Student Edc Lab Manual

7/22/2019 Student Edc Lab Manual

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EDC Lab manual

Sasi Institute of Technology & Engineering Page 1

PART-A

1. Identification, Specification & Testing of R, L, C Components

Aim: - To identify and test different components.

Apparatus: -

Theory:-

Resistors:-

Opposition to flow of current is called resistance. The elements having resistance are

called resistors. They are of two types:

1. Fixed resistor

2. Variable resistor

Fixed resistor

Variable resistor

Resistor Color Code:-

The resistance value and tolerance of carbon resistor is usually indicated by color

coding. Color bands are printed on insulating body. They consist of four color bands or 5

color bands & they are read from left to right.

S.No Apparatus Type Requirement

1 Resistors Different types 1Each

2 Capacitors Different types 1Each

3 Inductors Different types 1Each

4 Switches Different types 1Each

5 Bread Board Different types 1Each


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A typical resistor with color bands is shown in figure

The above resistor has 4 color bands.

The first band represents first digit

The second band represent second digit

The third band represents multiplier (this gives the no. of zeros after the 2 digits)

The 4thband represents tolerance in %

The color codes:

Color

First digit for

the 1stband

Second

digit for

the 2nd

band

Multiplier digit

for the 3rdband

Resistance

tolerance

Black 0 0 10^0 -

Brown 1 1 10^1 1%

Red 2 2 10^2 2%

Orange 3 3 10^3 3%

Yellow 4 4 10^4 -

Green 5 5 10^5 -

Blue 6 6 10^6 -

Violet 7 7 10^7 -

Gray 8 8 10^8 -

White 9 9 10^9 -

Gold - - 10^-1 5%

Silver - - 10^-2 10%

No color - - - 20%


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If third band is gold the first two digit are multiplied by 10^-1

If the third band is silver the first two digits are multiplied by 10^-2

If the 4thband is gold the tolerance is 5%

If the 4

th

band is silver is the tolerance is 10%If the 4thband is no color the tolerance is20%

The numerical value associated with each color

B B R O Y G B V G W

black brown red orange Yellow green blue violet gray White

0 1 2 3 4 5 6 7 8 9

Examples:-

The resistor has a color band sequence green, blue, brown and silver identify the resistance

value.

1stBand 2n band 3r band 4t band

1stdigit 2n digit multiplier tolerance

5 6 10^1 10%

The resistance value=56x10^110%

=56010%

Therefore the resistance should be within the range of 555 to 565


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Capacitors:-

Capacitors are used to store energy in the form of electric field. Capacitor acts as open

circuit for DC and acts as short circuit for AC. They are three types

1. Disk capacitor

2. Fixed capacitor

3. Variable capacitor

Fixed capacitor

Variable capacitor

Capacitor value identification:-

Most capacitors indicated with XYZK/M volts V, where XYZ stands for the capacitance, K

and M indicates the tolerance 10% and 20% and working voltage.

Eg: A capacitors indicated with 105k330 is identified as 10105pF10% with a working

voltage of 330 V. Similarly 103M100V = 10103pF 10% =0.01F

Capacitor Specifications:-

1. Value of capacitance

2. Tolerance

3. Voltage rating

4. Temperature coefficient

5. Leakage resistance

6. Frequency range

7. Dielectric constant

8. Dielectric strength

9. Power factor

10.Stability


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Inductors:-

Fixed inductor

Variable inductor

Inductance:-

The inductance is defined as the ability of an inductor which opposes the change in

current. It is denoted by the letter L and its unit is Henry (H). An inductor can be tested

with continuity test.

Inductor Specifications:-

1. Inductance value

2. Resistance

3. Capacitance

4. Frequency value

5. Quality Factor

6. Power Losses

7. Current Rating

8. Electro Magnetic Radiations


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Switches:-

SPST: Single pole single through

SPDT: Single pole double through

DPST: Double pole single throughDPDT: Double pole double through

SPST

SPDT

DPST

DPDT

Bread Board:-

An experimental version of a circuit generally layout on a flat board and assembled with

temporary connections so that circuit elements may be easily substituted or changed. Thename originates from the fact that early electrical circuits were actually wired on wood

bread boards.

It is used to connect an electronic circuit temporarily for testing and experimentation.

A typical bread board is shown in fig.


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Procedure:-

Different components can be identified by using their different symbols.

Result:-

Components should be identified by using their symbols.Viva Questions:-

1. Define resistance?

2. What are different types of resistors and list their specifications and applications?

3. Define passive components?

4. Define capacitor?

5. What are the types of capacitors and list their specifications and applications?

6. Define Inductance? What is the necessity of inductor? List different types of inductors?

7. Define Switch and list various types of Switches?

8. What is Bread board and what is its use?

9. What are the types of boards are used in soldering?

10. What are the active components and mention active components?

11. What is a Diode and list different types of Diodes?

12. What are the specifications of 1N4007?

13. What is transistor and list various types of transistors?

14. How can we identify the Transistors? Write the circuit symbol for different transistors?


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2. Identification, specifications and testing of active devices

Aim: -To identify and test the active devices.

Apparatus:-

S.No Apparatus Type Requirement1 PN diode -- 1 Each

2 JFET -- 1 Each

3 MOSFET -- 1 Each

4 Power transistor -- 1 Each

5 LED -- 1 Each

6 LCD -- 1 Each

7 Opto electronic device -- 1 Each8 SCR -- 1 Each

9 UJT -- 1 Each

10 DIAC -- 1 Each

11 TRIAC -- 1 Each

12 Linear and Digital ICs -- 1 Each

Theory:Semiconductors:-

Semiconductors are partial conductors which conduct electricity partially through

them.

They play major role in electronics.

1 P-N Junction diode

2. Zener diode

Semiconductor is a material for which the width of the forbidden gap between the

valence band conduction band is very small. As gap is every small valence electron acquire

required energy to go in to the conduction band. These free electrons constitute of current

under the influence of applied electric field. The conductivity of a semiconductor lies

between that of a conductor and an insulator. The conductivity of a semiconductor lies in a

range of 10^5 and 10^-4 siemens/meter.


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Diodes:-

Diodes have more priority now a days. They are mostly used in electronic systems.

They are

1.

P-N Junction diode(rectifier)2. Zener diode (voltage regulator)

Circuit Symbols:-

P-N Junction diode

Zener diode

Diode testing:

On an (analog) VOM, use the low ohms scale. A regular signal diode or rectifier

should read a low resistance (typically 2/3 scale or a couple of hundred ohms) in the forward

direction and infinite (nearly) resistance in the reverse direction. It should not read near 0

ohms (shorted) or open in both directions. A germanium diode will result in a higher scale

reading (lower resistance) due to its lower voltage drop.

On a (digital) DMM, there will usually be a diode test mode. Using this, a silicon diodeshould read between .5 to .8 V in the forward direction and open in reverse. For a germanium

diode, it will be lower, perhaps .2 to .4 V or so in the forward direction. Using the normal

resistance ranges any of them will usually show open for any semiconductor junction since

the meter does not apply enough voltage to reach the value of the forward drop. Note,

however, that a defective diode may indeed indicate resistances lower than infinity especially

on the highest ohms range. So, any reading of this sort would be an indication of a bad device

but the opposite is not guaranteed.


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Transistors:-

They are of 4 types

1. BJT: Bipolar junction transistor again 2 types

NPNPNP

2. FET: Field effect transistors again 2 types

P-Channel FET

N-Cannel FET

3. JFET: Junction field effect transistors they similar to FET.

4. MOSFET: Metal oxide semiconductor field effect transistor

These are of two types

a. Depletion MOSFET:

These are again classified into two types

N-Channel MOSFET

P-Channel MOSFET

b. Enhancement MOSFET:

These are again classified into two types

N-Channel MOSFET

P-Channel MOSFET

Testing of a transistor:

Set the DMM to the diode test. Connect the red meter lead to the base of the

transistor. Connect the black meter lead to the emitter. A good NPN transistor will read a

Junction Drop voltage of between 0.45v and 0.9v. A good PNP transistor will read OPEN.

Leave the red meter lead on the base and move the black lead to the collector. The reading

should be the same as the previous test. Reverse the meter leads and repeat the test. This time,

connect the black meter lead to the base of the transistor. Connect the red meter lead to the

emitter. A good PNP transistor will read a Junction Drop voltage of between 0.45v and 0.9v.

A good NPN transistor will read OPEN. Leave the black meter lead on the base and move the

red lead to the collector. The reading should be the same as the previous test. Place one meter

lead on the collector, the other on the emitter. The meter should read OPEN. Reverse the


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meter leads. The meter should read OPEN. This is the same for both NPN and PNP

transistors.

Testing of SCR and TRIAC:

For SCRs, the gate to cathode should be tested like a diode on a multimeter. The

anode to cathode and gate to anode junctions should read open in both directions.

For TRIACS, the gate to main terminal 1 (MT1) should test like a diode junction

in both directions. MT1 to MT2 and gate to MT2 junctions should read open in

both directions.

For DIACS and there is no gate terminal - resistance should be infinite in both

directions.


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3. Soldering Practice- Simple Circuits Using Active and Passive Components

Aim: - To practice soldering of simple circuits using active and passive components.

Apparatus:-

S.No Apparatus Type Requirement1 Soldering Iron 100 w 1

2 Lead, Flux --- ---

3 Various Components --- ---

4 PCB --- 1

Theory:

Soldering is a process for joining thin metal parts or wires with the aid of molten metal,

where the melting temperature is situated below that of material joined and where by thesurface of part are coated without turn in becoming molten. A soldering connection ensures

metal continuity on the other hand; when two metals are joined behave like a single solid

metal by joining disconnected (or) physically attaching to each other, the connection could

be

Types of soldering:

1. Iron soldering

2. Mass soldering

3. Dip soldering

4. Wave soldering

Solder Alloys:-

Tin lead, tin antimony, Tin lead antimony, Tin silver, Tin Zinc Soldering is an alloying

process between two metals with which it divides some of the metal, with which it comes

into contact. A flux is used to remove this oxide from the area to be soldered.

Soldering Of Solder Alloy:-

Even though the alloy Sb 60/pb 60 is cheaper and still finds a good market, it is advisable to

prefer Sn63/pb 37 for high quality inter connection because

Flux: -To aid the soldering process, a substance called flux is used. Flux has below three

purposes.

(i)Remove the film of tarnish from the metal surface to be soldered.

(ii)To prevent the base metals from being re-exposed to oxygen in the air to be avoiding

oxidation during heating, which means rotation of welding by preventing from oxidation?

(iii)Assist in the transfer of heat to metal being soldered.


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The soldering process involves

1. Melting of the solder which makes the higher flux and brings the impurities suspended in

it to the surface.

2. Partial dissolution of some metals in the connection by solder.3. Cooling and fusing solder with the metal quest often for locating a problem in the

functioning of the circuit. It is necessary to remove a component from the printed circuit

board and carryout the requisite tests on it. The process of repair usually involves

disassembly of a particular component. Testing of component replacing of the component

found defective.

4. In this process of removal and replacement of electronic devices, the process of

soldering is employed. Specific gravity of Sn63/ pb 37 is also lesser than that of Sn60/p 40

that makes the equipment lighter.

Procedure:

The electronic components are carefully assembled as per the circuit design. The

assembling of electronic components on a PCB involves the following steps.

Components Lead Preparation:

Components such as capacitors have leads and are bent carefully to mount on PCB.

The lead bending radius should be approximately two times the diameter of the lead. The

bent leads should fit into the holes perpendicular to the board, so that the stress on the

component lead junction is minimized. Suitable bending tools may be used for perfect

bending. Leads are bent and assembled on board in such a way that the polarity symbols are

seen after mounting the component.

Component Mounting:

Components are mounted on one side of the board and leads are soldered on the other

side of the board. The components are oriented both horizontally in vertically but

uniformity in reading directions must be maintained. The uniformity in orientation of

diodes, capacitors, transistors, ICs etc, is determined at the time of PCB design.

Components dissipating more heat should be separated from the board surface.

Manual Assembly of Components:

The components to be assembled on a PCB are arranged conveniently. The board to

be assembled is held in a suitable frame and the components are kept in trays or bins. The


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insertion tools, if required must be kept in the easy reach of the worker. The work is divided

depending on number of parts to be assembled and the size of each part. The number of

different components for one worker should be more than 20.

Inspection and Testing:

The components assembled on the PCB are tested before they are soldered to the

board. It is a practice to have the assembled boards checked prior to soldering. An assembly

inspector is located at the end of the assembly line for inspection. The inspection includes

verifying component polarity, orientation, value and physical mounting.

Soldering and Lead Cutting:

The components are soldered on the PCB. The excess lead is cut after soldering. The

performance and reliability of the solder joints are best if lead cutting is carried before

soldering so that the lead end gets protected. However, this is not practiced in hand

soldering.

PCB Cleaning:

The soldering PCB may have contaminants that could cause trouble during the

functioning of the circuit. The contaminants include flux and chips of plastics, metals, and

other materials. Hence, the PCB must be cleaned before use. A wide range of cleaning

media is available; usually chemicals such as acetone and alcohols are used.

Result: Thus the soldering of active and passive components was practiced.


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4. Single layer and Multi layer PCBs

Aim: -To study the single layer and multi layer PCBs.

Apparatus: - PCB

Theory:-The design of PCB is considered as the last step in electronic design as well as the

major step in the production of PCB. It is a board consisting of printed circuit of electronic

equipment on it and is used for the designing of circuit. A PCB is an abbreviation of printed

circuit board. It is hardware used in electronics and many other industries to connect the

electronic components of a scheme and mechanically support them. Connection is ensured

using thin conductive copper traces printed on a board made of non-conductive material.

Printed circuit boards are divided into single layer and multilayer PCB. In modern day

electronics space is one of the most important factors. Basically, multilayer PCB saves

space because it can hold electronic components on both sides.

Single Layer PCB

A single-sided PCB contains copper tracks on one side of the board only, as shown in

figure. Holes are drilled at appropriate points on the track so that each component can be

inserted from the non-copper side of the board, as shown in figure .Each pin is then soldered

to the copper track.

Multilayer PCB

It is a very important hardware element and it is almost certain you will find one

in a wide array of devices starting from a mobile phone and TV, ending with military

machines and space ships.


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Inmulti-layer PCB's, each side contains several Layers of track patterns which are insulated from one

another. These layers are laminated under heat and high pressure. A multi-layer PCB is shown in

figure

The steps for designing PCB are

1. Layout planning

2. Art work

3. Film master production

4. Pattern transfer (photo/screen printing)

5. Plasting

6. Etching

7. Mechanical matching operations

The layout is the work done before the art work in the PCB. It provides all the

information about the circuit, which has to drawn on PCB. Protection of copper tracks is

very much essential Plasting is such processes which forms a thin layer over copper tracks

and protect them. Generally, it is done with gold.

Types of copper plating:

Copper plating

Nickel plating

Gold plating

Tin plating

Tin lead plating

Etching means to draw on board by the action of acid, especially by coating the surface

with wax and letting the acid cast into the lines or area laid bar with needle. Spray etching

Laminate etching Splash etching (Configured force by rotating in centre). The double sided


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PCBs are made with or without plated through holes. Fabrication of plated through holes

type boards is very expensive.

Two types: (i) Plated through holes

(ii) No plated through holes.In plated through holes, the total no. of holes is kept minimum for economy and

reliability. In no plated through holes, contacts are made by soldering the component lead

on both sides of board when required and jumper wires are added. There should be

minimum solder joints on the component sides. Replacing of such components is different.

Result: -Single Layer and Multilayer PCBs are studied


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5. Study and Operation of Multimeters, Function Generator, Regulated Power

Supplies

Aim: - To study and operation of multimeters, function generator, and regulated powersupply.

Apparatus: -


1 Multimeter Analog and Digital 1Each

2 Function generator 1MHz 1Each

3 Regulated power supply 0-30V 1Each

Theory:-

Regulated Power Supply:-

Power supplies provided by a regulated DC voltage facilities fine and coarse

adjustments and monitoring facilities for voltage and current. They will work in constant

voltage and current mode depending on current limit and output load.

The current limit has good stability, load and line regulations. Outputs are protected

against overload and short circuit damages. They are available in single and dual channel

models with different voltage and current capacities. Overload protection circuit of constant

self restoring type is provided to prevent the unit as well as the circuit under use. The power

supplies are specially designed and developed for well regulated DC output. These are

useful for high regulation laboratory power supplies, particularly suitable for experimental

setup and circuit development in R&D.


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Function Generator:-

A different types of electrical waveforms over a wide range of frequencies. Some of

the most common Function Generator is usually a piece of electronic test equipment or

software used to generate waveforms produced by the function generator are the sine,square, triangular and saw tooth shapes. These waveforms can be either repetitive or single-

shot (which requires an internal or external trigger source).

Other important features of the function generator are continuous tuning over wide

bands with max-min frequency ratios of 10:1 or more, a wide range of frequencies from a

few Hz to a few MHz, a flat output amplitude and modulation capabilities like frequency

sweeping, frequency modulation and amplitude modulation.

S.No Designation Specifications

1 Wave form Sine, squares, triangles, TTL square waves

2 Amplitude 0-20V for all the functions

3 Sine distortion Less than 1% from 0.1 HZ to 100 HZ harmonics

Modulation showed down fundamental for 100KHz to 1MHz4 Offset Continuously variable 10V

5 Frequency range 0.1 HZ to 1hz in ranges

6 Output impedance 600 ohms, 5%.

7 Square wave duty

cycle

49% to 51%.

8 Differential

linearity

0.5%
http://en.wikipedia.org/wiki/Waveformhttp://en.wikipedia.org/wiki/Electronic_test_equipmenthttp://en.wikipedia.org/wiki/Softwarehttp://en.wikipedia.org/wiki/Softwarehttp://en.wikipedia.org/wiki/Electronic_test_equipmenthttp://en.wikipedia.org/wiki/Waveform


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Range selectors:-Decode frequency by multiplying the range selected with the frequency

indicated by dial gives the output frequency, which applies for all functions.

Function selectors:-Selected desired output wave form which appears at 600 output.

VCO input:- An external input will vary the output frequency. The change in frequency is

directly proportional to input voltage.

TTL output:- A TTL square wave is available at this jack. The frequency is determined by

the range selected and the setting of frequency dial. This output is independent of amplitude

andD.C offset controls.

Amplitude Control:-Control the amplitude of the output signal, which appears at 600ohms.

Offset Control:-Control the DC offset of the output. It is continuously variable for 5V,

100V.

Fine frequency dial:- Multiplying the setting of this dial to the frequency range selected

gives the output frequency of the wave forms at the 600ohms.

Multimeter:-

Digital Multimeter:-

A Multimeter is a versatile instrument and is also called Volt-Ohm-Milliammeter

(VOM). It is used to measure the d.c and a.c voltages and resistance values.

A digital multimeters essentially consists of an analog to digital converters. It

converters analog values in the input to an equivalent binary forms. These values are

processed by digital circuits to be shown on the visual display with decimal values. The

liquid crystal display system is generally employed. Actually all the functions in DMM

depend on the voltage measurements by the converter and comparator circuits


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Result:-The operation of multimeters, function generator, and Regulated Power Supply are

studied


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6. Study and Operation of CRO

Aim: - To observe front panel control knobs and to find amplitude, time period and

frequency for given waveformsand also find phase by using the Lissajous figures.

Apparatus: - Cathode Ray Oscilloscope, function generator, connecting wires.

Theory: - C.R.O is a versatile instrument used for display of wave forms and is a fast x-y

plotter. The heart of C.R.O is and the rest is the circuitry to operate C.R.O

The main parts are

1. Electron gun: - It is used to produce sharply focused beam of electron accelerated to

very high velocity.

2. Deflection system: - It deflects the electron both in horizontal and vertical plan.

3. Florescent screen: - The screen which produces, spot of visible light. When beam of

electrons are incident on it the other side of tube is coated with phosphorus material.

Front Panel:-

On-Power: Toggle switch for switching on power.

Intensity: Controls trace intensity from zero to maximum.

Focus: It controls sharpness of trace a slight adjustment of focus is done after changing

intensity of trace.

AC-DC Ground:-It selects coupling of AC-DC ground signal to vertical amplifier.

X-Mag: It expands length of time base from 1-5 times continuously and to maximum time

base to 40 ns/cm.

Square:-This provides square wave 2v (p-p) amplitude and enables to check y calibration

of scope.


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Sawtooth Waveform:- This provides saw tooth wave form output coincident to sweep

speed with an output of saw tooth wave (p-p)

Vertical Section (y position):-This enables movement of display along y-axis.

Y-Input:- It connects input signal to vertical amplifier through AC-DC ground coupling

switch

Calibration:- 15mv-150mv dc signal depending on position selection is applied to vertical

amplifier.

DC Balance:- It is control on panel electrostatic ally in accordance with waveforms to be

displayed.

Volts/Cm:- Switch adjusts sensitivity.

Horizontal Section:-

X-Position:This control enables movement of display along x-axis.

Triggering Level:-It selects mode of triggering.

Time Base:- This controls or selects sweep speeds.

Vernier: - This control the fine adjustments associated with time base sweep.

Sign Selector:- It selects different options of INT/EXT, NORM/TO.

Stab:- Present on panel

Exit CAD:- It allows time base range to be extended.

Horizontal Input:- It connects external signal to horizontal amplifier.

Ext SYN:it connects external signal to trigger circuit for synchronization.

Observations:-

Amplitude = no. of vertical divisions Volts/div.


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Time period = no. of horizontal divisions Time/div.

Frequency=1/T

Amplitude taken on vertical section (y).

Time period taken on horizontal section(x)

Model Wave Forms:-

Measurement of Phase:-

= sin -1 (Y1/Y2) = sin -1 (X1/X2) = 180- sin -1(Y1/Y2)

Applications of CRO:-

1. Measurement of current

2.Measurement of voltage

3. Measurement of power

Y1 Y2

x1

X2

Y2 Y1


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4. Measurement of frequency

5. Measurement of phase angle

6. To see transistor curves

7.To trace and measuring signals of RF, IF and AF in radio and TV.

8. To trace visual display of sine waves.

Result: -To calculated the given waveform, frequency, amplitude and phase.


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PART-B

1. Frequency Measurement using Lissajous Figures

Aim:-a) To measure phase difference between two waveforms using CRO.

b) To measure an unknown frequency from Lissajous figures using CRO.

Apparatus:-


1 CRO 20MHz 1

2 Function generators 1MHz 2

3 Bread Board --- 1

4 Resistance 1K 1

5 Capacitance 0.1F 1

6 Connecting wires --- ---

Theory:

(a) Measurement of Phase:

Since sine waves are based on circular motion they illustrate phase

difference very well. One complete cycle of a sine wave relates to one complete

circle and therefore to 360.This means that the phase angle of a sine wave can

be repr esented us ing degrees . Figure shows how a complete sine wave cycle relates

directly to 360.


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A Complete Sine wave

Phase shift describes the timing difference between two otherwise similar

s ignals . The example in f igure below shows two s imi lar s ine waves o ft h e s ame f req u en cy . T denotes the period of one complete cycle (10 cm on

screen), andt signifies the time between the zero transition point of both signals (3 cm

on screen).

Phase Shift Example

The phase difference in degrees is calculated from:

( b ) Measurement of Frequency using CRO:

A simple method of determining the frequency of a signal is to estimate its

periodic time from the trace on the screen of a CRT. However th is method has

limited accuracy, and should only be used where other methods are not available. To

calculate the frequency of the observed sign al, one has to measure the period, i.e.

the time taken for 1 complete cycle, using the calibrated sweep scale. The period could

be calculated by

T = (no. of squares in cm) x ( selected Time/cm scale )

Once the period T is known, the frequency is given by

f (Hz)= 1/T(sec)


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Using Lissajous Patterns:

If a well calibrated CRO time base is not available, a signal generator can be

used to measure the frequency of an unknown sinusoidal signal. It is connected to the vertical

channel (or horizontal) and the calibrated signal source is fed to the horizontal channel (orvertical).The frequency of the signal generator is adjusted so that a steady Lissajous pattern

is obtained. The frequency relationship between the horizontal and vertical inputs is given

by

Fv/Fh= No. of tangencies (vertical)/ No. of tangencies (horizontal)

Precautions:

1 . Co n n ec t io n s sh o u ld b e t ig h t .

2. There should be no short circuiting in the circuit.

Procedure:

1. Switch on the CRO. Rotate the intensity control clockwise. After some time you will see

either a bright spot or a line on screen. If you see none, adjust X-POS and Y-POS controls to

get the display in the centre of the screen.

2. Operate the INTEN and FOCUS controls and observe the effect on the spot (or line).

Adjust them suitably.

3 . To measure the voltage of the signal generator, adjust the vertical amplifier sensitivity

suitably, so as to get a sufficiently large display. Read on the calibrated graticule, the

vertical length of the display. This corresponds to the peak-to-peak value of the

signal. Multiply this length by the sensitivity (in V/cm). Dividing this result by 22 gives

the rms value of the s ignal voltage. Repeat the measurement procedure for two or

three other values of the output signal voltages.

4. For measuring the frequency of the signal feed the unknown signal (taken from the signal

generator) to the Y-Input terminals. Take a standard signal generator, and connect its output

to the X-Input terminals of the CRO. Put the Time-Base or Horizontal amplifier knob at EXT

position. Change the frequency of the standard signal generator till you get a stable Lissajous

pattern. For the various frequency ratios, fv/fh, the Lissajous patterns are shown in Fig. The

unknown frequency can thus be determined using the relationship:


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fv = No. of tangencies (vertical)

fh= No. of tangencies (horizontal)

Where f vis the unknown frequency

5. To me as ur e ph as e s hi ft in tr od uc ed by an RC phase-shift network, make

connections as shown in Fig. Put the Time-Base control at EXT position. Adjust the vertical

and horizontal amplifier gains (sensitivities) so as to get an ellipse of suitable size, as shownin Fig. Measure the lengths YIand Y 2(or X1and X 2).

Y1 = cm

Y2 = cm

Calculate the phase difference between the two waves using the relation.

Sin = Y1/Y2= X1/X2

Observations:

S.No

Known

frequency

No. of

vertical

tangencies

No. of

Horizontal

Tangencies

Pattern obtained

Unknown

frequency=

fh/ fv

1

2

3


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Results:

1. Measured frequency is __________.

2. Measured phase angle is _________.


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2. P-N Junction diode characteristics

Aim:- (1)To plot the V-I characteristics of a P-N Junction diode

(2) To find the cut-in voltage, static, dynamic and reverse bias resistance.

Apparatus:-S.No Apparatus Type Requirement

1 P-N Diode 1N4007 1

2 Regulated Power supply 0-30V 1

3 Resistor 1K 1

4 Ammeters 0-100mA/A 1 Each

5 Voltmeter 0-20 V 1

6 Bread board --- 1


Theory:-

A p-n junction diode conducts only in one direction. The V-I characteristics of the

diode is a curve between voltage across the diode and current through the diode. When

external voltage is zero, circuit is open and the potential barrier does not allow the current to

flow. Therefore, the circuit current is zero. When P-type (Anode is connected to +ve terminal

and n- type (cathode) is connected to ve terminal of the supply voltage, it is known as

forward bias. The potential barrier is reduced and the diode is in the forward biased

condition. At some forward voltage, the potential barrier altogether eliminated and current

starts flowing through the diode and also in the circuit. The diode is said to be in ON state.

The current increases with increasing forward voltage.

When N-type (cathode) is connected to +ve terminal and P-type (Anode) is

connected ve terminal of the supply voltage is known as reverse bias and the potential

barrier across the junction increases. Therefore, the junction resistance becomes very high

and a very small current (reverse saturation current) flows in the circuit. The diode is said to

be in OFF state. The reverse bias current is due to minority charge carriers.


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Circuit Diagram:-

Forward Bias:

Reverse Bias:-

Model Graph:-


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Precautions:-

1. There should not be any loose connections.

2. Readings should be taken without parallax errors.

Procedure:-Forward Bias:-

1. Connections are made as per the circuit diagram.

2. Keep the current control knob at maximum and voltage control knob at minimum position

before turning ON the power supply.

3.For forward bias, the RPS +ve is connected to the anode of the diode andve is connected

to the cathode of the diode,

4. Increase the forward voltage in Steps of 0.1V up to 1V and note down the corresponding

forward current.

5. Repeat the step 4 for different values of VFand record the corresponding IF.

6. Plot the graph VFvs IF.

7. Identify cut-in voltage and calculate static resistance from the graph.

Observations:-

S.No Forward

Voltage (Volts)

Forward

Current (mA)

1

2

3

4

5

6

7

8

9

10


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Reverse Bias:-


2. Keep the current control knob at maximum and voltage control knob at minimum position

before turning ON the power supply3. For reverse bias, the RPS +ve is connected to the cathode of the diode and ve is connected

to the anode of the diode.

4. Switch ON the power supply and increase the reverse voltage in steps of 1V upto5V and

note down the corresponding reverse current.

5. Plot the graph VRvs IR.

6. Calculate reverse resistance

Observations:-

S.No Reverse voltage

(Volts)

Reverse

current (A)

1

2

3

4

56

7

8

9

10

Calculations:-

Cut in voltage =

Static resistance = V/I =

Dynamic resistance =V/I =

Result: -


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3. Zener diode characteristics and Zener as a regulator

Aim: - a) To plot the V-I characteristics of a Zener diode in the forward and reverse bias

b) To verify the Zener as a regulator.

Apparatus: -S.No Apparatus Type Requirement

1 Zener diode BZX5V1 1

2 Regulated Power supply 0-30V 1

3 Resistor 1K 1

4 Ammeters 0-100mA/A 1 Each

5 Voltmeter 0-20 V 1

6 Bread board --- 1


Theory:-

A Zener diode is heavily doped p-n junction diode, specially made to operate in the

break down region. A p-n junction diode normally does not conduct when reverse biased.

But if the reverse bias is increased, at a particular voltage it starts conducting heavily. This

voltage is called Break down Voltage. High current through the diode can permanently

damage the device

To avoid high current, we connect a resistor in series with Zener diode. Once the diode

starts conducting it maintains almost constant voltage across the terminals whatever may be

the current through it, i.e., it has very low dynamic resistance. It is used in voltage

regulators.

Precautions:-

1. The terminals of the Zener diode should be properly identified

2. Parallax error should be avoided while taking the readings.


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Circuit Diagram:-

Forward Bias:-

Reverse Bias:-

Procedure:-

Forward bias:-


2. Keep the current control knob at maximum and voltage control knob at minimum

position before turning ON the regulated power supply.

3. Increase the forward voltage in steps of 0.1V and note down the corresponding forward

current values.

4. Repeat the step 3 for different values of forward voltage and tabulate the Izvalues.

5. Plot the graph VFvs Iz

6. Identify the cut-in voltage and calculate the static resistance and dynamic resistance

from the graph.


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Observations:-

Reverse bias:-


2. Keep the current control knob at maximum and voltage control knob at minimum

position before turning ON the regulated power supply.

3. Increase the reverse voltage in steps of 0.5V until breakdown occurs and note down the

corresponding Zener current values.

4. Repeat the step 3 for different values of reverse voltage and tabulate the readings.

5. Plot the graph between Zener current (IR) and Zener voltage (VR).

6. Identify the reverse saturation current and breakdown voltage Vzof the Zener diode.

S.No Forward

voltage (volts)

Forward

current (mA)

1

2

3

4

5

67

8

9

10


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Observations:-

Reverse Bias:-

Model Graph:-

S.No Reverse

voltage(volts)

Reverse

current(mA)

1

2

3

4

5

6

7

8

9

10


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Calculations (forward and reverse bias):-

Static resistance (forward bias) = V/I=

Dynamic resistance (forward bias) = V/I= (V2-V1)/ (I2-I1)

=Static resistance (reverse bias) =

Dynamic resistance (reverse bias) =

Result:-


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4. Transistor CB characteristics (Input and Output) & h-Parameter Calculations

Aim: - 1.To plot the input and output characteristics of a transistor connected in common

base configuration.

2. To calculate the h parameters of the given transistor.

Apparatus:-


1 Transistor BC 107 1

2 Regulated power supply 0-30V,1A 1

3 Voltmeter 0-20V 1

4 Ammeters 0-100mA 1

5 Resistor 1K 2

6 Bread board --- 1


Theory:-

A transistor is a three terminal active device. The terminals are emitter, base,

collector. In CB configuration, the base is common to both input and output. For normal

operation, the E-B junction is forward biased and C-B junction is reverse biased. In CB

configuration, IEis +ve, IC isve and IBisve. So,

VEB=f1(VCB, IE) and

IC=f2(VCB,IB)

With an increasing the reverse collector voltage, the space-charge width at the

output junction increases and the effective base width W decreases. This phenomenon is

known as Early effect. Then, there will be less chance for recombination within the base

region. With increase of charge gradient with in the base region, the current of minority

carriers injected across the emitter junction increases. The current amplification factor of

CB configuration is given by,

= IC/ IE

Output resistance is the ratio of change of collector emitter voltage V CE, to change in

collector current ICwith constant IB.


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Input Impedance hie= VEB / IE at VCB constant

Output impedance hoe= VCB / IC at IE constant

Reverse Transfer Voltage Gain hre = VEB / VCB at IE constant

Forward Transfer Current Gain hfe= IC / IE at constant VCB

Precautions:-

1. The supply voltages should not exceed the rating of the transistor.

2. Meters should be connected properly according to their polarities.

Circuit Diagram:-

Procedure:-

Input Characteristics:-


2. Set VCBto 0V, vary the input voltage VEBand note down the emitter current IE.

3. Repeat the above step keeping VCBat 1V, 2V, and 3V.

4. A graph is drawn between VEBand IE for constant VCB.

Output Characteristics:-


2. Set IEto 1mA by varying VEBand keep it constant.

3.

Vary the collector to base voltage VCBfrom -0.5V to 0 in steps of 0.1V and later in stepsof 1V up to 10V and note down the collector current IC.


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4. Repeat the steps 2 and 3 for constant values of IEat 2 mA, 3 mA, and 4mA.

5. A graph is drawn between VCB and Ic for constant IE.

Observations:-


S.NO VCB= VCB= VCB=

VEB(V) IE(mA) VEB(V) IE(mA) VEB(V) IE(mA)

1

2

3

4

56

7

8

9

10


S.No

IE= IE= IE=

VCB(V) IC(mA) VCB(V) IC(mA) VCB(V) IC(mA)

1

2

3

4

5

6

7

8

9

10

11


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Model Graph:-



Calculations:-

1. Input Impedance hie =VEB/IE=2. Reverse Voltage Gain hre =VCB/VEB=3.

Forward Current Gain hfe =IC/=IE=

4. Output conductance hoe ==IC/=VCB=Result:-


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5. Transistor CE characteristics(Input and Output) &h-Parameter CalculationsAim: -1.To plot the input and output characteristics of transistor connected in CE

configuration

2. To calculate the h parameters of the given transistor.

Apparatus:-


1 Transistor BC 107 1

2 Resistor 10K,1K 1Each

3 Ammeter 0-200mA/A 2

4 Voltmeter 0-15V 2

5 Regulated power supply 0-30V 26 Bread Board --- 1


Theory:-

A transistor is a three terminal device. The terminals are emitter, base, collector.

In common emitter configuration, input voltage is applied between base and emitter

terminals and output is taken across the collector and emitter terminals. Therefore theemitter terminal is common to both input and output.

The input characteristics resemble that of a forward biased diode curve. This is

expected since the Base-Emitter junction of the transistor is forward biased. As compared to

CB arrangement IB increases less rapidly with VBE. Therefore input resistance of CE circuit

is higher than that of CB circuit.

The output characteristics are drawn between Ic and VCE at constant IB. The

collector current varies with VCE up to few volts only. After this the collector current

becomes almost constant, and independent of VCE. The value of VCE up to which the

collector current changes with VCE is known as Knee voltage. The transistor always

operated in the region above Knee voltage, IC is always constant and is approximately equal

to IE.

The current amplification factor of CE configuration is given by

= IC/IB.


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The transistor always operates in the active region. i.e. the collector current IC increases

with VCE very slowly. For low values of the VCE the IC increases rapidly with a small

increase in VCE. The transistor is said to be working in saturation region.

Output resistance is the ratio of change of collector to emitter voltage VCE , to

change in collector current ICwith constant IB.

Input Impedance hie = VBE / IB at VCE constant

Output impedance hoe= VCE / IC at IB constant

Voltage Gain hre= VCE / VBE at IB constant

Current Gain hfe= IC / IB at constant VCE

Precautions:-

1. The supply voltage should not exceed the rating of the transistor

2. Meters should be connected properly according to their polarities

Circuit Diagram:-


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Procedure:-



1.

The output voltage VCEis kept constant at 0V and vary the input voltage VBE and notedown the values of base current IB.

2. Repeat the above step by keeping VCE at 1V and 2V and tabulate IBvalues.

3. Plot the graph between VBE and IB for constant VCE


1 Connections are made as per the circuit diagram.

2. Set IBto 20 A by varying VBEand kept it constant.

3. Vary the VCEand record the values of IC.

4. Repeat the above step for constant values of IBat 40 A ,60 A and tabulate

the values of IC.

5. Plot the graph between VCEand ICfor constant IB

Observations:-


S.No

VCE= VCE= VCE=

VBE(V) IB(A) VBE(V) IB(A) VBE(V) IB(A)

1

2

3

4

5

6

7

8


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S.NO

IB= IB= IB=

VCE(V) IC(mA) VCE(V) IC(mA) VCE(V) IC(mA)

1

2

3

4

5

6

7

8

9

10

11

12

Model Graphs:-



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Calculations:-

1. Input Impedance hie =

2. Voltage Gain hre =

3. Current Gain hfe = IC / IB at constant VCE

4. Output Impedance hoe =VCE/IC=

Result:-


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6. Half wave Rectifier with & without filter

Aim: - (a) To observe the input and output waveforms of a half-rectifier.

(b) To find ripple factor and regulation without and with Filter.

Apparatus:-


1 Diode 1N 4007 1

2 Resistors 100, 330, 820 1K . 1Each

3 Electrolytic capacitor 470 F 1

4 Transformer 12-0-12 1

5 C.R.O 20MHz DTO 1

6 Ammeter 0-200 mA 1

7 Bread Board --- 1


Theory: -

During positive half-cycle of the input voltage, the diode D1 is in forward bias and

conducts through the load resistor RL. Hence the current produces an output voltage across

the load resistor RL, which has the same shape as the +ve half cycle of the input voltage.

During the negative half-cycle of the input voltage, the diode is reverse biased and

there is no current through the circuit i.e., the voltage across RLis zero. The net result is that

only the +ve half cycle of the input voltage appears across the load. The average value of

the half wave rectified o/p voltage is the value measured on dc voltmeter.

Precautions:-

1. The primary and secondary sides of the transformer should be carefully identified.

2. The polarities of the diode and electrolytic capacitor should be carefully identified.

3. While determining the % regulation, first full load should be applied and then it should be

decremented in steps


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Procedure:-


2. Connect the primary side of the transformer to ac mains and the secondary side to the

rectifier input.3. By the multimeter, measure the ac input voltage of the rectifier and, ac and dc voltage at

the output of the rectifier.

4. Find the theoretical of dc voltage by using the formula,

Vdc=Vm/

Where, Vm=2Vrms, (Vrms=output ac voltage.)

The Ripple factor is calculated by using the formula

r=ac output voltage/dc output voltage.

Regulation Characteristics:-


2. By increasing the value of the rheostat, the voltage across the load and current flowing

through the load are measured.

3. The reading is tabulated.

4. Draw a graph between load voltage (VL) and load current ( IL ) taking VLon X-axis and IL

on y-axis

5. From the value of no-load voltages, the %regulation is calculated using the formula,

Circuit Diagram without Filter:-


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With Filter:-

Model waveforms: -

Observations & calculations:-:-

Without filter:-

VNL=

S.No RL

Vm

V

IL

mA

Vrms= Vm/2 Vdc=Vm/ Ripplefactor

=[(Vrms/Vdc)2-1]

%Regulation

=(VNL-VFL)/VFL100

1

2

With filter:-

S.No RL

Vm

V

IL

mA

Vrms=

Vm/23

Vdc=Vm Ripplefactor

=Vrms/Vdc

%Regulation

=(VNL-VFL)/VFL100

1

2

Result:-


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7. Full wave Rectifier without & with filter

Aim:-To find the Ripple factor and regulation of a Full-wave Rectifier with and without

filter.

Apparatus:-


1 Experimental Board

2 Transformer 6-0-6v 1No

3 PN Diodes lN4007 2 Nos

4 Multimeters --- 2Nos

5 Filter Capacitor 100F/25v 1No

6 Load resistor 1K 1No

Theory:-

The circuit of a center-tapped full wave rectifier uses two diodes D1&D2. During

positive half cycle of secondary voltage (input voltage), the diode D1 is forward biased and

D2is reverse biased. The diode D1 conducts and current flows through load resistor RL.

During negative half cycle, diode D2 becomes forward biased and D1 reverse biased. Now,

D2 conducts and current flows through the load resistor RLin the same direction. There is a

continuous current flow through the load resistor RL, during both the half cycles and will get

unidirectional current as show in the model graph. The difference between full wave and

half wave rectification is that a full wave rectifier allows unidirectional (one way) current to

the load during the entire 360 degrees of the input signal and half-wave rectifier allows this

only during one half cycle (180 degree).

Precautions:

1. The primary and secondary side of the transformer should be carefully identified

2. The polarities of all the diodes should be carefully identified.

Procedure:-


2. Connect the ac mains to the primary side of the transformer and the secondary side to the

rectifier.

3. Measure the ac voltage at the input side of the rectifier.


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4. Measure both ac and dc voltages at the output side the rectifier.

5. Find the theoretical value of the dc voltage by using the formula Vdc=2Vm/.

6. Connect the filter capacitor across the load resistor and measure the values of Vac and

Vdc at the output.7. The theoretical values of Ripple factors with and without capacitor are calculated.

From the values of Vac and Vdc practical values of Ripple factors are calculated. The

practical values are compared with theoretical values.

Circuit diagram:-

Without Filter:

With Filter: -


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Model waveforms: -

Without filter:-

With filter: -

Observations & calculations: -

With Out Filter: -

VNL =

S.No RL

Vm

V

IL

mA

Vrms=

Vm/2

Vdc=2Vm/ Ripplefactor

=[(Vrms/Vdc)2

-1]

%Regulation

=(VNL-VFL)/VFL100

1

2

With Filter: -

VNL =

S.No RL

Vm

V

IL

mA

Vrms=

Vm/2

Vdc=Vm Ripplefactor

=Vrms/Vdc

%Regulation

=(VNL-VFL)/VFL

100

1

2

Result:-


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8. FET characteristics

Aim: -a). To draw the drain and transfer characteristics of a given FET.

b). To find the drain resistance (rd) amplification factor () and transconductance(gm) of the given FET.

Apparatus:


1 FET BFW-11 1

2 Regulated power supply 0-30V 1

3 Voltmeter 0-20V 1

4 Ammeter 0-100 mA 15 Resistors 100,560 1Each

6 Bread board --- 1

7 Connecting wires --- 1

Theory:

A FET is a three terminal device, having the characteristics of high input impedance

and less noise, the Gate to Source junction of the FET s always reverse biased. In responseto small applied voltage from drain to source, the n-type bar acts as sample resistor, and the

drain current increases linearly with VDS. With increase in ID the ohmic voltage drop

between the source and the channel region reverse biases the junction and the conducting

position of the channel begins to remain constant. The VDSat this instant is called pinch of

voltage.

If the gate to source voltage (VGS) is applied in the direction to provide additional

reverse bias, the pinch off voltage ill is decreased. In amplifier application, the FET is

always used in the region beyond the pinch-off.

IDS=IDSS(1-VGS/VP)^2


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Precautions:-

1. The three terminals of the FET must be carefully identified.

2. Practically FET contains four terminals, which are called source, drain, Gate,

substrate.3. Source and case should be short circuited.

4. Voltages exceeding the ratings of the FET should not be applied.

Circuit Diagram:

Procedure:

1. All the connections are made as per the circuit diagram.

2. Switch ON the power supply VGG, and set VGS= 0V.

3. Vary the VDDand change VDS in steps of 0.2V up to 1V and later in steps of 1V up to 7V

and note down the values of ID.

4. Repeat the above step3 for different values of VGS at -1V and -2V.

5. Plot the drain characteristics VDSvs IDfor constant VGS

6. To plot the transfer characteristics, keep VDSconstant at 1V.

7. Vary VGGand change the values of VGSin steps of 0.5V and note down the values of ID.

8. Repeat steps 6 and 7 for different values of VDSat 2 V and 3V.

9. plot the transfer characteristics, VGSVs IDkeep VDSconstant

10.From drain characteristics, calculate the values of dynamic resistance (rd) by using the

formula

rd = VDS/ID

11.From transfer characteristics, calculate the value of transconductance (gm) by using the

formula


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gm = ID/VGS

12.Amplification factor = gmrd

= VDS/VGS

Observations:-

Drain Characteristics:-

S.NO VGS= VGS= VGS =

VDS(V) ID(mA) VDS(V) ID(mA) VDS(V) ID(mA)

1

2

3

4

5

6

7

8

9

10

11

12


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Transfer Characteristics:-

S.NO

VDS= VDS= VDS=

VGS(V) ID(mA) VGS(V) ID(mA) VGS(V) ID(mA)

1

2

3

4

5

6

7

8

9

10

11

Model Graph:-

Drain characteristics:-


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Transfer Characteristics:-

Result:-


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9. SCR Characteristics

Aim:-To draw the V-I Characteristics of SCR

Apparatus:


1 SCR 2P4M 1

2 Regulated Power Supply 0-30V 2

3 Resistors 3.3k, 1k 1Each

4 Ammeter (0-50)A 1

5 Voltmeter (0-10V) 1

6 Breadboard --- 1

7 Connecting Wires --- ---

Theory:

It is a four layer semiconductor device with alternate P-type and N-type silicon. It

consists of 3 junctions J1, J2, J3.The J1 and J3 operate in forward direction and J2operates in

reverse direction and three terminals called anode A , cathode K, and a gate G. The operation

of SCR can be studied when the gate is open and when the gate is positive with respect to

cathode.

When gate is open, no voltage is applied at the gate due to reverse bias of the junction

J2no current flows through R2and hence SCR is at cut off. When anode voltage is increased

J2tends to breakdown.

When the gate positive, with respect to cathode J3junction is forward biased and J2isreverse biased. Electrons from N-type material move across junction J3towards gate while

holes from P-type material moves across junction J3towards cathode. So gate current starts

flowing, anode current increase is extremely small. Junction J2 break down and SCR

conducts heavily.

When gate is open thee break over voltage is determined on the forward voltage at

which SCR conducts heavily. Now most of the supply voltage appears across the load


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resistance. The holding current is the maximum anode current gate being open,when break

over occurs.

Circuit Diagram:

Procedure:

1. Connections are made as per circuit diagram.

2. Keep the gate supply voltage at some constant value

3. Vary the anode to cathode supply voltage and note down the readings of voltmeter and

ammeter. Keep the gate voltage at standard value.

4. A graph is drawn between VAK and IAK.

Observations:

IG= IG=

S.No VAK(Volts) IAK( A) VAK(Volts) IAK( A)

1

2

3

4

5

6

7


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Model Waveform:-

Result:


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10. UJT Characteristics

Aim:To draw the characteristics of UJT and to calculate the Intrinsic Stand-Off Ratio ().

Apparatus:


1 UJT 2N2646 1

2 Regulated Power Supply 0-30V, 1A 2

3 Multimeters MC 2

4 Resistors 10k, 47, 330 1 Each

5 Breadboard --- ---


Theory:

A Uni Junction Transistor (UJT) is a semiconductor device with only one junction.

The UJT has three terminals viz emitter (E) and two bases (B 1and B2). The base is formed

by lightly doped n-type bar of silicon. Two ohmic contacts B1 and B2 are attached at its

ends. The emitter is of p-type and it is heavily doped. The resistance between B1 and B2,

when the emitter is open-circuit is called inter base resistance. The original Uni Junction

Transistor, or UJT, is a simple device that is essentially a bar of N type semiconductor

material into which P type material has been diffused somewhere along its length. The

2N2646 is the most commonly used version of the UJT.

The UJT is biased with a positive voltage between the two bases. This causes a potential

drop along the length of the device. When the emitter voltage is driven approximately one

diode voltage above the voltage at the point where the P diffusion (emitter) is, current will

begin to flow from the emitter into the base region. Because the base region is very lightly

doped, the additional current (actually charges in the base region) causes (conductivity

modulation) which reduces the resistance of the base between the emitter junction and the

B2 terminal. This reduction in resistance means that the emitter junction is more forwardbiased, and so even more current is injected. Overall, the effect is a negative resistance at


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the emitter terminal. This is what makes the UJT useful, in oscillator circuits. When the

emitter voltage reaches Vp, the current starts to increase and the emitter voltage starts to

decrease. This is represented by negative slope in the characteristics and is referred to as the

negative resistance region. Beyond the valley point,RB1reaches minimum value and in thisregion, VEBproportional to IE.

Circuit Diagram:-

Procedure:

1. Connection is made as per circuit diagram.

2. Output voltage is fixed at a constant level and by varying input voltage corresponding

emitter current values are noted down.

3. This procedure is repeated for different values of output voltages.

4. All the readings are tabulated and Intrinsic Stand-Off ratio is calculated using

= (Vp-VD) / VBB

5. A graph is plotted between VEEand IEfor different values of VBE.


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Model Graph:-

Observations:-

VBB= VBB=

S.No VE(V) IE(mA) VE(V) IE(mA)

1

2

3

4

5

6

7

8

9

10

11

Calculations:-

VP= VBB+ VD

= (VP-VD) / VBB

When VBB= ,Vp= ,VD=

=

Result:-


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Additional Experiments

11. CE AMPLIFIER

Aim: - 1. To plot the frequency response of the CE amplifier

2. To Measure the voltage gain and bandwidth of a CE amplifier

Apparatus:-


1 Transistor BC-107 BC107 1

2 Regulated power Supply 0-30V,1A 1

3 Function Generator 1

4 CRO 20MHz 1

5 Resistors 1K,2.2K,

10K,100K,

1Each

6 Capacitors 10 F,100 F 2Each

7 Bread Board --- 1


Theory:-

The CE amplifier provides high gain & wide frequency response. The emitter

lead is common to both input & output circuits and is grounded. The emitter-base circuit is

forward biased. The collector current is controlled by the base current rather than emitter

current. The input signal is applied to base terminal of the transistor and amplifier output is

taken across collector terminal. A very small change in base current produces a large change

in collector current. When +ve half-cycle is fed to the input circuit, it opposes the forward

bias of the circuit which causes the collector current to decrease, it decreases the voltage

moreve. Thus when input cycle varies through a -ve half-cycle, increases the forward bias

of the circuit, which causes the collector current to increases thus the output signal is

common emitter amplifier is in out of phase with the input signal.


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Circuit Diagram:-

Procedure:-

1. Connect the circuit as shown in circuit diagram

2. Apply the input of 40mV peak-to-peak and 1 KHz frequency using Function Generator

3. Increase the input signal frequency in steps and note the corresponding output voltage

from CRO and record in the tabular form.

4. voltage gain in dB is calculated by using the expression Av=20 log10(V0/Vi)

5. For plotting the frequency response the input voltage is kept Constant at

20mV peak-to-peak

6. A graph is drawn by taking frequency on x-axis and gain in dB on y-axis on Semi-log

graph. The band width of the amplifier is calculated from the graph using the

expression,

Bandwidth, BW= (f2-f1) Hz

Where f1 lower cut-off frequencyand f2 upper cut-off frequency

7. The bandwidth product of the amplifier is calculated using the expression

Gain Bandwidth product=3 dB mid band gain Bandwidth


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Observations:-

Frequency Response: - Vi=40mv (constant)

S.No Frequency(Hz)

OutputVoltage (v0)

Gain in dBAv=20 log10(v0/vi)

1

2

3

4

56

7

8

9

10

11

1213

14

15

16

17

18

19

20

21


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Model Frequency Response:-

Result:


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12. COMMON COLLECTOR AMPLIFIER

Aim: To plot the frequency response curve of the CC amplifier & calculate cutoff

frequencies, bandwidth, and input resistance.

Apparatus:-S.No Apparatus Type Requirement

1 Regulated Power Supply 0-30V DC 1

2 CRO (0-20) MHz 1

3 Function Generator (0-1) MHz 1

4 Transistor BC107 1

5 Resistors 1 k,2.2k,

33k,10 k 1Each

6 Capacitors- 470F2

Theory:

In common-collector amplifier the input is given at the base and the output is taken

at the emitter. In this amplifier, there is no phase inversion between input and output. The

input impedance of the CC amplifier is very high and output impedance is low. The voltage

gain is less than unity. Here the collector is at ac ground and the capacitors used must have a

negligible reactance at the frequency of operation.

This amplifier is used for impedance matching and as a buffer amplifier. This

circuit is also known as emitter follower.


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Circuit Diagram:-

Procedure:-

1. Connect the circuit as shown in circuit diagram

2. Apply the input of 0.5V peak-to-peak and 1 KHz frequency using Function

Generator

3. Keeping the input voltage constant vary the input frequency from 100Hz to 1MHz

in regular steps and note down the corresponding output voltage for each

frequency

4.

Tabulate the readings in the tabular form.5. All the readings are tabulated and voltage gain in dB is calculated by using the

expression

Av in dB =20 log10(V0/Vi) .

6. A graph is drawn by taking frequency on x-axis and gain in dB on y-axis on

Semi-log graph. The band width of the amplifier is calculated from the graph

using the expression,

Bandwidth BW=f2-f1

Where f1 lower cut-off frequency, and f2 upper cut-off frequency

Voltage gain = Output Voltage (VO) / Source Voltage (VS)


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Observations:-

Vi= 0.5V (constant)

S.No Frequency(Hz)

OutputVoltage V0)

GainAV=(V0/Vi)

Gain in dBAv=20log10(V0/Vi)

1

2

3

4

56

7

8

9

10

11

1213

14


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Model Graph: -

Result: -

Documents

Student Edc Lab Manual