diploma in engg. (electronics/computer) · 2019-01-21 · gripping, cutting and wire handling, and...

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Diploma in Engg. (Electronics/Computer)

Ist Semester

BLE-191, Basic Electronics Workshop

List of Experiments

1. To identify the various tools related to electronics workshop.

2. Soldering and de-soldering of different circuit elements on PCB.

3. Assembling and testing of circuit elements in series and parallel.

4. Assembling and testing of resistors in star and delta configuration.

5. Assembling and Testing of a Half Wave Rectifier.

6. Assembling and testing of a Centre Tap full wave rectifier Circuit.

7. Assembling and testing of full wave Bridge rectifier circuit.

Revised: September 2018

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Diploma in Engg. (Electronics/Computer), Ist Semester


Experiment No. 1

Object: To identify the various tools related to electronics workshop.

The following are the various components used in electronics workshop.

1. Multimeter

For troubleshooting and repair testing, nothing can replace a multimeter. Not only are you able to test

voltage, current or power, you can also test for polarity and resistance. Most multimeters are designed

to be used in both AC and DC circuits. If your model uses batteries, be sure to keep fresh ones

installed, to be sure of get accurate results.

2. Pliers

One can expect to need several different types of pliers. Lineman's pliers are good for all-purpose

gripping, cutting and wire handling, and a pair of wire strippers will be handy when working with

many connectors or small wires. For reaching into cramped spaces, a pair of needle-nosed pliers will

be important.

3. Soldering Iron

This device is used for making solid wire-to-circuit board connections, affixing wire ends to

terminals, and many other functions. If one choose a soldering gun over the complete station, a gun-

grip design is easier to control, but be sure to use a gun with interchangeable tips, as the task

requirements can range from tiny to large, and different applications will be necessary.

4. Side cutters

The side cutters are used for trimming component leads close to the circuit board. It is also used to cut

the connecting wires.

5. Wire stripper

The wire strippers are used to remove the insulation of the connecting leads. Most strippers are

designed to include a cutter at the tip as well, but they are not suitable for trimming component

leads.

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6. Small pliers

The small pliers used in the electronics workshop are used for bending the component leads etc.

Usually these are called 'snipe nose' pliers.

7. Small flat-blade screwdriver

The small flat screw drivers are used for scraping away excess flux and dirt between tracks, as well as

for fastening the screws.

8. Soldering iron:

In electronics workshop the soldering iron of 230 V is used. It should have a heatproof silicone cable

for safety. The iron's power rating should be 10-15 W and it should be fitted with a small bit of

2- 3 mm diameter.

9. Soldering iron stand

You must have a safe place to put the iron when you are not holding it. Preferably a wooden stand

with iron holder is used to place the iron when it is not in use.

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Electronic Components And Their Functions In Electronics:

1. Terminals and Connectors: Components to make electrical connection.

2. Resistance: Resistance is a measure of how easily (or with what difficulty) electrons will flow

through the device. Copper wire has a very low resistance, so a small voltage will allow a large

current to flow. Likewise, the plastic insulation has a very high resistance, and prevents current from

flowing from one wire to those adjacent. Resistors have a defined resistance, so the current can be

calculated for any voltage. Its unit is Ohms Ω) and it is denoted by R. Resistance in passive devices is

always positive (i.e. > 0). The symbol of resistance is given below:

3. Capacitor: A capacitor is an electrical device characterized by its capacity to store an electric

charge. A capacitor is a passive electrical component that can store energy in the electric field

between a pair of conductors (called "plates"). In simple words, we can say that a capacitor is a device

used to store and release electricity, usually as the result of a chemical action. A capacitor is also

called a storage cell, a secondary cell, a condenser or an accumulator. The unit of capacitor is Farad

and its symbol is given below:

4. Inductor: An inductor is an electrical device (typically a conducting coil) that introduces

inductance into a circuit. An inductor is a passive electrical component designed to provide

inductance in a circuit. It is basically a coil of wire wrapped around an iron core. The simplest form of

an inductor is made up of a coil of wire. The inductance measured in henrys (H), is proportional to the

number of turns of wire. Its symbol is given below:

5. Diodes: A Diode is an electronic device that allows current to flow in one direction only. It is a

semiconductor that consists of a p-n junction. They are used most commonly to convert AC to DC,

because they pass the positive part of the wave, and block the negative part of the AC signal, or, if

they are reversed, they pass only the negative part and not the positive part

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6. Integrated circuits

A microelectronic computer circuit incorporated into a chip or semiconductor; a whole system rather

than a single component. Integrated Circuits play a very important part in electronics. Most are

specially made for a specific task and contain up to thousands of transistors, diodes and resistors.

Special purposes IC's such as audio-amplifiers, FM radios, logic blocks, regulators and even a whole

micro computers in the form of a micro controller can be fitted inside a tiny package. One such IC is

shown below.

RESISTOR COLOUR CODE

Tolerance: The tolerance of resistors is mostly 1%, 2%, 5% and 10%. In the old days, 20% was also

common, but these are now rare. Even 10% resistors are hard to get except in extremely high or low

values (> 1M or < 1R), where they may be the only options available at a sensible price.

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Experiment No. 2

Object: Soldering and de-soldering of different circuit elements on PCB.

Before performing the soldering and de-soldering of the components, the following points are to be

remembered.

Printed Circuit Board:

A PCB is made from glass reinforced plastic with copper tracks in the place of wires. Components are

fixed in position by drilling holes through the board, locating the components and then soldering them

in place. The copper tracks link the components together forming a circuit.

PCB is board that has lines and pads that connect various points together. Components are fixed in

position by drilling holes through the board, locating the components and then soldering them in

place. The copper tracks link the components together forming a circuit.

On a PCB we can connect the various connectors and components to each other. A PCB allows

signals and power to be routed between physical devices. Solder is the metal that makes the electrical

connections between the surface of the PCB and the electronic components. Being metal, solder also

serves as a strong mechanical adhesive.

Fig. PCB

Soldering is the only permanent way to ‘fix’ components to a circuit. However, soldering requires a

lot of practice as it is easy to ‘destroy’ many hours preparation and design work by poor soldering.

Guidelines for Soldering

1. Use a soldering iron in good condition. Inspect the tip to make sure that it is not past good

operation. If it looks in bad condition it will not help you solder a good joint. The shape of the tip

may vary from one soldering iron to the next but generally they should look clean and not burnt.

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Fig. Soldering of component on PCB

Fig. Soldering Iron Holder

2. Place the PCB, with its components in position, in the bull clip. This will steady the PCB when

you try to use the soldering iron.

3. The heated soldering iron should then be placed in contact with the track and the component and

allowed to heat them up. Once they are heated the solder can be applied. The solder should flow

through and around the component and the track.

4. Having completed soldering the circuit the extended legs on the components need to be trim

Guidelines For De-Soldering

1. De-soldering requires two main things: a soldering iron and a device to remove solder. Soldering

irons are the heat source used to melt solder. Irons of the 15 W to 30 W range are good for most

electronics/printed circuit board work. When de-soldering, the resin in the solder and the coating

on the board may releases fumes. These fumes are harmful to your eyes and lungs. Therefore,

always work in a well ventilated area.

2. Before de-soldering make sure to get any grease, varnish or glue off the joint before you start

heating. If you don't, you will probably foul the tip of your soldering iron pretty quickly.

3. Lay the iron tip so that it rests against both the component lead and the board. Normally, it takes

one or two seconds to heat the component up enough to solder, but larger components and larger

soldering pads on the board can increase the time.

4. You may wish to clean the solder pad and surrounding pad to remove any resin and left over

solder.

Soldering Wire:

It is a metallic wire with a 'low' melting point. Low melting point means low enough to be melted

with a soldering iron. For electronics, it is traditionally a mixture of Tin and Lead. Lead has a lower

melting point than tin, so more lead means a lower melting point. Most common Lead based solder

wire is an alloy of 60Sn/40Pb (60% Tin, 40% Lead). there are some other minor variations on

composition of soldering wire such as 63Sn/37Pb, but for general laboratory work, 60Sn/40Pb

composition serves the purpose.

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Experiment No. 3

Object: Assembling and testing of circuit elements in series and parallel.

Theory & Procedure: An electric circuit is a complete path from the positive terminal to the negative

terminal of a power source (battery). If the elements of the circuit are arranged in such a way that only

one path exists for current flow (i.e. the current is same through all elements), then the circuit is a

series one. If the same voltage exists across a number of alternative current paths then the circuit is a

parallel one. Most practical circuits involve various combinations of series and parallel components.

In this experiment, we will use resistors, connect them in series and parallel connections on a PCB

and determine the equivalent resistance. For series connection, connect the resistors in a line, one after

the another so that the current can pass through a single path. For parallel connection, connect the

resistors side by side, so that the current can pass through multiple paths. Calculate the equivalent

resistance in both cases.

Fig. 1 Resistors in series combination and equivalent resistance

s 1 2 3RR R R

Fig. 2 Resistors in parallel combination & equivalent resistance

p 1 2 3

1 1 1 1

R R R R

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Observations:

Series Connection

R1

(Ω)

R2

(Ω)

R3

(Ω)

Theoretical

Value of Series

Equivalent

Resistance (Ω)

Practical Value

Through

Multimeter

Reading (Ω)

Parallel Connection

R1

(Ω)

R2

(Ω)

R3

(Ω)

Theoretical

Value of Parallel

Equivalent

Resistance (Ω)

Practical Value

Through

Multimeter

Reading (Ω)

Report:

1. What are the applications of series and parallel connections?

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Experiment No. 4

Object: Assembling and testing of resistors in star and delta configuration.

Star Connection: When three resistance are so connected that either in starting point or the finishing

point of each resistance is shorted together, then it is called as star connection.

Delta Connection: When three resistance are so connected that the finishing point of one resistance is

connected to the starting point of the other resistance, then it is called delta connection.

Circuit Diagram:

Fig. (a) Delta Connection Fig. (b) Star Connection

Conversion Formula:

Convert a delta (Δ) to Wye (Y)

AB ACA

AB AC BC

AB BC

AB AC BC

AC BCC

AB AC BC

B

RR

R

RR

R

RR

R

R R

R

R R

R

RR R

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Convert a Wye (Y) to delta (Δ)

A B A BAB

C

A B A BBC

A B A BAC

B

C C

C C

A

C C

R RR

R RR

R

R R R R

R

R R R R

R

R R RR

R

R R

Observations:

Star Connection

RA

(Ω)

RB

(Ω)

RC

(Ω)

Resistance values for equivalent

delta network

RAB(Ω) RBC(Ω) RAC(Ω)

Delta Connection

RAB

(Ω)

RBC

(Ω)

RAC

(Ω)

Resistance values for equivalent

star network

RA(Ω) RB(Ω) RC(Ω)

Report:

1. What are the applications of star and delta connections?

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Experiment No. 5

Object: Assembling and Testing of a Half Wave Rectifier.

Apparatus / Components required:

S. No. Apparatus/components Specifications/Rating Quantity

Circuit Diagram:

Fig-1(a)

In Mode-I

D

RC

A

B

Fig. 1(b)

In mode-I operation of the circuit as shown in fig.-1(b) the positive half cycle of the input A.C voltage

is considered. During this half cycle the polarity of the voltage across the secondary is as shown in

fig.2 this polarity makes the diode forward biased because it tries to push the current in the direction

of the diode arrow.

This current makes terminal A positive with respect to terminal B. Since forward biased diode offers a

very low resistance, the voltage drop across it is very small. Therefore, the voltage appearing across

the load terminals AB is practically the same as that the voltage Vi at every instant.

230 V 50 Hz

supply AC

D

R C

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In Mode-II

During the negative half cycle of the input voltage, the polarity gets reversed. The voltage tries to

send current against the direction of the diode arrow. Hence the diode is now reversed biased. As a

result practically no current flows through the circuit. Therefore, almost no voltage is developed

across the load resistance. All the input voltage appears across the diode itself.

The waveforms corresponding to positive and negative half-cycle of input voltage are given as:

Hence as shown in waveforms, during positive half cycles all the input voltage appears across the load

as Vo, whole during the negative half cycle Vo = 0. Vdc represents the average d.c. voltage that would

be available at output terminals (across the load).

Observation:

Input Voltage, Vi = _______ volts

Output Voltage, Vo = ______ volts

Wave form:

Report

1. What do you mean by PIV rating of diode?

2. What is the use of capacitor in the circuit?

3. For an a. c. quantity define average, peak and r. m. s. values?

4. List different types of Diode?

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Experiment No. 6 Object: Assembling and testing of a Centre Tap full wave rectifier Circuit.

Apparatus / Components required:


Circuit Diagram:

Fig-2(a)

Theory:

In full wave rectification, current flows through the load in the same direction for both half

cycles of input a. c. voltage. This can be achieved with two diodes working alternatively. The circuit

employs two diodes Dl and D2 as shown in fig.2 (a). A centre tapped secondary winding AB is used

with two diodes connected so that during positive half cycle of input voltage, one diode supplies

current to the load and for the negative half, the other diode does so; current being always in the same

direction through the load.

I / P AC

D 1

C

R

A

B D 2

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Mode-I

I/PAC

D1

C

R

A

BD2

Fig-2(b)

During the positive half cycle of secondary voltage, the end A of the secondary winding becomes

positive and end B negative as shown in fig-2(b). This makes the diode Dl forward biased and diode

D2 reverse biased. Therefore, diode Dl conducts while diode D2 does not. The conventional current

flow is through diode D1 load and upper half of secondary winding of as shown in fig. 2(b).

Mode-II

I/PAC

D1

C

R

A

BD2

Fig. 2(c)

During the negative half cycle of the input voltage, end A the secondary winding becomes negative

end B becomes positive. Therefore diode D2 conducts while diode D1 does not. The conventional

current flow is through diode D2, load & lower half winding as shown in fig.2(c).

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The waveforms corresponding to positive and negative half-cycles of input voltage are given as:

Observation:

Input Voltage, Vi = _____________ volts

Output voltage, Vo=_____________ volts

Report:

1. What are the advantages and disadvantages of centre tapped full wave rectifier.

2. What do you mean by ripples?

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Experiment No. 7

Object: Assembling and Testing of full wave Bridge rectifier circuit.

Apparatus/Components required:


Circuit Diagram:

D3

D1D4

D2

AC

FULL-WAVE BRIDGE RECTIFIER

A

B

Fig. 3(a)

Theory:

The need for a centre tapped power transformer is eliminated in the bridge rectifier. It contains

four diodes D1, D2, D3 and D4 connected to form bridge as shown in fig. 3(a). The a. c. supply to

be rectified is applied to the diagonally opposite ends of the bridge through the transformer.

Between other two ends of the bridge, the load is connected.

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D3

D1

AC

MODE-I

A

B

Fig. 3(b)

During the positive half cycle of secondary voltage, the end A of the secondary winding becomes

positive and end B negative as shown in fig-3(b). This makes the diodes D1 and D3 forward biased

while diode D2 and D4 are reverse biased. Therefore, only diodes D1 and D3 conducts. These two

diodes will be in series through the load as shown in fig.3(b). the conventional current flow is through

diode D1, load and D3.

Mode-II

D4

D2

AC

Fig. 3(c)

During the negative half cycle of the input voltage, end A of the secondary winding becomes negative

and end B positive. This makes diodes D2 and D4 forward biased whereas diodes Dl and D3 are

reverse biased. Therefore, only diodes D2 and D4 conducts. These two diodes will be in series through

the load as shown in fig.3 (c). The conventional current flow is through diode D2, load and D4 as

shown in fig. 3(c). The waveforms corresponding to positive and negative half-cycles of input voltage

are given as

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Observation:

Input Voltage, Vi = _____________ volts

Output voltage, Vo =_____________ volts

Report:

1. What are the advantages and disadvantages of Bridge Rectifier?

2. What are the different types of filters?

diploma in engg. (electronics/computer) · 2019-01-21 · gripping, cutting and wire handling, and...

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