LICA LAB - Raghu Institute of Technology

RAGHU INSTITUTE OF TECHNOLOGY

Dakamarri(vill), Bheemunipatnam Mandal,

Visakhapatnam Dist, Andhra Pradesh, PIN- 531162

(Approved by AICTE, New Delhi, and Affiliated to Jawaharalal Nehru Technological University: Kakinada(AP)

2015-2016

III B.Tech ECE: 1 st

Semester

LABORATORY MANUAL

For

LINEAR INTEGRATED CIRCUIT APPLICATIONS LAB

Student Manual

Prepared by

A.Sai Ramya, M.Tech

Assistant Professor

DEPARTMENT OF

ELECTRONICS & COMMUNICATION ENGINEERING

RAGHU INSTITUTE OF TECHNOLOGY

(Affiliated to JNTU-KAKINADA)

Visakhapatnam-531162

CERTIFICATE

Name of the Laboratory : Linear Integrated Circuit Applications

Name of the Faculty : Miss.A.Sai Ramya

Department : Electronics and Communication Engineering

Program : B.Tech

Year : III Year

Semester : I Semester

IQAC Members

Name :

Signature(s) :

HOD - ECE

CONTENTS

S.NO

1.

Course Description

2.

General Instructions

3.

Additional Instructions

4.

University Syllabus

DESCRIPTION

5.

List of Experiments

6.

Cycle-Wise List of Experiment

7.

Study of op amp IC-741,IC555,IC565,IC566,IC1496-functioning,parameters and specifications.

8.

Op-amp applications-adder, subtractor, comparator circuits.

PAGE NO i v vii viii ix x

1

12

9.

Integrator, differentiator circuits using IC 741. 17

10.

Active Filter Applications – LPF, HPF (first order) 24

11.

Active Filter Applications – BPF & Band Reject (Wideband and Notch Filters)

38 12.

Wein Bridge Oscillaor

13.

Function Generator using Op-Amps 42

46 14.

IC 555 Timer-Astable Operation Circuit

15.

IC 555 Timer - Monostable Operation Circuit

16.

IC 565- PLL Applications

50

54

57 17.

Schmitt Trigger Circuits- using IC 741 & IC 555

18.

IC 566 – VCO Applications

19.

Voltage Regulator using IC723

20.

Three Terminal Voltage Regulators- 7805, 7809, 7912

21.

4 bit DAC using Op-Amp

ADDITIONAL EXPERIMENTS

22.

Voltage- to- Current Converter

61

65

69

76

81

86 23.

Precision Rectifier

24.

Clipper Circuits using IC 741

25.

Appendix-A

89

94

26.

Appendix-B

27.

Reference

95

96

Department of Electronics & Communication Engg. LICA LAB

COURSE DESCRIPTION

Course Context and Overview:

The course consists of laboratory tasks dealing with different types of Analog IC , timers and regulators . It is a credit based laboratory course designed as a supplement to the

Linear Integrated Circuit Applications theory course. Primary emphasis is placed on practical performance of Circuits which are designed by analog IC’s. Practical information relating to

Input and Output characteristics are studied. Laboratory experiments are conducted to reinforce theory and to provide practical experience with analog IC’s , timers and Regulators.

The course covers practical experiments on different Applications of Analog IC’s.

Course Prerequisites:

Pulse and Digital Circuits

Literature:

Faculty Manual

Books Recommended:

Text Books:

1. Linear Integrated Circuits – D. Roy Chowdhury, New Age International (p) Ltd, 2nd

Edition,2003.

2. Op-Amps & Linear ICs - Ramakanth A. Gayakwad, PHI,1987.

Reference Books:

1. Design with Operational Amplifiers & Analog Integrated Circuits - Sergio Franco,

McGraw Hill, 1988.

2. Operational Amplifiers & Linear Integrated Circuits–R.F.Coughlin & Fredrick Driscoll,

PHI, 6th Edition.

3. Micro Electronics – Millman, McGraw Hill,1988.

4. Operational Amplifiers – C.G. Clayton, Butterworth & Company Publ. Ltd./ Elsevier,

1971.

Programme Educational Objectives:

PEO No.

Programme Educational Objectives

PEO 1 Our graduates will be productive in the professional practice and obtain employment.

PEO 2

PEO 3

Our Graduates will function effectively as individual and within a team with good leadership qualities.

Our Graduates will recognize the need for continuous self-improvement and with good moral values.

Raghu Institute of Technology, Dakamarri, Visakhapatnam

Page i


Programme Outcomes:

PO No.

Programme Outcomes a b c an ability to apply knowledge of mathematics, science and engineering an ability to design and conduct experiments, as well as to analyze and interpret data an ability to design a system, component, or process to meet desired needs within realistic constraints such as economic, environmental, social, political, ethical, health and safety, d g h k l i e f j an ability to identify, formulate, and solve engineering problems an ability to understanding of professional and ethical responsibility an ability to communicate effectively the broad education necessary to understand the impact of engineering solutions in a global, economic, environmental, and societal context a recognition of the need for, and an ability to engage in life-long learning a knowledge of contemporary issues an ability to use the techniques, skills, and modern engineering tools necessary for engineering practice an ability to implement MATLAB, Embedded systems design for electronics and communications engineering applications.

Course Objectives :

To expose the students to know about different Applications of Analog IC’s of IC-741, IC-

555 timer with experimental experience and also to impart industry oriented learning.

Course Outcomes:

S.No Course Outcomes

1 Gains knowledge in IC Design

2 Gains knowledge in Op-Amp and its Applicaitons

3 Gains knowledge in design of function generator using Op-Amp

4 Gains Knowledge in design of Voltage regulators and PLL.

Mapping of Course Outcomes to Programme Outcomes and Programme Educational

Objectives:

S.No

1

Course Outcomes

Student Gains knowledge in IC Design

Programme

Outcomes

B

Programme

Educational

Objectives

PEO I


Page ii


2 Student Gains knowledge in Op-Amp and its Applicaitons

3

4

Student Gains knowledge in design of function generator using Op-Amp

Student Gains Knowledge in design of Voltage regulators and

PLL.

Assessment Strategy:

B

B

B

PEO I

PEO I

PEO I

A variety of learning strategies are used throughout the course.

S.No

1

2

3

Teaching Learning and Assessment Strategy

Classroom Demonstration by Faculty In-charge through different Teaching

4

5

Student- Faculty In charge Discussion

Collaborative and Co-operative learn

Independent student study and Practice

Evaluation of Marks for the Laboratory Exam

Internal Marks - 25

For Laboratory courses there should be continuous evaluation during the semester for 25

Internal Marks. The distribution of Internal Marks is given below.

Serial No Criteria Marks

1

2

3

Day to Day Work

Record

Internal Examination

10

5

10

Total Marks 25

External Lab Exam - 50

Each semester end lab Examination shall be evaluated by an External Examiner along with an

Internal Examiner.


1

2

Pre practical

Practical

30

10

3

4

Post practical

Viva

10

10

Total Marks 50

Total Lab Exam Marks - 75

Each semester Total Final lab Examination marks is the sum of marks obtained in both internal and external Exams.


1 Internal 25


Page iii


2 External

Total Marks

50

75


Page iv


GENERAL INSTRUCTIONS

SAFETY:

1.

When students are doing experiment they have to be very care full.

2.

Students should have the prior knowledge about the lab they are doing.

3.

If any kind of wrong thing happened while doing the experiment. Students have to immediately switch off power supply on the work table.

4.

Wearing loose garments inside the lab is strictly prohibited .

ATTENDANCE:

1.

Students have to come to the laboratory with proper dress code and ID Cards.

2.

Students have to bring Observation note book , Record note book and calculators etc.. to the Laboratory.

3.

Students have to sign in the log register after entering into the lab and before leaving the laboratory.

4.

Students have to show their observations with results after completion of their experiments and they have to get is signed.

5.

After completion of experiment students have to submit their completed records to the faculty of their lab with in a week.

DOING EXPERIMENTS:

1.

Start the experiment as per the procedure.

2.

Enter all readings in the tabulation.

3.

Do not make any interconnections on the bread board when power is switched ON.

4.

Take readings without any parallax error.

5.

If any of the things are wrong, then switch off and modify the connections. Inform to the staff and then START.

CALCULATION:

Calculate all required quantities and enter in the tabulation. Units are very, very important.

Draw the necessary graphs. Write the result. Show it to the staff for getting Signature.


Page v


RECORD:

1.

As the name Implies, it is a record: permanent record for reference. Write neatly; Draw circuit diagrams neatly and label correctly.

2.

Enter readings in the tabulation.

3.

Draw Graph. Complete the record before you come for next lab class.

4.

Bring the record for submission during next lab class.


Page vi


ADDITIONAL INSTRUCTIONS

1.

Before entering into the laboratory class, you must be well prepared for the experiment that you are going to do on that day.

2.

You must bring the related textbook, which may deal with the relevant experiment.

3.

Get the circuit diagram and block diagram without any wrong connections.

4.

Get the reading verified. Then inform the technician so that supply to the worktable can be switched off.

5.

You must get the observation note corrected within two days from the date of completion of experiment.

6.

Write the answer for all the discussion questions in the observation note. If not, marks for concerned observation will be proportionately reduced.

7.

If you miss any practical class due to unavoidable reasons, intimate the staff in charge and do the missed experiment in the repetition class.

8.

Such of those students who fail to put in a minimum of 75% attendance in the laboratory class will run the risk of not being allowed for the University Practical Examination. They will have to repeat the lab course in subsequent semester after paying prescribed fee.

9.

Acquire a good knowledge of the surrounding of your worktable. Know where the various live points are situated in your table.

10.

In case of any unwanted things happening, immediately switch off the mains in the worktable. The same must be done when there is a power break during the experiment being carried out .


Page vii


LIST O F EXPERI MENTS RECO MMENDED BY JNT U KAKI NADA

JAWAHARLAL TECHNOLOGICAL UNIVERSITY KAKINADA

ELECTRONICS AND COMMUNICATION ENGINEERING

III Year B.Tech ECE I Semester T P C

0 3 2

Minimum Twelve Experiments to be conducted :

1. Study of OP AMPs – IC 741, IC 555, IC 565, IC 566, IC 1496 – functioning,

parameters and Specifications

2. OP AMP Applications – Adder, Subtractor, Comparator Circuits.

3. Integrator and Differentiator Circuits using IC 741.

4. Active Filter Applications – LPF, HPF (first order)

5. Active Filter Applications – BPF, Band Reject (Wideband) and Notch Filters.

6. IC 741 Oscillator Circuits – Phase Shift and Wien Bridge Oscillators.

7. Function Generator using OP AMPs.

8. IC 555 Timer – Monostable Operation Circuit.

9. IC 555 Timer – Astable Operation Circuit.

10. Schmitt Trigger Circuits – using IC 741 and IC 555.

11. IC 565 – PLL Applications.

12. IC 566 – VCO Applications.

13. Voltage Regulator using IC 723.

14. Three Terminal Voltage Regulators – 7805, 7809, 7912.

15. 4 bit DAC using OP AMP.

Equipment required for Laboratories:

1. RPS

2. CRO

3. Function Generator

4. Multi Meters

5. IC Trainer Kits (Optional)

6. Bread Boards

7. Components:- IC741, IC555, IC565, IC1496, IC723, 7805, 7809, 7912 and other

Essential components.

8. Analog IC Tester


Page viii


List of Experiment

1.Study of OP AMPs – IC 741, IC 555, IC 565, IC 566, IC 1496 – functioning, .













Additional Experiments:

13. Voltage- to- Current Converter

14. Clipper Circuits using IC 741


Page ix


CYCLE-WISE L IST O F E XPE RI MENT S

CYCLE – I : i.Study of OP AMPs – IC 741, IC 555, IC 565, IC 566, IC 1496 – functioning, .








CYCLE – II :






12. Voltage- to- Current Converter

13. Clipper Circuits using IC 741


Page x

Department of Electronics & Communication Engineering LICA lab

1. STUDY OF OP AMPS - IC 741, IC 555, IC 565, IC 566,

IC 1496-FUNCTIONING, PARAMETERS AND SPECIFICATIONS

IC 741

General Description:

The IC 741 is a high performance monolithic operational amplifier constructed using the planer epitaxial process. High common mode voltage range and absence of latch-up tendencies make the IC 741 ideal for use as voltage follower. The high gain and wide range of operating voltage provide superior performance in integrator, summing amplifier and general feed back applications.

Block Diagram of Op-Amp:

Pin Configuration:

Raghu Institute of Technology, Dakamarri , Visakhapatnam 1


Features:

1.

No frequency compensation required.

2.

Short circuit protection

3.

Offset voltage null capability

4.

Large common mode and differential voltage ranges

5.

Low power consumption

6.

No latch-up

Specifications:

1.

Voltage gain A = α typically 2,00,000

2.

I/P resistance R

L

= α Ω, practically 2MΩ

3.

O/P resistance R =0, practically 75Ω

4.

Bandwidth = α Hz. It can be operated at any frequency

5.

Common mode rejection ratio = α

(Ability of op amp to reject noise voltage)

6.

Slew rate + α V/μsec

(Rate of change of O/P voltage)

7.

When V

1

= V

2

, V

D

=0

8.

Input offset voltage (Rs ≤ 10KΩ) max 6 mv

9.

Input offset current = max 200nA

10.

Input bias current : 500nA

11.

Input capacitance : typical value 1.4pF

12.

Offset voltage adjustment range : ± 15mV

13.

Input voltage range : ± 13V

14.

Supply voltage rejection ratio : 150 μV/V

15.

Output voltage swing: + 13V and – 13V for R

L

> 2KΩ

16.

Output short-circuit current: 25mA

17.

supply current: 28mA

18.

Power consumption: 85mW

19.

Transient response: rise time= 0.3 μs

Overshoot= 5%



Applications:

1.

AC and DC amplifiers

2.

Active filters

3.

Oscillators

4.

Comparators

5.

Regulators

IC 555:

Description:

The operation of SE/NE 555 timer directly depends on its internal function. The three equal resistors R

1

, R

2

, R

3

serve as internal voltage divider for the source voltage. Thus onethird of the source voltage V

CC

appears across each resistor.

Comparator is basically an Op-amp which changes state when one of its inputs exceeds the reference voltage. The reference voltage for the lower comparator is +1/3 V

CC

.

If a trigger pulse applied at the negative input of this comparator drops below +1/3 V

CC

, it causes a change in state. The upper comparator is referenced at voltage +2/3 V

CC

. The output of each comparator is fed to the input terminals of a flip flop.

The flip-flop used in the SE/NE 555 timer IC is a bistable multivibrator. This flip flop changes states according to the voltage value of its input. Thus if the voltage at the threshold terminal rises above +2/3 V

CC

, it causes upper comparator to cause flip-flop to change its states. On the other hand, if the trigger voltage falls below +1/3 V

CC

, it causes lower comparator to change its states. Thus the output of the flip flop is controlled by the voltages of the two comparators. A change in state occurs when the threshold voltage rises above +2/3 V

CC

or when the trigger voltage drops below +1/3 V cc

.

The output of the flip-flop is used to drive the discharge transistor and the output stage. A high or positive flip-flop output turns on both the discharge transistor and the output stage. The discharge transistor becomes conductive and behaves as a low resistance short circuit to ground. The output stage behaves similarly. When the flip-flop output assumes the low or zero states reverse action takes place i.e., the discharge transistor behaves as an open circuit or positive V

CC

state. Thus the operational state of the discharge transistor and the output stage depends on the voltage applied to the threshold and the trigger input terminals.



Block Diagram of IC 555:

Pin Configuration :

Function of Various Pins of 555 IC:

Pin (1) of 555 is the ground terminal; all the voltages are measured with respect to this pin.

Pin (2) of 555 is the trigger terminal, If the voltage at this terminal is held greater than onethird of V

CC

, the output remains low. A negative going pulse from V cc

to less than V ec

/3 triggers the output to go High. The amplitude of the pulse should be able to make the comparator (inside the IC) change its state. However the width of the negative going pulse must not be greater than the width of the expected output pulse.



Pin (3) is the output terminal of IC 555. There are 2 possible output states. In the low output state, the output resistance appearing at pin (3) is very low (approximately 10 Ω). As a result the output current will goes to zero , if the load is connected from Pin (3) to ground , sink a current I

Sink

(depending upon load) if the load is connected from Pin (3) to ground, and sinks zero current if the load is connected between +V

CC

and Pin (3).

Pin (4) is the Reset terminal. When unused it is connected to +V cc

. Whenever the potential of Pin (4) is drives below 0.4V, the output is immediately forced to low state. The reset terminal enables the timer over-ride command signals at Pin (2) of the IC.

Pin (5) is the Control Voltage terminal.This can be used to alter the reference levels at which the time comparators change state. A resistor connected from Pin (5) to ground can do the job. Normally 0.01μF capacitor is connected from Pin (5) to ground. This capacitor bypasses supply noise and does not allow it affect the threshold voltages.

Pin (6) is the threshold terminal. In both astable as well as monostable modes, a capacitor is connected from Pin (6) to ground. Pin (6) monitors the voltage across the capacitor when it charges from the supply and forces the already high O/p to Low when the capacitor reaches

+2/3 V

CC

.

Pin (7) is the discharge terminal. It presents an almost open circuit when the output is high and allows the capacitor charge from the supply through an external resistor and presents an almost short circuit when the output is low.

Pin (8) is the +V cc

terminal. 555 can operate at any supply voltage from +3 to +18V.

Features of 555 IC:

1.

The load can be connected to o/p in two ways i.e. between pin 3 & ground 1 or between pin 3 & V

CC

(supply)

2.

555 can be reset by applying negative pulse, otherwise reset can be connected to +V cc

to avoid false triggering.

3.

An external voltage effects threshold and trigger voltages.

4.

Timing from micro seconds through hours.

5.

Monostable and bistable operation

6.

Adjustable duty cycle

7.

Output compatible with CMOS, DTL, TTL

8.

High current output sink or source 200mA

9.

High temperature stability

10.

Trigger and reset inputs are logic compatible.



Specifications:

1.

Operating temperature : SE 555-- -55 o

C to 125 o

C

NE 555-- 0 o

to 70 o

C

2.

Supply voltage

3.

Timing

:

:

4.

Sink current :

5.

Temperature stability :

+5V to +18V

μSec to Hours

200mA

50 PPM/ o

C change in temp or 0-005% / o

C.

Applications:

1.

Monostable and Astable Multivibrators

2.

dc-ac converters

3.

Digital logic probes

4.

Waveform generators

5.

Analog frequency meters

6.

Tachometers

7.

Temperature measurement and control

8.

Infrared transmitters

9.

Regulator & Taxi gas alarms etc.

IC 565:

Description:

The Signetics SE/NE 560 series is monolithic phase locked loops. The SE/NE 560, 561, 562,

564, 565, & 567 differ mainly in operating frequency range, power supply requirements and frequency and bandwidth adjustment ranges. The device is available as 14 Pin DIP package and as 10-pin metal can package. Phase comparator or phase detector compare the frequency of input signal f s

with frequency of VCO output f o

and it generates a signal which is function of difference between the phase of input signal and phase of feedback signal which is basically a d.c voltage mixed with high frequency noise. LPF remove high frequency noise voltage. Output is error voltage. If control voltage of VCO is 0, then frequency is center frequency (f o

) and mode is free running mode. Application of control voltage shifts the output frequency of VCO from f o

to f. On application of error voltage, difference between f s

& f tends to decrease and VCO is said to be locked. While in locked condition, the PLL tracks the changes of frequency of input signal.



Block Diagram of IC 565:


Specifications:

1.

Operating frequency range

2.

Operating voltage range

3.

Inputs level required for tracking

:

:

:

4.

Input impedance

5.

Output sink current

6.

Drift in VCO center frequency

:

0.001 Hz to 500 KHz

±6 to ±12V

10mV rms minimum to 3v (p-p) max.

10 KΩ typically

:

:

1mA typically

300 PPM/ o

C typically



(f out

) with temperature

7.

Drif in VCO centre frequency with : 1.5%/V maximum supply voltage

8.

Triangle wave amplitude

9.

Square wave amplitude

10.

Output source current

11.

Bandwidth adjustment range

:

:

:

: typically 2.4 V

PP

at ± 6V typically 5.4 V

PP

at ± 6V

10mA typically

<±1 to >± 60%

Center frequency f out

= 1.2/4R

1

C

1

Hz

= free running frequency

F

L

= ± 8 f out

/V Hz

V = (+V) – (-V) f c

= ±



 f

L

2



( 3 .

6 ) x 10

3 xC 2



1 / 2

Applications:

1.

Frequency multiplier

2.

Frequency shift keying (FSK) demodulator

3.

FM detector

IC 566:

Description:

The NE/SE 566 Function Generator is a voltage controlled oscillator of exceptional linearity with buffered square wave and triangle wave outputs. The frequency of oscillation is determined by an external resistor and capacitor and the voltage applied to the control terminal. The oscillator can be programmed over a ten to one frequency range by proper selection of an external resistance and modulated over a ten to one range by the control voltage with exceptional linearity.



Block Diagram of IC566:

Pin diagram:

Specifications:

Maximum operating Voltage --- 26V

Input voltage

Storage Temperature

Operating temperature

--- 3V (P-P)

--- -65 o

C to + 150 o

C

--- 0 o

C to +70 o

C for NE 566

-55 o

C to +125 o

C for SE 566

Power dissipation --- 300mv



Applications:

1.

Tone generators.

2.

Frequency shift keying

3.

FM Modulators

4.

clock generators

5.

signal generators

6.

Function generator

IC 1496

Description:

IC balanced mixers are widely used in receiver IC’s. The IC versions are usually described as balanced modulators. Typical example of balanced IC modulator is MC1496.

The circuit consists of a standard differential amplifier (formed by Q

5

_ Q

6

combination) driving a quad differential amplifier composed of transistor Q

1

– Q

4

. The modulating signal is applied to the standard differential amplifier (between terminals 1 and 4). The standard differential amplifier acts as a voltage to current converter. It produces a current proportional to the modulating signal. Q

7

and Q

8

are constant current sources for the differential amplifier

Q

5

– Q

6

. The lower differential amplifier has its emitters connected to the package pins ( 2 &

3) so that an external emitter resistance may be used. Also external load resistors are employed at the device output (6 and 12 pins).The output collectors are cross-coupled so that full wave balanced multiplication takes place. As a result, the output voltage is a constant times the product of the two input signals.

Schematic of IC1496:




Applications of MC 1496: a) Balanced modulator b) AM Modulator c) Product Modulator d) AM Detector e) Mixer f) Frequency Doublers.



2. OP AMP APPLICATIONS – ADDER, SUBTRACTOR,

COMPARATOR CIRCUITS

Aim: To design adder, subtractor and comparator for the given signals by using operational amplifier.

Apparatus required:

S.No

1

2

3

Equipment/Component name

IC 741

Resistor

Regulated Power supply

Specifications/Value

Refer page no 2

1kΩ

(0 – 30V),1A

Quantity

1

4

2

4

5

6

Function Generator

Cathode Ray Oscilloscope

Multimeter

(.1 – 1MHz), 20V p-p

(0 – 20MHz)

3

½ digit display

1

1

1

Theory:

Adder : A two input summing amplifier may be constructed using the inverting mode. The adder can be obtained by using either non-inverting mode or differential amplifier. Here the inverting mode is used. So the inputs are applied through resistors to the inverting terminal and non-inverting terminal is grounded. This is called “virtual ground”, i.e. the voltage at that terminal is zero. The gain of this summing amplifier is 1, any scale factor can be used for the inputs by selecting proper external resistors.

Subtractor: A basic differential amplifier can be used as a subtractor as shown in the circuit diagram. In this circuit, input signals can be scaled to the desired values by selecting appropriate values for the resistors. When this is done, the circuit is referred to as scaling amplifier. However in this circuit all external resistors are equal in value. So the gain of amplifier is equal to one. The output voltage V o

is equal to the voltage applied to the noninverting terminal minus the voltage applied to the inverting terminal; hence the circuit is called a subtractor.

Comparator: The circuit diagram shows an op-amp used as a comparator. A fixed reference voltage V ref

is applied to the (-) input, and the other time – varying signal voltage V in

is applied to the (+) input; Because of this arrangement, the circuit is called the non-inverting comparator. Depending upon the levels of V in

and V ref

, the circuit produces output. In short,


Department of Electronics & Communication Engineering LICA lab the comparator is a type of analog-to-digital converter. At any given time the output waveform shows whether V in

is greater or less than V ref

. The comparator is sometimes also called a voltage-level detector because, for a desired value of V ref

, the voltage level of the input V in

can be detected

Circuit Diagrams:

Fig 1: Adder

Fig 2: Subtractor



Fig 3: Comparator

Procedures:

A) Adder:

1.

Connect the circuit as per the diagram shown in Fig 1.

2.

Apply the supply voltages of +15V to pin7 and pin4 of IC741 respectively.

3.

Apply the inputs V

1

and V

2

as shown in Fig 1.

4.

Apply two different signals (DC/AC ) to the inputs

5.

Vary the input voltages and note down the corresponding output at pin 6 of the IC 741 adder circuit.

6.

Notice that the output is equal to the sum of the two inputs.

B) Subtractor :

1. Connect the circuit as per the diagram shown in Fig 2.

2. Apply the supply voltages of +15V to pin7 and pin4 of IC741 respectively.

3 Apply the inputs V

1

and V

2

as shown in Fig 2.

4. Apply two different signals (DC/AC ) to the inputs

5. Vary the input voltages and note down the corresponding output at pin 6 of the IC

741 subtractor circuit.

6. Notice that the output is equal to the difference of the two inputs.

C) Comparator:

1.

A fixed reference voltage V ref

is applied to the (-) input, and to the other input a varying voltage V in

is applied as shown in Fig 3.

2.

Vary the input voltage above and below the V ref

and note down the output at pin 6 of 741

IC.



3.

Observe that, when V in

is less than V ref

, the output voltage is -V sat

(



- V

EE

) when V in

is greater than V ref

, the output voltage is +V sat

(



+V

CC

)

Observations:

Adder:

V

1

(V) V

2

(V) V o

(V)

Subtractor:

V

1

(V) V

2

(V) V o

(V)

Comparator:

V in

(V) V ref

(V) V o

(V)

Model Calculations: a) Adder

V o

= - (V

1

+ V

2

)

If V

1

= 2.5V and V

2

= 2.5V, then

V o

= - (2.5+2.5) = -5V. b) Subtractor

V o

= V

2

– V

1

If V

1

=2.5 and V

2

= 3.3, then

V o

= 3.3 – 2.5 = 0.8V


Department of Electronics & Communication Engineering LICA lab c) Comparator

If V in

< V ref

, V o

= -V sat



- V

EE

V in

> V ref

, V o

= +V sat

= +V

CC

Precautions:

Check the connections before giving the power supply.

Readings should be taken carefully.

Result:

Inference:

Different applications of opamp are observed.

Questions & Answers:

1.

What is the saturation voltage of 741 in terms of V

CC

?

2.

What is the maximum voltage that can be given at the inputs?

.



3. INTEGRATOR AND DIFFERENTIATOR CIRCUITS USING IC 741

Aim: To design and verify the operation of an integrator and differentiator for a given input.


S.No Equipment/Component name Specifications/Value

1

2

3

741 IC

Capacitor

Resistors

Refer page no 2

0.1μf

Quantity

1

1

1KΩ, 1KΩ ,1MΩ , 100KΩ Each one

4 Regulated Power supply (0 – 30)V,1A 1

5

6

Function generator (1Hz – 1MHz)

Cathode Ray Oscilloscope (0 – 20MHz)

1

1

Theory:

Integrator: In an integrator circuit, the output voltage is integral of the input signal. The t output voltage of an integrator is given by V o

= -1/R

1

C f



Vidt o

At low frequencies the gain becomes infinite, so the capacitor is fully charged and behaves like an open circuit. The gain of an integrator at low frequency can be limited by connecting a resistor in shunt with capacitor.

Differentiator: In the differentiator circuit the output voltage is the differentiation of the input voltage. The output voltage of a differentiator is given by V o

= -RfC

1 dV i dt

.The input impedance of this circuit decreases with increase in frequency, thereby making the circuit sensitive to high frequency noise. At high frequencies circuit may become unstable.




Fig 1: Integrator

Assume C f

and find R f

Select R f

= 10R

1



1

V o (p-p)

=

R

1

C f

T



/ 2 o

V i ( p

 p ) dt

Fig 2: Differentiator

Design equations:

Integrator:

Choose T = 2πR f

C f

Where T= Time period of the input signal



Differentiator:

Select given frequency f a

= 1/(2πR f

C

1

), Assume C

1

and find R f

Select f b

= 10 f a

= 1/2πR

1

C

From R

1

C

1

= R f

C f

, find Cf

1 and find R

1

Procedures:

Integrator

1.

Connect the circuit as per the diagram shown in Fig 1

2.

Apply a square wave/sine input of 4V(p-p) at 1KHz

3.

Observe the output at pin 6.

4.

Draw input and output waveforms as shown in Fig 3.

Differentiator

1.

Connect the circuit as per the diagram shown in Fig 2

2.

Apply a square wave/sine input of 4V(p-p) at 1KHz

3.

Observe the output at pin 6

4. Draw the input and output waveforms as shown in Fig 4

Wave Forms:

Integrator



Fig 3: Input and output waves forms of integrator

Differentiator



Fig 4 :Input and output waveforms of Differentiator

Sample readings:

Integrator

Input –Square wave Output - Triangular

Amplitude(V

P-P

)

(V)

Time period

(ms)

Amplitude (V

P-P

)

(V)

Time period

(ms)

Input –sine wave

Amplitude(V

(V)

P-P

) Time period

(ms)

Output – cosine

Amplitude (V

(V)

P-P

) Time period

(ms)



Differentiator:

Input –square wave Output – Spikes

Amplitude (V

P-P

)

(V)

Time period

(ms)

Amplitude (V

P-P

)

(V)

Time period

(ms)

Input –sine wave Output – cosine

Amplitude (V

P-P

)

(V)

Time period

(ms)

Amplitude (V

P-P

)

(V)

Time period

(ms)

Model Calculations:

Integrator:

For T= 1 msec

f a

= 1/T = 1 KHz

f a

= 1 KHz = 1/(2πR f

C f

)

Assuming Cf= 0.1μf, R f

is found from R f

=1/(2πf a

C f

)

R f

=1.59 KΩ

R f

= 10 R

1

R

1

= 159Ω

Differentiator

For T = 1 msec

f= 1/T = 1 KHz

f a

= 1 KHz = 1/(2πR f

C

1

)

Assuming C

1

= 0.1μf, R f

is found from R f

=1/(2πf a

C

1

)

R f

=1.59 KΩ

f b

= 10 f a

= 1/2πR

1

C

1

for C

1

= 0.1μf;

R

1

=159Ω

Precautions : Check the connections before giving the power supply.




Result :

Inferences: Spikes and triangular waveforms can be obtained from a given square waveform by using differentiator and integrator respectively.


1.

What are the problems of ideal differentiator?

2.

What are the problems of ideal integrator?

3.

What are the applications of differentiator and integrator?

4.

What is the need for R f

in the circuit of integrator?

5.

What is the effect of C

1 on the output of a differentiator?



4. ACTIVE FILTER APPLICATIONS – LPF, HPF (FIRST ORDER)

Aim: To design and obtain the frequency response of i) First order Low Pass Filter (LPF) ii) First order High Pass Filter (HPF)


S.No Equipment/Component name Specifications/Value Quantity

1

2

3

IC 741

Resistors

Capacitors

Refer page no 2

10KΩ

0.01μf

1

3

1

4 Cathode Ray Oscilloscope (0 – 20MHz) 1

5

6


Function Generator

(0 – 30V),1A

(1Hz – 1MHz)

1

1

Theory: a) LPF:

A LPF allows frequencies from 0 to higher cut of frequency, f

H

. At f

H

the gain is

0.707 A max

, and after f

H

gain decreases at a constant rate with an increase in frequency. The gain decreases 20dB each time the frequency is increased by 10. Hence the rate at which the gain rolls off after f

H is 20dB/decade or 6 dB/ octave, where octave signifies a two fold increase in frequency. The frequency f=f

H

is called the cut off frequency because the gain of the filter at this frequency is down by 3 dB from 0 Hz. Other equivalent terms for cut-off frequency are -3dB frequency, break frequency, or corner frequency.

b) HPF:

The frequency at which the magnitude of the gain is 0.707 times the maximum value of gain is called low cut off frequency. Obviously, all frequencies higher than f

L

are pass band frequencies with the highest frequency determined by the closed –loop band width all of the op-amp.



Circuit diagrams :

Fig 1: Low pass filter

Fig 2: High pass filter

Design:

First Order LPF : To design a Low Pass Filter for higher cut off frequency f

H

= 4 KHz and pass band gain of 2 f

H

= 1/( 2πRC )

Assuming C=0.01 µF, the value of R is found from

R= 1/(2πf

H

C) Ω =3.97KΩ

The pass band gain of LPF is given by A

F

= 1+ (R

F

/R

1

)= 2

Assuming R

1

=10 KΩ, the value of R

F

is found from

R

F

=( A

F

-1) R

1

=10KΩ



First Order HPF: To design a High Pass Filter for lower cut off frequency f

L

= 4 KHz and pass band gain of 2

f

L

= 1/( 2πRC )

Assuming C=0.01 µF,the value of R is found from

R= 1/(2πf

L

C) Ω =3.97KΩ

The pass band gain of HPF is given by A

F

= 1+ (R

F

/R

1

)= 2

Assuming R

1

=10 KΩ, the value of R

F

is found from

R

F

=( A

F

-1) R

1

=10KΩ

Procedure:

First Order LPF

1.

Connections are made as per the circuit diagram shown in Fig 1.

2.

Apply sinusoidal wave of constant amplitude as the input such that op-amp does not go into saturation.

3.

Vary the input frequency and note down the output amplitude at each step as shown in

Table (a).

4.

Plot the frequency response as shown in Fig 3 .

First Order HPF:

1. Connections are made as per the circuit diagrams shown in Fig 2.

2.

Apply sinusoidal wave of constant amplitude as the input such that op-amp does not go into saturation.

3.

Vary the input frequency and note down the output amplitude at each step as shown in

Table (b).

4. Plot the frequency response as shown in Fig 4.



Tabular Form and Sampled Values : a)LPF b) HPF

Input voltage V in

= 0.5V

O/P Voltage

Frequency Voltage(V) Gain

Gain indB

Vo/Vi

Frequency O/P Voltage

Voltage(V) Gain

Gain indB

Vo/Vi



Model graphs :

Fig (3) Fig(4)

Frequency response characteristics Frequency response characteristics

of LPF of HPF

Precautions:

1. Check the connections before giving the power supply.

2. Readings should be taken carefully.

Result :

Inferences: By interchanging R and C in a low-pass filter, a high-pass filter can be obtained.


1.

What is meant by frequency scaling?

2.

How do you convert an original frequency (cut off) f

H

to a new cut off frequency f

H

?

3.

What is the effect of order of the filter on frequency response characteristics?

4.

What modifications in circuit diagrams require to change the order of the filter?



5 ACTIVE FILTER APPLICATIONS – BPF & BAND REJECT

(WIDEBAND ) AND NOTCH FILTERS .

Aim: To design and obtain the frequency response of i) Wide Band pass filter ii) Wide Band reject filter

iii) Notch filter


3

4

5

6

7

S.No Equipment/Component name

1

2

741 IC

Resistors

Resistors

Resistors

Capacitors

Capacitors

Capacitors


Function Generator


Specifications/Value Quantity

Refer page no 2

5.6kΩ

39kΩ

(20kΩ pot)

0.01μf

0.1μf

0.2μf

(0 – 30)V,1A

(1Hz – 1MHZ)

(0 – 20MHz)

3

9

2

2

2

2

1

1

1

1

Theory :

Band pass filter: A band pass filter has a pass band between two cutoff frequencies f

H

and f

L such that f

H

> f

L

. Any input frequency outside this pass band is attenuated. There are two types of band-pass filters. Wide band pass and Narrow band pass filters. We can define a filter as wide band pass if its quality factor Q <10. If Q>10, then we call the filter a narrow band pass filter. A wide band pass filter can be formed by simply cascading high-pass and low-pass sections. The order of band pass filter depends on the order of high pass and low pass sections.

Band Rejection Filter: The band-reject filter is also called a band-stop or band-elimination filter. In this filter, frequencies are attenuated in the stop band while they are passed outside


Department of Electronics & Communication Engineering LICA lab this band. Band reject filters are classified as wide band-reject narrow band-reject. Wide band-reject filter is formed using a low pass filter, a high-pass filter and summing amplifier.

To realize a band-reject response, the low cut off frequency f

L

of high pass filter must be larger than high cut off frequency f

H

of low pass filter. The pass band gain of both the high pass and low pass sections must be equal.

Notch Filter:

The narrow band reject filter, often called the notch fitter is commonly used for the rejection of a single frequency. The most commonly used notch filter is the twin-T network .This is a passive filter composed of two T-shaped networks. One T network is made up of two resistors and a capacitor, while the other uses two capacitors and a resistor. There are several ways to make the notch filter. One way is to subtract the band pass filter output from its input

.The notch-out frequency is the frequency at which maximum attenuation occurs and is given by

f

N

= 1/( 2πRC )

Circuit diagrams :

Fig 1: Wideband pass filter



Fig 2: Wideband reject filter

Design:

Fig 3: Notch filter

Band pass filter: To design a band pass filter having f

H

= 4KHz and f

L

= 400Hz and pass band gain of 2. As shown in Fig 1,the first section consisting of Op Amp,R

F

,R

1

,R and C is the high pass filter and second consisting of low pass filter. The design of low pass and high pass filters.



Low Pass Filter Design:

Assuming C’=0.01μf, the value of R’ is found from

R’ = 1/(2πf

H

C’) Ω =3.97KΩ


LPF

= 1+ (R’

F

/ R’

1

)=2

Assuming R’

1

=5.6 KΩ, the value of R’

F

is found from R’

F

=( A

F

-1) R’

1

=5.6KΩ

High Pass Filter Design:

Assuming C=0.01μf, the value of R is found from

R = 1/(2πf

L

C) Ω =39.7KΩ


HPF

= 1+ (R

F

/ R

1

)=2

Assuming R

1

=5.6 KΩ, the value of R

F

is found from

R

F

= ( A

F

-1) R

1

=5.6KΩ

Band reject filter: To design a band reject filter with f

H

= 4 KHz, fL = 400Hz and pass band gain of 2

Low Pass Filter Design:

Assuming C’=0.01μf, the value of R’ is found from

R’ = 1/(2πf

H

C’) Ω =3.97KΩ


LPF

= 1+ (R’

F

/ R’

1

)=2

Assuming R’

1

=5.6 KΩ, the value of R’

F

is found from

R’

F

=( A

F

-1) R’

1

=5.6KΩ

High Pass Filter Design:

Assuming C=0.01μf, the value of R is found from

R = 1/ (2πf

L

C) Ω =39.7KΩ


HPF

= 1+ (R

F

/ R

1) =

2

Assuming R

1

=5.6 KΩ, the value of R

F

is found from

R

F

= (AF-1) R

1

=5.6KΩ

Adder circuit design: Select all resistors equal value such that gain is unity.

Assume R

2

=R

3

=R

4

=5.6 KΩ

Notch Filter Design: f

N

= 400Hz

Assuming C=0.1μf,the value of R is found from

R = 1/ (2πf

N

C)=39 KΩ



Procedure:

Wide Band Pass Filter:

1.

Connect the circuit as per the circuit diagram shown in Fig1

2.

Apply sinusoidal wave of 0.5V amplitude as input such that opamp does not go into saturation (depending on gain).

3.

Vary the input frequency from 100 Hz to 100 KHz and note down the output amplitude at each step as shown in Table (a).

4.

Plot the frequency response as shown in Fig 4.

Wide Band Reject Filter:

1.

Connect the circuit as per the circuit diagram shown in Fig 2

2.

Apply sinusoidal wave of 0.5V amplitude as input such that opamp does not go into saturation (depending on gain).

3.

Vary the input frequency from 100 Hz to 100 KHz and note down the output amplitude at each step as shown in Table( b).

4.


Notch Filter:

1.

Connect the circuit as per the circuit diagram shown in Fig 3

2.

Apply sinusoidal wave of 2Vp-p amplitude as input such that opamp does not go into saturation (depending on gain).

3.

Vary the input frequency from 100 Hz to 4 KHz and note down the output amplitude at each step as shown in Table( c).

4.




Observations:

a) Band pass filter: b) Band Reject Filter

Input voltage(V i

)=0.5V

Frequeny O/P

Voltage

Vo(V)

Gain

Vo/Vi

Gain indB

Frequency O/P Gain

Voltage(V) Vo/Vi

Gain indB


Department of Electronics & Communication Engineering LICA lab c) Notch filter

Input voltage=2Vp-p

Model graphs:

Frequency O/P

Voltage(V)

Vo/Vi Gain in dB

Fig 4 : Frequency response of Fig 5 : Frequency response of

Band pass filter wide band reject filter



Fig 6: Frequency response of notch filter

Precautions:



Result:

Inferences: Cascade connection of HPF and LPF produces wideband pass filter and parallel connection of the above filters gives wideband reject filter. The notch filter is used to reject the single frequency.


1.

What is the relation between f

C

& f

H

, f

L

?

2.

How do you increase the gain of the wideband pass filter?

3. What is the application of Notch filter?



4. What is the order of the filter (each type) ?.What modifications you suggest for the

circuit diagram to increase the order of the filter?

5. What is the gain roll off outside the pass band?

6. What is the difference between active and passive filters?

7. What are the advantages of active filters over passive filters?



6. WEIN BRIDGE OSCILLATOR

Aim: Design a Wein-Bridge Oscillator to produce 100kHz, ±9V output.

Apparatus Required:

3

S.no Component

1

2

IC

Resistors

4

5

6

Capacitor

Variable Resistor

Fixed power supply

Connecting wires

Specification

LM 565

1.5kΩ,10kΩ,2kΩ

4.7kΩ

0.047µf,0.1µf

10 kΩ

±15V

Single starned

Quantity

1

1

2

1

1

1

As required

7

8

CRO

CRO Probes

0-30MHz

Crocodile Clips

1

3

9 Bread Board 1

Theory: An oscillator consists of an amplifier and a feedback network.

1) 'Active device' i.e. Op Amp is used as an amplifier.

2) Passive components such as R-C or L-C combinations are used as feed back net work To start the oscillation with the constant amplitude, positive feedback is not the only sufficient condition. Oscillator circuit must satisfy the following two conditions known as

Barkhausen conditions:

a. The first condition is that the magnitude of the loop gain (Aβ) = 1

A = Amplifier gain and _ = Feedback gain.

b. The second condition is that the phase shift around the loop must be 360° or 0°.

The feedback signal does not produce any phase shift. This is the”basic principle of a

Wien bridge oscillator”. The given circuit shows the RC combination used in Wien bridge oscillator. circuit is also known as lead-lag circuit. Here, resistor R1 and capacitor C1 are connected in the series while resistor R2and capacitor C2 are connected in parallel. At high frequencies, the reactance of capacitor C1 and C2 approaches zero. This causes C1 and C2 appears short. Here, capacitor C2 shorts the resistor R2. Hence, the output voltage Vo will be zero since output is taken across R2 and C2 combination. So, at high high frequencies,


Department of Electronics & Communication Engineering LICA lab circuit acts as a 'lag circuit'. C1combination. Here, the circuit acts like a 'lead circuit'. But at one particular frequency between the two extremes, the output voltage reaches to the maximum value. At this frequency only, resistance value becomes equal to capacitive reactance and gives maximum output. Hence, this particular frequency is known as resonant frequency or oscillating frequency. The maximum output would be produced if

R = Xc.= 1/(2_fC)

If R 1 = R 2 = R and C 1 = C 2 = C

Then the resonant frequency f = 1/(2_RC)

Due to limitations of the op-amp, frequencies above 1MHz are not achievable.

The basic version of Wein bridge has four arms. The two arms are purely resistive and other two arms are frequency sensitive arms. These two arms are nothing but the lead-lag circuit.

The series combination of R1 and C1 is connected between terminal a and d. The parallel combination of R2 and C2 is connected between terminal d and c . So the two circuits (Fig.1 and Fig.2) are same except in shape. Here, bridge does not provide phase shift at oscillating frequency as one arm consists of lead circuit and other arm consists of lag circuit. There is no need to introduce phase shift by the operational amplifier. Therefore, non inverting amplifier is used.

Circuit diagram:



Design:

Gain required for sustained oscillation is Av = 1/b = 3

(PASS BAND GAIN) (i.e.) 1+Rf/R1 = 3

R f

= 2R1

Frequency of Oscillation fo = 1/2p R C

Given fo = 1 KHz

Let C = 0.05 μF

R = 1/2 π f o

C

R = 3.2 KW

Let R

1

= 10 KΩ \ R f

= 2 * 10 KΩ

Procedure:

1. Connect the components as shown in the circuit

2. Switch on the power supply and CRO.

3. Note down the output voltage at CRO.

4. Plot the output waveform on the graph.

5. Redesign the circuit to generate the sine wave of frequency 2KHz.

6. Compare the output with the theoretical value of oscillation.

Observation:

Peak to peak amplitude of the output = __________Volts.

Frequency of oscillation = __________Hz.



Result:


1.

State the two conditions for oscillations.

2.

Classify the Oscillators?

3.

Define an oscillator?

4. What is the frequency range generated by Wein Bridge Oscillator?

5. What is frequency stability?



7. FUNCTION GENERATOR USING OPAMPS

Aim: To generate square wave and triangular wave form by using OPAMPs.


S.No Equipment/Component name Specifications/Value

1

2

741 IC

Capacitors

Refer page no 2

0.01μf,0.001μf

3 Resistors

Resistors

86kΩ ,68kΩ ,680kΩ

100kΩ

Quantity

2

Each one

Each one

2

4

5



(0 – 30V),1A

(0 -20MHz)

1

1

Theory: Function generator generates waveforms such as sine, triangular, square waves and so on of different frequencies and amplitudes. The circuit shown in Fig1 is a simple circuit which generates square waves and triangular waves simultaneously. Here the first section is a square wave generator and second section is an integrator. When square wave is given as input to integrator it produces triangular wave.

Circuit Diagram:

Fig1: Function generator

OR



Function generator

Design:

Square wave Generator:

T= 2R f

C ln (2R

2

+R

1

/ R

1

)

Assume R

1

= 1.16 R

2

Then T= 2R f

C

Assume C and find R f

Assume R

1

and find R

2

Integrator:

Take R

3

C f

>> T

R

3

C f

= 10T

Assume C f

find R

3

Take R

3

C f

= 10T

Assume C f

= 0.01μf

R

3

= 10T/C

= 20KΩ

Procedure:

1.

Connect the circuit as per the circuit diagram shown above.

2.

Obtain square wave at A and Triangular wave at V o2

as shown in Fig 1.

3.

Draw the output waveforms as shown in Fig 2 (a) and (b).



Model Calculations:

For T= 2 m sec

T = 2 R f

C

Assuming C= 0.1μf

R f

= 2.10

-3

/ 2.01.10

-6

= 10 KΩ

Assuming R

1

= 100 K

R

2

= 86 KΩ


Square Wave:

V p-p

= 26 V(p-p)

T = 1.8 msec

Triangular Wave:

V p-p

= 1.3 V

T= 1.8 msec

Wave Forms:

Fig 2 (a): Output at ‘A’

(b): Output at V

02



Precautions:



.

Result:

Inferences: Various waveforms can be generated.


1.

How do you change the frequency of square wave?

2.

What are the applications of function generator?



8 . IC 555 TIMER - ASTABLE OPERATION CIRCUIT

Aim: To generate unsymmetrical square and symmetrical square waveforms using

IC555.


S.No Equipment/Component name Specifications/Value Quantity

1 IC 555

2 Resistors

3

4

Capacitors


Refer page no 6

5.6kΩ,2.2kΩ

0.1μf,0.01μf

(0 – 30V),1A

1

Each one

Each one

1

5 Cathode Ray Oscilloscope (0 – 20MHz) 1

Theory:

When the power supply V

CC

is connected, the external timing capacitor ‘C” charges towards V

CC

with a time constant (R

A

+R

B

) C. During this time, pin 3 is high (≈V

CC

) as Reset

R=0, Set S=1 and this combination makes Q =0 which has unclamped the timing capacitor

‘C’.

When the capacitor voltage equals 2/3 V

CC

, the upper comparator triggers the control flip flop on that Q

=1. It makes Q1 ON and capacitor ‘C’ starts discharging towards ground through R

B

and transistor Q1 with a time constant R

B

C. Current also flows into Q1 through

R

A

. Resistors R

A

and R

B

must be large enough to limit this current and prevent damage to the discharge transistor Q1. The minimum value of R

A

is approximately equal to V

CC

/0.2 where

0.2A is the maximum current through the ON transistor Q1.

During the discharge of the timing capacitor C, as it reaches V

CC

/3, the lower comparator is triggered and at this stage S=1, R=0 which turns Q =0. Now Q =0 unclamps the external timing capacitor C. The capacitor C is thus periodically charged and discharged between 2/3 V

CC

and 1/3 V

CC

respectively. The length of time that the output remains HIGH is the time for the capacitor to charge from 1/3 V

CC

to 2/3 V

CC

.

The capacitor voltage for a low pass RC circuit subjected to a step input of V

CC

volts is given by V

C

= V

CC

[1- exp (-t/RC)]

Total time period T = 0.69 (R

A

+ 2 R

B

) C f= 1/T = 1.44/ (R

A

+ 2R

B

) C




Fig.1 555 Astable Circuit

Design:

Formulae: f= 1/T = 1.44/ (R

A

+2R

B

) C

Duty cycle (D) = t c

/T = R

A

+ R

B

/(R

A

+2R

B

)

Procedure:

I) Unsymmetrical Square wave

1.

Connect the circuit as per the circuit diagram .

2.

Observe and note down the waveform at pin 6 and across timing capacitor pin 3.

3.

Measure the frequency of oscillations and duty cycle and then compare with the given values.

4.

Sketch both the waveforms to the same time scale.

Model calculations:

Given f=1 KHz. Assuming c=0.1μF and D=0.25



1 KHz = 1.44/ (RA+2R

B

) x 0.1x10

-6

and 0.25 =( R

A

+R

B

)/ (R

A

+2R

B

)

Solving both the above equations, we obtain R

A

& R

B

as

R

A

= 7.2K Ω

R

B

= 3.6K



Waveforms:

Fig 2 (a) Unsymmetrical square wave output

2 (b) Capacitor voltage of Unsymmetrical square wave output

Sample Readings:

Parameter

Voltage V

PP

Time period

T

Duty cycle

Unsymmetrical Symmetrical

Precautions:

Check the connections before giving the power supply.Readings should be taken carefully.

Result :

Inferences: Unsymmetrical square wave of required duty cycle and symmetrical square

waveform can be generated.




1.

What is the effect of C on the output?

2.

How do you vary the duty cycle?

3.

What are the applications of 555 in astable mode?

4.

What is the function of diode in the circuit?

5.

On what parameters T c

and T d designed?

6.

What are charging and discharging times



9. IC 555 TIMER-MONOSTABLE OPERATION CIRCUIT

Aim: To generate a pulse using Monostable Multivibrator by using IC555


Specifications/Value Quantity S.No Equipment/Component name

1 555 IC

2

3

4

Capacitors

Resistor


5 Function Generator

Refer page no 6

0.1μf,0.01μf

10kΩ

(0 – 30V),1A

(1HZ – 1MHz)

1

Each one

1

1

1

6 Cathode ray oscilloscope (0 – 20MHz) 1

Theory : A Monostable Multivibrator, often called a one-shot Multivibrator, is a pulsegenerating circuit in which the duration of the pulse is determined by the RC network connected externally to the 555 timer. In a stable or stand by mode the output of the circuit is approximately Zero or at logic-low level. When an external trigger pulse is obtained, the output is forced to go high (



V

CC

). The time for which the output remains high is determined by the external RC network connected to the timer. At the end of the timing interval, the output automatically reverts back to its logic-low stable state. The output stays low until the trigger pulse is again applied. Then the cycle repeats. The Monostable circuit has only one stable state (output low), hence the name monostable. Normally the output of the Monostable Multivibrator is low.



Fig1: Monostable Circuit using IC555

Design:

Consider V

CC

= 5V, for given t p

Output pulse width t p

= 1.1 R

A

C

Assume C in the order of microfarads & Find R

A

Typical values:

If C=0.1 µF , R

A

= 10k then t p

= 1.1 mSec

Trigger Voltage =4 V

Procedure:

1.

Connect the circuit as shown in the circuit diagram.

2.

Apply Negative triggering pulses at pin 2 of frequency 1 KHz.

3.

Observe the output waveform and measure the pulse duration.

4.

Theoretically calculate the pulse duration as T high

=1.1. R

A

C

5.

Compare it with experimental values.



Waveforms:

Fig 2 (a) Trigger signal (b) Output Voltage (c) Capacitor Voltage

Sample Readings:

Trigger Output wave Capacitor output

Precautions:



Result:

Inferences: Output pulse width depends only on external components R

A

and C connected

to IC555.




1.

Is the triggering given is edge type or level type? If it is edge type, trailing or raising edge?

2.

What is the effect of amplitude and frequency of trigger on the output?

3.

How to achieve variation of output pulse width over fine and course ranges?

4.

What is the effect of Vcc on output?

5.

What are the ideal charging and discharging time constants (in terms of R and C) of capacitor voltage?

6.

What is the other name of monostable Multivibrator? Why?

7.

What are the applications of monostable Multivibrator?



10. IC 565 – PLL APPLICATIONS

Aim: Design a Phase Locked Loop Application (Voltage Controlled Oscillator) using IC

LM565.

Apparatus Required:

S.No Component

1 IC

2 Resistors

Specification

LM 565

1.5kΩ, 10kΩ, 2kΩ

4.7kΩ

Quantity

1

1

2

3

4

5

6

7

8

9

Capacitor

Variable Resistor

Fixed Power Supply

Connecting Wires

CRO

CRO Probes

Bread Board

0.047µF, 0.1µF

10kΩ

±15V

Single Strand

0-30MHz

Crocodile Clips

1

1

1

As Required

1

3

1

Theory:

This oscillator uses a special IC chip, the LM565 that is designed to function as a phase locked loop (PLL). The chip contains a VCO (which we will utilize in this experiment) and a phase detector. A combination of an input control voltage on pin 7 and the RC time constant formed by the components on pins 8 and 9 set the VCO output frequency. The VCO within the LM565 is not designed like a conventional oscillator. It is really a current controlled oscillator. Remember that as the charging current in a capacitor is increased, the rate of capacitor charging (as evidenced in its voltage rise) also increases. The same is true for capacitor discharging as well. The LM565 simply translates the control voltage on pin 7 into a charging and discharging current for the timing capacitor , C1. So what is the function of the resistors on pin 8? The resistors on pin 8 also help set the charge and discharge current for the timing capacitor C1. In other words, the output frequency of the LM565 VCO depends on three factors:

1) The control voltage on pin 7;



2) The total resistance on pin 8 (R3 and R4);

3) The capacitance on pin 9 (C1).

When a capacitor is charged by a constant current, its voltage rises linearly (straightline).

Thus, one of the output waveforms of the LM565 is a triangle wave. The other output is a square wave -- the result of the triangle wave going through a Schmitt trigger. Two different

LM565 VCO circuits will be examined in this experiment, and they are shown in Figures 1 and 2. In Figure 1, the control voltage of the VCO is held constant by resistors R1 and R2, and the RC time-constant is varied by R3. (Note that the total resistance

Rt in Figure 1 is the series combination of R3 and R4). In Figure 2, the timing resistance Rt is equal to R2, and is constant. A potentiometer has been substituted in R1's place, allowing the control voltage to be varied over a range of approximately 7.5 V to 15 V. Note that the control voltage should be adjusted to be in the range 11.25 V to 15 V in part two of this experiment

Circuit Diagram Of PLL:



Observations:

S.No R

1

C

1

Output Voltage(V) Theoreical Practical

Square Wave Triangular Wave

Frequency(Hz) Frequency

Procedure:

1. Connections are made as per the circuit diagram.

2. Measure the output voltage and frequency of both triangular and squares.

3. Vary the values of R1 and C1 and measure the frequency of the waveforms.

4. Compare the measured values with the theoretical values.

Precautions:

1. Connect the wires properly.

2. Maintain proper Vcc levels.

Result:


1.

What are the applications of VCO?

2.

Draw the pin diagram of NE/SE 565.

3.

What is the need of connecting 0.0047μF capacitor between pin 5 and pin



11. SCHMITT TRIGGER CIRCUITS- USING IC 741 & IC 555

Aim : To design the Schmitt trigger circuit using IC 741 and IC 555


S.No

Equipment/Component name Specifications/Value Quantity

1 IC 741

2 555IC

Refer page no 2

Refer page no 6

1

1

3 Cathode Ray Oscilloscope (0 – 20MHz)

4 Multimeter

5

6

Resistors

Capacitors

100K Ω,1KΩ

10KΩ

0.1 μf, 0.01 μf

1

1

2

1

Each one

1 7 Regulated power supply (0 -30V),1A

Theory:

The circuit shows an inverting comparator with positive feed back. This circuit converts orbitrary wave forms to a square wave or pulse. The circuit is known as the Schmitt trigger (or) squaring circuit. The input voltage V in

changes the state of the output V o

every time it exceeds certain voltage levels called the upper threshold voltage V ut

and lower threshold voltage V lt

.

When V o

= - V sat

, the voltage across R

1

is referred to as lower threshold voltage, V lt

.

When V o

=+V sat

, the voltage across R

1

is referred to as upper threshold voltage V ut

. The comparator with positive feed back is said to exhibit hysterisis, a dead band condition.




Fig 1: Schmitt trigger circuit using IC 741

Fig 2: Schmitt trigger circuit using IC 555

Design:

V utp

= [R

1

/(R

1

+R

2

)](+V sat

)

V ltp

= [R

1

/(R

1

+R

2

)](-V sat

)

V hy

= V utp

– V ltp

=[R

1

/(R

1

+R

2

)] [+V sat

– (-V sat

)]



Procedure:

1.

Connect the circuit as shown in Fig 1 and Fig2.

2.

Apply an orbitrary waveform (sine/triangular) of peak voltage greater than UTP to the input of a Schmitt trigger.

3.

Observe the output at pin6 of the IC 741 and at pin3 of IC 555 Schmitt trigger circuit by varying the input and note down the readings as shown in Table 1 and Table 2

4.

Find the upper and lower threshold voltages (V utp

, V

Ltp

) from the output wave form.

Wave forms:

Fig 3: (a) Schmitt trigger input wave form

(b) Schmitt trigger output wave form


Table 1:

Parameter Input

Voltage( V p-p

)

Time period(ms)

741 555 741

Output

555



Table 2:

Parameter 741

V utp

V ltp

Precautions:



555

.

Results:

Inferences: Schmitt trigger produces square waveform from a given signal.


1.

What is the other name for Schmitt trigger circuit?

2.

In Schmitt trigger which type of feed back is used?

3.

What is meant by hysteresis?

4.

What are effects of input signal amplitude and frequency on output?



12. IC 566 – VCO APPLICATIONS

Aim : i) To observe the applications of VCO-IC 566. ii) To generate the frequency modulated wave by using IC 566.


4

5

S.No Equipment/Component Name Specifications/Value Quantity

1

2

3

IC 566

Resistors

Capacitors

Refer page no 10

10KΩ

1.5KΩ

0.1 μF

100 pF

1

2

1

1

1

Regulated power supply


0-30 V, 1 A

0-20 MHz

1

1

6 Function Generator 0.1-1 MHz 1

Theory: The VCO is a free running Multivibrator and operates at a set frequency f o

called free running frequency. This frequency is determined by an external timing capacitor and an external resistor. It can also be shifted to either side by applying a d.c control voltage v c

to an appropriate terminal of the IC. The frequency deviation is directly proportional to the dc control voltage and hence it is called a “voltage controlled oscillator” or, in short, VCO.

The output frequency of the VCO can be changed either by R

1

, C

1

or the voltage V

C at the modulating input terminal (pin 5). The voltage V

C

can be varied by connecting a R

1

R

2 circuit. The components R

1

and C

1

are first selected so that VCO output frequency lies in the centre of the operating frequency range. Now the modulating input voltage is usually varied from 0.75 V

CC

which can produce a frequency variation of about 10 to 1.




Fig1: Voltage Controlled Oscillator

Design:

1.

Maximum deviation time period =T.

2.

f min

= 1/T. where f min

can be obtained from the FM wave

3.

Maximum deviation, ∆f= f o

- f min

4.

Modulation index β = ∆f/f m

5.

Band width BW = 2(β+1) f m

= 2 (∆f+f m

)

6. Free running frequency,f o

= 2(V

CC

-V c

) / R

1

C

1

V

CC

Procedure:

1.

The circuit is connected as per the circuit diagram shown in Fig1.

2.

Observe the modulating signal on CRO and measure the amplitude and frequency of the signal.

3.

Without giving modulating signal, take output at pin 4, we get the carrier wave.

4.

Measure the maximum frequency deviation of each step and evaluate the modulating

Index. m f

= β = ∆f/f m



Waveforms:

Fig 2 (a) Input wave of VCO

(b) Output of VCO at pin3

(c) Output of VCO at pin4


V

CC

=+12V; R

1

=R

3

=10KΩ; R

2

=1.5KΩ; f m

=1KHz

Free running frequency, f o

= 26.1KHz

f min

= 8.33KHz

∆f= 17.77 KHz

β = ∆f/f m

= 17.77

Band width BW ≈ 36 KHz

Precautions:





Result:

Inferences:

During positive half-cycle of the sine wave input, the control voltage will increase, the frequency of the output waveform will decrease and time period will increase. Exactly opposite action will take place during the negative half-cycle of the input as shown in Fig (b).


1. What are the applications of VCO?

2. What is the effect of C

1

on the output?



13. VOLTAGE REGULATOR USING IC723

Aim : To design a low voltage variable regulator of 2 to 7V using IC 723.


S.No

1

2

Equipment/Component name Specifications/Value Quantity

IC 723 Refer appendix A 1

Resistors

3.3KΩ,8.2KΩ,

1KΩ, 2KΩ

2

1

3

4

5

6

7

Capacitor


Multimeter

Ammeter

Voltmeter

100µf

0 -30 V,1A

3

½ digit display

(0-20 mA)

(0-20 V)

1

1

1

1

1

Theory:

A voltage regulator is a circuit that supplies a constant voltage regardless of changes in load current and input voltage variations. Using IC 723, we can design both low voltage and high voltage regulators with adjustable voltages.

For a low voltage regulator, the output V

O

can be varied in the range of voltages V o

<

V ref

, where as for high voltage regulator, it is V

O

> V ref

. The voltage V ref

is generally about

7.5V. Although voltage regulators can be designed using Op-amps, it is quicker and easier to use IC voltage Regulators.

IC 723 is a general purpose regulator and is a 14-pin IC with internal short circuit current limiting, thermal shutdown, current/voltage boosting etc. Furthermore it is an adjustable voltage regulator which can be varied over both positive and negative voltage ranges. By simply varying the connections made externally, we can operate the IC in the required mode of operation. Typical performance parameters are line and load regulations which determine the precise characteristics of a regulator. The pin configuration and specifications are shown in the Appendix-A.




Fig1: Voltage Regulator

Design of Low voltage Regulator :-

Assume I o

= 1mA,V

R

=7.5V

R

B

= 3.3 KΩ

For given V o

R

1

= ( V

R

– V

O

) / I o

R

2

= V

O

/ I o

Procedure: a) Line Regulation :

1. Connect the circuit as shown in Fig 1.

2. Obtain R

1

and R

2 for V o

=5V

3. By varying V n

from 2 to 10V, measure the output voltage V o

.

4. Draw the graph between V n

and V o

as shown in model graph (a)

5. Repeat the above steps for V o

=3V


Department of Electronics & Communication Engineering LICA lab b) Load Regulation : For V o

=5V

1.

Set V i

such that V

O

= 5 V

2.

By varying R

L

, measure I

L

and V o

3.

Plot the graph between I

L

and V o

as shown in model graph (b)

4. Repeat above steps 1 to 3 for V

O

=3V.

Sample Readings: a) Line Regulation:

Vi(V) Vo(V) a) Load Regulation :

Regulated O/p

(V)

Load Current

(mA)

Load Resistance

R

L

(Ω)

V

FL

% Regulation



Model graphs: a) Line Regulation : b) Load Regulation :

Precautions:



Results:

Inferences:

Variable voltage regulators can be designed by using IC 723.


1.

What is the effect of R

1

on the output voltage?

2. What are the applications of voltage regulators?

3. What is the effect of V i on output?



14. THREE TERMINAL VOLTAGE REGULATORS- 7805, 7809, 7912

Aim: To obtain the regulation characteristics of three terminal voltage regulators.


Specifications/Values Quantity S.No Equipment/Component

Name

1 Bread board

2

3

IC7805

IC7809

Refer appendix A

Refer appendix A

1

1

1

4

5

6

7

8

9

IC7912

Multimeter

Milli ammeter

Regulated power supply

Connecting wires

Resistors pot

Refer appendix A

3

½ digit display

0-150 mA

0-30 V

100Ω ,1k Ω

1

1

1

1

Each one

Theory:

A voltage regulator is a circuit that supplies a constant voltage regardless of changes in load current and input voltage. IC voltage regulators are versatile, relatively inexpensive and are available with features such as programmable output, current/voltage boosting, internal short circuit current limiting, thermal shunt down and floating operation for high voltage applications.

The 78XX series consists of three-terminal positive voltage regulators with seven voltage options. These IC’s are designed as fixed voltage regulators and with adequate heat sinking can deliver output currents in excess of 1A.

The 79XX series of fixed output voltage regulators are complements to the 78XX series devices. These negative regulators are available in same seven voltage options.

Typical performance parameters for voltage regulators are line regulation, load regulation, temperature stability and ripple rejection. The pin configurations and typical parameters at 25

0

C are shown in the Appendix-B.




Fig 1: Positive Voltage Regulator

Fig 2: Negative Voltage Regulator

Procedure: a) Line Regulation:

1.

Connect the circuit as shown in Fig 1 by keeping S open for 7805.

2.

Vary the dc input voltage from 0 to 10V in suitable stages and note down the output voltage in each case as shown in Table1 and plot the graph between input voltage and output voltage.

3.

Repeat the above steps for negative voltage regulator as shown in Fig.2 for 7912 for an input of 0 to -15V.

4.

Note down the dropout voltage whose typical value = 2V and line regulation typical value = 4mv for V in

=7V to 25V.


Department of Electronics & Communication Engineering LICA lab b) Load regulation:

1.

Connect the circuit as shown in the Fig 1 by keeping S closed for load regulation.

2.

Now vary R

1

and measure current I

L

and note down the output voltage V o

in each case as shown in Table 2 and plot the graph between current I

L

and V o

.

3. Repeat the above steps as shown in Fig 2 by keeping switch S closed for

negative voltage regulator 7912. c) Output Resistance:

R o

= (V

NL

– V

FL

) Ω

I

FL

V

NL

- load voltage with no load current

V

FL

- load voltage with full load current

I

FL

- full load current.




1) IC 7805

a) Line Regulation

Vi(V) Vo(V) b) Load Regulation V

NL =

15 V

Load Current

(mA)

Load

Resistance

R

L

(Ω)

V dc(FL)

(V) % Regulation



2) IC 7912

a) Line Regulation

Vi(V) Vo(V) c) Load Regulation

Load Current

(mA)

V dc(FL)

(V)

Load

Resistance

R

L

(Ω)

% Regulation



Graphs:

IC 7805

IC 7809

IC7912

% load regulation = V

NL

- V

FL

x 100

V

FL



Precautions:



Result:

Inferences:

Line and load regulation characteristics of fixed positive and negative three terminal voltages are obtained. These voltage regulators are used in regulated power supplies.


1.

Mention the IC number for a negative fixed three terminal voltage regulator of 12V.

2.

Explain the significance of IC regulators in power supply

3.

What is drop-out voltage?

4. What is the role of C

1

and C

2?

4.

What are C1 and C

2 called?



15. 4-BIT DAC USING OP AMP

Aim: To design 1) weighted resistor DAC

2) R-2R ladder Network DAC


5

6

3

4

1

2


Digital trainer Board


741 IC

Resistors

Refer page no 2

1KΩ,2KΩ,4KΩ,

8KΩ

Regulated Power supply 0-30 V , 1A

Multimeter(DMM) 3

½ digit display connecting wires

Quantity

1

Each one

1

1

1

Theory: Digital systems are used in ever more applications, because of their increasingly efficient, reliable, and economical operation with the development of the microprocessor, data processing has become an integral part of various systems Data processing involves transfer of data to and from the micro computer via input/output devices. Since digital systems such as micro computers use a binary system of ones and zeros, the data to be put into the micro computer must be converted from analog to digital form. On the other hand, a digital-to-analog converter is used when a binary output from a digital system must be converted to some equivalent analog voltage or current. The function of DAC is exactly opposite to that of an ADC.

A DAC in its simplest form uses an op-amp and either binary weighted resistors or R-

2R ladder resistors. In binary-weighted resistor op-amp is connected in the inverting mode, it can also be connected in the non inverting mode. Since the number of inputs used is four, the converter is called a 4-bit binary digital converter.




Fig 1: Binary weighted resistor DAC

Fig 2: R – 2R Ladder DAC

Design:

1. Weighted Resistor DAC

V o

= -R f



 b

A

8 R

 b

B

4 R

 b c

2 R

 b

D

R



For input 1111, R f

= R = 4.7KΩ

V o

= -





1

8



1

4



1

2



1

 R

R f x 5

V o

= - 9.375 V



2.R-2R Ladder Network:

V o

= -R f



 b

A

16 R

 b

B

8 R

 b c

4 R

 b

D

2 R



X 5

For input 1111, R f

= R= 1KΩ

Procedure:

1. Connect the circuit as shown in Fig 1.

2. Vary the inputs A, B, C, D from the digital trainer board and note down the output at pin 6.

For logic ‘1’, 5 V is applied and for logic ‘0’, 0 V is applied.

3. Repeat the above two steps for R – 2R ladder DAC shown in Fig 2.

Observations:

Weighted resistor DAC

S.No D C B A Practical Voltage(V) Theoretical

Voltage(V)



R-2R Ladder Network:

S.No D C B A Theoretical

Voltage(V)

Practical Voltage(V)

Model Graph:

Decimal Equivalent of Binary inputs



Precautions:



Results:

Inferences:

Different types of digital-to-analog converters are designed.


1.

How do you obtain a positive staircase waveform?

2.

What are the drawbacks of binary weighted resistor DAC?

3.

What is the effect of number of bits on output ?



OTHER EXPERIMENTS

16 . VOLTAGE- TO- CURRENT CONVERTER

Aim :

To design voltage to current converter with floating load and grounded load using op amp




1

2

3

4

5

6

741 IC

Resistors


Multimeter

Ammeter


Refer page no 2

10 KΩ

1KΩ

(0-30V),1A

3

½ digit display

(0 – 30) μA

1

5

1

1

1

1

1

Theory:-

In many applications we must convert the given voltage into current. The two types of voltage to current converters are

1.

V to I converters with floating load

2.

V to I converters with grounded load.

Floating load V – I converters are used as low voltage ac and dc voltmeters, diode match finders, light emitting diodes and zener diode testers. V to I converters Grounded load are used in testing such devices as zeners and LEDs forming a ground load.



Circuit Diagrams:-

Fig 1: V – I converter with floating load

Fig 2: V – I converter with grounded load



Design:

V – I converter with floating load

V in

= V id

+ V f

where V id

is input difference voltage and V f

is the feedback voltage

But V id

= 0

V in

= V f

= R

1

R

L

I

L

= V in

/R

L

V – I converter with grounded load

I

1

+I

2

=I

L

(V in

-V

1

)/R+(V o

-V

1

)/R=I

L

V in

+V o

-2V i

=I

L

R

Since op-amp is non inverting

Gain=1+(R/R)=2

Vo=2Vi

V in

=Vo-Vo+I

L

R

I

L

=V in

/R

Procedure:-


1. Connect the circuit as per the circuit diagram in Fig 1.

2. Apply input voltage to the non-inverting terminal of 741.

3. Observe the output from CRO and note down the ammeter reading for various values of input voltage.


1. Connect the circuit as per the circuit diagram shown in Fig 2.

2. Set ac input to any desired value.

3. Switch on the dual trace supply and note down the readings of ammeter

4. Repeat the above procedure for varies values input voltages.





V in

(V)


Vin

RL=1KΩ

Current (mA)

RL=10KΩ

Current(mA)

Precautions:



Results:



Inferences:

Different types of V-I converters are designed.


1.

What is the effect of R

L

on the output current in V-to-I converter with floating load?

2.

What is the effect of R on the output current in V-to-I converter with grounded load?

3.

For what ranges of currents the circuits are useful?



17. PRECISION RECTIFIER

Aim : To obtain a precision rectifier (half wave rectifier using IC 741).

Apparatus required :

3

5

1

2


741 IC

Resistors


Refer page no 2

10 KΩ

1KΩ

Regulated Power supply (0-30V),1A

Quantity

1

5

1

1

6



(0-20MHz) 1

1

Theory :

There are two types of half wave rectifiers. One is inverting half wave rectifier and second one is non-inverting half wave rectifier. The below circuit show the non-inverting half wave rectifier with diode (0A79) in the feed back loop of an op-amp.

Circuit diagram :



Procedure :

1.

Connect the circuit as per the circuit diagram.

2.

Give the sinusoidal input of 100mVp-p, 1 KHz from function generator.

3.

Switch on the dual power supply of + 15V.

4.

Note down the output from CRO.

Model Graphs:

Fig.a) Input waveform to the half wave rectifier

b ) Output to (a)


Parameter

Amplitude (V),V p-p

Time period (ms)

Input

Precautions:



Output



Results:

Inferences:

Precision half-wave rectifier is obtained by using IC 741.


1. What is the output if the diode is reversed?

2. What is a super diode?

3.

What is precision rectifier?

4.

What modifications you suggest to get negative half cycles at output?



18. CLIPPER CIRCUITS USING IC 741

Aim : To obtain the clipped waveforms of the input using IC741.



1

2

3


741 IC

Resistors

Refer page no 2

10 KΩ

Regulated Power supply (0-30V),1A

1

1

1

4

5

Function generator

Diode

(0-1MHz)

0A79

1

1

6 Cathode Ray Oscilloscope (0-20MHz) 1

Theory:

A positive clipper is a circuit that removes positive parts of the input signal. In this circuit the op-amp is basically used as a voltage follower with a diode in the feed back path. The clipping level is determined by the reference voltage Vref which should be less than input voltage range of op-amp. Additionally since Vref is derived from the positive supply voltage, dc supply voltage is well regulated.

During the positive half cycle of the input, the diode(IN4007) conducts only until Vin =Vref. This happens because Vin < V ref the voltage Vref at ‘-‘ve input is higher than that at the ‘+’ve input. Hence the output voltage Vo’ the op-amp become sufficiently negative to drive D1 into conducting. When D1 conducts it closes the feed back loop and opamp operates as a voltage follower i.e. output Vo follows input Vin until Vin =Vref.

Circuit diagrams:



Fig 1: Positive Clipper

Fig 2: Negative Clipper

Procedure:



Positive clipper

1.

Connect the circuit as per the circuit diagram shown in Fig 1.

2.

Apply the reference voltage of 1V.

3.

Apply a 6Vp-p of sine wave as input.

4.

Note down the output waveform as shown in Fig 3(a) and 3(b).

Negative clipper

1. Connect the circuit as per the circuit diagram shown in Fig 2.

2. Apply the reference voltage of 1V.

3. Apply a 6Vp-p of sine wave as input.

4. Note down the output waveform as shown in Fig 3(c) and 3(d).

Waveforms:

Positive clipper

Negative clipper

Fig 3 (a) : Input wave form (b) : output wave form



Fig 3 (c): Input 3 (d): output

Sample readings: a) Positive clipper

Parameter

Amplitude (V),V p-p

Time period (ms)

Input Voltage Output Voltage b) Negative clipper

Parameter

Amplitude (V), V p-p

Time period (ms)

Input Voltage Output Voltage

Precautions:

1.Check the connections before giving the power supply.

2. Readings should be taken carefully.

Result:



Inferences:

The application of IC 741 as a clipper is observed.


1. What is the effect of Vref on the output?

2. How do you change a positive clipper into negative clipper?



APPENDIX-A

IC723


Specifications of 723:

Power dissipation :

Input Voltage :

Output Voltage

Output Current

Load regulation :

:

:

: Line regulation

1W

9.5 to 40V

2 to 37V

150mA for Vin-Vo = 3V

10mA for Vin-Vo = 38V

0.6% Vo

0.5% Vo



APPENDIX-B

Pin Configurations:

78XX 79XX

Plastic package

Typical parameters at 25 o

C:

Parameter

Vout,V

Imax,A

Load Reg,mV

Line Reg,mV

Ripple Rej,dB

Dropout

Rout,mΩ

I

SL,

A

LM 7805

5

1.5

10

3

80

2

8

2.1

LM 7809

9

1.5

12

6

72

2

16

0.45

LM 7912

-12

1.5

12

4

72

2

18

1.5



REFERENCES

1.

D.Roy Choudhury and Shail B.Jain, Linear Integrated Circuits, 2 nd

edition, New Age

International.

2.

James M. Fiore, Operational Amplifiers and Linear Integrated Circuits: Theory and

Application, WEST.

3.

Malvino, Electronic Principles, 6 th

edition, TMH

4.

Ramakant A. Gayakwad, Operational and Linear Integrated Circuits,4 th

edition, PHI.

5.

Roy Mancini, OPAMPs for Everyone, 2 nd

edition, Newnes.

6.

S. Franco, Design with Operational Amplifiers and Analog Integrated Circuits, 3 rd edition, TMH.

7.

William D. Stanley, Operational Amplifiers with Linear Integrated Circuits, 4 th edition, Pearson.

8.

www.analog.com


LICA LAB - Raghu Institute of Technology

RAGHU INSTITUTE OF TECHNOLOGY

LINEAR INTEGRATED CIRCUIT APPLICATIONS LAB

RAGHU INSTITUTE OF TECHNOLOGY

CONTENTS

GENERAL INSTRUCTIONS

ADDITIONAL INSTRUCTIONS

Minimum Twelve Experiments to be conducted :

List of Experiment

Additional Experiments:

1. STUDY OF OP AMPS - IC 741, IC 555, IC 565, IC 566,

IC 1496-FUNCTIONING, PARAMETERS AND SPECIFICATIONS

2. OP AMP APPLICATIONS – ADDER, SUBTRACTOR,

COMPARATOR CIRCUITS

3. INTEGRATOR AND DIFFERENTIATOR CIRCUITS USING IC 741

4. ACTIVE FILTER APPLICATIONS – LPF, HPF (FIRST ORDER)

5 ACTIVE FILTER APPLICATIONS – BPF & BAND REJECT

(WIDEBAND ) AND NOTCH FILTERS .

6. WEIN BRIDGE OSCILLATOR

7. FUNCTION GENERATOR USING OPAMPS

8 . IC 555 TIMER - ASTABLE OPERATION CIRCUIT

Questions & Answers:

9. IC 555 TIMER-MONOSTABLE OPERATION CIRCUIT

10. IC 565 – PLL APPLICATIONS

11. SCHMITT TRIGGER CIRCUITS- USING IC 741 & IC 555

12. IC 566 – VCO APPLICATIONS

13. VOLTAGE REGULATOR USING IC723

14. THREE TERMINAL VOLTAGE REGULATORS- 7805, 7809, 7912

15. 4-BIT DAC USING OP AMP

OTHER EXPERIMENTS

16 . VOLTAGE- TO- CURRENT CONVERTER

17. PRECISION RECTIFIER

18. CLIPPER CIRCUITS USING IC 741

APPENDIX-A

IC723

APPENDIX-B

REFERENCES

Related documents

Products

Support

LICA LAB - Raghu Institute of Technology

RAGHU INSTITUTE OF TECHNOLOGY

LINEAR INTEGRATED CIRCUIT APPLICATIONS LAB

RAGHU INSTITUTE OF TECHNOLOGY

CONTENTS

GENERAL INSTRUCTIONS

ADDITIONAL INSTRUCTIONS

Minimum Twelve Experiments to be conducted :

List of Experiment

Additional Experiments:

1. STUDY OF OP AMPS - IC 741, IC 555, IC 565, IC 566,

IC 1496-FUNCTIONING, PARAMETERS AND SPECIFICATIONS

2. OP AMP APPLICATIONS – ADDER, SUBTRACTOR,

COMPARATOR CIRCUITS

3. INTEGRATOR AND DIFFERENTIATOR CIRCUITS USING IC 741

4. ACTIVE FILTER APPLICATIONS – LPF, HPF (FIRST ORDER)

5 ACTIVE FILTER APPLICATIONS – BPF & BAND REJECT

(WIDEBAND ) AND NOTCH FILTERS .

6. WEIN BRIDGE OSCILLATOR

7. FUNCTION GENERATOR USING OPAMPS

8 . IC 555 TIMER - ASTABLE OPERATION CIRCUIT

Questions & Answers:

9. IC 555 TIMER-MONOSTABLE OPERATION CIRCUIT

10. IC 565 – PLL APPLICATIONS

11. SCHMITT TRIGGER CIRCUITS- USING IC 741 & IC 555

12. IC 566 – VCO APPLICATIONS

13. VOLTAGE REGULATOR USING IC723

14. THREE TERMINAL VOLTAGE REGULATORS- 7805, 7809, 7912

15. 4-BIT DAC USING OP AMP

OTHER EXPERIMENTS

16 . VOLTAGE- TO- CURRENT CONVERTER

17. PRECISION RECTIFIER

18. CLIPPER CIRCUITS USING IC 741

APPENDIX-A

IC723

APPENDIX-B

REFERENCES

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