EC3102 Edc Lab Manual

EC 1302 ELECTRONIC DEVICES AND CIRCUITS LAB

LAB MANUAL

FOR

I SEMESTER B.E (CSE)

SAVEETHA UNIVERSITY

NAME: ……………………………………………

REG.NO:………………………………………

BATCH: …………………………………………..

DEPARTMENT OF COMPUTER SCIENCE ENGINEERING

SAVEETHA SCHOOL OF ENGINEERINGCHENNAI – 602 105

EC3102 ELECTRONIC DEVICES AND CIRCUITS LABLAB MANUAL

SYLLABUS

1. Study of electronic components - devices and equipment.

2. Study of Cathode Ray Oscilloscopes

3. Characteristics of PN junction diode

4. Characteristics of zener diode

5. Transistor as a switch

6. Clipper

7. Characteristics of BJT in CC configuration

8. Characteristics of BJT in CE configuration.

9. Half-wave rectifier.

10. D.C characteristics of common drain FET

11. Clamper

12. Characteristics of the BJT in CB configuration

INDEX

STUDY OF ELECTRONIC COMPONENTS

EXP NO.

DATE

TITLE OF EXPERIMENT

PAGE NO.

MARKS

STAFF INITIAL

1

Study of electronic

components - devices and

equipment.

2Study of Cathode Ray

Oscilloscopes

3Characteristics of PN

junction diode

4Characteristics of zener

diode

5 Transistor as a switch

6 Clipper

7Characteristics of BJT in CC

configuration

8Characteristics of BJT in CE

configuration.

9 Half-wave rectifier.

10D.C characteristics of

common drain FET

11 11. Clamper

12Characteristics of the BJT in

CB configuration

EXPT. NO. : 1 DATE :

AIM:To study the electronic components and equipment.

APPARATUS REQUIRED:

Resistor, capacitor, transistor, diode, led, cro, bread board.

THEORY

Electronic components are classed into either being Passive devices or

Active devices.

Active Devices

An active device is any type of circuit component with the ability to electrically control electron flow (electricity controlling electricity). All active devices control the flow of electrons through them.Eg: transistor, diode, SCR, FET, MOSFET

Passive Devices

A device that does not require a source of energy for its operation. Components incapable of controlling current by means of another electrical signal are called passive devices .Eg: . Resistors, capacitors, inductors, transformers, and diodes

Diodes

Diodes are basically a one-way valve for electrical current. They let it flow in one direction (from positive to negative) and not in the other direction. Most diodes are similar in appearance to a resistor and will have a painted line on one end showing the direction or flow (white side is negative).

Transistors

A transistor is a semiconductor device, commonly used as an amplifier or an electrically controlled switch. The transistor is the fundamental building block of the circuitry in computers, cellular phones, and all other modern electronic devices.

The three terminals of transistor are

1. Emitter

2. Base

3. Collector

Capacitors

A capacitor is a passive electrical component that can store energy in the electric field between a pair of conductors (called "plates"). The process of storing energy in the capacitor is known as "charging", and involves electric charges of equal magnitude, but opposite polarity, building up on each plate. A capacitor's ability to store charge is measured by its capacitance, in units of farads. This property makes them useful in electronic filters. Its symbol is

Resistor

A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. The current through a resistor is in direct proportion to the voltage across the resistor's terminals. Thus, the ratio of the voltage applied across a resistor's terminals to the intensity of current through the circuit is called resistance. This relation is represented by Ohm's law

Its symbol is

Color coding

The electronic color code is used to indicate the values or ratings of electronic components. To distinguish left from right there is a gap between the C and D bands.

band A is first significant figure of component value (left side) band B is the second significant figure band C is the decimal multiplier

Band D if present, indicates tolerance of value in percent (no band means 20%)

Inductor

An inductor (also choke, coil or reactor) is a passive two-terminal electrical component that stores energy in its magnetic field. For comparison, a capacitor stores energy in an electric field, and a resistor does not store energy but rather dissipates energy as heat.Any conductor has inductance. An inductor is typically made of a wire or other conductor wound into a coil, to increase the magnetic field. Its unit is henry, represented by L. Its symbol is

COLOR CODING

BASIC DIAGRAM OF TRANSISTOR

BJT FET

PNP NPN P-CHANNEL N-CHANNEL

Diodes

Result:

Thus electrical components are studied.

STUDY OF CATHODE RAY OSCILLOSCOPE

EXPT. NO. : 2 DATE :

AIM:To study about cathode ray oscilloscope.

APPARATUS REQUIRED:

Cathode ray oscilloscope, function generator, probe.

THEORY:

CRO:

The cathode ray oscilloscope is an extremely useful and versatile laboratory instrument used for studying wave shapes of alternating currents and voltages as well as for measurement of voltage, current, power and frequency, in fact, almost any quantity that involves amplitude and waveform. It allows the user to see the amplitude of electrical signals as a function of time on the screen.

CRT:

The instrument employs a cathode ray tube (CRT), which is the heart of the oscilloscope. It generates the electron beam, accelerates the beam to a high velocity, deflects the beam to create the image, and contains a phosphor screen where the electron beam eventually becomes visible. \

DEFLECTION PLATES:

A basic block diagram of a general purpose oscilloscope is shown in figure. Horizontal and vertical deflection plates are fitted between electron gun and screen to deflect the beam according to input signal. Electron beam strikes the screen and creates a visible spot. This spot is deflected on the screen in horizontal direction (X-axis) with constant time dependent rate. This is accomplished by a time base circuit provided in the oscilloscope. The signal to be viewed is supplied to the

vertical deflection plates through the vertical amplifier, which raises the potential of the input signal to a level that will provide usable deflection of the electron beam. Now electron beam deflects in two directions, horizontal on X-axis and vertical on Y-axis.

Electron Gun Assembly.

The electron gun assembly consists of an indirectly heated cathode, a control grid surrounding the cathode, a focusing anode and an accelerating anode. The sole function of the electron gun assembly is to provide a focused electron beam which is accelerated towards the phosphor screen. The cathode is a nickel cylinder coated with an oxide coating and emits plenty of electrons, when heated. The emitting surface of the cathode should be as small as possible, theoretically a point.

Screen For CRT.

As we know that some crystalline materials, such a phosphor, have property of emitting light when exposed to radiation. This is called the fluorescence characteristic of the materials These fluorescent materials continue to emit light even after radiation exposure is cut off. This is called the phosphorescence characteristic of the materials. The end wall of the CRT, called the screen, is coated with phosphor. When electron beam strikes the CRT screen, a spot of light is produced on the screen

Glass Body and Base.

The whole assembly is protected in conical highly evacuated glass housing through suitable supports. The inner walls of CRT between neck and screen are usually coated with a conducting material known as aquadag and this coating is electrically connected to the accelerating anode. The coating is provided in order to accelerate the electron beam after passing between the deflecting plates and

to collect the electrons produced by secondary emission when electron beam strikes the screen. Thus the coating prevents the formation of – ve charge on the screen and state of equilibrium of screen is maintained. Horizontal and vertical marks are marked on the screen of the CRT to provide user a correct measurement. These marks, usually in rectangular form, are called graticule.

Position Controls.

There are two knobs — one for controlling the horizontal position and another for controlling the vertical position. The spot can be moved to left or right i.e. horizontally with the help of a knob. Similarly the spot can be moved up and down i.e. vertically with the help of another knob.

Types of cro

Dual-beam oscilloscope

The dual-beam analog oscilloscope can display two signals simultaneously. A special dual-beam CRT generates and deflects two separate beams. Although multi-trace analog oscilloscopes can simulate a dual-beam display with chop and alternate sweeps, those features do not provide simultaneous displays.

Analog storage oscilloscope

Trace storage is an extra feature available on some analog scopes; they used direct-view storage CRTs. Storage allows the trace pattern that normally decays in a fraction of a second to remain on the screen for several minutes or longer. An electrical circuit can then be deliberately activated to store and erase the trace on the screen.

Digital oscilloscopes

While analog devices make use of continually varying voltages, digital devices employ binary numbers which correspond to samples of the voltage. In the case of digital oscilloscopes, an analog-to-digital converter (ADC) is used to change the measured voltages into digital information.

RESULT:

Thus, cro was studied successfully.

Types of waveform:

Block diagram of cro

CHARACTERISTICS OF PN JUNCTION DIODE

EXPT. NO. : 3 DATE :

AIM

To observe and draw the Forward and Reverse bias V-I Characteristics of a

P-N Junction diode

APPARATUS Required:

THEORY

SL No. COMPONENT SPECIFICATION QTY

1. P-N Diode IN4007 1

2. Regulated Power supply (0-30)V 1

3. Resistor 470KΩ 1

4. Ammeters(0-100 mA),(0-500mA)

1

5. Voltmeter (0-15)V 1

6. Bread board - 1

7. Connecting wires - -

P-N Junction diode

A p-n junction diode conducts only in one direction. The V-I characteristics of the diode are 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 positive terminal and n- type (cathode) is connected to negative terminal of the supply voltage, is known as forward bias. The potential barrier is reduced when 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 positive terminal and P-type (Anode) is connected negative terminal of the supply voltage are 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 due to minority charge carriers.

PROCEDURE FOR FORWARD BIAS and REVERSE BIAS OF DIODE

1. Connections are made as per the circuit diagram.2. For forward bias, the RPS positive is connected to the anode of the diode and RPS negative is connected to the cathode of the diode,3. For reverse bias, the RPS positive is connected to the cathode of the diode and RPS negative is connected to the anode of the diode.4. Switch on the power supply and increases the input voltage (supply voltage) in steps.5. Note down the corresponding current flowing through the diode and voltage

across the diode for each and every step of the input voltage.6. The reading of voltage and current are tabulated.7. Graph is plotted between voltage and current.

MODEL WAVEFORM FOR PN JUNCTION DIODE (FORWARD AND

REVERSE BIAS)

CIRCUIT DIAGRAM OF FORWARD BIASED PN JUNCTION DIODE

CIRCUIT DIAGRAM OF REVERSE BIASED PN JUNCTION DIODE

Tabulation:

FORWARD BIAS: REVERSE BIAS:

S.NOVOLTAGE

(v)

CURRENT

(in mA)S.NO

VOLTAGE

(v)

CURRENT

(in mA)

RESULT

Thus the Forward and Reverse bias V-I Characteristics of diodes was drawn and the biasing

voltage was found at

Forward bias: ……………………..v

Reverse bias:…………………..….v

CHARACTERISTICS OF ZENER DIODE

EXPT. NO. : 4 DATE :

AIM

To determine the breakdown voltage of a Zener diode

APPARATUS REQUIRED:

THEORY

Zener diode

SL No. COMPONENT SPECIFICATION QTY

1. Zener diode IN4735A 1

2. Regulated Power supply (0-30)V 1

3. Resistor 470 Ω, 1k Ω 1

4. Ammeters(0-500) μA,(0-20)mA 1

5. Voltmeter (0-20v) 1

6. Bread board - 1

7. Connecting wires - -

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.

CIRCUIT DIAGRAM OF FORWARD BIASED ZENER DIODE

CIRCUIT DIAGRAM OF REVERSE BIASED ZENER DIODE

MODEL WAVEFORM FOR ZENER DIODE (FORWARD AND REVERSE

BIAS)

PROCEDURE FOR FORWARD BIAS and reverse bias OF DIODE

1. Connections are made as per the circuit diagram.

2. For forward bias, the RPS positive is connected to the anode of the diode and RPS negative is connected to the cathode of the diode.3. For reverse bias, the RPS positive is connected to the cathode of the diode and RPS negative is connected to the anode of the diode.4. Switch on the power supply and increases the input voltage (supply voltage) in steps.5. Note down the corresponding current flowing through the diode and voltage

across the diode for each and every step of the input voltage.6. The reading of voltage and current are tabulated.7. Graph is plotted between voltage and current.

RESULT

Thus the Forward and Reverse bias V-I Characteristics of zener diodes was drawn

and the biasing voltage was found.

OBSERVATION FOR FORWARD BIAS OF ZENER JUNCTION

S.NO R.P.S VOLTAGE (V) VOLTAGE (V) CURRENT

(mA)

OBSEVATION FOR REVERSE BIAS OF ZENER JUNCTION

S.NO R.P.S VOLTAGE

(V)

VOLTAGE

(V)

CURRENT (mA)

TRANSISTOR AS SWITCH

EXPT. NO. : 5 DATE :

AIM:

To design a transistor as switch.

COMPONENTS REQUIRED:

SL NO. COMPONENT SPECIFICATION QTY

1. RPS (0-30)V 1

2. Transistor BC107 1

3. Resistors 275Ω, 90KΩ 1

4. LED - 1

5. Bread board - 1

6. Connecting wires -

PROCEDURE:

1. Connections are given as per the circuit diagram.2. First we fix Vcc=5V.3. Vary the voltage V1=(0-5)V , then check the LED.4. After 0.7 LED starts glowing5. 2V-lightly, greater than 2V-brightly.

CIRCUIT DIAGRAM:

TABULATION:

VOLTAGE(V)LED

Vcc Ve

LED OFF

LED ON

RESULT:

Thus the transistor is used to turn on and off led as a switch successfully.

CLIPPER

EXPT. NO. : 6 DATE :

AIM:

To construct negative and positive clipper and observe the output.

COMPONENTS REQUIRED: -

SL NO. COMPONENT SPECIFICATION QTY

1. CRO - 1

2. Function generator (0-3)MHz 1

3. Resistors 1KΩ

4. Diode In4007 1

5. Connecting wires - -

THEORY:

Clipper:

This circuit is basically a rectifier circuit, which clips the input waveform

according to the required specification. The diode acts as a clipper. There are

several clippers like positive clipper, negative clipper, etc. Depending upon the

connection of diode it can be classified as series and shunt.

CIRCUIT DIAGRAM OF:

POSITIVE CLIPPER NEGATIVE CLIPPER

MODEL GRAPH :

POSITIVE CLIPPER

NEGATIVE CLIPPER

PROCEDURE:

1. Connect the circuit as per the circuit diagram.2. Connect the cro across the two ends of resistor3. Change the position of the diode as in the diagram4. Observe the Output waveform and plot the graph

Tabulation:

Clipper Amplitude(volts) Time period(sec)

positive

negative

RESULT:

The clipper circuits were designed and implemented

CHARACTERISTICS OF COMMON COLLECTOR

CONFIGURATION USING BJT

EXPT. NO. : 7

DATE :

AIM

To draw the input and output characteristics of transistor connected in

Common collector (CC) configuration

APPARATUS

SL No. COMPONENTSPECIFICATIO

NQTY

1. Transistor BC 107 1

2.Regulated Power supply

(0-30)V 2

3. Resistor 1KΩ 2

4. Ammeters(0-500)mA,(0-30)mA

1

5. Voltmeter (0-20v) 2

6. Bread board - 1

7. Connecting wires - -

THEORY

A transistor is a three terminal device. The terminals are emitter, base, collector. In common collector configuration, input voltage is applied between base and collector terminals and output is taken across the collector and emitter terminals. Therefore the collector terminal is common to both input and output. The input characteristics resemble that of a forward biased diode curve. The output characteristics are drawn between IE and VCE .

CIRCUIT DIAGRAM OF COMMON COLLECTOR CONFIGURATION

OF A TRANSISTOR

PROCEDURE TO FIND

INPUT CHARACTERISTICS OF CC TRANSISTOR

1. Connect the circuit as per the circuit diagram.

2. For plotting the input characteristics the output voltage VCE is kept constant at 1V and for

different values of VBC. Note down the values of IB

3. Repeat the above step by keeping VCE at 2V.

4. Tabulate all the readings.

5. plot the graph between VBE and IB for constant VCE

OUTPUT CHARACTERISTICS OF CC TRANSISTOR

1. Connect the circuit as per the circuit diagram

2. For plotting the output characteristics the input current IB is kept constant at 40μA and

for different values of VCE note down the values of IE

3. repeat the above step by keeping IB at 60 μA

4. tabulate the all the readings

5. plot the graph between VCE and IE for constant IB

OBSERVATIONS FOR

INPUT CHARACTERISTICS OF CC TRANSISTOR

S.NOVCE = 1V VCE = 2V

VBC(V) IB(μA) VBC(V) IB(μA)

OUTPUT CHARACTERISTICS OF CC TRANSISTOR

S.NO IB = 40 μA IB = 60 μA

VCE(V) IE(mA) VCE(V) IEmA)

MODEL GRAPHS

INPUT CHARACTERISTICS OF CC TRANSISTOR:

OUTPUT CHARACTERISTICS OF CC TRANSISTOR

RESULT

Thus the input and output characteristics of a transistor in CC configuration

are drawn

CHARACTERISTICS OF COMMON EMITTER CONFIGURATION

USING BJT

EXPT. NO. : 8

DATE :

AIM

To draw the input and output characteristics of transistor connected in

Common Emitter (CE) configuration

APPARATUS

THEORY

A transistor is a three terminal device In common emitter configuration, input voltage is applied between base and emitter terminals and output is taken across the collector and emitter terminals. Therefore the emitter 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 unto 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 V CE is known as Knee voltage. The transistor always operated in the region above Knee voltage, IC is always constant and is approximately equal to IB.

CIRCUIT DIAGRAM OF COMMON EMITTER CONFIGURATION OF

A TRANSISTOR

SL No. COMPONENT SPECIFICATION QTY

1. Transistor BC 107 1

2. Regulated Power supply (0-30)V 2

3. Resistor 1KΩ 1

4. Ammeters(0-500)mA,(0-30)mA 1

5. Voltmeter (0-20v) 2

6. Bread board - 1

7. Connecting wires - -

PROCEDURE TO FIND

INPUT CHARACTERISTICS OF CE TRANSISTOR

1. Connect the circuit as per the circuit diagram.

2. For plotting the input characteristics the output voltage VCE is kept constant

at 3V and for different values of VBE. Note down the values of IC

3. Repeat the above step by keeping VCE at 7V.

4. Tabulate all the readings.

5. plot the graph between VBE and IB for constant VCE

OUTPUT CHARACTERISTICS OF COMMON EMITTER TRANSISTOR

1. Connect the circuit as per the circuit diagram

2. for plotting the output characteristics the input current IB is kept constant at

100μA and for different values of VCE note down the values of IC

3. repeat the above step by keeping IB at 300 μA

4. tabulate the all the readings

5. plot the graph between VCE and IC for constant IB

RESULT

Thus the input and output characteristics of a transistor in CE configuration

are drawn

OBSERVATIONS FOR

INPUT CHARACTERISTICS OF COMMON EMITTER TRANSISTOR

S.NOVCE = 5V VCE = 7V

VBE(V) IB(μA) VBE(V) IB(μA)

OUTPUT CHARACTERISTICS OF COMMON EMITTER TRANSISTOR

S.NOIB = 100 μA IB = 300 Μa

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

MODEL GRAPHS

INPUT CHARACTERISTICS OF COMMON EMITTER TRANSISTOR:

OUTPUT CHARACTERISTICS OF COMMON EMITTER TRANSISTOR

HALF – WAVE RECTIFIER

EXPT. NO. : 9 DATE :

AIM

To obtain the load regulation and ripple factor of a half-rectifier.

APPARATUS

THEORY

During positive half-cycle of the input voltage, the diode D1 is in forward bias and conducts through the load resistor R1. Hence the current produces an output voltage across the load resistor R1, which has the same shape as the positive 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 R1 is zero. The net result is that only the positive 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.

For practical circuits, transformer coupling is usually provided for two reasons.

1. The voltage can be stepped-up or stepped-down, as needed. 2. The ac source is electrically isolated from the rectifier. Thus preventing

shock hazards in the secondary circuit.

SL No. COMPONENT SPECIFICATION QTY

1. Diode 1N 4007 1

2. Transformer 6-0-6 1

3. Resistor 440Ω 1

4. Connecting wires

5. Experimental Board 1

CIRCUIT DIAGRAM OF HALF-WAVE RECTIFIER

PROCEDURE FOR HALF-WAVE RECTIFIER

1. Connections are made as per the circuit diagram.

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/П

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

The Ripple factor is calculated by using the formula

r=ac output voltage/dc output voltage.

Tabulation:

CALCULATIONS

Vrms = Vp/2

Vdc=Vp/П

Ripple factor r = R.M.S value of AC component/D.C value of the component

= √ (Vrms/ Vdc) 2 -1

Efficiency:

Peak Factor

Transformer Utilization Factor

Amplitude Time period

Transformer Utilization Factor, TUF can be used to determine the rating of a transformer secondary.

In half wave rectifier the rated voltage of the transformer secondary is

But actually the RMS current flowing through the winding is only .

Form Factor

Form factor is given by,

PRACTICAL CALCULATIONS OF HALF WAVE RECTFIER

Vrms=

Vdc=

Ripple factor=

RESULT

1. The Ripple factor for the Half-Wave Rectifier is measured.

2. The % regulation of the Half-Wave rectifier is calculated

FIELD EFFECT TRANSISTOR CHARACTERISTICS

EXPT. NO. : 10 DATE :

AIM

To draw the drain and transfer characteristics of a given Field Effect Transistor (

FET).

APPARATUS

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 response to 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 VDS at 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.

SL No. COMPONENT SPECIFICATION QTY

1. FET BFN101 1

2. Regulated Power supply (0-30)V 2

3. Resistor 1KΩ , 470Ω 1

4. Ammeters (0-30)mA 1

5. Voltmeter (0-20v) 2

6. Bread board - 1

7. Connecting wires - -

CIRCUIT DIAGRAM OF FIELD EFFECT TRANSISTOR

PROCEDURE TO FIND FET CHARACTERSTICS

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

2. To plot the drain characteristics, keep VGD constant at 1V.

3. Vary the VSS and observe the values of VDS and IS.

4. To plot the transfer characteristics, keep VDS constant at 0V.

5. Vary VGS and observe the values of VGS and IS.

6. The readings are tabulated.

RESULT

Thus the drain and transfer characteristics of Field effect transistor was drawn and the

characteristics are calculated.

OBSERVATIONS

DRAIN CHARACTERISTICS TRANSFER CHARACTERISTICS

VGD=1V VDS=0V

VDS(V) IS(mA) VGD(V) IS(mA)

MODEL GRAPH FOR

TRANSFER CHARACTERISTICS DRAIN CHARACTERISTICS

CLAMPER

EXPT. NO. : 11 DATE :

AIM:

To design and implement the clamper circuits.

COMPONENTS REQUIRED:

THEORY:

Clamper:The clamper circuit is a type of wave shaping circuit in which the DC level

of the input signal is altered. The DC voltage is varied accordingly and it is classified as positive clamper or negativeClamper accordingly.

SL NO. COMPONENTSPECIFICATION QTY

1. CRO (0-20M)Hz 1

2. Function generator - 1

3. Diode IN4007 1

4. Resistors 1KΩ, 100KΩ

5. Capacitors 0.1μf

6. Connecting wires - -

CIRCUIT DIAGRAM OF:

POSITIVE CLAMPER NEGATIVE CLAMPER

MODEL GRAPH FOR:

POSITIVE CLAMPER NEGATIVE CLAMPER

PROCEDURE:

1. Connect the circuit as per the circuit diagram.2. Connect the cro across the two ends of resistor3. Change the position of the diode as in the diagram4. Observe the Output waveform and plot the graph

TABULATION

Clamper Amplitude(volts) Time period(sec)

positive

negative

RESULT:

The clamper circuits were designed and implemented

CHARACTERISTICS OF COMMON -BASE CONFIGURATION

USING BJT

EXPT. NO. : 12 DATE :

AIM

To observe and draw the input and output characteristics of a transistor

connected in common base (CB) configuration.

APPARATUS

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 (emitter) and output (collector). For normal operation, the E-B junction is forward biased and C-B junction is reverse biased.

In CB configuration, IE is positive IC is negative and IB is negative. 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 within the base region, the current of minority carriers injected across the emitter junction increases. The current amplification factor of CB configuration is given by,

α= ∆IC/ ∆IE

SL No. COMPONENT SPECIFICATION QTY

1. Transistor BC 107 1

2. Regulated Power supply (0-30)V 2

3. Resistor 1KΩ 1

4. Ammeters (0-100mA) 1

5. Voltmeter (0-20v) 2

6. Bread board - 1

7. Connecting wires - -

CIRCUIT DIAGRAM OF COMMON BASE CONFIGURATION OF A

TRANSISTOR

PROCEDURE TO FIND

INPUT CHARACTERISTICS OF COMMON BASE TRANSISTOR

1. Connections are made as per the circuit diagram.2. For plotting the input characteristics, the output voltage VCE is kept constant at 0V and for different values of VEB note down the values of IE.3. Repeat the above step keeping VCB at 2V, 4V, and 6V.All the readings is tabulated.4. A graph is drawn between VEB and IE for constant VCB.

OUTPUT CHARACTERISTICS OF COMMON BASE TRANSISTOR

1. Connections are made as per the circuit diagram.2. For plotting the output characteristics, the input IE is kept constant at 10m A

and for different values of VCB, note down the values of IC.

3. Repeat the above step for the values of IE at 20 mA, 40 mA, and 60 mA, all the readings are tabulated.

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

OBSERVATIONS FOR

INPUT CHARACTERISTICS OF COMMON BASE TRANSISTOR

S.No VCB=0V VCB=1V

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

OUTPUT CHARACTERISTICS OF COMMON BASE TRANSISTOR

S.No

IE=10mA IE=20mA

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

MODEL GRAPHS

INPUT CHARACTERISTICS OF COMMON BASE TRANSISTOR

OUTPUT CHARACTERISTICS OF COMMON BASE TRANSISTOR

RESULT

Thus the input and output characteristics of a Common-base configuration

transistor was drawn.