EDC Lab Manual Eee

E-mail: [email protected]

AN INSTITUTION ACCREDITED BY NBA, NEWDELHI

Sivagamipuram, PAVOORCHATRAM - 627808, Tirunelveli District, TamilNadu.

LAB MANUAL( K-Scheme)

YEAR: II SEM: III

PUBLISHER : MSPVL POLYTECHNIC COLLEGE, PAVOORCHATRAM, TIRUNELVELI DIST 627 808

1

Ex. NO CONTENTS

PAGE NO

PREFACE

1 V-I characteristics of semiconductor diode 9

2 V-I characteristics of zener diode 15

3 CHARACTERISTICS OF JFET 21

4 V-I characteristics of silicon controlled rectifier. 27

5 V-I characteristics of DIAC 31

6 V-I characteristics of TRIAC 37

7 V-I characteristics of Light Dependent resistor 41

8 V-I characteristics of Light Emitting Diode 45

9 Characteristics of CE configuration 49

10 Characteristics of CB configuration 55

11 V-I characteristics of Insulated Gate Bipolar Transistor 61

12 Observe the waveform of half wave and full wave rectifier circuits 65

13 Observe the waveform of Bridge rectifier circuits 73

14 Load regulation and Line regulation 77

15 Trace the waveform of UJT relaxation oscillator 83

16 Characteristics of UJT 87

17 Zener diode voltage regulator 91

EXTRA SYLLABUS

1 Clipper circuit 95

2 Clamper circuit 103

3 RC phase shift oscillator 107

2

PREFACE

The branch of engineering which deals with current conduction through a vacuum or gas or semiconductor is known as electronics.

This electronics essentially deals with electronic devices and their utilization. An electronic device is that in which current flows through a vaccum or gas or semiconductor. Such devices have valuable properties which enable them to function and behave as the friend of man today.

Electronic devices are being used in almost all the industries for quality control and automation. Before handling these devices and some instruments, we have to follow some precautions.

They are as follows: Safety Precautions: CRO: An cathode Ray oscilloscope is an instrument capable of presenting a luminous xy graph of any two related electrical parameters

Do not place objects on the top of CRO Do not insert wires or pins into ventilation holes. Do not pull the instrument by probes Never place a soldering iron on the oscilloscope frame. Do not turn the focus & intensity knob to maximum position these should be in

middle position. Do not apply signals which exceed 400v peak 1KHZ

Function Generator: It is an electronic device which is used to produce signals such as sine wave, square wave, and triangular wave, saw tooth wave.

Frequency fine & course knob should be in minimum position. We should select only one of frequency range & required wave forms of

function generator. Attenuation knob should be in released position. Do not pull & Do not place any objects on the top of function generator

3

RPS: It means regulated power supply. It produce DC voltage of range from 0 to 30v, 50v etc.

Initially voltage fine & course knob should be in minimum position. Initially current knob should be in maximum position. All the knobs are handled by slow manner not by rough manner. Any things are not placed on top of the RPS.

General Precautions:

Do not touch the live terminal. Wear rubber soled shoes, when you are doing the experiment. Shut off power supply before connecting the instruments. Select proper type & range of (AC / DC) meters Do not change the +ve & -ve terminal Do not make any short circuit Safety depends upon good earthing always keep earth connections in good

condition.

In this lab we have some safety devices they are 1. Fuses 2. Circuit breaker.

4

CHARACTERISTICS OF PN JUNCTION DIODE Forward Bias:

Reverse Bias:

5

1. FORWARD & REVERSE CHARACTERISTICS OF SEMI CONDUCTOR DIODE

AIM: To draw the forward & Reverse characteristics of semi conductor diode & to determine it's cut-in voltage.

APPARATUS REQUIRED:

SL. NO APPARATUS NAME RANGE QUANTITY

1 RPS (0-30)V 1

2 Ammeter (0-30 mA) MC (0-100 mA) MC 1 1

3 voltmeter (0-1V) MC (0-30V) MC 1 1

4 Resistors 1 K 10 K 1 1

5 Diode 1 N 4001 1

6 Bread board - 1

7 Connecting Wires - 1 set

THEORY: A PN junction is known as a semiconductor (or) crystal diode. The outstanding property of a crystal diode is to conduct current in one direction only.

FORWARD BIASING: When we apply forward bias across the diode,

The potential barrier is reduced and at some forward voltage (0.1 to 0.3v) it is eliminated altogether.

The junction offers low resistance Current flows in the circuit.

REVERSE BIASING: To apply reverse bias, connect negative terminal of the battery to Anode and positive terminal of the battery to cathode. In this biasing.

The potential barrier is increased. The junction offers very high resistance to current flow. No current flows in the circuit.

6

MODEL GRAPH:

I r (m

A)

Vf (Volts) Vr (Volts)

I f (m

A)

Vc VBR

VC = cut-in voltage VBR = break down voltage

7

PROCEDURE

FORWARD BIASING:

Connect the circuit as per the circuit diagram Vary the power supply voltage in such a way that the readings are taken in

steps of 0.1v in the voltmeter till the needle of the power supply shows 20 v. Note down the corresponding ammeter readings. Plot the graph: V against I Find the dynamic resistance=del V/del I

REVERSE BIASING:

Connect the circuit as per the circuit diagram Vary the power supply voltage in such a way that the readings are taken in

steps of 1v in the voltmeter till the needle of the power supply shows 20v. Note down the corresponding ammeter readings. Plot the graph: V against I Find the dynamic resistance ,r=del V/del I

8

TABULATION Forward Bias

Sl. No Input voltage (volts) Output voltage

(volts) Output current

(Amps)

Model calculation: V Dynamic resistance = r = ----- I

TABULATION Reverse Bias



(Amps)

Model calculation: V Dynamic resistance = r = ----- I

9

Application: 1. Computer 2. Radio, TV 3. TV receivers 4. Video cassette recorders 5. Rectifier, amplifier, detectors 6. Oscillators.

Employment: 1. TV assemble 2. UPS manufacturing 3. Radio assemble

List of viva voce questions:

1. What does a diode do? 2. Define semi conductor diode 3. What is barrier potential? 4. What is the use of diode? 5. Define the term cut-in voltage? 6. Define breakdown voltage? 7. What is the difference between PN junction diode & zener diode? 8. Define semi conductors. 9. What is doping? 10. What are the doping materials used? 11. What is the material used for P layer & N layer. 12. What is the name of the layer which is developing at reverse biased

condition at the junctions? 13. What is the value cut in voltage in silicon, germanium? 14. What is bias?

RESULT: Forward & reverse bias characteristics of junction diode are plotted & their dynamic resistances, cut-in voltage are as follows,

Dynamic forward resistance = --------------ohm Dynamic reverse resistance = --------------ohm Cut-in- voltage = -------------------volt

* * * * * * * * * *

10

CHARACTERISTICS OF ZENER DIODE Forward Bias:

Reverse Bias:

11

2. FORWARD & REVERSE CHARACTERISTICS ZENER DIODE

AIM: To draw the forward & reverse characteristics of zener diode. Determine its cut-in voltage & breakdown voltage.

OBJECTIVE: To measure the effects of forward & reverse bias ON current in zener diode.

APPARATUS REQUIRED:

Sl. No Apparatus Name Range Quantity 1 RPS (0-30) V 1 No 2 Voltmeter (0-3V) MC (0-30V) MC 1 No 3 Ammeter (0-100mA) MC 1 No 4 Bread board 1 No 5 Resistors 1 K 10 K 1 No 6 Zener diode FZ5.1 1 No 7 Connecting Wires 1 set

THEORY: A zener diode is a special type of diode that is designed to operate in the reverse breakdown region. It is heavily doped to reduce the reverse breakdown voltage. This causes a very thin depletion layer. As a result, a zener diode has a sharp breakdown voltage Vz. In reverse bias condition two things happen when Vz is reached.

1. The diode current increases rapidly. 2. The reverse voltage Vz across the diode remains almost constant,

In forward biased condition, it is similar to the ordinary PN junction diode.

12

TABULATION

Forward Bias



m(Amps)

Reverse Bias



mA (Amps)

13

PROCEDURE:

FORWARD BIASING: Connect the circuit as per the circuit diagram Vary the power supply voltage in such a way that the readings are taken in

steps of 0.1v in the voltmeter till the needle of the power supply shows 20 v. Note down the corresponding ammeter readings. Plot the graph: V against I

REVERSE BIASING: Connect the circuit as per the circuit diagram Vary the power supply voltage in such a way that the readings are taken in

steps of 1v in the voltmeter till the needle of the power supply shows 20v. Note down the corresponding ammeter readings. The reverse characteristics graph is decreasing upto breakdown voltage. Beyond this voltage, current increases, but supply voltage constant. Plot the graph: V against I

14

MODEL GRAPH:

I r (m

A)


I f (m

A)

Vc Vz

Vc = cut-in voltage Vz = Zener break down voltage

15

Application: 1. Voltage Stabilizers 2. Regulator circuits 3. Voltage reference standards.

Employment 1. Voltage stabilizer manufacturing

Viva voce question: 1. Define the term zener diode 2. Which part of the material is heavily doped? 3. What is zener breakdown? 4. Which is the most important semiconductor material? 5. How many types of diodes? What are they? 6. What is power diode? 7. What portion of a zener diode characteristic is most useful for voltage

regulator application? Why? Result: Thus the VI characteristics of zener diode was drawn & its cut-in voltage & breakdown voltage were determined.

Cut - in voltage = -------------V Break down voltage = --------------V

* * * * * * * * * *

16

CHARACTERISTICS OF JFET: CIRCUIT DIAGRAM:

+

+

-

-

-

+

- +

BFW11

470

1.2K

(0-5) V RPS

(0-30) V

RPS (0-30) V

G D

S

(0-10) mA

VGS V V

A

+

-

VDS

17

3. CHARACTERISTICS OF JFET

AIM: To draw the drain and transfer characteristics of JFET and determine the pinch off voltage

APPARATUS REQUIRED:

Apparatus Range Quantity

RPS (0 30V) 1

Resistors 470 1.2 K 1 1

Ammeter (0 10 mA) 1 Voltmeter (0 30V) MC (0 15V) MC

1 1

JFET BFW 11 1

Bread board - 1

Connecting Wires - 1 set

THEORY: A junction field effect transistor is a 3 terminal semiconductor device in which current conduction is done by one type of carrier, ie, electrons and holes.

It acts like a voltage controlled device that means input voltage (VGS) controls the output current (ID)

18

MODEL GRAPH:

DRAIN CHARACTERISTICS:

TRANSFER CHARACTERISTICS:

19

PROCEDURE: DRAIN CHARACTERISTICS:

Connections are given as per the circuit diagram The voltage VGS is kept constant by varying RPS 1, the voltage across

drain and source (VGS) and the corresponding ammeter readings (ID) are noted.

The above process is repeated for two more constant VGS values.

TRANSFER CHARACTERISTICS: By using RPS 2, the voltage VDS is kept constant, the gate source voltage (VGS) and the corresponding ammeter readings (ID) are noted and tabulated.

20

TABULATION: DRAIN CHARACTERISTICS:

S.NO VGS = 0V VGS = -1V VGS = -2V VDS(V) ID(mA) VDS(V) ID(mA) VDS(V) ID(mA)

TRANSFER CHARACTERISTICS: S.NO VDS = VP VGS(V) ID(mA)

21

APPLICATIONS: 1. JEET can act as an buffer amplifier 2. Used in phase shift oscillators 3. In communication electronics, we have to use JFET RF amplifier in a

receiver.

VIVA: 1. What is a FET? 2. Why is the input impedance of a FET higher than that of an ordinary

transistor?

3. What is the basic operational difference between a FET and an ordinary transistor?

RESULT: Thus the drain and transfer characteristics of JFET were drawn.

* * * * * * * * * *

22

CIRCUIT DIAGRAM:

23

4. CHARACTERISTICS OF SILICON CONTROLLED RECTIFIER

AIM: To draw the V I characteristics of the given SCR & to determine the gate current for different anode voltage

OBJECTIVE: To observe how gate current is used to switch SCR on.

APPARATUS REQUIRED:

SL. NO APPARATUS NAME RANGE QUANTITY

1 RPS (0-30) V 2

2 Ammeter 0-100mA (MC) 0-10mA (MC) 1

3 Voltmeter 0-30v (MC) 1 4 SCR TYN 604 1 5 Bread board - 1 6 Resistors 1K / 5W 2 7 Connecting Wires - 1 set

THEORY: A silicon controlled rectifier is a semiconductor device that acts as a true electronic switch. It can change AC into DC as like as an ordinary rectifier and at the same time it can control the amount of power fed to the load.

FORWARD CHARACTERISTICS: When anode is positive w.r.t cathode, the curve between V-I is called forward characteristic. If the supply voltage is increased from zero, a point is reached when SCR starts conducting. Under this condition, the voltage across SCR suddenly drops and most of the voltage appears across the load resistance RL. If proper gate current is made to flow, SCR can close at much smaller supply voltage.

REVERSE CHARACTERISTICS: When the anode is made negative w.r.t to cathode, the curve between V & I is called reverse characteristics. If the reverse voltage is increased, avalanche breakdown occurs and the SCR starts conducting heavily in reverse direction. It is similar to the ordinary PN junction diode.

24

MODEL GRAPH:

TABULATION:

IG 1 = IG2 = Sl. No VAK (V) IA (mA) VAK (V) IA (mA)

Ir (mA)


If (mA)

VBO VBR

VBO = Break Over Voltage VBR = Break Down Voltage

ON state

IH

IH = Holding Current

25

PROCEDURE: Connect the circuit as per the circuit diagram. Set gate current IG equal to firing current vary anode to cathode

voltage, VAK, in steps of 0.5 V & note down the corresponding anode current IA.

VBO is the point where voltage suddenly drops & there is sudden increase in anode current IA.

Note down the current at that point called latching current. Increase the VAK in steps of 1 V till its maximum. Open the gate terminal & decreases the VAK.

Application: Speed control of A.C. & D.C. machines Temperature control A.C. & D.C circuit breaker It can be used as inverter Battery chargers Phase control. It can be used as converter. It is used in light dimming control circuits It can be used as static contactor.

Employment: This skill used for wind mill control. you can assemble inverter, rectifier

Viva voce: What is SCR? What is the function of SCR What is latching current? What is holding current? When the SCR is ON? What is avalanche break down? What are the classifications of thyristors? Which is called uni directional devices? Why this name? What is the difference between uni directional & bidirectional devices? Which device is the best device? What are the turns off methods? What is natural commutation? What is forced commutation? Which method is the best for turn on SCR? Draw the symbol of SCR? How many terminals in thyristor or SCR? What is break over voltage?

Result: Thus the given SCR characteristics were drawn.

* * * * * * * * * *

26

MT1 NEGATIVE MT2 POSITIVE:

MT1 POSITIVE MT2 NEGATIVE:

27

5. CHARACTERISTICS OF DIAC

AIM: To draw the VI characteristics of the given Diac & to determine the cut - in voltage

OBJECTIVES: To study the forward & reverse current characteristics of a DIAC

APPARATUS REQUIRED:

Sl. No Apparatus Name Range Quantity

1 RPS (0-300) V 1 2 Voltmeter (0-100V) MC 1 3 Ammeter (0-10mA) MC 1 4 Resistors 1 K 1 5 Diac DB3 1 6 Bread board 1 7 Connecting Wires 1 set

THEORY: A diac is a two terminal bidirectional semiconductor device which can be switched from OFF state to ON state for either polarity of applied voltage.

When a positive or negative voltage is applied across the terminals, only a small amount of leakage current flow through it. As the applied voltage is increased, the leakage current will continue to flow until the voltage reaches the break over voltage VBO. At this point avalanche breakdown occurs and the device exhibits negative resistance, ie, current through the device increases with the decreasing values of applied voltage.

28

Tabulation: MT1 is positive with respect to MT2 negative.

Sl. No Voltage (V) Current (mA)

MT2 is positive with respect to MT1 negative

Sl. No Voltage (V) Current (mA)

29

PROCEDURE: MT1 is positive with respect to MT2 Rig up the circuit as per the circuit diagram. Varying the supply Vary the power supply voltage in such a way that the readings are

taken in the voltmeter. Note down the corresponding ammeter readings. Plot the graph V against I In the above procedure is repeated for MT1 is negative with respect to

MT2.

APPLICATION:

1. Diac is used as triggering device in light - dimming circuits. 2. In heat control circuits 3. In motor control circuits. 4. Relaxation oscillator 5. Phase control

30

MODEL GRAPH:

- VBO

+ VBO

IBO

ON state MT2 + IVE w.r.t MT1

MT1 + IVE w.r.t MT2 VBO = Break Over Voltage

31

EMPLOYMENT: This skill is used for lighting industry Domestic appliance industry

VIVA VOCE QUESTIONS:

1. What is Diac? 2. Why Diac is a bidirectional device? 3. How many layers in the diac? 4. Why the diac terminal name is MT1, MT2? 5. Does the diac conduct equally during the positive & negative

alternations? 6. Define cut-in voltage? 7. In a diac, Is the doping of the two junctions equal? 8. When the diac is turn - on? 9. How the doping level in the transistors compare to Diac? 10. Why doping level equal in Diac?

RESULT:

Thus the V-I characteristics of the given diac was drawn and cut-in voltage was determined.

Cut-in voltage=--------------- V

* * * * * * * * * *

32

CIRCUIT DIAGRAM:

A

V A

(0-100) mA

(0-50) mA RPS (0-30) V (0-15) V

RPS (0-30) V

MT1

MT2

IG

1K/5W

1K/5w

IMT2

+

+

+

+

+

-

-

-

-

-

G

BT136

G

33

6. CHARACTERISTICS OF TRIAC

AIM: To draw the V-I characteristics of the given triac. To determine the gate current for different anode voltage.

OBJECTIVES: To observe the V-I characteristics.

APPARATUS REQUIRED:


1 RPS (0-30) V 2 2 Voltmeter (0-15V) Mc 1 3 Ammeter (0-50mA) Mc (0-100mA) Mc 1 4 Resistors 1 K / 5 w 1 5 Triac BT 136 1 6 Bread board 1 7 Connecting Wires 1 set

THEORY: A triac is a 3 terminal semiconductor switching device which can control alternating current in a load.

The traic consists of 2 SCRS connected in anti-parallel, so, its characteristics in I and III quadrants are essentially identical to those of an SCR in the I quadrant.

The traic can be operated with either positive or negative gate control voltage, but in normal operation usually the gate voltage is positive in I quadrant and negative in III quadrant.

The supply voltage at which the traic is turned ON depends upon the gate current. The greater the gate current, the smaller the supply voltage at which the traic is turned on.

PROCEDURE: 1. Connect the circuit as per the circuit diagram 2. To set gate current Ig set VMT1, VMT2 & vary Vg till VAK suddenly drop

note down the corresponding IG. Set have gate current equal to firing current vary anode to cathode voltage.

3. Vary VAK supply voltage in steps & note down the corresponding ammeter readings.

4. Open the gate terminal & decrease VAK.

34

Tabulation:

IG 1 = IG2 = Sl. No VAK (V) IA (mA) Sl. No VAK (V) IA (mA)

MODEL GRAPH:

- VBO

+ VBO

IBO

ON state MT2 + ve, Gate +ve

MT1 +ve, Gate -ve VBO = Break Over Voltage

35

Application:

Light dimming control circuits In motor control, heat control circuits Other industrial applications Motor speed control For minimizing radio interference. Electronic change over of transformer taps Static switch.

Employment:

This skill used for transformer industry Many type of industry

Viva voce question:

1. What is triac? 2. What is the main function of Triac? 3. Why the triac is a bidirectional device? 4. How many layers, terminal in the triac? 5. What is break over voltage? 6. Draw the symbol of Triac, Diac?

Result:

Thus the VI characteristic of the given triac was plotted of the gate current for various anode voltage.

* * * * * * * * * *

37

7. CHARACTERISTICS OF LDR

AIM: To draw the VI characteristics of the given LDR under

a) Various illumination level at constant supply voltage. b) Various supply voltage at constant illumination level.

OBJECTIVES: To study the effect of an increase or decrease of light on the resistance of a photo conductive cell.

Apparatus Required:

Sl. No Apparatus Name Range Quantity 1 RPS (0-30) V 1 2 Voltmeter (0-3V) Mc 1 3 Ammeter (0-10mA) Mc 1 4 Resistors 1 K 1 5 LDR 1 6 Bread board 1 7 Connecting Wires 1 set 8 Lamp 100w 1

THEORY:

Light dependent resistors (LDRs) are made from cadmium sulphide containing no or very free electrons when not illuminated. Its resistance is then quite high. when it absorbs light, electrons are liberated and conductivity of the material increases.

The resistance rises to several megaohms under dark conditions.

38

TABULATION:

Sl. No

Distance between bulb and LDR 5 cm

Distance between bulb LDR 10 cm

Distance between bulb and LDR 15 cm

Voltage (V) Current (A)

Voltage (V)

Current (A)

Voltage (V)

Current (A)

Voltage = 10 volt

Sl.No Distance (cm) Current (A)

39

PROCEDURE: 1. Rig up the circuit as per the circuit diagram. 2. maintain a known distance (first 5 cm, second 10 cm, third 15 cm)

between bulb & the LDR 3. Vary the voltage in the power supply in steps note down the

corresponding voltmeter & ammeter readings. 4. Maintain the constant input voltage, By varying the distance, the

corresponding Ammeter readings are noted.

APPLICATION:

ON - OFF switch Relay control Voltage regulator Burglar alarms Object counters

VIVA VOCE QUESTIONS:

1. Define LDR 2. What is the another name of LDR? 3. Which type of material used for making LDR? 4. What is the value of resistance of LDR at absolute darkness condition? 5. What is the value of resistance of LDR at strong light condition? 6. What is photo conductive effect? 7. What is illumination? 8. Draw a symbol of LDR? 9. What is dark resistance?

RESULT: Thus the V-I characteristics of LDR was drawn for various illuminations level

at constant supply voltage and various and supply voltage as constant illumination level.

* * * * * * * * * *

41

8. CHARACTERISTICS LIGHT EMITTING DIODE

AIM: To draw the VI characteristics of the given LED. To determine the conduction voltage for satisfactory brightness.

OBJECTIVES: To determine the characteristics of LED

APPARATUS REQUIRED:


1 RPS (0-30) V 1 2 Voltmeter (0-3V) MC 1 3 Ammeter (0-30mA) MC 1 4 Resistors 1 K 1 5 LED (Red, Green) 1 6 Bread board 1 7 Connecting Wires 1 set

THEORY: A light emitting diode (LED) is a diode that gives off visible light when forward biased.

LEDs are made by elements like gallium, phosphorus and arsenic. By varying these quantities, it is possible to produce light of different wavelengths with colours that include red, yellow and blue.

When LED is forward biased, the electrons from the N-type material cross the PN junction and recombine with holes in the P-type material. These free electrons are the conduction band and at higher energy level than the holes in the valence band. When recombination takes place, the recombining electrons release energy in the form of heat and light. The light energy is sufficient to produce quite intense visible light.

42

TABULATION: S.No Voltage (V) Current (Amps)

43

PROCEDURE:

Rig up the circuit as per the circuit diagram. Vary the power supply voltage in such a way that the readings are

taken in steps of 0.1 V in the voltmeter till the needle of the power supply shows 20 V

Note town the corresponding ammeter readings Plot the graph V against I.

APPLICATION: Infra red LEDs are used in burglar alarms Used in solid state video displays Used in the field of optical communication. Used in image sensing circuits. Used in numeric displays like watches, pocket calculators

VIVA QUESTIONS: 1. What are the advantages of LED? 2. What is the full form of LED 3. What is the function of LED? 4. What action made when the LED reverse bias conditions? 5. What is the difference between LED & LCD 6. What is the function of photo transistor? 7. What is the range of value of operating voltage? 8. What is the difference between LED & LDR? 9. What are the advantages of opto coupler? 10. What are the different materials used for the LED? 11. What is the value of current when the typical voltage across and LED is

from 1.5 V to 2.5 V? 12. What is the value of voltage at the reverse bias condition?

RESULT: V-I characteristics of LED were plotted & their cut-in voltage (or) conduction voltage is as follows. Cut - in voltage = --------- V.

* * * * * * * * * *

45

9. CHARACTERISTICS OF COMMON EMITTER CONFIGURATION

AIM: To draw the input and output characteristics of common Emitter configuration for a given transistor and find the input and output resistance.

APPARATUS REQUIRED:

Sl. No Apparatus Name Range Quantity 1 RPS (0-30) V 2 2 Voltmeter (0-2V) MC (0-30V) MC 1 3 Ammeter (0-100 A) MC (0-50mA) MC 1 4 Resistor 1 k,

68k 1 1

5 Transistor BC 107 1

6 Bread board - 1


THEORY: In this arrangement, input is applied between base and emitter and output is taken from the collector and emitter. Here emitter is common to both input and output circuits and hence the name common emitter connection.

INPUT CHARACTERISTICS: It is the curve between base current (IR) and base emitter voltage VBE at constant collector emitter voltage (VCE) This characteristic resembles that of a forward biased diode curve.

OUTPUT CHARACTERISTICS: It is the curve between collector current (IC) and collector emitter voltage (VCE) at constant base current (IB). The collector current IC varies with VCE for VCE between O and IV only. After this, collector current becomes almost constant and independent of VCE. This value of VCE upto which collector current IC changes with VCE is called the knee voltage (Vknee).

46

INPUT CHARACTERISTICS MODEL GRAPH:-

Tabulation: Input characteristics:

Sl. No VCE (V) = VCE = 5V VCE (V) = VBE (V) IB (A) VBE (V) IB (A) VBE (V) IB (A)

47

PROCEDURE: I/P Char:

1. Rig up the circuit as per the circuit diagram. 2. Set VCE = 5 V, Vary VBE insteps of 0.1 V & note down the corresponding

IB. 3. Repeat the above procedure for 10 V, 15 V etc. 4. Plot the graph VBE Vs IB for a constant VCE 5. Find the input resistance.

Formula: VBE Input resistance Ri = ------- At constant VCE IB

O/P Char: 1. Rig up the circuit as per the circuit diagram.

2.Set IB =20 micro Amps, Vary VCE insteps of 1 V & note down the corresponding IC.

3. Repeat the above procedure for 40 micro Amps, 80 micro amps etc. 4. Plot the graph Vce Vs IC for a constant IB 5. Find the output resistance.

Formula: VCE Output resistance Ro = ------- At constant IB IC

Application: Main application of transistor is as an amplifier. Used as switch Oscillator circuits Logic circuits Modulation circuits Buffer CE amplifier are used in audio, radio Modulation Wave form generation.

48

OUTPUT CHARACTERISTICS MODEL GRAPH:-

Tabulation: OUTPUT CHARACTERISTICS:

Sl. No

IB= IB= IB=

VCE (V) Ic A

VCE(V) IC(A)

VCE(V) IC(A)

49

EMPLOYMENT: This skill is used for electronics product manufacturing industry (i.e. audio,

control panel circuits,video) This skill is used for digital based project. This skill is used for telephone department,

VIVA QUESTIONS: 1. What is transistor? 2. Why transistor is called bipolar junction transistors? 3. What is the advantage of transistor? 4. What is transistor configuration? 5. Why transistor is used as an amplifier? 6. Why the transistors is used as a switch 7. How many terminals in the transistors? 8. What are the three regions? 9. What mode of operation is used has amplification action? 10. What type of mode of operation condition the C-B forward bias, E-B

junction reverse bias? 11. What is active region? 12. What is cut-off region? 13. What is saturation region? 14. Define amplification factor? 15. What is gain? 16. What is the difference between BJT & UJT?

RESULT: Thus the input and output characteristics were drawn.

* * * * * * * * * *

50

- IC

-

+

-

RPS (0-30) V (0-1) V

+

RPS (0-30) V

(0-50) mA 1.2 K

(0-50) mA 470

BC 147

P

E

VBE

A

V

A

V (0-15) V

+

VCE

C

B

N

IE

N

Input and Output Characteristics of transistor in CB configuration:

BC 547

E B C

51

10. CHARACTERISTICS OF CB CONFIGURATION

AIM: To draw the input & output characteristics of common base configuration and find the input and output resistance.

APPARATUS REQUIRED:


Transistor BC 147 1

Resistors 470 1.2 K 1

RPS (0 30V) 1 Voltmeter (0 1)V (0 15V)

1 1

Ammeter (0 10 mA) (0 50 mA) 1 1

Bread board - 1

Connecting Wires - 1 set

THEORY: In this circuit arrangement input is applied between base and emitter and output is taken from the base and collector. Here, base is common to both input and output.

INPUT CHARACTERISTICS: It is the curve between base emitter voltage (VBE) and emitter current (IE) at constant collector base voltage (VCB).

INPUT RESISTANCE: It is defined as

E

BEI

ViR =

52

MODEL GRAPH: INPUT CHARACTERISTICS:

OUTPUT CHARACTERISTICS:

V CB =

5V

IC

V CB =

0V

V CB =

10

V

VBE

I C(m

A) Ic = 10mA

Ic = 7mA

Ic = 3mA

VCB = (Volts)

53

OUTPUT CHARACTERISTICS: It is the curve between collector base voltage (VCB) and collector current (IC) at constant emitter current (IE).

OUTPUT RESISTANCE: It is defined as

CICBV

oR =

PROCEDURE: INPUT CHARACTERISTICS:

Connections are given as per the circuit diagram. By varying RPS VCB is kept constant at a particular voltage. Base emitter voltage is increased in number of steps and the

corresponding emitter current IE are noted and tabulated.

OUTPUT CHARACTERISTICS: BY using RPS, IE is kept at constant Collector base voltage is increased in number of steps and the

corresponding value of collector current (IC) are noted and tabulated.

54

TABULATION:

INPUT CHARACTERISTICS:

S.NO VCB = 0V VCB = 5V VCB = 10V VBE(V) IE(mA) VBE IE VBE IE

TABULATION: OUTPUT CHARACTERISTICS:

S.NO IE=3mA IE=5mA IE=10mA VCB(V) IC(mA) VCB(V) IC(mA) VCB(V) IC(mA)

55

APPLICATIONS: It is used in high frequency application Common base amplifier is used as a buffer amplifier.

VIVA QUESTIONS:

1. What is meant by buffer amplifier? 2. Why it is used in high frequency application? 3. Which material is commonly used for transistor manufacturing?

RESULT: Thus the input and output characteristics of CB configuration was drawn.

* * * * * * * * * *

57

11. CHARACTERISTICS OF IGBT

AIM: To conduct an experiment and to draw the VI Characteristics of IGBT

OBJECTIVE: To observe the relation between the collector current and collector - emitter voltage different values of gate - source voltage of an IGBT.

APPARATUS REQUIRED: S.No Name of the Apparatus Numbers Reqd

1 Characteristics of IGBT kit 1 2 IGBT IRG4BC20S 1 3 DC Voltmeter (0-30)V 1 4 DC Voltmeter (0-15)V 1 5 DC Ammeter (0-5)A 1 6 Rheostat 50 ohms ,2A 1 7 Connecting wires 1 set

PROCEDURE: 1. Connect the IGBT in the circuit. 2. Connect the meters and Rheostat in the experiment board. 3. Switch ON the power supply. 4. Keep the Vge at 5.25volts and adjust the rheostat to 50 ohms 5. Note down the values of Vce and Ic for every rise in 1v in the collector

emitter voltage. 6. Repeat the above procedure for Vge = 5.35v. Plot the VI characteristics in the

graph sheet.

58

Tabular column: STATIC CHARACTERISTICS

S.No GATE VOLTAGE VG = GATE VOLTAGE VG =

Vce (volts) Ic (mA) Vce (volts) Ic (mA)

59

THEORY: IGBT has the combined advantage of Power MOSFET and power BJT. It has three terminals. The IGBT is a three terminal device It has a collector, an emitter like a BJT and an insulated gate as it is in a MOSFET.

With no gate voltage applied, the IGBT is in the forward blocking mode. When a positive gate voltage greater than the threshold voltage is applied, the inversion layer is formed and the current begins to flow. Hence the device turns ON. The inversion layer cannot be maintained when the gate voltage is below the threshold voltage. To turn OFF the device, a negative voltage must be applied to the gate.

The IGBT has low on-state voltage drop and high forward current density compared to the power BJT and MOSFET. Due to the input MOS gate structure, it requires simple drive circuit and it consumes less power.

The VI Characteristics shows the relation between the Collector Current and the Collector-Emitter voltage, for different values of Gate-Source voltage. It is identical with the output Characteristics of the BJT. But the controlling parameter is Gate voltage rather than the base current in a BJT.

APPLICATION: AC and DC drives. UPS Solid state relays and contactors.

VIVA VOCE: 1. What is IGBT 2. What are the applications of IGBT? 3. Say the current rating of IGBT 4. Why is inculcated gate bipolar transistor (IGBT) popular now - a days? 5. What is the control pulse of an IGBT?

RESULT: Thus the VI characteristic of IGBT was drawn by conducting an experiment.

* * * * * * * * * *

60

FULL WAVE RECTIFIER:

61

12. OBSERVE THE WAVEFORMS OF HALF WAVE & FULL WAVE RECTIFIER

AIM: To construct half wave & full wave rectifier circuits using diodes & observe the input & output wave forms with & without filter.

OBJECTIVES:

1. To observe & measure the output wave forms of a half - wave rectifier. 2. To observe & measure the output wave forms of a full - wave rectifier.

APPARATUS REQUIRED:

Sl. No Apparatus Name Range Quantity 1 CRO (0-20 MHZ) 1 2 Transformer 9-0-9 V 1

3 Diode 1N 4001 2

4 Resistor 2 K 1 5 Capacitor 1000 F 1 6 Bread board - 1


62

HALF WAVE RECTIFIER:

63

THEORY:

HALF WAVE RECTIFIER: In half wave rectification, the rectifier conducts current only during the positive half cycles of input ac supply. The negative half cycles are suppressed. During positive half cycle, the diode becomes forward biased and hence half cycle. The diode is reverse biased and it conducts no current.

FULL WAVE RECTIFIER: In full wave rectification, current flows through the load in the same direction for both half cycles of input ac voltage. This can be achieved with two diodes working alternately. For positive half cycle, one diode supplies current to the load and for the negative half cycle, the other diodes does so. In this way full wave rectifier produces dc output.

64

Half wave rectifier tabulation:

Description

Amplitude (V)

Time period

Input voltage waveform

Output voltage waveform without filter

Output voltage waveform with filter

Input Waveform

Output Waveform (Without filter)

Output Waveform (With filter)

t (ms)

t (ms)

t (ms)

Vo (v)

Vo (v)

Vin (v)

65

PROCEDURE:

WITHOUT FILTER: Test your transformer: Give 230 V, 50 HZ source to the primary coil of the

transformer & observe the AC wave forms of rated value without any distortion at the secondary of the transformer.

Connect the circuit to the secondary terminals of the transformer Connect CRO across the load. Keep the CRO switch in ground mode & observe the horizontal line & adjust it

to the x axis. Switch the CRO into DC mode & observe the wave form. Note its amplitude,

Vm & frequency from the screen along with its multiplication factor. Switch on the CRO into AC mode & observe the waveform. Note down its

amplitude Vm & frequency from the screen along with its multiplication factor.

WITH FILTER: Rig up the circuit as per the circuit diagram Connect the capacitor across the load resistance & proceed with the above

procedure.

APPLICATION: Radio, TV Computer

EMPLOYMENT: This skill very useful to all service and assembler. Battery charger, emergency light All type of electronic industry using these circuits

.

66

Full wave rectifier circuit tabulation:

Description

Amplitude (V)

Time period

Input voltage waveform

Output voltage waveform without filter

Output voltage waveform with filter

67

VIVA QUESTION: 1. What is rectifier? 2. Which rectifier is mostly used? Why? 3. Which components are used for rectification? 4. What is filter? 5. What are the types of filter? 6. Why the filter used in rectifier circuit? 7. What is rectifier efficiency? 8. What is the function of transformer? 9. Why step down transformer used for rectification? 10. What is ripple factor? 11. What is peak inverse voltage? 12. How many numbers of diodes are used in full wave rectifier? 13. Which rectifier circuit has low efficiency? Why? 14. How much efficiency in the full wave, half wave rectifier? 15. What are the types of phase rectifier? 16. What is advantages of three phase rectifier compound to the single

phase?

RESULT: Thus the half wave & full wave rectifier was constructed the input & output wave forms with & without filters were observed.

* * * * * * * * * *

68

BRIDGE RECTIFIER

69

13. BRIDGE RECTIFIER

AIM: To construct a bridge rectifier circuits using diodes & observe the input & output waveforms with & without filters.

APPARATUS REQUIRED:

Sl. No Apparatus Name Range Quantity 1 CRO (0-20 MHZ) 1 2 Transformer 9-0-9 V 1

3 Diode 1N 4001 4

4 Resistor 2 K 1 5 Capacitor 1000F 1 6 Bread board - 1


THEORY: The bridge rectifier is a full wave rectifier. It contains four diodes connected in the form bridge. During positive half cycle, two diodes become forward biased. So these diodes conduct current in one direction. During negative half cycle, the remaining two diodes become forward biased, so the current flow is by these diodes in same direction. Using the bridge circuit, the AC voltage is converted into DC.

70

Tabulation:

Bridge wave rectifier circuit tabulation

Description

Amplitude (V)

Time period

Input voltage

Output voltage without filter

Output voltage with filter

71

PROCEDURE:

WITHOUT FILTER: Test your transformer: Give 230 V, 50 HZ source to the primary coil of the

transformer & observe the AC wave forms of rated value without any distortion at the secondary of the transformer.

Connect the circuit to the secondary terminals of the transformer Connect CRO across the load. Keep the CRO switch in ground mode & observe the horizontal line & adjust it

to the x axis. Switch the CRO into DC mode & observe the wave form. Note its amplitude,

Vm & frequency from the screen along with its multiplication factor. Switch on the CRO into AC mode & observe the waveform. Note down its

amplitude Vm & frequency from the screen along with its multiplication factor.

WITH FILTER: Rig up the circuit as per the circuit diagram Connect the capacitor across the load resistance & proceed with the above

procedure.

APPLICATION: 1. D.C. motor speed control circuits 2. Battery charger 3. TV 4. Computer

VIVA QUESTION: 1. How many diodes are required in bridge method? 2. Which type of transformer used for bridge rectifier circuit? 3. What are the advantages of bridge rectifier? 4. What is the value of ripple factor? 5. What is average value? 6. What is value ripple frequency? 7. What is the use of bleeder resistor?

RESULT: Thus the bridge rectifier was constructed the input & output wave forms with & without filter were observed.

* * * * * * * * * *

73

14. LOAD REGULATION & LINE REGULATION

AIM: To construct a voltage regulator using IC 7812 & to determine the load regulation & line regulation.

OBJECTIVE: To measure regulation using IC 7812

APPARATUS REQUIRED:

Sl. No Apparatus Name Range Quantity 1 RPS (0-30V) 1 2 Voltmeter (0-15V)MC 1 3 Ammeter (0-100mA) MC 1 4 DRB - 1 5 IC 7812 1 6 Capacitor 1000F 2 7 Bread board - 1


THEORY: Initially voltage regulator circuits were constructed using discrete components which had the problem of unreliable operation, occupying more space, frequent breakdown of components. Nowadays, voltage regulators are available on integrated circuits form to avoid the above drawbacks.

IC 7805 has 3 pins. Pin 1 is input 2 output and pin 3 is ground. IC 7805 has the output of +5V. In the same way negative voltage regulators are designed.

74

Tabulation: Load regulation:

Input voltage = (constant)

Sl. No

Output voltage Resistance (k ohm)

Line regulation:

Load constant:

Sl. No Input voltage Output voltage

75

PROCEDURE:

LINE REGULATION: 1. Rig up the circuit as per the circuit diagram. 2. Connect the load resistance of higher wattage. 3. Vary the input DC supply in regular steps. 4. Note down the corresponding output voltage using a voltmeter. 5. Plot the graph: Vin Vs Vo

LOAD REGULATION: 1. Rig up the circuit as per the circuit diagram 2. Fix the input DC supply voltage (Say, 12 V) more than the regulations

value. 3. Replace the fixed resistance by a decade resistance box. 4. Vary the load in regular steps. 5. Note down the corresponding output voltage across the load using

voltmeter.

APPLICATION:

It is used for regulated power supply. It is used for radio TV It is used for computer and all type of electronic item using this voltage

regulated IC

77

EMPLOYMENT:

This is very useful to regulate power supply industry.

VIVA QUESTION:

1. What is the function of regulator? 2. What is regulation? 3. What are the types of regulation? 4. What is negative voltage regulator? 5. What is +ve voltage regulator? 6. What is zener voltage regulator? 7. What is series regulator? 8. What is the output voltage in 7805 IC? 9. What is the output voltage value for 7905 IC? 10. What is linear regulator? 11. What are the disadvantages of linear regulator? 12. How many terminals in the IC voltage regulator?

RESULT: Thus the voltage regulator IC 7812 was constructed & its load & line regulation was determined.

Line regulation = ------- Load regulation = ------

* * * * * * * * * *

78

CIRCUIT DIAGRAM:

79

15. TRACE THE WAVE FORM OF UJT RELAXATION OSCILLATOR

AIM: To construct a relaxation oscillator using UJT & trace the wave form & also measure the frequency.

OBJECTIVE: To connect the UJT as a relaxation oscillator & observe the output wave forms.

APPARATUS REQUIRED:

Sl. No Apparatus Name Range Quantity 1 RPS (0-30V) 1 2 CRO (0-20 MHZ) 1 3 UJT 2N 2646 1

4 Capacitor 0.1F 1

5 Resistor DRB 10K 100K

1 1 1

6 Bread board - 1 7 Connecting Wires - 1 set

THEORY: When the battery VBB is turned on, the capacitor C charges through resistor R1. During the charging period, the voltage across the capacitor rises in an exponential manner until it reaches the peak point voltage. Now, the UJT goes to conducting mode and the capacitor is discharged between E and B1. As the capacitor voltage reached the valley point (VV), the UJT is switched off. The next cycle then begins, allowing the capacitor C to charge again.

PROCEDURE: 1. Rig up the circuit as per the circuit diagram. 2. Set VBB = 10 V (say) ( Supply voltage normally used lies in the range

10 to 35 V) 3. Connect CRO across capacitor. 4. Switch on the power supply set VBB = 10 V & observe the wave form on

the CRO 5. Note down the practical frequency. 6. Switch off the supply 7. Connect CRO across R1 switch on the supply & observe the wave

forms. 8. Note down the practical frequency.

80

Tabulation:

Peak voltage (V) Time in sec Frequency = 1/t Hz

Tabulation:

Peak voltage (V) Time in sec Frequency = 1/t Hz

81

APPLICATION: 1. Pulse generator for firing SCR. 2. In the negative resistance region, it can be operated as a relaxation

oscillator. 3. Used as a fast acting switch. 4. Used as sine wave generator, square wave generators, saw tooth

generators. 5. Used in time delay circuits. 6. Used in TV 7. Used in radar equipment 8. Used in oscilloscope.

EMPLOYMENT: TV assembler This skill is used for army Oscilloscope assembler industry

VIVA QUESTIONS: 1. What is the function of oscillator? 2. Which portion of the characteristics used in a relaxation oscillator? 3. Which oscillator is very suitable for audio range applications? 4. Which oscillator is suitable for RF range application? 5. How does oscillation start in oscillators? 6. What is the difference between oscillator & amplifier? 7. How many classifications of oscillators? 8. What are types of oscillators based on frequency generator? 9. What is crystal oscillator? 10. Define intrinsic stand - off ratio? 11. How the frequency of oscillation determined in theoretical? 12. How many terminals in the UJT? 13. Which Condition of region the UJT is off state? 14. When the UJT is ON? Which region? 15. What is negative resistance region?

RESULT: Thus the UJT relaxation oscillator circuit was constructed & its waveforms

were drawn.

* * * * * * * * *

82

E

B1

B2

2N2646

CHARACTERISTICS OF UJT:

A

V

B1

+

-

+

-

+

+

-

E +

-

V

RPS (0-30) V (0-15) V

RPS (0-30) V

470

(0-15) V

(0-50) mA -

470

2N2646

B2

83

16. CHARACTERISTICS OF UJT

AIM: To draw the V-I characteristics of UJT and find the peak point voltage

APPARATUS REQUIRED:


RPS (0 30V) 2 Resistors 470 2

Ammeter (0 50 mA) 1 Voltmeter 0 15V 1

UJT 2 N 2646 1

Bread board 1

Connecting Wires 1 set

THEORY: Uni junction transistor (UJT) is a 3 terminal semiconductor switching device. It has only one PN junction. It has no ability to control the AC power with a small gain. It exhibits a negative resistance characteristics and hence it can be used as a oscillator.

PROCEDURE: Connections are made as per the circuit diagram. BY using RPS, the voltage VB1 B2 is kept constant, the emitter

voltage (VE) and the corresponding ammeter reading (IE) are noted and tabulated.

The above process is repeated for two more constant VB1 B2 values.

84

MODEL GRAPH:

TABULATION:

S.NO VB1B2 = 4V VB1B2 = 7V VB1B2 = 10V VE (V)

IE (mA)

VE (V) IE(mA) VE(V) IE(mA)

85

CIRCUIT DESIGN: 1. When no voltage applied to UJT, the interbase resistance is given by

RBB = RB1 + RB2

2. If a voltage VBB is applied between the bases with emitter open. The voltage will divide up across RB1 and RB2,

Voltage across RB1, V1 =( RB1 / (RB1 + RB2))VBB = V1 / VBB.

= RB1 / (RB1 + RB2) V1 = VBB

3. If rising positive voltage is applied to the emitter, the diode become forward biased when input voltage exceeds VBB by VD.

Vp = VBB + VD Vp peak point voltage VD forward voltage drop across the diode (for si 0.7v)

Vp = VBB + VD = 0.65 x 10 + 0.7 (VB1 B2 = 10v) = 6.5 + 0.7

Vp = 7.2v

APPLICATIONS: UJT is used in oscillator. In pulse generating circuits. It is used in relaxation oscillator to generate saw tooth output.

VIVA: 1. Why it is called uni junction transistor? 2. What is peak point voltage? 3. What is valley voltage?

RESULT: Thus the characteristic of UJT was obtained.

* * * * * * * * *

86

RL [DRB] Fz 5.1 +

-

5K R r

+

-

RPS (0-30) V

ZENER DIODE VOLTAGE REGULATOR:

87

17. ZENER DIODE VOLTAGE REGULATOR:

AIM: To construct a voltage regulator using zener diode.

APPARATUS REQUIRED: Apparatus Range Quantity

RPS (0 30V) 2 Resistors 5 K 1

zener diode F Z5.1 1

Voltmeter 0 10V 1

DRB 1

THEORY: A zener diode can be used as a voltage regulator to provide a constant voltage from source whose voltage may vary over sufficient range.

The zener diode is connected in reverse direction. The series resistance R absorbs the output voltage fluctuations so as to maintain constant voltage across the load. The load voltage remains constant even though the input voltage and load resistance may vary over a wide range.

89

PROCEDURE: Connections are given as per the circuit diagram. Vary the input voltage and note down the corresponding zener voltage. Fix the input voltage and vary the RL. The Corresponding zener voltage is noted. In any case the zener voltage is constant.

APPLICATIONS: It can be used as a voltage regulator in many of the rectifier circuit.

VIVA: 1. How does a zener diode maintain constant voltage across the load? 2. Can zener be used as a rectifier? 3. What for purpose we connect the series resistance in the zener circuit?

RESULT: Thus the zener voltage regulator was constructed and the characteristics were observed.

* * * * * * * * *

91

EXTRA SYLLABUS

1. CLIPPER CIRCUIT

AIM: To construct the biased positive & negative Clipper circuits using diodes.

APPARATUS REQUIRED:

S. NO. APPARATUS REQUIRED RANGE QUANTITY

1. RPS (0 30) V 1 2. Diode 1N4001 1

3. Resistor 10 K 1

4. CRO 0-20 MHZ- 1

5. FGR -- 1

6. Bread Board -- 1

7. Connecting Wires -- 1 Set

THEORY:

It is a nonlinear wave shaping circuit. The clipping circuit requires a minimum of two components i.e. a diode and a resistor. DC battery is also used to fix the clipping level. The input waveform can be clipped at different levels by simply changing the battery voltage and by interchanging the position of various elements.

93

PROCEDURE:

Connections are made as shown in fig.

Power supply is switched ON.

Using Function Generator we can vary the frequency and fixed at particular frequency.

Now the corresponding input and output waveforms are drawn.

Amplitude and time, input & output waveforms are drawn.

And graph is drawn for input and output waveform.

Power supply is switched OFF.

95

APPLICATION:

It is used in radar applications.

Used in digital computers

Widely used in radio and television receivers

VIVA QUESTIONS:

What is clipper?

What is meant by biased clipper?

Mention the application of clipper?

Differentiate between series and shunt positive clipper?

96

MODEL GRAPH

NEGATIVE BIASED CLIPPER Circuit Diagram

10 K

- 5 VR

K A

FGR CRO

IN 4001

-

+

97

RESULT:

Thus the Positive and Negative Clipper Circuits were studied and constructed and its input and output waveforms were drawn.

* * * * * * * * * *

98

CIRCUIT DIAGRAM OF POSITIVE CLAMPER:

CIRCUIT DIAGRAM OF NEGATIVE CLAMPER:

- +

100 K

100 F

IN 4001 K

A

FGR CRO

100 F

FGR CRO 100 K

K

IN 4001

- +

99

2. CLAMPER CIRCUIT AIM: To construct and study the output waveform of Clamper Circuit.

APPARATUS REQUIRED: S. NO. APPARATUS REQUIRED RANGE QUANTITY

1. Diode 1N4001 1 2. Capacitor 100F/25V 1 3. CRO 0- 20 MHZ 1 4. FGR -- 1 5. Bread Board -- 1 6. Connecting Wires -- 15

THEORY: Clamping is the process of introducing a dc level into an ac signal. Clampers are also sometimes known as dc restorers. Clamping is the process of shifting the input signal above or below the zero level. A clamping circuit should not change peak to peak value of the signal; it should only change the DC level. To do so, a clamping circuit uses a capacitor together with a diode and a resistor.

PROCEDURE: Connections are made as shown in fig.

Switched ON the Function generator

Now corresponding input and output waveforms are visible at the monitor of CRO.

Amplitude and Time of input and output waveform is measured and tabulated.

100

MODEL GRAPH POSITIVE CLAMPER

NEGATIVE CLAMPER

Time (ms)

Time (ms)

Amplitude (v)

2Vm

Vm

Time (ms)

Time (ms)

Amplitude (v)

-Vm

-2Vm

101

APPLICATION:-

1. Used in television receivers to restore the original D.C reference signal to the video signal.

2. Used to produce a D.C voltage whose value is multiple of peak AC input applied voltage.

VIVA QUESTIONS:

1. What is the other name for clamper? 2. What is clamper? 3. Mention the application of clamper? 4. What is the difference between the clipper and clamper?

RESULT:

Thus the Clamper Circuits were constructed and its input and output waveforms were drawn.

* * * * * * * * * *

103

3. RC PHASE SHIFT OSCILLATOR

AIM:

To construct and draw characteristics of RC Phase Shift Oscillator.

APPARATUS REQUIRED:

S. NO. APPARATUS REQUIRED RANGE QUANTITY

1. Transistor BC 108 1

2. Capacitor 0.1 f 4

3. Rheostat 1K 1

4. Resistor 3.3K 4

THEORY:

It is a circuit which self generating some waveform like sine, triangular, and square wave etc.

It is basically an amplifier circuit with positive feedback introduced.

In this case the CE amplifier is followed by a frequency determining network. The R1, R2 combination provides dc potential divider bias and Ro, CE provides temperature stability and provides ac signal degeneration. The high pass or low pass RC - RC network may be used as positive feedback between input and output.

104

MODEL GRAPH

RC PHASE SHIFT OSCILLATOR

Amplitude (V)

Time (ms)

105

PROCEDURE: Connections are made as shown in circuit diagram. Power supply is

switched ON.

Varying the RPS and kept at a fixed voltage between 6V 12V.

Now corresponding output is taken in CRO. The amplitude and time are measured then the graph is drawn.

FORMULA:

6RC21F

pi=

DESIGN: R = 200k C = 100pF F=?

6RC21F

pi=

6101001020021

123 pi=

= 3.248 kHz

VIVA QUESTIONS:

Why is an RC phase shift oscillator so called? Mention two low frequency oscillators Why LC oscillators are not used at audio frequencies? What is the condition to initiate oscillations?

RESULT:

Thus RC Phase Shift Oscillator characteristics were drawn and constructed.

* * * * * * * * * *

EDC Lab Manual Eee

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