
1892
▪ In the US, Seward Babbit designed motorized crane with gripper
to remove ingots from a furnace.
1921
▪ First reference to the word robot appears in a play opening in
London entitled “Rossum’s Universal Robots”. The play was written
by Czechoslovakian Karel Capek introduces the word robot from the
Czeck “robota” meaning serf or subservient labor
1939
▪ Isaac Asimov’s science fiction writing introduces robots designed
for humanity and work safely. He formulate the “Three Laws of
Robotics”
1946
▪ George Devol patents a general purpose playback device for
controlling machines
1948
▪ Norbert Wiener, a professor of Massachusetts Institute of
Technology (MIT) publishes Cybernetics, a book that describes the
concept of communications and control in electronic, mechanical
and biological systems
1951
▪ A tele-operator equipped articulated arm is designed by Raymond
Goertz for the Atomic Energy Commission
1954
▪ The first programmable robot is designed by George Devol who
coined the term Universal Automation. Devol is joined by Joseph
Engelberger in 1956 and shorten the name to Unimation and form
the first successful robot manufacturing company
II. ROBOTS
▪ A reprogrammable, multifunctional manipulator designed to move
parts, materials, tools or special devices through variable
programmed motions for the performance of a variety of different
tasks.
▪ These multi-purpose machines are generally designed to carry out
repetitive function and be adapted to other functions.
1. Components of a Robot
a. Actuator
▪ Serves as the muscle of the system, produces the motion with
power supplied electrically, pneumatically or hydraulics
b. Communicator
▪ A unit transmitting information and receiving instructions from a
remote operator
c. Control Computer/ Controller
▪ The central computer that integrates the activity of several
microprocessors
▪ Brain of the robot
d. End effectors
▪ Device at the end of the manipulator arm and use to make
intentional contact with an object
▪ Gripper, hooks, scoops
e. Manipulator
▪ Mechanism consisting of several segment or arms
f. Power Supply
▪ Generally some energy storage device such as battery for a
mobile unit otherwise hook up to the power grid
g. Sensor
▪ Usually a transducer of some kind whose inputs are physical
phenomena and whose outputs consists of electronic signals
2. Axes Control
a. Non Servo Control
▪ Movement of the robots axes is stopped by a hard mechanical
stop placed in the travel path
▪ Non-self correcting and not-self regulating
b. Servo Control
▪ The servo control allows the mechanics of the robot to
communicate with the electronics of the controller.
▪ Equipped with feedback sensors so that controller knows the
exact position of the end effector at all times
▪ self correcting and self regulating
3. Drive Systems / Actuations
a. Pneumatic Drive
▪ reserved for smaller robots which are limited to simple, fast cycle
and pick place operation
▪ have two to four degrees of freedom
▪ quick response
▪ lower initial and operating cost than a hydraulic system
▪ accurate positioning and velocity control are impossible (requires
mechanical stops
▪ weak force capability
b. Hydraulic Drive
▪ used in larger robots
▪ generally heavy and require large floor space and heavy floor
loadings
▪ great force capability
▪ great holding strength when stopped (will not sag)
▪ intrinsic safe in flammable environments such as paintings
▪ accurate servo type positioning and velocity control can be
achieved
▪ Messy-tends to leak oil even in the periods when the robot is not
in motion
▪ High initial and operating cost
c. Electric Drive
▪ Good for robots in light duty, precision applications but does not
offer the speed and strength of a hydraulic drive
▪ Used in electronic assembly where precision is required
▪ Clean –no oil leaks
▪ Lower initial and operating cost compared as compared to
hydraulic and pneumatic drive
▪ Less force capability as compared to hydraulic system
4. Robot’s Manipulator Arm Geometry
a. Cartesian Coordinates
▪ Uses three perpendicular slides to construct the X, Y and the Z
axes
▪ Rectangular work space or work envelope
▪ Work envelope refers to the space with which the robot can use
its wrist
b. Cylindrical Coordinates
▪ Cylindrical configurations uses a vertical column and a slide that
moves up and down the column
▪ The work space is approximately a cylinder
c. Polar Coordinates
▪ Uses a telescoping arm that can be lowered or raised about a
horizontal pivot which is mounted on a rotating base
d. Articulate Coordinates
▪ This configuration consists of two straight components mounted
on a vertical pedestal
▪ A rotary joint connects one of the straight components to the
pedestal while another joins the straight components
▪ A wrist is attached to the end of the second straight component
and provides several additional joints
5. Wrist Rotation
a. Yaw axis
▪ Describes the wrist angular movement from the left side to the
right side
b. Pitch axis
▪ Describes the wrist’s rotational movement up and down
c. Roll axis
▪ Describes the rotation around the end of the wrist
6. Degrees of Freedom
▪ Refers to different axes of motion of robotic arm
▪ The movement about one axis is hardware independent of
movement about any other axis.
Total no. of locations = 2n
Where n – degrees of freedom
III. BIOENGINEERING
▪ A developing specialty featuring a multidisciplinary approach to
the solution of problems in medicine and biology
▪ Based on the application of advances in science, engineering and
technology
IEEE 1073: Standard for Medical Device Communication
1. IEEE 1073.31
▪ Standard for Medical Device Communications Transport ProfileConnection Mode
▪ Defines the service and requirements for bedside sub network
2. IEEE 1073.41
▪ Physical layer, cable connected
▪ Defines cables, connector data rates and bio level encoding
MEDICAL DEVICES and EQUIPMENTS
1. DIAGNOSTIC EQUIPMENTS
▪ Medical imaging equipment
a. Radiography (X-RAY)
▪ Art and science of using ionizing radiation to provide images of
tissues, organs,bones and vessels that comprise the body
▪ The first body imaging test
▪ X-Rays was discovered by Wilhelm Roentgen in 1895
▪ Consist of electromagnetic radiation like light but behaves a
shorter wavelength
▪ Penetrate on the body and formed image on the film
Myelogram
▪ An X-ray test of the spine
Arthrogram
▪ X-ray of joint usually the knee or hip
Flouroscopy
▪ A moving picture of the body is seen as the test is performed
and recorded on videotapes
▪ Evaluates gastrointestinal tract, respiratory system and the
bladder
Intravenous Pyelogram (IVP)
▪ Uses contrast dye to outline kidneys, ureters and bladders
▪ Radioisotope is attached to another substance that is injected.
Inhaled or swallowed
▪ Reverse of an X-ray because the radiation instead of directed o
the body, the radiation comes from the inside
▪ Detects electrical signals from the heart
M-Mode
▪ Provides a single dimension images that allow accurate
measurement of the heart chambers
g. Bone Scan
▪ Test that can detect changes in bone metabolism or growth
▪ It identifies cancer, infections of the cause of unexplained bone
pain such as break that didn’t show up on X-ray
▪ Done by seeing how a radio active isotope which work as a
“tracer”
2-D echo
▪ Capable at displaying a cross sectional slice of the beating
heart, including the chambers, valves and the major blood
vessels that exist from the left and the right ventricle
h. Ultrasound (Sonography)
▪ Uses high frequency sound waves to “echo” off the body and
create a picture of it
▪ Organs being examined by the ultrasound are kidneys, the liver
and spleen, the brain, the female pelvis and the hips
2. THERAPEUTIC EQUIPMENTS
a. Cardioversion
▪ Process of restoring the heart’s normal rhythm by applying a
controlled electric shock to the exterior of the chest
▪ Lower electric level than defibrillator
b. Pacemaker
▪ Regulates the beating of the heart
▪ Natural pacemaker is the sinoatrial (SA) node or sinus node
▪ The artificial pacemaker is a small battery operated device that
helps the heart beat in a regular rhythm
b. Mamography
▪ Used for detection of breast disease such as breast cancer using
low dose X-ray
c. Diathermy
▪ Involves the passage of high frequency alternating current through
the body tissue
c. CT Scan (Computed Tomography)
▪ Obtain multiple cross sectional images of the body by using
special X-rays and computer enhancement
d. Defibrillator
▪ A device that administers an electric shock through the chest wall
to the heart
▪ High voltage power supply, storage capacitor and electrodes are
primary components
▪ Uses two electrical pads to stimulate heart beat
▪ Can be manual or automatic
b. Electroneurogram (ENG)
▪ Detects electrical signals from the nerves
c. Electromyogram (EMG)
▪ Assess the health of the muscles and the nerves controlling the
muscles
▪ A needle electrode is inserted through the skin into the muscle.
The electrical activity detected by the electrode is inserted through
the skin into the muscle
d. Electroencephalogram (ECG)
▪ Detects the electrical signals from the brain
▪ Recorded by 8 to 160 pairs of electrodes attached to the scalp
e. Electro-oculogram
▪ Detects the electrical potential from the eyes(retina and cornea)
f. Electronystagmogram
▪ A recording of the eye movements
IV. WELDING SYSTEMS
d. Echocardiography
▪ This procedure uses a special device to detect the sound that is
reflected from a beating of the heart
▪ It is also called “diagnostic cardiac ultrasound” because it uses
reflected sound waves to “look” directly at your child’s heart
e. MRI (Magnetic Resonance Imaging)
▪ Method of creating images of the inside of opaque organs in living
organisms as well as detecting the amount of bound water in
geological structures
▪ Uses magnetism and radio waves
f. Radioisotope (Nuclear Scan)
▪ Number of tests that uses very small quantities of radioactive
materials called radio isotopes to image parts of the body
3. MONITORING EQUIPMENTS
a. Electrocardiogram (ECG)
▪ A non-invasive test that records the electrical activity of the-heart
▪ It was invented by a Dutch physiologist Wilhem Einthoven (18601927)
▪ Used to measure the rate and regularity of heartbeats as well as
the size and position of the chambers, the presence of any damage
to the heart and the effects of drugs
WELDING
▪ The process of joining metals usually by heat or sometimes with
pressure and sometimes with an intermediate or filler material with
high melting point
1. BASIC INTERVALS
a. Squeeze Interval
▪ Welding electrode comes forward and engage the metal pressing
against the surface
▪ Typical squeeze time is 1 sec
b. Weld Interval
▪ Welding transformer is energized, current flows and creates a
weld
▪ On heat subinterval is a condition when the current is on
▪ On cool subinterval is when the current is off
▪ Typical duration (2 – 10 sec)
c. Hold Interval
▪ Weld interval is finished
▪ Electrode pressure is maintained
d. Release
▪ Welding electrode is retracted
e. Standby Interval
▪ The time after release interval to the next start sequence
2. POPULAR WELDING PROCESSES
a. Arc Welding
▪ It is simply the use of electric arc to provide heat
▪ Process of utilizing the concentrated heat of an electric arc to join
metal by fusion of the parent metal and the addition of metal to
joint usually provided by a consumable electrode.
TIG Welding
▪ Gas tungsten arc welding
▪ An arc is formed between a non-consumable tungsten electrode
and the metal being welded.
▪ Some of its benefits includes superior quality welds, precise
control of heat, free of splatter and low distortion
MIG Welding
▪ Gas Metal Arc Welding
▪ Commonly used high deposition rate welding process.
▪ Referred to as a semiautomatic welding process.
▪ Benefits include all position capability, long weld can be made
without start and stops and minimal post weld cleaning is required
b. Solid State Welding
▪ Group of welding processes which produces coalescence at
temperatures essentially below the melting point of the base
materials being joined, without the addition of brazing filler metal.
▪ Sometimes called solid state bonding processes
c. Resistance Welding
▪ uses the application of electric current and mechanical pressure to
create a weld between two pieces of metal
V. SYNCHROS
1. SYNCHRO and its SYSTEM
▪ Synchro resembles a small electric motor in size as well as in
appearance and it operates like a variable motor
▪ Synchros are used primarily for the rapid and accurate
transmission of data as well as control device in servo systems
▪ Synchros are designed for use on either a 115 volt or a 26-volt
power source.
▪ Operating frequencies includes either 60 or 400 Hz
▪ Electromagnetic theory forms the basis for all synchro operations
SYNCHRO SYSTEMS
▪ Consist of two or more synchros electrically connected
a. Torque Synchro System
▪ Uses torque synchros that are very functional in moving light
loads
Correspondence
▪ The term given to the positions of the rotors of a synchro
transmitter and a synchro receiver when both rotors are on 0˚ by
the same angle
Signal
▪ Defined as the angle through which a transmitter rotor is
mechanically turned and simply the transmitter’s mechanical input
b. Control Synchro Systems
▪ Uses control synchros to control servo systems
▪ The servo system with the control synchro system is used to move
heavy loads and control large amount of power with high degree
of accuracy
Control Transformer
▪ A synchro device that compares two signals, the electrical signal
applied to its stator and the mechanical signal applied to its rotor.
Hence the output is an electrical voltage taken from the rotor
winding
▪ ERROR SIGNAL is the name given to the electrical output of the
control transformer
Synchro Capacitor
▪ A unit containing three delta connected capacitors
b. Velocity Servo
▪ Same principle of error signal generation as position servo except
that the velocity is being sensed rather than the position
c. Acceleration Servo
▪ Similar to velocity and position servos except that the acceleration
of the load is being sensed rather than position or velocity
▪ The tachometer of the velocity loop
is replaced with an
accelerometer
3. DAMPING
Time Lag
▪ Servo characteristics defined as the time between the input of the
signal and the actual movement of the load
Damping
▪ Used to stabilized a system to minimize or eliminate the problem
of overshot
a. Damping Conditions
Underdamped
time
Delta-Connected
Synchro Capacitor
VI. SERVO
1. CONTROL SYSTEM
a. Open Loop Control System
▪ Controlled directly by an input signal
▪ It has no feedback and therefore less accurate
b. Closed Loop Control System
▪ Can respond and move loads quickly
▪ With greater accuracy
▪ Has an automatic feedback system that informs the input the
desired movement has taken place
2. SERVO SYSTEM
▪ Classified as closed-loop system
a. Position Servo
▪ Control the position of the load
▪ In AC position servo, the amplitude and phase of the AC error
signal determine the amount and direction the load will be driven
▪ Potentiometer is one of the simplest position sensor device and is
generally used because of its small size, high accuracy and
output which can either be AC or DC
Overdamped
Overdamped
▪ Takes as excessive amount of time to reach synchronization
Underdamped
▪ Provides instant response to an error signal but results in the load
oscillating about the point of synchronism
b. Methods of Damping
Friction Clutch Damping
▪ Simplest type of damping
Magnetic Clutch Damping
▪ Magnetic coupling uses a magnetic field o draw friction plates
together to produce damping
Error-Rate Damping
▪ Method of damping that anticipates the amount of overshot
▪ Corrects the overshot by introducing a voltage in the error
detector that is proportional to the rate of change of the error
signal
VII. GYROS
GYROSCOPE
▪ Applied to any rapidly spinning object
▪ A functional gyroscope is constructed and mounted
▪ Rate Gyros are specially mounted so they are free to precess in
only one direction and are used to measure angular rates
▪ The angular degrees of an AC cycle during which the SCR is
turned on
SCR’s Firing Delay Angle (FDA)
▪ Angular degrees of an AC cycle that elapses before SCR is turned
on
Anode
Anode Gate
(determine on and off)
Cathode Gate
2. Triac
▪ Triode AC
▪ A three-terminal device used to control the average current flow to
a load
▪ Can conduct current in either direction when it is turned on so it is
called a bidirectional triode thyristor
▪ Acts like two SCR’s connected in inverse parallel so that each
SCR conducts alternately for every half cycle of an AC signal
▪ Gated DIAC
GYRO
PROPERTIES
1. Rigidity
▪ Tendency of a spinning wheel to remain in fixed position in space
Factors that Affect the Rigidity
a. weight
b. shape
c. speed of rotation of the rotor
2. Precession
▪ Property of a gyro that causes it to tilt in a direction perpendicular
to the direction of any outside force
▪ The direction of precession in a gyro is always 90 degrees from
the direction of the applied force
3. BREAK-OVER DEVICES
▪ Small thyristors which do not switch the main load current
▪ Useful as triggering devices
a. Shockley Diode
▪ A 4-layer diode constructed like an SCR but without gate terminal
▪ Unilateral triggering device for SCR
b. Silicon Unilateral Switch
▪ Solid-state device that provides a positive pulse
▪ Also a 4-layer diode with a typical break-over voltage of 8 volts
▪ In terms of firing, it has faster rate than Shockley diode
Cathode
Anode
Gate
Components of a Universally Mounted Gyro
1. Rotor
2. Inner Gimbal
3. Outer Gimbal
4. Base
c. DIAC
▪ Diode AC
▪ Constructed like a TRIAC but without a gate terminal
▪ Used as a trigger for TRIAC circuits
▪ Bilateral trigger diode
▪ Symmetrical trigger diode because its break-over voltage is close
 32 Volts
VIII. THYRISTOR
▪ Solid state devices used as a switch in applications that handles
larger voltage and currents
▪ Have at least four semiconductor layers
1. Silicon Controlled Rectifier (SCR)
▪ Most commonly used thyristor
▪ Three-terminal device used to control large currents to a load
SCR Gate Characteristics
▪ SCR is fired by a short burst of current into the gate typically 0.1 –
50 mA
SCR’s Conduction Angle (CA)
d. Silicon Bilateral Switch (SBS)
▪ A bilateral or bidirectional break-over device
▪ Two SUS connected back to back in parallel
▪ Popular in low voltage trigger control circuits
▪
e. Silicon Controlled Switch (SCS)
Cathode
SCS turn off time is 1 – 10 μsec
g. Unijunction Transistor (UJT)
▪ Break-over type switching device
▪ Double-based diode
▪ Semiconductor device consisting of thin silicon bar on which a pn
junction acting as emitter is formed near one end
▪ Operates in the negative resistance region
Intrinsic Stand-off ratio (η)
η=
R B1
R B1 + R B2
Firing Potential (Vp)
▪ Necessary to fire the UJT
▪ Equal or greater than voltage across emitter and base1
Vp = ηVBB + Vdiode
h. Programmable Unijunction Transistor (PUT)
▪ Similar operating characteristics as UJT
▪ Programmable because the internal resistances of UJT are
external for PUT and can be selected to a certain desired
response
ELECTRONICS ENGINEERING
-MIXED TOPICS-
15. Two cells are connected in series to form a battery. Their internal
resistance is 0.1. The internal resistance of the battery will be
- 0.2 
1. “the mass of an ion liberated at an electrode is directly proportional to the
quantity of electricity which passes through the electrolyte. “ The statement is
associated with
- Faraday’s Laws of Electrolysis
16. On ampere-hour basis the efficiency of a lead acid battery is in the range
- 90 to 95 %
2. The plates of a lead acid battery are made of
- cast anomonial lead alloy
18. Excessive overcharging of a battery may result in
- increased internal resistance
- loss of water
- excessive gassing
3. In a lead acid battery, separators are provided
- to avoid internal short circuits
4. Container of a lead acid battery is made of
- moulded hard rubber
- ceramics
- celluloid
17. The life of a lead acid battery is expected to be
- 2 - 5 years
19. The indication of the state of charge of a battery is best given by
- specific gravity of electrolyte
20. Common impurity in battery electrolyte is
- lead sulphate
5. Filters in a lead acid battery are provided
- to facilitate flow of gases
21. Open circuit voltage of a fully-charged lead acid is
- 2.5 V
6. In case of a lead acid battery, during discharging
- both anode and cathode become PbSO4
22. The capacity of storage battery is expressed as
- the number of cells it contains
7. In lead acid battery, during charging
- specific gravity of acid increases
23. On watt hour basis the efficiency of a lead acid battery is in the range
- 70 to 85 %
8. The condition of a fully charged lead acid battery can be ascertained by
- voltage
- specific gravity
- gassing
24. What is the arrangement to get the maximum current in 3 ohms resistance
in case of 24 cells, each of internal resistance 2 ohms?
- 4 cells in series with six rows in parallel
9. The value of specific gravity of acid when a lead acid battery is fully
charged is
- 1.285
25. Trickle charge is required for
- lead acid batteries
- nickel iron cells
- primary cells
10. The active materials on the positive and negative plates of a fully charged
lead acid battery are
- lead peroxide and pure lead
11. A floating battery is one
- which supplies current intermittently and also during off cycle gets
charged
12. Which cells has reversible chemical reaction?
- lead acid
26. A wet battery cover in case of lead acid battery indicates
- excessive gassing during charging
- leaky seals at covers
- overfilling of the battery
- maximum current
32. One ampere hour charge is equivalent to
- 3,600 C
33. When water is added to sulphuric acid
- lot of heat is generated
34. The electro-chemical reactions are not reversible in case of
- primary cells only
35. The energy in a lead acid battery is stored in the form of
- chemical energy
36. The electrolyte in a Leclanche cell is
- aqueous solution of ammonium chloride
37. The electrode for a battery must be
- a good conductor of electricity
38. For a discharged lead acid battery, the specific gravity of the acid is
- 1.12
39. Even when not in used, a lead acid battery should be recharged once in
- 6 weeks
40. The specific gravity of acid is checked with the help of
- hydrometer
41. Sedimentation in lead acid batteries occurs due to
- overcharging at high rate
42. The term trickle charge is associated with
- lead acid batteries
43. When a battery is being charged, the terminal voltage decrease with
- Increasing temperature
44. When a battery is being discharged, the terminal voltage decrease with
- decreasing discharge rate
45. The ampere hour capacity of a battery used on cars is
- 30-60 Ah
27. Internal resistance of a battery is due to
- surface contact resistance
46. The ampere hour capacity of a battery used in truck is
- 100-150 Ah
28. The emf of a storage battery depends upon
- nature of electrodes
47. Which test is used to ascertain whether the battery plates are defective or
not?
- cadmium test
13. Manufacturers normally specify that the lead acid battery should not
remain discharged for more than
- 24 hours
29. The internal resistance of a dry cell is of the order of
- 0.2 - 0.4 
14. During charging, the electrolyte of a lead acid battery become
- stronger
30. Proper charging for lead acid battery is
- 1/8 of rated ampere hour capacity
31. For a group of cells when internal resistance of the group is equal to the
external resistance due to the load, the battery will give
48. Which of the following is the common voltage of automobile batteries?
-2V
49. Cells are connected in parallel to
- increase the current capacity
50. Which laws find application is electrolysis?
- Faraday’s laws
- open
51. What is the drawback of special purpose computers?
- Lack of versatility
68. How does an inductor react at low frequencies?
- short
52. What is the common name for enamel-insulated wire?
- magnet wire
69. How does a capacitor react at high frequencies?
- short
53. What is the standard unit of measurement for a round wire cross sectional
area?
- circular mil
70. How does an inductor react at high frequencies?
- open
54. What is the reciprocal of conductivity?
- resistivity
71. Shunts are usually made from what alloy?
- manganine
85. Iron core material of inductor use in radio at high frequencies
- Ferrite
86. Color of the positive plate of a fully charge lead acid cell
- Deep Chocolate brown
87. Commonly used for extending the range of an AC ammeter
- current transformer
88. What is the most common impurity found in battery electrolyte
- ion
89. What alloy consists of 55 percent copper and 45 percent nickel
- Constantan
72. In the d’arsonval, many turns of fine wire would be used. The coil is wound
in an aluminum frame called
- Bobbin
90. Who designed microprocessor in 1969?
- Ted Hoff
56. A meter used to measure small values of current is called
- galvanometer
73. A resistor place in parallel with the meter terminals and used to provide
increase range capability
- meter shunt
91. What discovery proved to be the foundation of the development of vacuum
tubes?
- Edison effect
57. The discharge of electricity from a conductor with a high potential
- Corona
74. Mechanical rotation frequency is measured using a device called
- Tachometer
92. What type of substrates are used for film and hybrid IC
- Glass or ceramic
58. A device used to absorb heat and protect heat sensitive components
during soldering
- heat sink
75. What equipment uses a calibrated resonant circuit to measure frequency?
- Wavemeter
93. What amplifiers are bias so that the collector current is cut off during one
half of the input cycle
- Class B
55. What is the movement of a aluminum wire away from a point where
pressure is applied?
- aluminum creep
59. What wave is compose of infinite number of odd harmonics in phase with
the fundamental wave?
- square wave
60. The ability of resonant circuit to operate continuously because of stored
energy
- flywheel effect
61. What is the condition of the diode in a series limiter when an output is
develop?
- conducting
62. A resonant circuit is often called
-tank circuit
63. Other name for non-sinusoidal oscillator
- relaxation oscillator
64. Which oscillator uses a tickler coil for feedback
- Armstrong
65. What is the identifying feature of a colpitts oscillator?
- Tapped capacitor
66. The ability of the filter to distinguish between low and high frequencies and
to eliminate unwanted signals
- discrimination
67. How does a capacitor react at low frequencies?
76. What device undergoes changes in resistance as changes in power
occur?
- bolometer
94. What is the faithful reproduction of a signal in an amplifier?
- Fidelity
77. Audio frequencies can be measured by the process known as
- Zero beating
95. A light controlled variable resistor
- photo diode
78. What is the other term for zero beating?
- Heterodyning
96. Transistors are identified by a _____ designation printed directly on the
case of the transistors
- Joint Army Navy
79. The rotation frequency of recording devices can be measured by the used
of a
- Stroboscope
97. What type of coupling is useful in impedance matching?
- transformer coupling
80. Air gap in the iron core of an inductor prevents
- core saturation
98. What class of operation has the highest fidelity?
- class A
81. A cross connection between two conductors in a multi conductor cable
may be located by the used of
- Varley Loop
99. What is the most common cause of electron tube failure?
- open filament
82. Conductor with the lowest resistivity at 273 K
- Copper
83. Nichrome is commonly used for
- heater coils
84. Insulator most affected by heat
- PVC
100. What is added to a sawtooth generator to produce a trapezoidal wave?
- Resistor
101. What is a VOM?
- A combination of ohmmeter, milliammeter and voltmeter
102. A iron vane is used to measure
- AC and DC
103. An instrument used to measure the voltage generated by human body
parts in relation to the action of the human heart
-ECG
120. Calculate the sensitivity of a voltmeter with a full scale deflection of 100
micro ampere.
-10 kohms/V
136. Is the force which sets up or tends to set up magnetic flux in a magnetic
circuit.
-magnemotive force
104. Find the voltage drop develop across D’ Arsonval meter movement
having an internal resistance of 1 kohm and full deflection current of 150
micro ampere
-150 mV
121. What materials are meter pointers normally made?
-Aluminum
137. Is the name given to that property of a material which opposes the
creation of magnetic flux in it?
-reluctance
105. What test instrument will you use to make a modulated envelope visible?
-Oscilloscope
106. What is the common type of meter movement?
-D’ Arsonval
122. A device that is used to measure current without opening the circuit
-Clamp probe
123. Which of the following is a dc bridge that is very useful for making
extremely accurate voltage measurements?
-Potentiometer bridge
107. How is an ammeter connected to the circuit under test?
-In series
124. Which meter is the most expensive?
-Dynamometer
108. At what point on a meter movement are the most accurate readings
taken?
-Midscale
125. What is the reduction in the power rating of a device because of an
increase in temperature?
-power derating
109. Which of the following cannot be easily measured with a simple meter
circuit?
-Impedance
126. What is the typical forward voltage drop of a LED?
-1.5 volts
110. ______ is a measure of consistency of measurement
-Precision
111. Other measurement an ohmmeter can make beside resistance
-Circuit continuity
127. What is one major application of a tunnel diode?
Oscillator ,amplifier
128. Coherent light has
Single wavelength
112. Electrical property measured by an ammeter
-Current
129. The term used to describe sudden reverse conduction of an electronic
component caused by excess reverse voltage across the device?
Avalanche
113. An ideal voltmeter should have ______ resistance
-Infinite
130. What is the typical voltage rating available in zener diode?
-2.4 to 200 volts
114. A common laboratory Multimeter cannot measure
-Frequency
131. A high power, low frequency diode is normally______than a low power,
high frequency diode.
-larger
115. An ohmmeter can be made using
-ammeter and a battery
116. An instrument that measure small amounts of current and its based on
the electromagnetic principle
-Galvanometer
117. How do you increase the range of a voltmeter?
-Through multiplier
118. In measuring high resistance values such as insulators, we normally
used a/ an
-Megger
119. Which type of meter requires its own power source?
-Ohmmeter
132. _____is usually used as a stable reference voltage in a linear voltage
regulator.
-zener diode
133. It is the AC component of a rectified signal
-ripple
134. It is the required voltage across the junction diode before the forward
current can flow significantly
-threshold voltage
135. How many capacitors are used in a diode-capacitor halfwave voltage
doubler?
-2
138. It is the reciprocal of reluctance and implies the case of readiness whit
which magnetic flux is developed.
-reluctivity
139. The flux that does not follow the intended path in a magnetic circuit is
called
-leakage flux
140. The ratio of the total flux (flux in iron path) to the useful flux(flux in air
gap) is called
-leakage factor
141. Comparing electric and magnetic circuit, the current electric circuit is
analogous to which parameter of magnetic circuit?
-flux
142. May be defined as that pole which when places in air from a similar and
equal pole repels it with a force of 1/4 Newtons
-unit pole
143. The phenomenon by which a magnetic substance becomes magnet
when it is placed near a magnet is called.
-magnetic induction
144. The space outside the magnet where its poles have a force attraction or
repulsion on a magnetic pole is called
-magnetic field
145. The total number of magnetic lines of force in a magnetic field is called
-magnetic flux
146. The lagging effect between flux density of the material and the
magnetizing force applied is called
-hysteresis
147. A law establishing the fact that the algebraic sum of the rises and drops
of the mmf around a closed loop of a magnetic circuit is equal to zero.
-Amperes Circuital Law
148. The unit of magnetomotive force
-Amperes-turn
149. Flux density is measured in
-Tesla
150. If a right handed bottle-opener cork screw is assumed to be along the
conductor so as to advance in the direction of current flow, the motion of its
handle will indicate the direction of magnetic flux produced around the
conductor is known as
-Cork Screw rule
151. A computer software that defeats a world champion in chess
-Deep Blue
152. Another name of secondary storage
-Auxiliary
153. An American that built a computer in 1946 that uses binary numbers and
stores information.
-John Von Neumann
154. Apple Computer launch with a $1.5 million commercial product during the
1984 Super Bowl.
-Macintosh
155. Computer device Douglas Engelbart invent in 1963.
-mouse
156. A device, tool, gripper, or hand located at the end of a manipulator and
used to perform work or movement on some object
- end effector
157. A reprogrammable, multifunctional manipulator designed to move
materials, parts, tools or specialized devices through variable programmed
motions, in order to perform various tasks.
-industrial robots
158. Materials where meter pointers normally made.
-Aluminum
159. SCARA stands for Selective Compliance Assembly Robot Arm, a
particular design developed in the late 1970’s by
-Hiroshi Makino
160. Most poular country level domain
-.uk
161. UK developed a robot that has the ability to recognize the gender of
women and men. It is consider as the most gender aware robot.
-Doki
162. Pi is accurately calculated to 1241100000000 decimal place by what
computer?
-MPP Computer
163. This robot has the record of being the most emotionally responsive robot
according to Guiness World of Records
-Kismet
164. The word gyroscope was first coined by a French Scientist in 1852
named
-Leon Focult