GE2114 ENGINEERING PRACTICES LABORATORY

ELECTRONICS ENGINEERING PRACTICE

1. Study of Electronic components and equipments – Resistor, colour coding measurement of AC signal parameter (peak-peak, rms period, frequency) using CR.

2. Study of logic gates AND, OR, EOR and NOT.

3. Generation of Clock Signal.

4. Soldering practice – Components Devices and Circuits – Using general purpose PCB.

5. Measurement of ripple factor of HWR and FWR.

Exp No: 1

Study of Electronic components and equipments – Resistor, colour coding measurement of AC signal parameter (peak-peak, rms period, frequency)

using CRO.

AIM:

To Study the various Electronic components and equipments – Resistor, colour coding, measurement of AC signal parameter (peak-peak, rms period, frequency) using CRO.

APPARATUS REQUIRED:

1. Resistors

2. Cathode ray oscilloscope (0-30) Mhz

3. Function generator (0-1) Mhz

4. Probe

THEORY:

An electronic circuit is made up of a large number of components and a necessary

interconnection between the components is made to produce the desire functionality. Electronic

components are broadly classified into mechanical, electromechanical, passive and active

components. Passive and active components are very important to design electronic circuits.

ACTIVE components increase the power of a signal and must be supplied with the signal

and a source of power. Examples are bipolar transistors, field effect transistors etc. The signal is

fed into one connection of the active device and the amplified version taken from another

connection. In a transistor, the signal can be applied to the base connection and the amplified

version taken from the collector. The source of power is usually a dc voltage from a battery or

power supply.

PASSIVE components do not increase the power of a signal. They often cause power to

be lost. Some can increase the voltage at the expense of current, so overall there is a loss of

power. Resistors, capacitors, inductors and diodes are examples of passive components.

Resistors

A resistor is a passive component. It introduces resistance in the circuit. Resistance is

basic property of conducting material and is given by

ρ = Resistivity.L = Length of the material.A = Area of cross section of material.The resistivity is measured in units of ohm-meters.

Resistor Color code

Color Value Multiplier Tolerance

Black 0 0 -

Brown 1 1 ±1

Red 2 2 ±2

Orange 3 3 ±0.05

Yellow 4 4 -

Green 5 5 ±0.5

Blue 6 6 ±0.25

Violet 7 7 ±0.1

Grey 8 8 -

White 9 9 -

Gold - -1 ±5

Silver - -2 ±10

None - - ±20

a b × 10c Ω ± d%

Capacitors

The capacitance of a set of charged parallel plates is increased by the insertion of a dielectric

material. The capacitance is inversely proportional to the electric field between the plates, and

the presence of the dielectric reduces the effective electric field.

Capacitance

This is a measure of a capacitor's ability to store charge. A large capacitance means that

more charge can be stored. Capacitance is measured in farads, symbol F. However 1F is very

large, so prefixes are used to show the smaller values.

Three prefixes (multipliers) are used, µ (micro), n (nano) and p (pico):

µ means 10-6 (millionth), so 1000000µF = 1F

n means 10-9 (thousand-millionth), so 1000nF = 1µF

p means 10-12 (million-millionth), so 1000pF = 1nF

Diodes

In electronics, a diode is a two-terminal device (except that thermionic diodes may also

have one or two ancillary terminals for a heater). Diodes have two active electrodes between

which the signal of interest may flow, and most are used for their unidirectional current property.

The varicap diode is used as an electrically adjustable capacitor.

The directionality of current flow most diodes exhibit is sometimes generically called the

rectifying property. The most common function of a diode is to allow an electric current to pass

in one direction (called the forward biased condition) and to block it in the opposite direction

(the reverse biased condition). Thus, the diode can be thought of as an electronic version of a

check valve. Real diodes do not display such a perfect on-off directionality but have a more

complex non-linear electrical characteristic, which depends on the particular type of diode

technology. Diodes also have many other functions in which they are not designed to operate in

this on-off manner.

Bread Boards

The bread boarding area on the experimental box has holes for component leads, #22

solid wire and IC pins. Don't try to force larger wire into these holes because it will spring them

too far and ruin the board. The horizontal rows of holes on the top and bottom of the breadboard

are connected together horizontally. The left and right halves are independent. We suggest that

you use these horizontal rows for power supply voltages and ground. You may wish to put a

jumper wire between the left and right halves so that the voltages are the same across the board.

The vertical columns of holes are connected electrically in groups of five along a vertical line.

The top and bottom halves are independent. Typically one inserts an ic chip straddling the centre

trough. There are then four empty holes for making connections to each ic pin. When you plug

IC’s into the breadboard, a common convention is to put pin 1 on the left. For other components,

make sure the leads are not in the same column of five unless you want them connected together.

Electronic Measurement using CRO

AIM:

To measure voltage, frequency, time period, phase difference, peak value, peak to peak value and RMS value of an alternating voltage.

THEORY:

Analogous to the CRO used for measuring the voltage, time period, frequency, peak voltage, peak to peak voltage and RMS voltage, we use Waveform Viewer, for measurement in EDWin.

Time Period: - The time taken by an alternating voltage to complete one cycle is called its Time period, T.

Using CRO: - Measure the number of divisions for a single cycle on the time axis and multiply it by the value indicated by the Times/Div knob on the CRO. This gives the Time Period of the alternating voltage.

Using EDWin: - Waveforms can be observed in the Waveform Viewer which is analogous to the CRO time Period can be directly obtained from the Waveform Viewer.

Frequency: - The number of cycles completed in one second is called the frequency of the alternating voltage. Its unit is Hertz. Frequency is given by the reciprocal of Time period T.

i.e.

Peak and Peak to Peak Value: - The maximum value, +ve or –ve of the alternating quantity is known as its peak value. It is also called maximum value or amplitude of the alternating quantity.

The total voltage measured from –ve peak to +ve peak is called the Peak to Peak voltage.

Using CRO: - Measure the number of divisions on the voltage axis and multiply it by the value indicated by the Volts/Div knob on the CRO. This gives the peak value.

Using EDWin: - Peak value and Peak to peak value can be directly obtained from waveform viewer.

RMS Value (Root Mean Square Value)

It is given by the steady dc current which when flowing through a given circuit for a given time produces the same heat as produced by the alternating current which when flowing through the same circuit for the same time.

RMS value of alternating voltage is related to its peak value by the relation

Time Period : - The time required to complete one cycle is referred to as Time Period, T.

TABULATION

S.No Amplitude (V) Time period (ms)

RESULT:

Thus the various Electronic components and equipments – Resistor, colour coding are studied and the output waveform may be observed in the waveform viewer.

Exp No: 2

STUDY OF LOGIC GATES

AIM:

To study about logic gates AND, OR, NOT, NOR, NAND, EX-OR by verifying their

truth table.

APPARATUS REQUIRED:

S.No Components Quantity

1

2

3

4

5

6

IC 7408(AND)

IC 7432(OR)

IC 7404(NOT)

IC 7400(NAND)

IC 7402(NOR)

IC 7486(EX-OR)

1

1

1

1

1

1

THEORY:

AND GATE

The AND gate is an electronic circuit that gives a high output (1) only if all its inputs are

high. A dot (.) is used to show the AND operation i.e. A.B. Bear in mind that this dot is

sometimes omitted i.e. AB

OR GATE

The OR gate is an electronic circuit that gives a high output (1) if one or more of its

inputs are high. A plus (+) is used to show the OR operation.

NOT GATE

The NOT gate is an electronic circuit that produces an inverted version of the input at its

output. It is also known as an inverter. If the input variable is A, the inverted output is known as

NOT A. This is also shown as A', or .

PIN DIAGRAM

AND GATE

OR GATE

NOT GATE

EX-OR GATE

NAND GATE

NOR GATE

NAND GATE

This is a NOT-AND gate which is equal to an AND gate followed by a NOT gate. The

outputs of all NAND gates are high if any of the inputs are low. The symbol is an AND gate with

a small circle on the output. The small circle represents inversion.

NOR GATE

This is a NOT-OR gate which is equal to an OR gate followed by a NOT gate. The

outputs of all NOR gates are low if any of the inputs are high.

The symbol is an OR gate with a small circle on the output. The small circle represents

inversion.

EXOR GATE

The 'Exclusive-OR' gate is a circuit which will give a high output if either, but not both,

of its two inputs are high. An encircled plus sign ( ) is used to show the EOR operation.

The NAND and NOR gates are called universal functions since with either one the AND and

OR functions and NOT can be generated.

PROCEDURE:

1. The supply voltage and ground are given to the appropriate pins of IC.

2. For various combinations of input, the output is taken.

3. If LED glows, the output is considered as 1. Otherwise it is 0.

4. The truth table is verified.

RESULT:

Thus the truth table of logic gates (AND, OR, NOT, NOR, NAND, EX-OR) are verified.

Exp No: 3

Generation of Clock Signal.

AIM:

Generation of Clock Signal Using IC 555

APPARATUS REQUIRED:

1. IC 555 – 01

2. Resistors

3. Capacitors

4. CRO (0-30) MHz

5. Function Generator (0-1) MHz

6. Probe

7. Bread Board

8. Connecting wires

THEORY

555 Timer Circuit.

The 555 Timer is a very versatile low cost timing IC that can produce a very accurate

timing periods with good stability of around 1% and which has a variable timing period from

between a few micro-seconds to many hours with the timing period being controlled by a single

RC network connected to a single positive supply of between 4.5 and 16 volts. The NE555 timer

and its successors, ICM7555, CMOS LM1455, DUAL NE556 etc, are covered in the 555

Oscillator tutorial and other good electronics based websites, so are only included here for

reference purposes. The 555 connected as an Astable oscillator is given below.

NE555 ASTABLE MULTIVIBRATOR CIRCUIT DIAGRAM

Here the 555 timer is connected as a basic Astable Multivibrator circuit. Pins 2 and 6 are

connected together so that it will retrigger itself on each timing cycle, thereby functioning as an

Astable oscillator. Capacitor, C1 charges up through Resistor, R1 and Resistor, R2 but

discharges only through Resistor, R2 as the other side of R2 is connected to the Discharge

terminal, pin 7. Then the timing period of t1 and t2 is given as:

    t1 = 0.693 (R1 + R2) C1

    t2 = 0.693 (R2) C1

    T = t1 + t2

The voltage across the Capacitor, C1 ranges from between 1/3 Vcc to 2/3 Vcc depending upon

the RC timing period. This type of circuit is very stable as it operates from a single supply rail

resulting in an oscillation frequency which is independent of the supply voltage Vcc.

PIN Diagram

TABULATION

S.No Amplitude (V) Time period (ms)

Pin Functions - 8 pin package

Ground (Pin 1)

Not surprising this pin is connected directly to ground.

Trigger (Pin 2)

This pin is the input to the lower comparator and is used to set the latch, which in turn causes the

output to go high.

Output (Pin 3)

Output high is about 1.7V less than supply. Output high is capable of I source  up to 200mA

while output low is capable of I sink  up to 200mA.

Reset (Pin 4)

This is used to reset the latch and return the output to a low state. The reset is an overriding

function. When not used connect to V+.

Control (Pin 5)

Allows access to the 2/3V+ voltage divider point when the 555 timer is used in voltage control

mode. When not used connect to ground through a 0.01 uF capacitor.

Threshold (Pin 6)

This is an input to the upper comparator. See data sheet for comprehensive explanation.

Discharge (Pin 7)

This is the open collector to Q14 in figure 4 below. See data sheet for comprehensive

explanation.

V+ (Pin 8)

This connects to Vcc and the Philips databook states the ICM7555 cmos version operates 3V -

16V DC while the NE555 version is 3V - 16V DC. Note comments about effective supply

filtering and bypassing this pin below under "General considerations with using a 555 timer"

RESULT:

Thus the clock signal have been Generated by using IC 555.

Exp No: 4Soldering practice – Components Devices and Circuits – Using general

purpose PCB.

AIM:

To solder the given circuit – Components Devices and Circuits – Using general purpose PCB.

APPARATUS REQUIRED:

1. Soldering Iron2. PCB (Printed Circuit Board)3. Flux4. Soldering lead5. Multimeter

THEORYIntroduction

Almost every electronic device today has a printed circuit board whether you are

assembling a PC board or repairing it, you must understand the basics of working with these

boards. A poorly soldered joint can greatly affect small current flow in circuits and can cause

equipment failure. You can damage a PC board or a component with too much heat or cause a

cold solder joint with insufficient heat. Sloppy soldering can cause bridges between two adjacent

foils preventing the circuit from functioning. Good soldering requires practice and an

understanding of soldering principles. This solder practice project will help you achieve good

soldering techniques, help you to become familiar with a variety of electronic components, and

provide you with dynamic results. If the circuit has been assembled and soldered properly, the

LED will alternately flash and the speaker will produce a wailing sound.

Solder

Solder is a fusible alloy composed of tin and lead. Some solder may contain small

amounts of other material for use in special purposes to enhance its characteristics. Solder has a

melting temperature around 360O to 370O, making it ideal for forming a metallic joint between

two metals. Solder is identified by the ratio of tin-to-lead. The most common ratios are 40/60,

50/50 and 60/40. Solder with a greater tin content melts at a lower temperature, takes less time to

harden, and generally makes it easier to do a good soldering job. The ratio of tin is a main factor

in the strength of the solder joint. Solder with a greater tin content has a greater holding ability

under stress. Solder with a tin ratio of 60% is the strongest, while solder with less than 30%

would be undesirable.

Flux

Most solder contains flux in the hollow core of the solder allowing it to be applied

automatically when you heat the solder. The flux will remove any oxide film on the metals

soldered creating a good metal-to-metal contact. This is called “wetting the metal”. There are

three types of solder of solder fluxes: chloride, organic and rosin. In the electronics industry,

only the rosin type is used. Rosin flux comes in two types, pure and active. The most reliable is

the pure type, since it doesn’t cause dendrites between tracks on the PC board as the active type

does. Due to the highly corrosive and moisture attracting characteristics of the chloride and

organic type fluxes, they should not be used in electronics.

The most important skill needed to successfully construct your device is soldering. Make

sure you start by using electronics solder, not plumber’s solder. The main trick to getting a

successful solder connection is to heat the junction up before applying the solder to the heated

area. Do NOT try to melt some solder onto the tip of the iron and smear it onto the joint - you

won’t get a strong joint. If the heat is applied unevenly, you will get solder blobs (see below). To

better apply heat, keep your soldering iron tip clean by wiping it frequently on a damp sponge or

cloth. The tip should always be shiny, and not covered in tarnish and burned crud (don’t burn

crud - bad!).

Desoldering and resoldering

Used solder contains some of the dissolved base metals and is unsuitable for reuse in

making new joints. Once the solder's capacity for the base metal has been achieved it will no

longer properly bond with the base metal, usually resulting in a brittle cold solder joint with a

crystalline appearance.

It is good practice to remove solder from a joint prior to resoldering—desoldering braids or

vacuum desoldering equipment (solder suckers) can be used. Desoldering wicks contain plenty

of flux that will lift the contamination from the copper trace and any device leads that are

present. This will leave a bright, shiny, clean junction to be resoldered.

The lower melting point of solder means it can be melted away from the base metal, leaving it

mostly intact, though the outer layer will be "tinned" with solder. Flux will remain which can

easily be removed by abrasive or chemical processes. This tinned layer will allow solder to flow

into a new joint, resulting in a new joint, as well as making the new solder flow very quickly and

easily.

PROCEDURE:

1. All parts must be clean and free from dirt and grease.

2. Try to secure the work firmly.

3. "Tin" the iron tip with a small amount of solder. Do this immediately, with new tips

being used for the first time.

4. Clean the tip of the hot soldering iron on a damp sponge.

5. Many people then add a tiny amount of fresh solder to the cleansed tip.

6. Heat all parts of the joint with the iron for under a second or so.

7. Continue heating, then apply sufficient solder only, to form an adequate joint.

8. Remove and return the iron safely to its stand.

9. It only takes two or three seconds at most, to solder the average P.C.B. joint.

10. Do not move parts until the solder has cooled.

RESULT:

The given circuits/components have been soldered Using general purpose PCB.

Exp No: 5

Measurement of ripple factor of HWR and FWR

AIM:

To construct and analyze the characteristics of a Half wave and Full wave rectifier with

and without filter.

APPARATUS REQUIRED:

S.No Components Range Quantity

1

2

3

4

5

6

7

8

Transformer

Resistor

Capacitor

Diode

Function Generator

Cathode Ray Oscilloscope

Bread board

Connecting wires

6-0-6 / 9-0-9 / 12-0-12

1 KΩ

100µF

BY 127

0-1 MHz

0-2 0 MHz

1

1

1

2

1

1

1

1

THEORY:

It is the function of a rectifier to change AC to DC. In single phase circuits the rectifier

changes the AC to a pulsating DC and some additional circuits are needed to change the

pulsating DC to a smooth DC.

Half-wave rectifier

The circuit of a half-wave rectifier is shown in Figure, along with its output waveform.

When the top end of the transformer secondary is positive with respect to the bottom end, current

will flow from the anode to the cathode of the diode. The forward drop across the diode is small

compared to the voltage of the transformer and almost all of the voltage appears across the load

resistor. The positive half-cycle appears across the load. When the top end of the transformer

secondary is negative with respect to the bottom end, current will not flow through the series

combination of the diode and load resistor. If there is no current through the load resistor, there

can be no voltage drop across it. The voltage of the transformer secondary is dropped across the

diode and does not appear across the load resistor. Thus we have only half of each cycle

appearing across the load. This should be called half-cycle rectification and the circuit is called a

half-wave rectifier.

Full-wave rectifier

Figure shows the circuit and output waveform of a full-wave rectifier. You will note that

the pulsations occur twice as often in Figure as they do in Half wave rectifier. A higher rate of

pulsations is easier to smooth out. It is for this reason that a half-wave rectifier is very rarely

used. A transformer with a center-tapped secondary is required to construct this circuit. The two

diodes and the two halves of the transformer work alternately. They can handle twice as much

current as either one working alone.

On the first half-cycle when the top end of the secondary is positive with respect to the

center-tap the bottom end is negative with respect to the center-tap. (Note that the load is

returned to the center-tap, not to the bottom of the secondary.) Diode D1 is forward biased and

D2 is reversed biased. D1 conducts current which flows through the load and back to the center-

tap. The first half-cycle appears across the load with the top end of the load resistor positive. On

the second half-cycle the top of the secondary is negative with respect to the center-tap and the

bottom is positive with respect to the center-tap. Diode D1 is reversed biased and D2 is forward

biased. D1 does not conduct but D2 does. Remember that the bottom end of the transformer

secondary is now positive and when D2 conducts, current flows downward through the load

resistor, making its top end positive. Current flows through the load on both halves of the input

sine wave and both halves appear positive across the load. This process is called full-wave

rectification and the circuit is called a full-wave center-tapped rectifier.

CIRCUIT DIAGRAM

FULL WAVE RECTIFIER (Without Filter)

FULL WAVE RECTIFIER (With Filter)

MODEL GRAPH

CIRCUIT DIAGRAM

HALF WAVE RECTIFIER (Without Filter)

HALF WAVE RECTIFIER (With Filter)

HALF WAVE RECTIFIER

MODEL GRAPH

Output voltage of capacitor filter is dc voltage

TABULATION

HALF WAVE RECTIFIER (Without filter)

S.No Amplitude (V) Time period (ms)

HALF WAVE RECTIFIER (With filter)

S.No Amplitude (V) Time period (ms)

FULLWAVE RECTIFIER (Without filter)

S.No Amplitude (V) Time period (ms)

FULLWAVE RECTIFIER (With filter)

S.No Amplitude (V) Time period (ms)

PROCEDURE:

HALF WAVE RECTIFIER

1. Connections are made as per the circuit diagram.

2. Apply AC input to rectifier.

3. The rectifier inputs are absorbed with and without filter.

4. Ripple factor are calculated and tabulated.

PROCEDURE:

FULLWAVE RECTIFIER

1. Connections are made as per the circuit diagram.

2. Apply AC input to rectifier.

3. The rectifier inputs are absorbed with and without filter.

4. Ripple factor are calculated and tabulated.

RESULT:

Thus the operation of half wave and full wave rectifier was studied and its output wave

forms are plotted.