engineering practices lab

I

DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING

YEAR: I SEMESTER: I

LAB MANUAL[Group – B]

ENGINEERING PRACTICESLABORATORY

Karthikeyan

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RAMCO INSTITUTE OF TECHNOLOGY, RAJAPALAYAM - 626117

II

DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING

Class/ Semester : I/ I

LIST OF EXPERIMENTS

STUDY OF SYMBOLS

SIMPLE WIRING CONNECTION

STAIRCASE WIRING

FLUORESCENT LAMP WIRING

MEASUREMENT OF POWER USING WATTMETER

MEASUREMENT OF ENERGY USING SINGLE PHASE ENERGY METER

STUDY OF MEASUREMENT OF RESISTANCE USING COLOR CODING

MEASUREMENT OF AC SIGNAL PARAMETERS USING CRO

STUDY OF BASIC LOGIC GATES

HALF WAVE AND FULL WAVE RECTIFIER

MEASUREMENT OF RESISTANCE TO EARTH OF ELECTRICAL

EQUIPMENT

Sub & Code : GE2116- Engineering Practices Laboratory – [Group – B]

Karthikeyan

Typewritten text


Karthikeyan

Typewritten text


1

STUDY OF SYMBOLSAIM:

To study the various symbols used in electric circuits.

COMPONENT CIRCUIT SYMBOL DESCRIPTION

WIRE CONNECTIONS

Wire To pass current very easily from one partof a circuit to another.

Wires joined

A 'blob' should be drawn where wires areconnected (joined), but it is sometimesomitted. Wires connected at 'crossroads'should be staggered slightly to form two T-junctions, as shown on the right.

Wires not joined

In complex diagrams it is often necessaryto draw wires crossing even though theyare not connected. I prefer the 'bridge'symbol shown on the right because thesimple crossing on the left may be misreadas a join where you have forgotten to add a'blob'!

POWER SUPPLIES

Cell

Supplies electrical energy.The larger terminal (on the left) is positive(+).A single cell is often called a battery, butstrictly a battery is two or more cells joinedtogether.

Battery

Supplies electrical energy. A battery ismore than one cell. The larger terminal (onthe left) is positive (+). The smallerterminal (on the right) is negative (-).

DC supplySupplies electrical energy.DC = Direct Current, always flowing inone direction.

AC supplySupplies electrical energy.AC = Alternating Current, continuallychanging direction.

FuseA safety device which will 'blow' (melt) ifthe current flowing through it exceeds aspecified value.

2

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 bythe magnetic field in the core. There is noelectrical connection between the coils.

Earth(Ground)

A connection to earth. For many electroniccircuits this is the 0V (zero volts) of thepower supply, but for mains electricity andsome radio circuits it really means theearth. It is also known as ground.

OUTPUT DEVICES: LAMPS, HEATER, MOTOR, etc.

Lamp (lighting)

A transducer which converts electricalenergy to light. This symbol is used for alamp providing illumination, for example acar headlamp or torch bulb.

Lamp (indicator)

A transducer which converts electricalenergy to light. This symbol is used for alamp which is an indicator, for example awarning light on a car dashboard.

Heater A transducer which converts electricalenergy to heat.

Motor A transducer which converts electricalenergy to kinetic energy (motion).

Bell A transducer which converts electricalenergy to sound.

Buzzer A transducer which converts electricalenergy to sound.

Inductor(Coil, Solenoid)

A coil of wire which creates a magneticfield when current passes through it. It mayhave an iron core inside the coil. It can beused as a transducer converting electricalenergy to mechanical energy by pulling onsomething.

Switches

Push Switch(push-to-make)

A push switch allows current to flow onlywhen the button is pressed. This is theswitch used to operate a doorbell.

3

Push-to-BreakSwitch

This type of push switch is normally closed(on), it is open (off) only when the buttonis pressed.

On-Off Switch(SPSTS)

SPSTS = Single Pole Single ThrowSwitch. An on-off switch allows current toflow only when it is in the closed (on)position.

2-way Switch(SPDTS)

SPDTS = Single Pole Double ThrowSwitch. A 2-way changeover switch directsthe flow of current to one of two routesaccording to its position. Some SPDTswitches have a central off position and aredescribed as 'on-off-on'.

Dual On-OffSwitch

(DPSTS)

DPST = Double Pole, Single ThrowSwitch. A dual on-off switch which isoften used to switch mains electricitybecause it can isolate both the live andneutral connections.

Reversing Switch(DPDTS)

DPDT = Double Pole, Double ThrowSwitch. This switch can be wired up as areversing switch for a motor. Some DPDTswitches have a central off position.

Relay

An electrically operated switch, forexample a 9V battery circuit connected tothe coil can switch a 230V AC mainscircuit.NO = Normally Open, COM = Common,NC = Normally Closed.

Resistors

Resistor A resistor restricts the flow of current, forexample to limit the current passingthrough an LED. A resistor is used with acapacitor in a timing circuit.Some publications still use the old resistorsymbol:

Variable Resistor(Rheostat)

This type of variable resistor with 2contacts (a rheostat) is usually used tocontrol current. Examples include:adjusting lamp brightness, adjusting motorspeed, and adjusting the rate of flow ofcharge into a capacitor in a timing circuit.

4

Variable Resistor(Potentiometer)

This type of variable resistor with 3contacts (a potentiometer) is usually usedto control voltage. It can be used like thisas a transducer converting position (angleof the control spindle) to an electricalsignal.

Variable Resistor(Preset)

This type of variable resistor (a preset) isoperated with a small screwdriver orsimilar tool. It is designed to be set whenthe circuit is made and then left withoutfurther adjustment. Presets are cheaperthan normal variable resistors so they areoften used in projects to reduce the cost.

CAPACITORS

Capacitor

A capacitor stores electric charge. Acapacitor is used with a resistor in a timingcircuit. It can also be used as a filter, toblock DC signals but pass AC signals.

Capacitorpolarized

A capacitor stores electric charge. Thistype must be connected the correct wayround. A capacitor is used with a resistor ina timing circuit. It can also be used as afilter, to block DC signals but pass ACsignals.

Variable Capacitor A variable capacitor is used in a radiotuner.

Trimmer Capacitor

This type of variable capacitor (a trimmer)is operated with a small screwdriver orsimilar tool. It is designed to be set whenthe circuit is made and then left withoutfurther adjustment.

DIODES

Diode A device which only allows current to flowin one direction.

LEDLight Emitting

Diode

A transducer which converts electricalenergy to light.

Zener Diode A special diode which is used to maintain afixed voltage across its terminals.

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Photodiode A light-sensitive diode.

TRANSISTORS

Transistor NPNA transistor amplifies current. It can beused with other components to make anamplifier or switching circuit.

Transistor PNPA transistor amplifies current. It can beused with other components to make anamplifier or switching circuit.

Phototransistor A light-sensitive transistor.

AUDIO AND RADIO DEVICES

Microphone A transducer which converts sound toelectrical energy.

Earphone A transducer which converts electricalenergy to sound.

Loudspeaker A transducer which converts electricalenergy to sound.

Piezo Transducer A transducer which converts electricalenergy to sound.

Amplifier(general symbol)

An amplifier circuit with one input. Reallyit is a block diagram symbol because itrepresents a circuit rather than just onecomponent.

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Aerial(Antenna)

A device which is designed to receive ortransmit radio signals. It is also known asan antenna.

METERS AND OSCILLOSCOPE

VoltmeterA voltmeter is used to measure voltage.Voltmeter must be connected across theterminal.

AmmeterAn ammeter is used to measure current. Itis always connected in series with thecircuit.

GalvanometerA galvanometer is a very sensitive meterwhich is used to measure tiny currents,usually 1mA or less.

OhmmeterAn ohmmeter is used to measureresistance. Most multimeters have anohmmeter setting.

Oscilloscope

An oscilloscope is used to display theshape of electrical signals and it can beused to measure their voltage and timeperiod.

SENSORS (INPUT DEVICES)

LDR

A transducer which converts brightness(light) to resistance (an electricalproperty).LDR = Light Dependent Resistor

Thermistor A transducer which converts temperature(heat) to resistance (an electrical property).

LOGIC GATES

NOT

A NOT gate can only have one input. The'o' on the output means 'not'. The output ofa NOT gate is the inverse (opposite) of itsinput, so the output is true when the inputis false. A NOT gate is also called aninverter.

ANDAn AND gate can have two or more inputs.The output of an AND gate is true when allits inputs are true.

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NAND

A NAND gate can have two or moreinputs. The 'o' on the output means 'not'showing that it is a Not AND gate. Theoutput of a NAND gate is true unless all itsinputs are true.

ORAn OR gate can have two or more inputs.The output of an OR gate is true when atleast one of its inputs is true.

NOR

A NOR gate can have two or more inputs.The 'o' on the output means 'not' showingthat it is a Not OR gate. The output of aNOR gate is true when none of its inputsare true.

EX-ORAn EX-OR gate can only have two inputs.The output of an EX-OR gate is true whenits inputs are different (one true, one false).

EX-NOR

An EX-NOR gate can only have twoinputs. The 'o' on the output means 'not'showing that it is a Not EX-OR gate. Theoutput of an EX-NOR gate is true when itsinputs are the same (both true or bothfalse).

RESULT:Thus the various symbols in electric circuits were studied and drawn.

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CIRCUIT DIAGRAM:

LAYOUT DIAGRAM:

9

SIMPLE WIRING CONNECTION

AIM:

To study and practice the various types of electrical wiring circuit

connections.

REFERENCE:

1.Engineering Practices Laboratory by V. Ramesh Babu – VRB Publishers.

2.Engineering Practice by M.S. Kumar – D D Publications.

TOOLS REQUIRED:

S.No. TOOLS QUANTITY (No.)

1. Tester 1

2. Electrician Knife 1

3. Wire Cutter 1

4. Screw Driver 1

MATERIAL REQUIRED:

1. Single Pole One Way Switch - 3 No.s

2. Lamps - 3 No.s

3. Wires - Required

4. Two Pins or Three Pins Wall Socket - 1 No.

5. Batten Holder - 3 No.s

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.

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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,etc…out of these for house hold applicatios PVC wires are used.

PRECAUTIONS:

The circuit should be checked by series test lamp.

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.

All the connections should be tight.

All the switches should be connected in positive wire.

Always keep the live wires on the right hand side.

PROCEDURE:

First the layout diagram of the electrical circuit is made.

The circuit is made with the given material.

The output is verified by switching ON the switches.

RESULT:

Thus the various electrical circuit connections were made and studied.

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STAIRCASE WIRING

CIRCUIT DIAGRAM:

13

STAIRCASE WIRING

AIM:

To construct and control the status of lamp using two way switch by Stair –

Case wiring.

REFERENCE:



TOOLS REQUIRED:


1. Tester 1


3. Wire Cutter 1

4. Screw Driver 1

5. Combination Plier 1

MATERIAL REQUIRED:

1. Two Way Switches - 2 No.s

2. Lamp - 1 No

3. Wires - Required

4. Lamp Holder - 1 No

PRECAUTIONS:

The circuit should be checked by series test lamp.

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.


All the switches should be connected in positive wire.


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LAYOUT DIAGRAM:

TABLULATION:

Sl.NO Switch A Switch B Output-Lamp

1 1 2 OFF

2

3

4

15

PROCEDURE:


The connections are made as per the wiring diagram.

The output table is verified by switching ON the switches.

RESULT:

Thus the stair – case wiring was constructed and output was verified.

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FLUORESCENT TUBE WIRING

CIRCUIT DIAGRAM:

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FLUORESCENT LAMP WIRING

AIM:

To construct and study the working of a fluorescent lamp circuit.

REFERENCE:



TOOLS REQUIRED:


1. Tester 1


3. Wire Cutter 1

4. Screw Driver 1

5. Combination Plier 1

MATERIAL REQUIRED:

1. Choke - 1 No.

2. Starter - 1 No.

3. Tube light holder, frame - 1 No.

4. Tube light - 1 No.

5. Connecting wires - Required

PRECAUTIONS:


Twisting of wires should be avoided.


THEORY:

The fluorescent tubes are usually available in lengths of 0.61 m and 1.22 m.

The various parts of fluorescent tube include.

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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:


The connections are made as per the wiring diagram.

The output is verified.

RESULT:

Thus the fluorescent lamp circuit connection was given and studied.

20

CIRCUIT DIAGRAM:

(0 – 10A) MI 300V, 10A, UPF

P 10 A M L

C V

230 V, 1 Φ (0 – 300V) MI

50 Hz, A.C.

N 10 A

1 Φ Variac

(0 – 270V)

TABULATION:

Multiplication Factor = …………….

S.No.Voltage

(Volts)

Current

(Ampere)

Wattmeter Reading (Watts)

Observed value Actual value

V

A

LOAD

DPSTS

21

MEASUREMENT OF POWER USING WATTMETER

AIM:

To measure the Power consumed by a Single Phase Resistive Load by using

Wattmeter.

REFERENCE:



APPARATUS REQUIRED:

S.No. APPARATUS TYPE / RANGE QUANTITY

1. Ammeter (0 – 10A) MI 1

2. Voltmeter (0 – 300V) MI 1

3. Wattmeter 300V, 10A, UPF 1

4. Single Phase Resistive Load 1

5. Connecting Wires Required

FORMULA USED:

Multiplication Factor = Current Coil Rating x Voltage Coil Rating x Power Factor

Full Scale Reading of Wattmeter

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(ωt + Ф) A, then the average power P measured by the wattmeter in watts is

½ Vm Im Cos Ф,where Ф = is the power factor angle. The voltage coil of the

wattmeter, its reading will be 0.707 Vm.

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PRECAUTIONS:

Single phase variac should be kept at minimum position, during starting

period.

No load should be connected when the DPSTS is closed or opened.

PROCEDURE:

The connections are made as per the circuit diagram.

Rated Voltage is set in the voltmeter, by gradually varying the single phase

variac.

Resistive load is switch ON.

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.

24

CIRCUIT DIAGRAM:

(0 – 10A) MI Energy Meter

P 10 A S1 C1 C2 L1

P1 P2

230 V, 1 Φ (0 – 300V) MI50 Hz, A.C.

N 10 A S2 L2

1 Φ Variac(0 – 270V)

TABULATION:

Energy Meter Constant = …………………

Sl.

No.

Voltage

(Volts)

Current

(Ampere)

Power

(Watts)

Time

(Seconds)

Number of

Revolutions

Actual

Energy

(KWh)

True

Energy

(KWh)

%

Error

DPSTS

V

A

LOAD

25

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:



APPARATUS REQUIRED:

S.No. APPARATUS TYPE / RANGE QUANTITY

1. Ammeter (0 – 10A) MI 1

2. Voltmeter (0 – 300V) MI 1

3. Single Phase Energy Meter 1

4. Stop Watch Analog 1

5. Single Phase Resistive Load 3 KW, 230 V 1

6. Connecting Wires Required

FORMULA USED:

Actual Energy in KWh = Power in Watts x Time Taken in Seconds1000 x 3600

Power in Watts = Voltage in Volts x Current in Amperes

True Energy in KWh = No. of Revolution / Energy Meter Constant

% Error = True Energy – Actual Energy x 100Actual 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

27

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:

Single phase variac should be kept at minimum position, during starting

period.

No load should be connected when the DPSTS is closed or opened.

PROCEDURE:

The connections are made as per the circuit diagram.

Rated Voltage is set in the voltmeter, by gradually varying the single phase

variac.

Resistive load is switch ON.

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.

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RESISTOR COLOUR CODING:

RESISTOR STANDARD COLOUR CODE TABLE:

Colour Value Digit Multiplier ToleranceBlack 0 x100

Brown 1 x101 ±1%Red 2 x102 ±2%

Orange 3 x103

Yellow 4 x104

Green 5 x105 ±0.5%Blue 6 x106 ±0.25%

Violet 7 x107 ±0.1%Grey 8 x108 ±0.05%White 9 x109

Gold x10-1 ±5%Silver x10-2 ±10%None ±20%

29

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 = ρL/ A

Where,

ρ - Specified resistivity.

L - Length of the material.

A - 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.

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TABULATION:

Sl. No.Resistance Value by

Colour Coding (Ω)

Resistance Value

by Multimeter (Ω)

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IDENTIFICATION MARKING OF RESISTORS

Universally recognized approaches have been established to identify the

electrical values. Two such markings are

(i) Colour code.

(ii) 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.

32

CIRCUIT DIAGRAM:

Measurement of AC Voltage amplitude and frequency

TABULATION:

Sl.

No

Maximum voltage ,

Vm in Volts

Peak- to-

Peak

Voltage

Vpp= 2Vm

in Volts

RMS

Voltage

Vrms

= Vm /

In Volts

Time in SecondsFrequency

f = 1/T

in HzPer

division

No of

divisions

Actual

Value

Per

division

No of

divisions

Actual

Value

1.

2.

3.

4.

AFO CRO

33

MEASUREMENT OF AC SIGNAL PARAMETERS USING CRO

AIM:

To measure the following when a sinusoidal voltage is applied.

1. Peak – Peak Magnitude of the Voltage,

2. RMS Value of the Voltage

3. Time Period

4. Frequency,

REFERENCE:



APPARATUS REQUIRED:

S.NO. NAME OF THE EQUIPMENT TYPE RANGEQUANTITY

(NO.S)

1. Cathode Ray Oscilloscope (CRO) Analog 30 MHz 1

2. Audio Frequency Oscillator Digital 2 MHz 1

3. Bread Board 1

4. Connecting Probes, wires As Required

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)

ω = 2 π f … (radian)

34

MODEL GRAPH: (Using CRO)

AC input Voltage:

Measurement of DC Voltage amplitude and frequency:

+

-

TABULATION:

SI.No. Applied Voltage

(V)

Number of

divisions

Volt/Division Measured

Voltage (V)

1.

2.

3.

4.

RPS (0-30V) CRO

35

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.

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AND GATE OR GATE

LOGIC DIAGRAM:

PIN DIAGRAM OF IC 7408 :

CIRCUIT DIAGRAM:

TRUTH TABLE:

S.NoINPUT OUTPUT

A B Y = A . B1. 0 0 02. 0 1 03. 1 0 04. 1 1 1

LOGIC DIAGRAM:


CIRCUIT DIAGRAM:

TRUTH TABLE:

S.NoINPUT OUTPUT

A B Y = A + B1. 0 0 02. 0 1 13. 1 0 14. 1 1 1

37

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:



APPARATUS REQUIRED:

S.No Name of the Apparatus Range Quantity

1. Digital IC trainer kit 1

2. AND gate IC 7408 1

3. OR gate IC 7432 1

4. NOT gate IC 7404 1

5. NAND gate IC 7400 1

6. NOR gate IC 7402 1

7. EX-OR gate IC 7486 1

8. Connecting wires As required

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’.

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NOT GATE NAND GATE

LOGIC DIAGRAM:

PIN DIAGRAM OF IC 7404:

CIRCUIT DIAGRAM:

TRUTH TABLE:

S.No

INPUT OUTPUTA Y = A’

1. 0 12. 1 0

LOGIC DIAGRAM:


CIRCUIT DIARAM:

TRUTH TABLE:

S.NoINPUT OUTPUT

A B Y = (A. B)’1. 0 0 12. 0 1 13. 1 0 14. 1 1 0

39

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:

Connections are given as per the circuit diagram

For all the ICs 7th pin is grounded and 14th pin is given +5 V supply.

Apply the inputs and verify the truth table for all gates.

40

NOR GATE EX-OR GATE

LOGIC DIAGRAM:


CIRCUIT DIAGRAM:

TRUTH TABLE:

S.NoINPUT OUTPUTA B Y = (A + B)’

1. 0 0 12. 0 1 03. 1 0 04. 1 1 0

LOGIC DIAGRAM


CIRCUIT DIAGRAM:

TRUTH TABLE:

S.NoINPUT OUTPUTA B Y = A B

1. 0 0 02. 0 1 13. 1 0 14. 1 1 0

41

RESULT:

The truth table of all the basic logic gates were verified.

42

CIRCUIT DIAGRAM:

Half Wave Rectifier:

P

IN 4007100 μF

230 V, 50 Hz1 Φ Supply 1 KΩ CRO

NStep-down Transformer

(0 – 12V)

Full Wave Rectifier:

P

D1 D2

230 V, 50 Hz1 Φ Supply

D4 D3 100 μF

1 KΩ CRON

TABULATION:

Rectifier

Without Filter With Filter

Vm (V) T (mS) Vm (V)T (mS)

Charging Discharging

Half Wave Rectifier

Full Wave Rectifier

43

HALF WAVE AND FULL WAVE RECTIFIER

AIM:

To obtain the output of Half wave and Full Wave rectifier and to plot

the characteristics.

REFERENCE:



APPARATUS REQUIRED:

S.NO. NAME OF THE EQUIPMENT TYPE RANGEQUANTITY

(NO.S)

1 Diode IN 4001 4

2 Resistor 1 KΩ 1

3 Capacitor 100 μF 1

4Transformer Step-down 230 V /

(12 – 0 – 12) V

1

5 CRO Analog 30 MHz 1

6 Bread Board 1

7 Connecting wires and probe As Required

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

44

WAVEFORMS:

Vin (V)Vm

0Time

Vout (V)Output of Half Wave Rectifier without filter

0Time

VmOutput of Half Wave Rectifier with filter

0

Time

Vm Output of Full Wave Rectifier withoutfilter

0

TimeVm

Output of Full Wave Rectifier withfilter

0Time

45

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 waveform’s 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 waveform’s 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.

47

MEASUREMENT OF RESISTANCE TO EARTH OF ELECTRICAL

EQUIPMENT

AIM:

To measure the resistance to earth / insulation resistance of the order of

mega ohms.

REFERENCE:



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.

49

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.

engineering practices lab

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