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P.S.R.ENGINEERING COLLEGE, SIVAKASI-626 140
DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING
YEAR: I
SEMESTER: I
ENGINEERING PRACTICES
LABORATORY
(12F1Z9)
LAB MANUAL
[Group B]
I
SHANMUGANATHAN ENGINEERING COLLEGE, ARASAMPATTI
DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING
Class/ Semester
Sub & Code
: I/ I
: EE6162 - Engineering Practices Laboratory [Group B]
LIST OF EXPERIMENTS
v STUDY OF SYMBOLS
v SIMPLE WIRING CONNECTION
v STAIRCASE WIRING
v FLUORESCENT LAMP WIRING
v MEASUREMENT OF POWER USING WATTMETER
v MEASUREMENT OF ENERGY USING SINGLE PHASE ENERGY METER
v STUDY OF MEASUREMENT OF RESISTANCE USING COLOR CODING
v MEASUREMENT OF AC SIGNAL PARAMETERS USING CRO
v STUDY OF BASIC LOGIC GATES
v HALF WAVE AND FULL WAVE RECTIFIER
v MEASUREMENT OF RESISTANCE TO EARTH OF ELECTRICAL
EQUIPMENT
I
Ex.No: STUDY OF SYMBOLS
Date:
AIM:
To study the various symbols used in electric circuits.
COMPONENT
WIRE CONNECTIONS
Wire
To pass current very easily from one part
of a circuit to another.
A 'blob' should be drawn where wires are
connected (joined), but it is sometimes
omitted. Wires connected at 'crossroads'
should be staggered slightly to form two T-
junctions, as shown on the right.
In complex diagrams it is often necessary
to draw wires crossing even though they
are not connected. I prefer the 'bridge'
symbol shown on the right because the
simple crossing on the left may be misread
as a join where you have forgotten to add a
'blob'!
CIRCUIT SYMBOL
DESCRIPTION
Wires joined
Wires not joined
POWER SUPPLIES
Supplies electrical energy.
The larger terminal (on the left) is positive
(+).
A single cell is often called a battery, but
strictly a battery is two or more cells joined
together.
Supplies electrical energy. A battery is
more than one cell. The larger terminal (on
the left) is positive (+). The smaller
terminal (on the right) is negative (-).
Supplies electrical energy.
DC = Direct Current, always flowing in
one direction.
Supplies electrical energy.
AC = Alternating Current, continually
changing direction.
A safety device which will 'blow' (melt) if
the current flowing through it exceeds a
specified value.
Cell
Battery
DC supply
AC supply
Fuse
1
Transformer
Two coils of wire linked by an iron core.
Transformers are used to step up (increase)
and step down (decrease) AC voltages.
Energy is transferred between the coils by
the magnetic field in the core. There is no
electrical connection between the coils.
A connection to earth. For many electronic
circuits this is the 0V (zero volts) of the
power supply, but for mains electricity and
some radio circuits it really means the
earth. It is also known as ground.
A transducer which converts electrical
energy to light. This symbol is used for a
lamp providing illumination, for example a
car headlamp or torch bulb.
A transducer which converts electrical
energy to light. This symbol is used for a
lamp which is an indicator, for example a
warning light on a car dashboard.
A transducer which converts electrical
energy to heat.
A transducer which converts electrical
energy to kinetic energy (motion).
A transducer which converts electrical
energy to sound.
Earth
(Ground)
OUTPUT DEVICES: LAMPS, HEATER, MOTOR, etc.
Lamp (lighting)
Lamp (indicator)
Heater
Motor
Bell
Buzzer
A transducer which converts electrical
energy to sound.
A coil of wire which creates a magnetic
field when current passes through it. It may
have an iron core inside the coil. It can be
used as a transducer converting electrical
energy to mechanical energy by pulling on
something.
A push switch allows current to flow only
when the button is pressed. This is the
switch used to operate a doorbell.
2
Inductor
(Coil, Solenoid)
Switches
Push Switch
(push-to-make)
Push-to-Break
Switch
On-Off Switch
(SPSTS)
This type of push switch is normally closed
(on), it is open (off) only when the button
is pressed.
SPSTS = Single Pole Single Throw
Switch. An on-off switch allows current to
flow only when it is in the closed (on)
position.
SPDTS = Single Pole Double Throw
Switch. A 2-way changeover switch directs
the flow of current to one of two routes
according to its position. Some SPDT
switches have a central off position and are
described as 'on-off-on'.
DPST = Double Pole, Single Throw
Switch. A dual on-off switch which is
often used to switch mains electricity
because it can isolate both the live and
neutral connections.
DPDT = Double Pole, Double Throw
Switch. This switch can be wired up as a
reversing switch for a motor. Some DPDT
switches have a central off position.
An electrically operated switch, for
example a 9V battery circuit connected to
the coil can switch a 230V AC mains
circuit.
NO = Normally Open, COM = Common,
NC = Normally Closed.
2-way Switch
(SPDTS)
Dual On-Off
Switch
(DPSTS)
Reversing Switch
(DPDTS)
Relay
Resistors
Resistor
A resistor restricts the flow of current, for
example to limit the current passing
through an LED. A resistor is used with a
capacitorinatimingcircuit.
Some publications still use the old resistor
symbol:
This type of variable resistor with 2
contacts (a rheostat) is usually used to
control current. Examples include:
adjusting lamp brightness, adjusting motor
speed, and adjusting the rate of flow of
charge into a capacitor in a timing circuit.
3
Variable Resistor
(Rheostat)
Variable Resistor
(Potentiometer)
This type of variable resistor with 3
contacts (a potentiometer) is usually used
to control voltage. It can be used like this
as a transducer converting position (angle
of the control spindle) to an electrical
signal.
This type of variable resistor (a preset) is
operated with a small screwdriver or
similar tool. It is designed to be set when
the circuit is made and then left without
further adjustment. Presets are cheaper
than normal variable resistors so they are
often used in projects to reduce the cost.
A capacitor stores electric charge. A
capacitor is used with a resistor in a timing
circuit. It can also be used as a filter, to
block DC signals but pass AC signals.
A capacitor stores electric charge. This
type must be connected the correct way
round. A capacitor is used with a resistor in
a timing circuit. It can also be used as a
filter, to block DC signals but pass AC
signals.
A variable capacitor is used in a radio
tuner.
This type of variable capacitor (a trimmer)
is operated with a small screwdriver or
similar tool. It is designed to be set when
the circuit is made and then left without
further adjustment.
Variable Resistor
(Preset)
CAPACITORS
Capacitor
Capacitor
polarized
Variable Capacitor
Trimmer Capacitor
DIODES
Diode
LED
Light Emitting
Diode
Zener Diode
A device which only allows current to flow
in one direction.
A transducer which converts electrical
energy to light.
A special diode which is used to maintain a
fixed voltage across its terminals.
4
Photodiode
TRANSISTORS
A light-sensitive diode.
Transistor NPN
A transistor amplifies current. It can be
used with other components to make an
amplifier or switching circuit.
Transistor PNP
A transistor amplifies current. It can be
used with other components to make an
amplifier or switching circuit.
Phototransistor
A light-sensitive transistor.
AUDIO AND RADIO DEVICES
Microphone
A transducer which converts sound to
electrical energy.
A transducer which converts electrical
energy to sound.
Earphone
Loudspeaker
A transducer which converts electrical
energy to sound.
Piezo Transducer
A transducer which converts electrical
energy to sound.
An amplifier circuit with one input. Really
it is a block diagram symbol because it
represents a circuit rather than just one
component.
Amplifier
(general symbol)
5
Aerial
(Antenna)
A device which is designed to receive or
transmit radio signals. It is also known as
an antenna.
METERS AND OSCILLOSCOPE
Voltmeter
A voltmeter is used to measure voltage.
Voltmeter must be connected across the
terminal.
An ammeter is used to measure current. It
is always connected in series with the
circuit.
A galvanometer is a very sensitive meter
which is used to measure tiny currents,
usually 1mA or less.
An ohmmeter is used to measure
resistance. Most multimeters have an
ohmmeter setting.
An oscilloscope is used to display the
shape of electrical signals and it can be
used to measure their voltage and time
period.
A transducer which converts brightness
(light) to resistance (an electrical
property).
LDR = Light Dependent Resistor
A transducer which converts temperature
(heat) to resistance (an electrical property).
A NOT gate can only have one input. The
'o' on the output means 'not'. The output of
a NOT gate is the inverse (opposite) of its
input, so the output is true when the input
is false. A NOT gate is also called an
inverter.
An AND gate can have two or more inputs.
The output of an AND gate is true when all
its inputs are true.
Ammeter
Galvanometer
Ohmmeter
Oscilloscope
SENSORS (INPUT DEVICES)
LDR
Thermistor
LOGIC GATES
NOT
AND
6
NAND
A NAND gate can have two or more
inputs. The 'o' on the output means 'not'
showing that it is a Not AND gate. The
output of a NAND gate is true unless all its
inputs are true.
An OR gate can have two or more inputs.
The output of an OR gate is true when at
least one of its inputs is true.
A NOR gate can have two or more inputs.
The 'o' on the output means 'not' showing
that it is a Not OR gate. The output of a
NOR gate is true when none of its inputs
are true.
An EX-OR gate can only have two inputs.
The output of an EX-OR gate is true when
its inputs are different (one true, one false).
An EX-NOR gate can only have two
inputs. The 'o' on the output means 'not'
showing that it is a Not EX-OR gate. The
output of an EX-NOR gate is true when its
inputs are the same (both true or both
false).
OR
NOR
EX-OR
EX-NOR
RESULT:
Thus the various symbols in electric circuits were studied and drawn.
7
LAYOUT DIAGRAM:
8
SIMPLE WIRING CIRCUIT
CIRCUIT DIAGRAM:
Ex.No: SIMPLE WIRING CONNECTION
Date:
AIM:
To study and practice the various types of electrical wiring circuit
connections.
TOOLS REQUIRED:
S.No.
1.
2.
3.
4.
Tester
Electrician Knife
Wire Cutter
Screw Driver
TOOLS
QUANTITY (No.)
1
1
1
1
MATERIAL REQUIRED:
1. Single Pole One Way Switch
2. Lamps
3. Wires
4. Two Pins or Three Pins Wall Socket
5. Batten Holder
THEORY:
Any conductor which is composed of a conducting material, and is uniform
in diameter and circular in cross section is called wire. A length of single insulated
conductor or two or more such conductors each provided with its own insulation
which are laid up together is called a cable. A cable consists of the following three
main parts: a) Conductor, b) Insulation Covering and c) Protective covering.
-
-
-
-
-
3 No.s
3 No.s
Required
1 No.
3 No.s
9
10
MODEL CALCULATION:
CONDUCTOR:
Any pure metal which offers low resistance to the passage of electric current
is called a conductor. The current is taken from one place to the other by means of
a conductor. Copper is used as a conductor in majority of applications.
INSULATION CONVERING:
It is the covering which bounds the current flow in a definite path. The
insulation of the cable must be strong enough because a leakage current will start
giving electrical shocks and cause fire.
PROTECTIVE COVERING:
It protects the insulation covering against any mechanical injury.
VARIOUS TYPES OF WIRES:
The various types of wires are vulcanized Insulation Rubber(VIR) wires,
Cab Type Sheathed(CTS), Poly Vinyl Chloride (PVC) wires,flexible
Wires,etcout of these for house hold applicatios PVC wires are used.
PRECAUTIONS:
v The circuit should be checked by series test lamp.
v Bare portion of the conductor should not come out of the terminal and the
insulation of the conductor should keep up to the end of the terminal.
v All the connections should be tight.
v All the switches should be connected in positive wire.
v Always keep the live wires on the right hand side.
PROCEDURE:
v First the layout diagram of the electrical circuit is made.
v The circuit is made with the given material.
v The output is verified by switching ON the switches.
RESULT:
Thus the various electrical circuit connections were made and studied.
11
STAIRCASE WIRING
CIRCUIT DIAGRAM:
12
Ex.No: STAIRCASE WIRING
Date:
AIM:
To construct and control the status of lamp using two way switch by Stair
Case wiring.
APPARATUS REQUIRED:
S.No.
1.
2.
3.
4.
5.
Tester
Electrician Knife
Wire Cutter
Screw Driver
Combination Plier
APPARATUS
QUANTITY
1
1
1
1
1
MATERIAL REQUIRED:
1. Two Way Switches
2. Lamp
3. Wires
4. Lamp Holder
PRECAUTIONS:
v The circuit should be checked by series test lamp.
v Bare portion of the conductor should not come out of the terminal and the
insulation of the conductor should keep up to the end of the terminal.
v All the connections should be tight.
v All the switches should be connected in positive wire.
v Always keep the live wires on the right hand side.
13
-
-
-
-
2 No.s
1 No
Required
1 No
LAYOUT DIAGRAM:
TABLULATION:
Sl.NO
1
2
3
4
Switch A
1
Switch B
2
Output-Lamp
OFF
14
PROCEDURE:
v First the layout diagram of the electrical circuit is made.
v The connections are made as per the wiring diagram.
v The output table is verified by switching ON the switches.
RESULT:
Thus the stair case wiring was constructed and output was verified.
15
FLUORESCENT TUBE WIRING
CIRCUIT DIAGRAM:
16
Ex.No: FLUORESCENT LAMP WIRING
Date:
AIM:
To construct and study the working of a fluorescent lamp circuit.
APPARATUS REQUIRED:
S.No.
1.
2.
3.
4.
5.
Tester
Electrician Knife
Wire Cutter
Screw Driver
Combination Plier
TOOLS
QUANTITY (No.)
1
1
1
1
1
MATERIAL REQUIRED:
1. Choke
2. Starter
3. Tube light holder, frame
4. Tube light
5. Connecting wires
PRECAUTIONS:
v All the connections should be tight.
v Twisting of wires should be avoided.
v Always keep the live wires on the right hand side.
THEORY:
The fluorescent tubes are usually available in lengths of 0.61 m and 1.22 m.
The various parts of fluorescent tube include.
-
-
-
-
-
1 No.
1 No.
1 No.
1 No.
Required
17
18
MODEL CALCULATION:1. Glass tube
2. Starter
3. Choke
4. Fluorescent materials
5. Filaments
The inside surface of the fluorescent tube is coated with a thin layer of fluorescent
material in the form of powder. The tube also contains low pressure argon gas and
one or two drops of mercury. The two filaments are coated with electron emissive
material. The starter (initially in closed position) puts the filaments directly across
the supply mains at the time of starting, there by initiating emission of electrons.
After 1 or 2 seconds the starter switch gets opened. The interruption of current
makes the choke to act like ballast providing a voltage impulse across the
filaments. Due to this, ionization of argon takes place. Mercury vapour arc
provides a conducting path between the filaments. The starter used may be of
thermal starter or glow starter whose function is to complete the circuit initially for
preheating the filaments (to initiate emission of electrons) and then to open the
circuit for high voltage across choke for initiating ionization.
PROCEDURE:
v First the layout diagram of the electrical circuit is made.
v The connections are made as per the wiring diagram.
v The output is verified.
RESULT:
Thus the fluorescent lamp circuit connection was given and studied.
19
CIRCUIT DIAGRAM:
(0 10A) MI
P
10 A
300V, 10A, UPF
M
V
L
A
C
230 V, 1
50 Hz, A.C.
D
P
S
T
S
10 A
1 Variac
(0 270V)
V
(0 300V) MI
L
O
A
D
N
TABULATION:
Multiplication Factor = .
S.No.
Voltage
(Volts)
Current
(Ampere)
Wattmeter Reading (Watts)
Observed value
Actual value
20
MEASUREMENT OF POWER USING WATTCIRCUIT
Ex.No: MEASUREMENT OF POWER USING WATTMETER
Date:
AIM:
To measure the Power consumed by a Single Phase Resistive Load by using
Wattmeter.
APPARATUS REQUIRED:
S.No.
1.
2.
3.
4.
5.
APPARATUS
Ammeter
Voltmeter
Wattmeter
Single Phase Resistive Load
Connecting Wires
TYPE / RANGE
(0 10A) MI
(0 300V) MI
300V, 10A, UPF
QUANTITY
1
1
1
1
Required
FORMULA USED:
v Multiplication Factor = Current Coil Rating x Voltage Coil Rating x Power Factor
Full Scale Reading of Wattmeter
v Actual Power in Watts = Observed Reading x Multiplication Factor
THEORY:
A wattmeter is an instrument specially designed to measure average power
consumed by a load. It has two coils:A current coil that measures the current and a
voltage coil that measures the voltage. The wattmeter takes into account the phase
shift, if there is any between the current sensed by its current coil and the voltage
sensed by its voltage coil. If the voltage drop across as measured the voltage coil is
Vm cos(t + ) A, then the average power P measured by the wattmeter in watts is
Vm Im Cos ,where = is the power factor angle. The voltage coil of the
wattmeter, its reading will be 0.707 Vm.
21
22
PRECAUTIONS:
v Single phase variac should be kept at minimum position, during starting
period.
v No load should be connected when the DPSTS is closed or opened.
PROCEDURE:
v The connections are made as per the circuit diagram.
v Rated Voltage is set in the voltmeter, by gradually varying the single phase
variac.
v Resistive load is switch ON.
v Load is gradually increased and the ammeter, voltmeter & wattmeter
readings are noted.
RESULT:
Thus the power consumed by a single phase resistive load was measured.
23
CIRCUIT DIAGRAM:
(0 10A) MI
P
10 A
Energy Meter
S1
C1
C2
L1
A
230 V, 1
50 Hz, A.C.
D
P
S
T
S
10 A
1 Variac
(0 270V)
V
P1
(0 300V) MI
P2
L
O
A
D
N
S2
L2
TABULATION:
Energy Meter Constant =
Sl.
No.
Voltage
(Volts)
Current
Power
Time
Number of
Actual
True
%
Error
(Ampere) (Watts) (Seconds) Revolutions
Energy Energy
(KWh)
(KWh)
24
MEASUREMENT OF ENERGY USING SINGLE PHASE ENERGY METER
AIM:
To measure the Energy consumed by a Single Phase Resistive Load by using
Single Phase Energy Meter.
REFERENCE:
1.Engineering Practices Laboratory by V. Ramesh Babu VRB Publishers.
2.Engineering Practice by M.S. Kumar D D Publications.
APPARATUS REQUIRED:
S.No.
1.
2.
3.
4.
5.
6.
APPARATUS
Ammeter
Voltmeter
Single Phase Energy Meter
Stop Watch
Single Phase Resistive Load
Connecting Wires
Analog
3 KW, 230 V
TYPE / RANGE
(0 10A) MI
(0 300V) MI
QUANTITY
1
1
1
1
1
Required
FORMULA USED:
v Actual Energy in KWh = Power in Watts x Time Taken in Seconds
1000 x 3600
v Power in Watts = Voltage in Volts x Current in Amperes
v True Energy in KWh = No. of Revolution / Energy Meter Constant
v % Error = True Energy Actual Energy
Actual Energy
THEORY:
An induction type meter is commonly used. It consists of two magnets, the
upper and lower magnets. The upper magnet carries a pressure coil, which is made
up of a thin wire and has large number of turns. This coil has to be connected in
parallel with the supply. The lower magnet carries the current coil which is made
x
100
25
26
up of a thick wire and has only few turns. This coil is to be connected in series with
the load. An aluminum disc mounted on the spindle is placed between the upper
and lower magnets. The disc can rotate freely between the magnets. Another
permanent magnet called as brake magnet is used for providing breaking torque
on the aluminium disc.
The power consumed is measured in terms of number rotations of the disc.
For example 1800 revolutions of the disc means 1 KWH power consumed by the
load connected to the energy meter.
PRECAUTIONS:
v Single phase variac should be kept at minimum position, during starting
period.
v No load should be connected when the DPSTS is closed or opened.
PROCEDURE:
v The connections are made as per the circuit diagram.
v Rated Voltage is set in the voltmeter, by gradually varying the single phase
variac.
v Resistive load is switch ON.
v Load is gradually increased and the ammeter, voltmeter & Energy meter
readings are noted.
RESULT:
Thus the Energy consumed by a single phase resistive load was measured.
27
RESISTOR COLOUR CODING:
RESISTOR STANDARD COLOUR CODE TABLE:
Colour
Black
Brown
Red
Orange
Yellow
Green
Blue
Violet
Grey
White
Gold
Silver
None
Value Digit
0
1
2
3
4
5
6
7
8
9
Multiplier
x100
x101
x102
x103
x104
x105
x106
x107
x108
x109
x10-1
x10-2
Tolerance
1%
2%
0.5%
0.25%
0.1%
0.05%
5%
10%
20%
28
STUDY OF MEASUREMENT OF RESISTANCE USING COLOR CODING
AIM:
To study the measurement of value of resistance using color coding
REFERENCE:
1. Engineering Practices Laboratory by V. Ramesh Babu VRB Publishers.
2. Engineering Practice by M.S. Kumar D D Publications.
MATERIALS REQUIRED:
1. Resistors
2. Multimeter
THEORY:
A resistor is a passive component. It introduces resistance in the circuit.
Resistance is basic property of conducting material and is given by
R = L/ A
Where,
L
A
-
-
-
Specified resistivity.
Length of the material.
Area of cross section of material.
We have a number of type of resistors such as carbon composition, metal
film, carbon film wire wound and variable resistors.
In our laboratory carbon resistors are used. For resistance of the order of
mega ohms, we use powdered carbon mixed with a suitable building material in
the proper proportion. Carbon resistors are quite cheap, but the value of resistance
may be easily affected by atmospheric changes and is also susceptible to high
tolerance.
29
TABULATION:
Sl. No.
Resistance Value by
Colour Coding ()
Resistance Value
by Multimeter ()
30
IDENTIFICATION MARKING OF RESISTORS
Universally recognized approaches have been established to identify the
electrical values. Two such markings are
(i)
(ii)
Colour code.
Alpha numeric code.
Normally in our laboratories low wattage general purpose resistors are
used. In this colour coding method is used to identify the value of the resistance.
In our colour coding method the value of the resistance is coded on the
resistor using three or four colour bands. The first two colour band gives the first
two significant digital values. The third band gives the value of multiplier. Fourth
band gives the tolerance value.
RESULT:
Thus the value of resistor using colour coding was studied and measured.
31
CIRCUIT DIAGRAM:
Measurement of AC Voltage amplitude and frequency
AFO
CRO
TABULATION:
Maximum voltage ,
Sl.
No
Per
division
1.
2.
3.
4.
Vm in Volts
No of
divisions
Actual
Value
Peak- to-
Peak
Voltage
Vpp= 2Vm
in Volts
RMS
Voltage
Vrms
= Vm /
In Volts
Per
Time in Seconds
Frequency
Actual
Value
f = 1/T
in Hz
No of
divisions
division
32
MEASUREMENT OF AC SIGNAL PARAMETERS USING CRO
AIM:
To measure the following when a sinusoidal voltage is applied.
1.
2.
3.
4.
REFERENCE:
1. Engineering Practices Laboratory by V. Ramesh Babu VRB Publishers.
2. Engineering Practice by M.S. Kumar D D Publications.
APPARATUS REQUIRED:
S.NO. NAME OF THE EQUIPMENT
1.
2.
3.
4.
Cathode Ray Oscilloscope (CRO)
Audio Frequency Oscillator
Bread Board
Connecting Probes, wires
TYPE
Analog
Digital
RANGE
30 MHz
2 MHz
QUANTITY
(NO.S)
1
1
1
As Required
Peak Peak Magnitude of the Voltage,
RMS Value of the Voltage
Time Period
Frequency,
FORMULA USED:
Measurement of unknown frequency = FV / FH (Hz)
= Number of loops cut in the horizontal axis
Number of loops cut in vertical axis
Where,
FV frequency of waveform given to the vertical plane
FH frequency of waveform given to the horizontal plane
VRMS = Vm / 2 (Volts)
f = 1 / T (Hz)
= 2 f (radian)
33
MODEL GRAPH: (Using CRO)
AC input Voltage:
Measurement of DC Voltage amplitude and frequency:
+
RPS (0-30V)
-
CRO
TABULATION:
SI.No.
1.
2.
3.
4.
Applied Voltage
(V)
Number of
divisions
Volt/Division
Measured
Voltage (V)
34
THEORY:
The Cathode Ray Oscilloscope is an extremely useful and versatile as laboratory
instrument for studying wave shapes of alternating currents and voltages as well as for
measurement of voltage, current and frequency. It generates the electron a high velocity,
deflects the beam to create the image and contains a phosphor beam, to screen where the
electron beam becomes visible. For accomplishing these tasks various electrical signals and
voltages are required, which are provided by the power supply circuit of the oscilloscope.
Low voltage supply is required for the heater of the electron gun for generation of electron
beam and high voltage is required for cathode ray tube to accelerate the beam. Normal
voltage supply is required for other control circuits of the oscilloscope. Electron beam
deflects in two directions horizontal on X axis and vertical on Y axis.
For measurement of direct voltage, firstly the spot is centered on the screen without
applying signal any voltage to the deflection plates. Then direst voltage to be measured is
applied between a pair of depletion plates and deflection of the spot is observed on the
screen. The magnitude of the deflection multiplied is the deflection factor gives the value of
direct voltage applied.
In case of measurement alternating voltage of sinusoidal waveform it is applied between a
pair of deflection plates and the length of the straight line is measured. Knowing be
determined the deflection sensitivity the peak to peak value of applied ac voltage can be
determined.
PROCEDURE:
1. The circuit connections are given as per the circuit diagram.
2. The sinusoidal voltage is applied with the help of AFO.
3. Readings are taken for different magnitudes and frequencies.
RESULT:
Thus the Peak Peak Magnitude of the voltage, RMS Value of the Voltage, Time
Period, Frequency are measured with help up CRO.
35
AND GATE
LOGIC DIAGRAM:
OR GATE
LOGIC DIAGRAM:
PIN DIAGRAM OF IC 7408 :
PIN DIAGRAM OF IC 7432 :
CIRCUIT DIAGRAM:
CIRCUIT DIAGRAM:
TRUTH TABLE:
S.No
1.
2.
3.
4.
INPUT
AB
00
01
10
11
OUTPUT
Y=A.B
0
0
0
1
TRUTH TABLE:
S.No
1.
2.
3.
4.
INPUT
A
0
0
1
1
B
0
1
0
1
OUTPUT
Y=A+B
0
1
1
1
36
STUDY OF BASIC LOGIC GATES
AIM:
To verify the truth table of basic logic gates of AND, OR, NOT, NAND,
NOR, EX-OR gates.
REFERENCE:
1. Engineering Practices Laboratory by V. Ramesh Babu VRB Publishers.
2. Engineering Practice by M.S. Kumar D D Publications.
APPARATUS REQUIRED:
S.No
1.
2.
3.
4.
5.
6.
7.
8.
Name of the Apparatus
Digital IC trainer kit
AND gate
OR gate
NOT gate
NAND gate
NOR gate
EX-OR gate
Connecting wires
IC 7408
IC 7432
IC 7404
IC 7400
IC 7402
IC 7486
As required
Range
Quantity
1
1
1
1
1
1
1
THEORY:
a. AND gate:
An AND gate is the physical realization of logical multiplication operation.
It is an electronic circuit which generates an output signal of 1 only if all
the input signals are 1.
b. OR gate:
An OR gate is the physical realization of the logical addition operation. It is
an electronic circuit which generates an output signal of 1 if any of the
input signal is 1.
37
NOT GATE
LOGIC DIAGRAM:
NAND GATE
LOGIC DIAGRAM:
PIN DIAGRAM OF IC 7404:
PIN DIAGRAM OF IC 7400 :
CIRCUIT DIAGRAM:
CIRCUIT DIARAM:
TRUTH TABLE:
S.N
o
1.
2.
INPUT
A
0
1
OUTPUT
Y = A
1
0
TRUTH TABLE:
S.No
1.
2.
3.
4.
INPUT
AB
00
01
10
11
OUTPUT
Y = (A. B)
1
1
1
0
38
c. NOT gate:
A NOT gate is the physical realization of the complementation
operation. It is an electronic circuit which generates an output signal
which is the reverse of the input signal. A NOT gate is also known as
an inverter because it inverts the input.
d. NAND gate:
A NAND gate is a complemented AND gate. The output of the NAND
gate will be 0 if all the input signals are 1 and will be 1 if any one of
the input signal is 0.
e. NOR gate:
A NOR gate is a complemented OR gate. The output of the OR gate
will be 1 if all the inputs are 0 and will be 0 if any one of the input
signal is 1.
f. EX-OR gate:
An Ex-OR gate performs the following Boolean function,
A
B = ( A . B ) + ( A . B )
It is similar to OR gate but excludes the combination of both A and B
being equal to one. The exclusive OR is a function that give an output
signal 0 when the two input signals are equal either 0 or 1.
PROCEDURE:
v Connections are given as per the circuit diagram
v For all the ICs 7th pin is grounded and 14th pin is given +5 V supply.
v Apply the inputs and verify the truth table for all gates.
39
NOR GATE
LOGIC DIAGRAM:
EX-OR GATE
LOGIC DIAGRAM
PIN DIAGRAM OF IC 7402 :
PIN DIAGRAM OF IC 7486 :
CIRCUIT DIAGRAM:
CIRCUIT DIAGRAM:
TRUTH TABLE:
S.No
1.
2.
3.
4.
INPUT
AB
00
01
10
11
OUTPUT
Y = (A + B)
1
0
0
0
TRUTH TABLE:
S.No
1.
2.
3.
4.
INPUT
AB
00
01
10
11
OUTPUT
Y=AB
0
1
1
0
40
RESULT:
The truth table of all the basic logic gates were verified.
41
CIRCUIT DIAGRAM:
Half Wave Rectifier:
P
IN 4007
230 V, 50 Hz
1 Supply
1 K
100 F
CRO
N
Step-down Transformer
(0 12V)
Full Wave Rectifier:
P
D1
230 V, 50 Hz
1 Supply
D4
N
D3
1 K
100 F
CRO
D2
TABULATION:
Without Filter
Rectifier
Half Wave Rectifier
Full Wave Rectifier
Vm (V)
T (mS)
Vm (V)
With Filter
T (mS)
Charging
Discharging
42
HALF WAVE AND FULL WAVE RECTIFIER
AIM:
To obtain the output of Half wave and Full Wave rectifier and to plot
the characteristics.
REFERENCE:
1. Engineering Practices Laboratory by V. Ramesh Babu VRB Publishers.
2. Engineering Practice by M.S. Kumar D D Publications.
APPARATUS REQUIRED:
S.NO. NAME OF THE EQUIPMENT
1
2
3
4
5
6
7
Diode
Resistor
Capacitor
Transformer
Step-down
TYPE
IN 4001
1 K
100 F
230 V /
(12 0 12) V
CRO
Bread Board
Connecting wires and probe
Analog
30 MHz
1
1
As Required
RANGE
QUANTITY
(NO.S)
4
1
1
1
THEORY:
Half wave rectifier converts alternating voltage into unidirectional
pulsating voltage. The half wave rectifier circuit using a diode with a load
resistance R. The diode is connected in series with the secondary of the
transformer and the load resistance R, the primary of the transformer is being
connected to the supply mains. The AC voltage across the secondary winding
changes polarities after every half cycle. During the positive half cycles of the
input AC voltage i.e. when upper end of the secondary winding is positive
with respect to its lower end, the diode is forward biased and therefore
43
WAVEFORMS:
Vin (V)
Vm
0
Time
Vout (V)
Output of Half Wave Rectifier without filter
0
Vm
Time
Output of Half Wave Rectifier with filter
0
Time
filter
Vm
Output of Full Wave Rectifier without
0
Vm
filter
Time
Output of Full Wave Rectifier with
0
Time
44
current conducts. During the negative half cycles of the input AC voltage i.e.
when lower end of the secondary winding is positive with respect to its upper
end, the diode is reverse biased and does not conduct. Thus for the negative
half cycles no power is delivered to the load. Since only one half cycles of the
input wave is converted as output, it is called as Half Wave Rectifier.
In Full Wave Rectifier the diode D2 and D4 will conduct during
the positive half of the input signal and during the negative half cycle of the
input signal the diode D1 andD3 conducts. Hence both the half cycles are
converted into output and the efficiency is high compared with the half wave
rectifier.
PROCEDURE:
1. Circuit connections were given as per the circuit diagram.
2. Input waveforms magnitude and frequency was measured with the
help of CRO.
3. Supply is switched ON and the output waveform was obtained in the
CRO.
4. Output waveforms magnitude and time period was measured.
5. Graphs were plotted for Half wave and Full wave rectifier outputs.
RESULT:
Thus the output of Half wave and Full wave rectifiers were obtained
and the curves were plotted.
45
46
MEASUREMENT OF RESISTANCE TO EARTH OF ELECTRICAL
EQUIPMENT
AIM:
To measure the resistance to earth / insulation resistance of the order of
mega ohms.
REFERENCE:
1. Engineering Practices Laboratory by V. Ramesh Babu VRB Publishers.
2. Engineering Practice by M.S. Kumar D D Publications.
THEORY:
Megger is the equipment used in this experiment. It is an instrument
for testing the insulation resistance of the order of mega ohms.
PRINCIPLE:
A megger consists of an EMF source and a Voltmeter. The voltmeter
scale is calibrated in ohms. In measurement, the EMF of the self contained
source should be equal that of the source used in calibration. The deflection of
the moving system depends on the ratio of the currents in the coils and is
independent of the applied voltage. The value of unknown resistance can be
found directly from the scale of the instrument. Figure shows the detailed
diagram of a megger. It consists of hand driven dc generator and ohmmeter, a
small permanent magnet. Hand driven dc generator generates a EMF about
500V. The permanent dc meter has two moving coils. First one is deflecting
coil and another one controlling coil. The deflecting coil is connected to the
generator through a resistor R. The torque due to the two coils opposes each
other. It consists of three terminals E, L and G.
OPERATION:
When the terminals are open circuited, no current flows through the
deflecting coil. The torque due to the controlling coil moves the pointer to one
end of the scale. When the terminals are short circuited, the torque due to the
controlling coil and the pointer is deflected to the other end of the scale, i.e.
47
48
zero mark. In between the two extreme positions the scale is calibrated to
indicate the value of unknown resistance directly. The unknown insulation
resistance is connected across E and L terminals. The effective insulation
resistance is the combination of insulation volume resistance and surface
leakage resistance. The guard wire terminal makes the surface leakage current
to by pass the instrument hence only insulation resistance is measured.
RESULT:
Thus the resistance to earth / insulation resistance of the order of mega
ohms can be measured.
49