MAHENDRA ENGINEERING COLLEGE
[AUTONOMOUS]
Mahendhirapuri, Mallasamudram, Namakkal Dt. - 637 503.
DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING
YEAR: I
SEMESTER: II
19EE23101 - ENGINEERING PRACTICES LABORATORY
STUDENT NAME
:
REG NO
:
YEAR
:
BRANCH
:
SEMESTER
:
1
Index
S.No.
1.
2.
NAME OF THE EXPERIMENTS
Study of Multimeter
Simple wiring connection
3.
Fluorescent Lamp Wiring.
4.
Stair Case Wiring
5.
Measurement of Electrical quantities – voltage, current, power &
Power factor in RLC Circuit.
6.
Measurement of Energy using Single Phase Energy Meter
7.
Measurement of Resistance to Earth of Electrical Equipment
8.
9.
Study of Moving coil and Moving iron
Study of Electronic Components and Equipments – Resistor
Colour Coding
10. Measurement of AC Signal Parameter
11. Study of Logic Gates
12.
Generation of Clock Signal.
13.
Soldering & Desoldering Practice
14.
Measurement of Ripple Factor of HWR and FWR
2
PAGE
No.
CIRCUIT SYMBOLS FOR ELECTRICAL & ELECTRONIC CIRCUITS
S.NO
SYMBOLS
COMPONENTS
Direct current
1.
2.
Alternative current
3.
Resistor
4.
Variable Resistor
5.
Inductor
Capacitor
6.
Variable Capacitor
7.
8.
Fuse
3
9.
Main Switch Light
10.
Main Switch Power
11.
Meter
12.
One Way Switch
13.
Two Way Switch
14.
Lamp
15.
Horn
4
16.
Buzzer
17.
Earth
18.
Single phase alternating current
19.
Neutral
20.
Generator
21.
Motor
22.
Alternator
5
23.
AC motor
24.
Two pin socket
25.
Three pin socket
26.
Choke
27.
Battery
28.
DC voltmeter
29.
DC ammeter
6
30.
AC ammeter
31.
Wattmeter
32.
Ohm meter
33.
Energy meter
34.
Lamp
35.
Wire
36.
Wires joined
7
37.
Wires not joined
38.
DPSTS
39.
Reversing Switch
40.
Relay
41.
Capacitor polarized
42.
Diode
8
43.
LED Light Emitting Diode
44.
Zener Diode
45.
Transistor NPN
46.
Transistor PNP
47.
Phototransistor
48.
Oscilloscope
49.
Ohmmeter
9
50.
Microphone
51.
Aerial (Antenna)
52.
Amplifier (general symbol)
53.
Loudspeaker
54.
Thermistor
55.
LDR
56.
NOT
10
57.
AND
58.
OR
59.
EXOR
60.
NOR
61.
NAND
62.
EX-NOR
11
CIRCUIT DIAGRAM:
12
Ex No:
Date :
RESIDENTIAL HOUSE WIRING USING SWITCHES, FUSE,
INDICATOR, LAMP
2 .a ) SINGLE LAMP CONTROLLED BY SINGLE SWITCH
AIM:
To construct a wiring for one lamp controlled by using one way switch.
APPARATUS REQUIRED:
S.NO
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
COMPONENTS
One way switch
Lamp holder
Lamp
Switch box
Junction box
(one way)
T-bend
Clamp
1/8 wire-3m
Screw
Insulating tape
Connecting Wire
RANGE
5A
60W
4”*4”
-
QUANTITY
1
1
1
1
1
1
1
1
1
1
As Required
TOOLS REQUIRED:
1. Screw driver
: 6”
2. Pocker
: 1
3. Insulator cutting plier : 6”
4. Wooden hammer
: 1
SAFETY PRECAUTIONS:

Ensure that the power is switched off or not before connections are being made.

Make sure that the fuse is connected in phase sheet select the correct current
rating of wires.
13
LAYOUT DIAGRAM:
14
PROCEDURE:

The wiring diagram of the one lamp controlled by one way switch was drawn one
the wiring chalk and scale.

The PVC pipe of required length and pipe fittings are taken and fixed in the
wiring board.As per the wiring diagram using clamp and screw.

The wires of required guage,colours are chosen and the wiring is being made
through PVC.

The lamp holder and switch are fixed in the corresponding location.

Using red colour wire the phase line was given the lamp through one way switch.

The other point of the lamp is being connected to neutral line using black wire.

The terminal of the red and black wires are connected to main switch.

The power supply was given to the circuit and the lamp was being made to glow
by operating the switch.
RESULT:
The wiring of one lamp controlled by one lamp controlled by one way switch was
constructed and operated successfully.
15
CIRCUIT DIAGRAM:
16
2 b)TWO LAMP CONTROLLED BY USING TWO ONE WAY SWITCH
AIM:
Construct a wiring for two lamp controlled by using two switch [one way].
APPARATUS REQUIRED:
S.NO
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
COMPONENTS
One way switch
Lamp holder
Lamp
Switch box
PVC pipe
Junction box
T-bend
Clamp
Screw
Insulating tape
Connecting Wire
RANGE
5A
240V,6V
60W
4”11*4”11
-------One way
----------------------
QUANTITY
2
2
2
2
-------2
2
5
Required
1
As Required
TOOLS REQUIRED:
1. Screw driver -6”
: 1
2. Poker
: 1
3. Insulating cutting plier 6” : 1
4. Wooden hammer
: 1
SAFETY PRECAUTIONS:

Ensure that the power is switched off or not before connections are being made.

Make sure that the fuse is connected in phase sheet select the correct current
rating of wires.
17
LAYOUT DIAGRAM:
18
PROCEDURE:

The wiring diagram of two lamp controlled by two way switches was drawn on the
wiring board using clamps.

The PVC pipe of required length and pipe fitting were taken and tired on the board as
per the diagram using screws.

The lamp holder and switches were fixed in the corresponding location.

Using red color wire the phase line was given to the two lamps using one way
switches.

The other points of the bulbs were being connected to the neutral line using black
wire.

The terminals of the red and black wires are connected to main switch.

The power supply was given to the circuit and it glow bright.
RESULT:
The wiring of the two lamps in parallel controlled by single switch was constructed and
operated successfully.
19
CIRCUIT DIAGRAM:
20
Ex No:
Date :
FLUORESCENT LAMP WIRING
AIM:
To construct a flourescent lamp wiring using the given components.
APPARATUS REQUIRED:
S.NO
1
2
3
4
5
6
7
COMPONENTS
Tube light frame
Tube light holder
Choke
Starter
Tube light
Wires
Insulating tape
QTY
1
2
1
1
1
Req
1
TOOLS REQUIRED:
1. Screw driver
:1
2. lnsulated cutting plier 6”
: 1.
3. Wooden hammer
: 1
SAFETY PRECAUTIONS:

Ensure that the power is switched off or not before connections are being made.

Make sure that the fuse is connected in phase sheet select the correct current
rating of wires
21
22
PROCEDURE:

The wire diagram of the fluroscent lamp controlled by one way switches drawn
on the wiring board.

The pvc pipe of the required length and pipe fittings were taken and fixed in the
wiring board as per the wiring diagram using clamp and screw.

The wire of required gauge and the wiring is being made through the pvc contact.

The bulb holder and switch were fixed in corresponding location.

The bulb holder consists of two points on either side.

The sound point of the bulb holder located on either side is being short circuited
through starter.

The first point of one side of the bulb holder was connected to the phase line
through one way switch and choke.

The first point of other end of the bulb holder was connected with neutral line.

The phase and neutral wires were connected to main switch.

The power supply was given to the circuit and the bulb was made to glow by
operating switch.
RESULT:
The wiring of fluorescent lamp was constructed and operated successfully.
23
CIRCUIT DIAGRAM:
24
Ex No:
Date :
STAIR- CASE WIRING
AIM:
To construct the wiring for one lamp controlled by using two switches (two way)
APPARATUS REQUIRED:
S.NO
1
2
3
4
5
6
7
8
9
10
COMPONENTS
Two way switch
Lamp holder
Lamp
Switch box
PVC pipe
Junction box
T-bend
L-bend
Screw
Wires
RANGE
5A
240,6A
60W
4”*4”
One way
1/18
QUANTITY
2
1
1
2
Required no’s
1
2
1
Required no’s
Required no’s
TOOLS REQUIRED:
1.
Screw driver -6”
:
1
2.
Pocker
:
1
3.
Insulation cutting plier-6” : 1
4.
Wooden hammer
: 1
SAFETY PRECAUTIONS:

Ensure that the power is switched off or not before connections are being made.

Make sure that the fuse is connected in phase sheet select the correct current
rating of wires
25
LAYOUT DIAGRAM: INDIRECT CONNECTION
26
PROCEDURE:

The wire diagram of one of the controlled by two one-way switches was drawn on
the wiring board using chalk and the scale.

The wires of required length and pipe fittings were taken and time in the wiring
board as per the wiring diagram using clamp and the screw.

The wire of required guage and colour was choosen wiring is being made through
the pvc contact.

The bulb holder and switches was fixed in a corresponding location.

The two way switch have three terminals the middle point of I switch was
connected to one end of the bulb.

The other point of the bulb being connected to the neutral like using black wire.

The terminal of the red,black wires was connected to main switch.

The power supply was given to the circuit and the bulb was being made close by
operation switch.
27
DIRECT CONNECTION
28
RESULT:
The stair-case wiring was constructed and operated successfully
29
CIRCUIT DIAGRAM:
30
Ex No:
Date :
MEASUREMENT OF ELECTRICAL QUANTITIESVoltage, Current, Power & Power factor
in RLC circuit.
AIM:
To measure the Voltage, Current ,Power & Power factor consumed by the
resisitive load using Voltmeter,Ammeter & Wattmeter respectively.
APPARATUS REQUIRED:
S.NO
COMPONENTS
RANGE
QUANTITY
1.
Wattmeter
300V,10A,UPF
1
2.
Voltmeter
(0-300)V
1
3.
Ammeter
(0-10)A
1
4.
Variac
(0-270V / 10A)
1
5.
Resistive load
230V,2.7KW
1
6.
Connecting Wire
-
As Required
FORMULA USED:
POWER =
V* I
Watts
Where,
V is voltmeter reading in volts
I is ammeter reading in amperes
SAFETY PRECAUTIONS:
Before switch on the supply
i) Load rheostat should be kept at off condition
ii) The wattmeter readings should be checked for power value
31
TABULATION:
Multiplication Factor:
S.No
Voltmeter
reading
(Volts)
Ammeter
reading
(Amps)
Wattmeter reading
(Watts)
Actual
Observed
value
Value (W)
(W)
32
Apparent
Power
(V * I)
P.F =
(W/VI)
PROCEDURE:

Connections are given as per the circuit diagram.

Switch on the single phase AC supply.

Load is varied gradually in each step. The ammeter, voltmeter and wattmeter
readings are tabulated and power factor is calculated.
RESULT:
Thus the Voltage, Current ,Power & Powerfactor consumed by the resistive load
was measured and calculated.
33
CIRCUIT DIAGRAM:
34
Ex No:
Date :
MEASUREMENT OF ENERGY USING SINGLE PHASE ENERGY
METER.
AIM:
To measure the energy using single phase energy meter at UPF load condition.
APPARATUS REQUIRED:
S.NO
1.
2.
3.
4.
5.
6.
COMPONENTS
Voltmeter
Ammeter
Stop clock
Energy meter
Watt meter
Lamp load
TYPE/RANGE
MI/(0-300)V
MI/(0-10)A
300V,10A,UPF
-
QTY
1
1
1
1
1
1
FORMULA:
Energy meter specification = 3200 imp/kwhr
3200 imp
1 imp
= 1 kwhr
= ( 1 kwhr ) / 3200
= (3600*1000) / 3200
= 1125 watt sec
For UPF conditions
Power calculated from energy meter reading = 1125 / Time for 3 imp
% Error = [( Power calculated from energy meter reading - Wattmeter reading) ] * 100
Wattmeter reading
SAFETY PRECAUTIONS:
1. There should be no load at the time of starting.
2. The connections must be made proper for UPF.
35
TABULATION:
Multiplication Factor:
Wattmeter Reading
Voltmeter Ammeter
S.No
Reading
Reading
(Volts)
(Amps)
(Watts)
Observed
Actual
Value
Value
Power
Time for
from
3
energy
impulse
meter
(Watts)
Energy meter constant: s
36
% Error
PROCEDURE:

The connections are given as per the circuit diagram.

The DPST switch is closed and the supply is effected and the load is adjusted to
full load value.

The time taken for 10revolutions of the aluminium disc in the energy meter is
noted.

The error is calculated if it is more than +- 3% the brake magnet is adjusted such
that the error is within +- 3%.

The load is reduced in steps and for each step the step3 is repeated and the %
error is calculated.
RESULT:
Thus the given single phase energy meter was used to measure the energy
consumed at UPF load conditions and the error curve was drawn successfully.
37
Ex No:
Date :
MEASUREMENT OF RESISTANCE TO EARTH OF ELECTRICAL
EQUIPMENT
AIM: To measure the resistance to earth / insulation resistance of the order of mega ohms.
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.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 bypass 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
38
ENGINEERING PRACTICES LABORATORY MANUAL
Ex. No:
STUDY OF ELECTRONIC COMPONENTS AND EQUIPMENTS.
Date:
1. Resistor.
It is a Electronic passive component. It’s used to control the flow of current
and to get required voltage drops in required places. The symbol of the
resistor is “R” the unit is “ohm”. The schematic representation of a resistor
is shown in the diagram.
Ohm: Ohm is defined as the amount of resistance that allows one ampere of
current to flow when one volt potential is applied.
(i)
(ii)
Resistors are classified into two types.
Fixed Resistors.
Variable Resistors.
FIG .1 FIXED RESISTANCE
FIG 2 VARIABLE RESISTANCE
Colour Coding of Resistor.
Colour coding is a system of colour used to indicate the electrical resistance value of a
component. In this colour bands are printed on the resistance body. The signification of each
colour is shown in the diagram. These are four colour bands 1,2,3 and 4.The first two bands 1
and 2 denotes the first and second digits of the resistance value and third 3 indicates how many
zeroes follow the first two digits. The fourth band 4 denotes the tolerance.
39
ENGINEERING PRACTICES LABORATORY MANUAL
Fig. 3 colour coding values
2. Capacitors.
Capacitor is an Electronic passive component. The materials those permit the
flow of electric current are known as capacitor (or) conductors.
It consists of two conducting plates separated by an insulator. The conducting
surfaces are called electrodes and insulating medium a=is called dielectric.
The capacitor unit is ‘Farad” and its symbol is denoted by ‘C’. Most of the
capacitors have their values printed on their bodies. The schematic
representation of a capacitor is shown in the diagram.
FIG .4 DISC CAPACITOR
FIG .5 ELECTROLYTIC CAPACITORS
Inductors.
The material those blocks the flow of electric current are called inductors or
insulators. The self inductance is the property of a coil by which it opposes
any change of current.
The inductance unit is ‘Henry” and its denoted by ‘L’.The schematic
40
ENGINEERING PRACTICES LABORATORY MANUAL
representation of an inductor is shown in the diagram.
FIG .6 TOROIDAL INDUCTOR
INDUCTOR
FIG .7 CORE
3. Transistors.
Transistor is an active component. It is a three terminal device. The three terminals
are
(i) Emitter.
(ii) Base
(iii) Collector.
(iv) Semiconductor device consisting of two PN junctions is formed by sand witching a thin
layer of n-type conductor s between two layers of p-type semiconductors. Transistors
are classified into two types.
(i) PNP Transistor.
(ii) NPN Transistor.
FIG .8 PNP TRANSISTOR
Diodes.
FIG .8 NPN TRANSISTOR
A Semiconductor diode is a two layer. one junction device, which is formed
by joining one p-type and one n-type semiconductor material. Schematic
representation of diode is shown in the diagram. The p-region of a diode is
called anode and n-region is called cathode.
41
ENGINEERING PRACTICES LABORATORY MANUAL
FIG .9.VARIOUS TYPES OF DIODES
4. Light emitting Diode (LED).
This Diode converts electrical energy into light energy (green or infrared
energy).They are used in electronic instrument.LED is a diode made up of
semiconductor. Gallium arsenium diphosphide. This material glows when
current passes through it.
FIG .10 LED
5. Rectifiers.
It is a Electronic device used for converting AC voltage into unidirectional
voltage. Rectifiers are classified into two types
(i)
Half Wave Rectifiers.
(ii)
Full Wave Rectifiers.
(iii)
Bridge Rectifiers
42
ENGINEERING PRACTICES LABORATORY MANUAL
RESULT:
Thus the study of Electronic components have been studied and verified.
43
ENGINEERING PRACTICES LABORATORY MANUAL
Ex.No:
MEASUREMENT OF AC SIGNAL PARAMETER
Date:
(PEAK-PEAK,RMS PERIOD,FREQUENCY) USING CRO
AIM:
To study the functions of different knobs of CRO and to measure
i) Amplitude
ii) Time period and Frequency
Apparatus Required:
S.No
1
2
3
Item
CRO
Signal Generator
BreadBoard
Specification
(0-20)MHZ
(0-1) MHZ
-
Quantity
1
1
1
THEORY:
An oscilloscope is a type of electronic test instrument that allows signal voltages to be
viewed, usually as a two dimensional graph of one are more electrical potential differences(
vertical axis) plotted as a function of time or of some other voltage(horizontal axis).
An oscilloscope is a measuring device used commonly for measurement of voltage,
current, frequency,phase difference and time intervals. The heart of oscilloscope is the cathode
ray tube, which generates the electron beam, accelerates the beam to create the image and
contains the phosphor screen where the electron beam eventually becomes visible.
To accomplish these tasks, various electrical signals and voltages are required. The
power suppy block provides the voltage is required by the cathode ray tube to generate and
accelerate the electron beam,as well as to supply the required operating voltages for the other
circuits of the oscilloscope.Relatively high voltages are required by the cathode tubes,on the
order of few thousand volts,for acceleration as well as a low voltage for the heater of electron
gun, which emits electrion.
Supply voltages for the other circuits are of various values usually not more than few
hundered volts. The oscilloscope has a time base, which generates the correct voltage to supply
the CRT to deflect this part at a constanttime dependent rate.The signal to be view is fed to
vertical amplifier which increases the potential of input signal to a level that will provide a useful
deflection of electron beam.To synchronise the horizontal deflection the vertical input, such that
the horizontal deflection starts at the same point of the vertical signal each time it sweeps,a
synchronizing or triggering circuit is used,.This circuit is the link between the vertical input and
the horizontal time base.
44
ENGINEERING PRACTICES LABORATORY MANUAL
FIG .11 CATHODE RAY OSCILLOSCOPE
Procedure:
Voltage and Time Peroid Measurement::
1.Select the sine output of the signal generator,set as 1KHZ.
2. Feed the signal to the vertical input of CRO.
3. Adjust level and time base to get one or two cycles of the sine signal on the
oscilloscope ,and calculate the vertical scale.
4.Count the number of vertical divisions NV on the scope and find peak-peak level.
Vpp=NV (volts/Division)
where NV = number of vertical divisions
5 calculate the Vrms values
Vrms = Vpp/ 2 √2
5. Measure the signal with an AC milli voltmeter as well.It gives the rms value of the
signal.
6. Measure the time period “T” of the signal by counting the number of horizontal
divisions.
NH covering the spam of one cycle.
T=NH *(Time/Division) where NH = No of Horizontal Divisions
7. Calculate the frequency as f=1/T
45
ENGINEERING PRACTICES LABORATORY MANUAL
8. Apply the DC voltage from the regulated power supply and measure the DC level on
the scope.(CRO)
Tabulation:
AC Voltage and Frequency Measurement:
S.No Number of divisions along Y-axis
S.No Number of divisions along
X-axis
Volt/div
Time/div
Peak to peak
voltage(volt/div)
Time
Period Frequency
time/div
F=1/T
RESULT:
Thus the study of electronic components has been studied and verified. And also the
operation and applications of Cathode Ray Oscilloscope have been studied.
46
ENGINEERING PRACTICES LABORATORY MANUAL
OR GATE:
AND GATE:
SYMBOL:
PIN DIAGRAM
47
ENGINEERING PRACTICES LABORATORY MANUAL
STUDY OF LOGIC GATES
EX NO:
DATE
:
Aim:
To study about logic gates and verify their truth tables.
Apparatus required:
SL No.
COMPONENT
SPECIFICATION
QTY
1.
AND GATE
IC 7408
1
2.
OR GATE
IC 7432
1
3.
NOT GATE
IC 7404
1
4.
NAND GATE 2 I/P
IC 7400
1
5.
NOR GATE
IC 7402
1
6.
X-OR GATE
IC 7486
1
7.
NAND GATE 3 I/P
IC 7410
1
8.
IC TRAINER KIT
-
1
9.
PATCH CORD
-
14
48
ENGINEERING PRACTICES LABORATORY MANUAL
NOT GATE:
SYMBOL:
PIN DIAGRAM:
X-OR GATE :
SYMBOL :
PIN
49
DIAGRAM
:
ENGINEERING PRACTICES LABORATORY MANUAL
THEORY:
Circuit takes that logical decision and the process are called logic gates. Each gate has
one or more input and only one output.
Basic Gates - OR, AND & NOT
Universal Gates - NOR, NAND & XOR
OR GATE: (Addition)
The OR gate performs a logical addition commonly known as OR function. The output is
high when any one of the inputs is high. The output is low level when both the inputs are low.
AND GATE: (Multiplication)
The AND gate performs a logical multiplication commonly known as AND function. The
output is high when both the inputs are high. The output is low level when any one of the inputs
is low.
NOT GATE: ( Inverter )
The NOT gate is called an inverter. The output is high when the input is low. The
output is low when the input is high.
NAND GATE:
The NAND gate is a contraction of AND-NOT. The output is high when both inputs are low and
any one of the input is low .The output is low level when both inputs are high.
NOR GATE:
50
ENGINEERING PRACTICES LABORATORY MANUAL
2-INPUT NAND GATE:
SYMBOL:
PIN DIAGRAM:
NOR GATE:
The NOR gate is a contraction of OR-NOT. The output is high when both inputs are low. The
output is low when one or both inputs are high.
X-OR GATE:
The output is high when any one of the inputs is high. The output is low when both the
51
ENGINEERING PRACTICES LABORATORY MANUAL
inputs are low and both the inputs are high.
Procedure:
(i)
Connections are given as per circuit diagram.
(ii)
Logical inputs are given as per circuit diagram.
(iii)
Observe the output and verify the truth table
RESULT:
Thus the basic logic gates are studied and the truth tables verified.
52
ENGINEERING PRACTICES LABORATORY MANUAL
Circuit Diagram:
FIG.12 CIRCUIT DIAGRAM OF GENERATION OF CLOCK SIGNAL
:
Tabulation:
S.No
Amplitude(V)
Model Graph:
53
Time Period(ms)
ENGINEERING PRACTICES LABORATORY MANUAL
GENERATION OF CLOCK SIGNAL
Ex No:
Date:
Aim:
To generate the clock signal using IC555
Apparatus required:
S.NO
NAME OF THE APPARATUS
RANGE
QUANTITY
1
2
3
4
5
6
7
NE555
Resistor
Capacitors
RPS
CRO
Bread Board
Connecting Wires
10k
0.1f
(0-30) Mhz
-
1
2
2
1
1
few
Theory:
INTRODUCTION ABOUT IC555:
One of the most versatile linear integrated circuit is the 555 timer. It was first
introduced by signetics corporation in early 1970. It is a monolithic timing circuit that can
produce accurate and highly stable time delays or oscillation. The timer basically operates in one
of the two modes:
A).Either as a monostable or
B).As a astable multivibrator
The important features of the 555 timer are:
1. It can operate +5V to +18V supply,
2. It has an adjustable duty cycle,
3. Timing is from microseconds to hours,
4. It has high current output,
5. It has a temperature stability of 50 parts per million per degree Celsius change in
temperature and,
6. Like a general purpose IC, it is reliable, easy to use, and low cost and its output can be
made compatible.
INTERNAL CIRCUITARY AND FUNCTIONS:
The function block diagram and the pin out details of 555 timers are shown in the left
hand side fig.1.The pin functions are detailed as follows:
PIN 1: GROUND:
All voltages are measured with respect to this terminal
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ENGINEERING PRACTICES LABORATORY MANUAL
PIN 2: TRIGGER:
The output of the timer depends on the amplitude of the external trigger pulse applied to
this pin. The output is low if the voltage at this pins greater than 2/3 Vcc. However , when a
negative going pulse of amplitude larger than 1/3Vcc is applied to this pin, the comparator output
goes low, which in turn switches the outout of the timer high. The output remains high as long as
the trigger terminal is held at a low voltage.
PIN 3: OUTPUT:
There are two ways a load can be connected to the output terminal: either between pin 3
and ground (pin 1) or between pin 3 and supply voltage +Vcc.
PIN 4: RESET:
The 555 timer can be reset by applying a negative pulse to this pin. When the reset
function is not in use, this terminal should be connected to +Vcc to avoid any possibility of false
triggering.
PIN 5: CONTROL VOLTAGE:
An external voltage applied to this terminal changes the threshold as well as the trigger
voltage. The pulse width of the output waveform can be varied by imposing a voltage on this pin
or by connecting a pot between this pin and ground. When not used, the control pin should be by
passed to ground with a 0.01Чf capacitor to prevent any noise problems
PIN 6: THRESHOLD:
This is the non inverting input terminal of the upper comparator [UC] which monitors the
voltage across the external capacitor C connected across it. When the output is low, Q1 is
saturated and act as a short circuit, shorting out the external capacitor C to ground.
PIN 7: DISCHARGE:
This pin is connected internally to the collector of transistor Q1. when the output is high,
Q1 is ”OFF” and act as an open circuit to the external capacitor C connected across it. When the
output is low, Q1 is saturated and act as a short circuit, shorting out the external capacitor C to
ground.
PIN 8: +Vcc:
The supply voltage voltage of +5V to +18Vis applied to this pin with respect to ground.
ASTABLE MULTIVIBRATOR USING 555:
The left hand side fig(2) shows the 555 timer connected as an astable multivibrator. Capacitor C
starts charging towards Vcc through RA and RB. As soon as capacitor voltage equals 2/3 VCC
upper comparator [UC] triggers the flip flop and the output switches low. Now capacitor C starts
discharging through RB and transistor Q1.
When the voltage across C equals 1/3 Vcc lower comparator(LC), output triggers the flip
flop and the output goes high. Then the cycle repeats.
The capacitor is periodically charged and discharged between 2/3 Vcc and 1/3 Vcc is
equal to the time the output is high and is given by
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ENGINEERING PRACTICES LABORATORY MANUAL
Tc=0.69(RA+RB)C
Where RA,RB are in ohms and C in farads. Similarly the time during which the capacitor
discharges from 2/3 Vcc to1/3 Vcc is equal to the time the output is low and is given by
Td= 0.69RBC
The total period of the output wave form is
T= tc +td=0.69(RA+2RB)
The frequency of oscillation
Fc = 1/T = 1.45/(RA+2RB)C
The above Eqn shows that f0 is independent of supply voltage Vcc.
DUTY CYCLE:
Duty cycle is the ratio of the time td, during which the output is low to the total time
period (t). This definition is applicable to 555 astable multivibrator only; conventionally the duty
cycle, ratio is defined as the ratio as the time during which the output is high to the total time
period.
%duty cycle= td/T *100
= RB/(RA+2RB) *100
To obtain 50% duty cycle, a diode should be connected R and RA must be a combination
of a fixed resistor potentiometer; so that the potentiometer can be adjusted for the exact square
value
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ENGINEERING PRACTICES LABORATORY MANUAL
PROCEDURE:
1. Rig-up the circuit of 555 astable multivibrator as shown in fig(2)
With the designed value of the components.
2. Connect the CRO probes to pin 3 and pin2 displays the output signal and the voltage
across the timing capacitor. Set suitable voltage sensitivity and time-base on the CRO.
3. Switch on the power supply to CRO and the circuit.
4. Observe the waveforms on the CRO and draw to scale on a graph sheet. Measure the
voltage levels at which the capacitor starts discharging, output high and low timings and
frequency, and compare the measured values with theoretical or designed values.
5. Switch off the power supply. Connect a diode across RB as shown in dashed lines in
fig(2), to make the astable with 50% duty cycle ratio. Switch on the power supply. Observe the
output waveform. If necessary change RA to get 50% duty cycle.
6. Take the output from pin no: 3 and measure the amplitude & time period.
7. Also measure the charging and discharging of the capacitor across pin no:2 &6 using
CRO
RESULT:
Thus the clock signal was generated using IC555 and wave forms were verified.
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ENGINEERING PRACTICES LABORATORY MANUAL
FIG .13 SOLDERING CIRCUIT FRONTSIDE
FIG .14 SOLDERING CIRCUIT BACKSIDE
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ENGINEERING PRACTICES LABORATORY MANUAL
Ex No:
Date:
Aim:
SOLDERING AND DE-SOLDERING PRACTICE
To practice soldering and de soldering for the given electronic circuit by assembling
and de-assembling the resistor R1 and R2 and capacitor C1 in the given printed circuit board
(PCB).
Components Required:
S. No
1.
2.
3.
4.
5.
6.
7.
8.
Component
PCB Board for the
given Circuit
Soldering Iron
Solder
Flux
Electrician’s knife
Noise Plier
Resistors
Capacitors
Range
Quantity
2
10W (or0 35W
60/40 Grade
1
1
1
1
2
1
10kΩ
0.01µf
Procedure:
Soldering.
1. Study the given Electronic circuit.
2. Clean the given PCB board.
3. Clean the tip of the soldering iron before heating and also clean the resistors, capacitors
which are to be soldered.
4. Heat the soldering iron and apply solder to the tip as soon as it is hot to melt on it.
5. Bend the Resistor (R1) leads to fit into the holes on the board. Insert the Resistor R1 as per
the circuit in the figure and bend the leads.
6. Apply the hot tip to the joints and apply solder.
7. Remove ht soldering tip and hold the resistor until the solder has cooled and set.
8. Trim excess component lead with side cutter.
9. Repeat the above steps to fix other Resistor R2 and capacitor C1 as shown in the circuit.
De-Soldering.
1. Hold the resistor R1 to be unsoldered by a hose plier.
2. Place the tip of the soldering iron on the joint until the solder is melt.
3. When the solder is melted, remove the resistor R1 with the Tweezer and brush away
the molten solder.
4. Repeat the above steps to remove resistor R2 and capacitor C1.
5. Clean the resistor and capacitors so that they can be used to make other circuits
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ENGINEERING PRACTICES LABORATORY MANUAL
RESULT:
Thus the soldering and de-soldering practice is done for the given Electronic circuit.
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ENGINEERING PRACTICES LABORATORY MANUAL
Half Wave Rectifier:
Circuit Diagram
HALF WAVE RECTIFIER WITHOUT FILTER:
HALF WAVE RECTIFIER WITH FILTER
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ENGINEERING PRACTICES LABORATORY MANUAL
MEASUREMENT OF RIPPLE FACTOR FOR HALF WAVE RECTIFIER.
Ex No:
Date:
Aim:
To Study the ripple factor and regulation characteristics of a half wave rectifier with and
without filter.
Components Required:
S.No Components
Type/range
Quantity
1.
Diode
IN 4007
1
2.
Capacitor
220µc,100µf,470µf
Each 1
3.
Transformer
230v/6A
1
4.
Resistor
1KΩ
1
5
Bread board
-
1
6
CRO
(0-30)MHz
1
Formula :
Ripple factor, γ = Vrms /Vdc & (Vrms / Vdc)2 – 1]1/2
Where, Vrms =The rms value of a.c. component of the output voltage.
Vdc = the average or d.c. value of the output voltage.
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ENGINEERING PRACTICES LABORATORY MANUAL
TABULATION:
HALF WAVE RECTIFIER: (WITHOUT FILLTER):
S.No
Time
Period(ms)
Amplitude
Vm(V)
Ripple Factor
Vrms = Vm/2
Vdc = Vm/ π
r = Vrms/Vdc
HALF WAVE RECTIFIER: (WITH FILTER):
S.No
Time
Period(ms)
Amplitude
Vm(V)
Ripple
Voltage
Vr(v)
Ripple Factor
Vrms = Vm/2
Vd = Vm/ π
r = Vrms/Vdc
Procedure :
(i) Connections are given as per the circuit diagram.
(ii) The AC supply is switched “ON” directly to filter circuit.
(iii) On moving the rheostat, get the voltage form AC voltage which gives V L such that the
rheostat is in minimum position.
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ENGINEERING PRACTICES LABORATORY MANUAL
RESULT:
Thus the ripple factor and regulation characteristics of half wave rectifier with and
without filter are studied and verified.
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ENGINEERING PRACTICES LABORATORY MANUAL
FULLWAVE RECTIFIER WITHOUT FILTER:
FULLWAVE RECTIFIER WITH FILTER:
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ENGINEERING PRACTICES LABORATORY MANUAL
MEASUREMENT OF RIPPLE FACTOR FOR FULL-WAVE
Ex No:
RECTIFIER.
Date:
Aim:
To study the ripple factor and regulation characteristics of full wave rectifier with and
without filter.
Components Required:
S.No
1.
2.
3.
4.
5.
6
Components
Diode
Step-down transformer
Resistor
Capacitor
Braed Board
CRO
Type/range
In 4007
(0-6v)
10Ω
100µF,220µF
(0-30)MHz
Quantity
2
1
1
1
1
1
Formula :
Ripple factor γ= (Vrms/Vdc) & (Vrms / Vdc)2 – 1]1/2
Where, Vrms=The rms value of the a.c. component of the output voltage.
Vdc= The average or d.c. value of the output voltage.
TABULATION:
FULL WAVE RECTIFIER:
WITHOUT FILLTER:
Time
S.NO
Period(ms)
Amplitude(V)
Ripple Factor
Vrms=Vm/2
Vd = Vm/ π
r = Vrms/Vdc
WITH FILLTER:
S.NO
Time
Period(ms) Amplitude(V)
Ripple Voltage
Vr(v)
66
Vrms=Vm/2
Vd =
Vm/
π
Ripple Factor
r = Vrms/Vdc
ENGINEERING PRACTICES LABORATORY MANUAL
Model Graph:
Procedure:
Without filter
(i) Connections are made as per the circuit diagram.
(ii) Switch on the AC supply and note down the no-load voltage, full load voltage.
(iii)Then vary the rheostat and note down the corresponding Vrms, Vdc and Idc in steps.
(iv) Calculate the ripple factor and regulation using the formula.
With filter.
(i)
(ii)
(iii)
Connections are made as per the circuit diagram.
Switch on the Ac supply and note down the corresponding Vrms, Vdc and Idc in
steps.
`Then decrease the rheostat and switch off the supply.
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ENGINEERING PRACTICES LABORATORY MANUAL
RESULT:
Thus the ripple factor and regulation characteristics of full wave rectifier with and
without filter are studied.
68