15EI204L-ANALOG ELECTRONIC CIRCUITS LAB MANUAL

Transcription

1 15EI204L-ANALOG ELECTRONIC CIRCUITS LAB MANUAL Department of Electronics and Instrumentation Engineering Faculty of Engineering and Technology Department of Electronics and Instrumentation Engineering SRM IST, SRM Nagar Kattankulathur Kancheepuram District Tamil Nadu 1

2 CONTENTS S.No. CONTENTS Page No. 1 Mark Assessment details 2 2 General Instructions for Laboratory classes 3 3 Syllabus 4 4 Introduction to the laboratory 5 5 List of Experiments 5.1Series and Shunt feedback amplifiers Design of Wein bridge oscillator Design of transistor RC phase shift oscillator Design of LC Hartley and Colpitt oscillator Integrators and Differentiators Clippers and Clampers Darlington Emitter follower Design of MonostableMultivibrator Design of BistableMultivibrator 45 2

3 1. MARK ASSESSMENT DETAILS ALLOTMENT OF MARKS: Internal assessment = 60 marks Practical examination = 40 marks Total = 100 marks INTERNAL ASSESSMENT (60 MARKS) Split up of internal marks Record Model exam Quiz/Viva Experiments Total 5 marks 10 marks 5 marks 40 marks 60 marks PRACTICAL EXAMINATION (40MARKS) Split up of practical examination marks Aim and Procedure Circuit Diagram Tabulation Result Viva voce Total 25 marks 30 marks 30 marks 05 marks 10 marks 100 marks 3

4 2. GENERAL INSTRUCTIONS FOR LABORATORY CLASSES 1. Enter the Lab with CLOSED TOE SHOES. 2. Students should wear lab coat. 3. The HAIR should be protected, let it not be loose. 4. TOOLS, APPARATUS and COMPONENT sets are to be returned before leaving the lab. 5. HEADINGS and DETAILS should be neatly written i. Aim of the experiment ii. iii. Apparatus / Tools / Instruments required Theory iv. Procedure / Algorithm / Program v. Model Calculations/ Design calculations vi. vii. Block Diagram / Flow charts/ Circuit diagram Tabulations/ Waveforms/ Graph viii. Result / discussions. 6. Experiment number and date should be written in the appropriate place. 7. After completing the experiment, the answer to pre lab viva-voce questions should be neatly written in the workbook. 8. Be REGULAR, SYSTEMATIC, PATIENT, ANDSTEADY. 4

5 3. SYLLABUS 15EI204L Analog Electronic Circuits Laboratory L T P C Co-requisite: 15EI204 Prerequisite: NIL Data Book / Codes/Standards NIL Course Category P PROFESSIONAL CORE ELECTRONICS ENGINEERING Course designed by Department of Electronics and Instrumentation Engineering Approval 32 nd Academic Council Meeting held on 23 rd July, 2016 PURPOSE The aim of this course is to familiarize the student with the analysis and design of basic transistor amplifier circuits, tuned amplifiers, wave shaping, multi vibrator circuits, voltage regulators and electronic circuit applications INSTRUCTIONAL OBJECTIVES At the end of the course, student will be able to 1. Know the design procedure of various electronic circuit configurations. a e 2. Have an idea about the frequency response of amplifiers a c 3. Have a clear understanding of operation of oscillators and power supplies a STUDENT OUTCOMES d Session Clippers and Clampers 3 C,D 3 1,2 Darlington Emitter follower 3 C,D 2 1,2 Complementary Symmetry Push-pull amplifier 3 D,I 3 1,2 Design of MonostableMultivibrator 3 D,I 2,3 1,2 Design of BistableMultivibrator 3 D,I 2,3 1,2 Total contact hours 30 LEARNING RESOURCES Sl. No. REFERENCE BOOKS 1. Analog Electronic circuits Laboratory Manual 2. David A. Bell, Electronic Devices and Circuits, 5 th Edition, Oxford University Press, Description of Topic Conduct C-Dhours I-O IOs Reference Series and Shunt feedback amplifiers 3 C 1 1,2 Design of Wein bridge oscillator 3 C 3 1,2 Design of transistor RC phase shift oscillator 3 C,D 3 1,2 Design of LC Hartley and Colpitt oscillator 3 C,D 3 1,2 Integrators and Differentiators 3 C,D 2 1,2 Course nature Assessment Method (Weightage 100%) Assessment Insemester Experiments tool Record MCQ/Quiz/Viva Voce Practical Model examination Total Experiments Weightage 40% 5% 5% 10% 60% 40% End semester examination Weightage : 40% STUDENT OUTCOMES: a,c. An ability to design and conduct experiments on amplifiers, oscillators &multivibrators. e,d. An ability to use the techniques, skills and modern engineering tools of electronic circuits for engineering practice. 5

6 4. INTRODUCTION ANALOG ELECTRONICS LABORATORY COURSE FLOW: This laboratory course completely deals with basics of analog electronic circuit design and their experimental observations. Here the students are exposed to design and implement the analog circuits like Clipping and Clamping circuits using diodes, Amplifiers using FET s or BJT s, verification of circuit theorems such as Thevenin s and maximum power transfer theorems, behavior of RL, RLC circuits, oscillators such as RC phase shift, Hartley, Colpitt s and Crystal oscillators, full wave and half wave rectifier circuits, resonance circuits, etc.. To start with this laboratory session, initially all students are trained to use the measuring instruments like Multi-meter and CRO. Thorough understanding of CRO is mandatory for proceeding with the course wear. The function or signal generators which generate the analog signals of desired frequency and amplitude (frequency and voltage levels) are made familiar to the students. Reading the values of the passive components like resistor, capacitor, etc. using color code are taught. After completing the above exercise, the design aspects of analog circuits are carried out. Thereafter the conduction of the experiments are started to verify and test the performance of the designed analog circuits. The input and generated output waveforms are sketched and the results are noted for further calculations. Instructions to the students are given in the start of this document which they are advised to read before they start conducting experiments. INSTRUCTIONS BEFORE STARTING THE EXPERIMENT 1. Study the circuit, theory and procedures, expected output before doing the experiment. 2. Get familiarize with the components and equipments used in the lab, Ex: Resistors, Capacitors Inductors, Signal generators, BJTs, FETs, CROs, Digital Multi-meter etc. 3. RESISTORS The Resistors used in this lab are of two types, (1)fixed value resistors which have colour bands and (2) Variable value resistors (Decade Resistance Box(DRBs)). Fig 1. A fixed value resistor Table 1. Colours with Digits 6

7 A Fixed value resistor looks as shown in the above image. The value of this kind of resistors is determined as shown below. We have to start from the side opposite to the gold or silver colour and go left to right. Now the Value of Resistor=(First colour digit)(second colour digit)(that many zeroes as third colour digit) ± (Fourth colour) ohms =(First Digit)(Second Digit)(Number of Zeroes) ± (Tolerance) Ω For example,if for a given resistor,first colour is Brown,second colour is White, third colour Yellow and fourth colour is Silver, then the value of this resistor is determined using Table 1 and above equation as, Value of resistor =( First Digit)(Second Digit)(Number of Zeroes) ±(Tolerance) Ω = (1) (9) (0000) ± 10% = ± KΩ (neglecting tolerance) Note : Finding the value of a variable value resistor (DRB) is straight forward in which we will set the value using knobs provided on the DRBs. The value of the resistor is sum of the values shown by each knob. 5. CAPACITORS Fig 2. Ceramic Capacitor Fig 3. Electrolytic Capacitor Capacitors are of two types, (a) Ceramic capacitor and (b) Electrolytic capacitors.they look like as shown in Fig 1 and Fig 2 given above. (a) Ceramic Capacitor : Ceramic capacitors have no polarity and the value of these capacitors is determined by using the digits shown on their body in fig 2, as follows, Value of capacitor= (First two digits)(that many Zeroes as third digit) pico farads For example. if the digits shown on the capacitor is 154, then its value is determined as, Value of capacitor = (First two digits)(that many Zeroes as third digit) pico farads = (15) (0000) pf = x F ( since pf=10-12 F ) =15 x 104 x F =15 x 10-8 =0.15 x 10-6 = 0.15 uf (b) Electrolytic Capacitor : Electrolytic Capacitors have polarities,so their terminals are 7

8 represented as positive and negative terminals that we can identify by seeing the body of Analog the capacitor that appears as shown in Fig 2 given above. Usually the lengthier terminal is the positive terminal and shorter terminal is the negative terminal. The value of the capacitor is given on the body of the capacitor itself. 5. SIGNAL GENERATOR AND ITS ADJUSTMENTS Signal generator or Function generator is an electronic instrument which is used as AC signal source to give AC input signals of different shapes ( square wave,sine wave,etc) and wide range of frequency required by the circuit. It has Voltage and Frequency knobs to adjust Voltage and Frequency of the input AC signals. Fig 4. Signal or Function generator Before connecting the signal generator to the circuit check the followings a. Set the shape of the waveform (sinusoidal). b. Set the frequency using coarse and fine adjustments. c. Set the offset adjustments. Set the CRO in DC mode and ensure the waveform is symmetry in both positive and negative cycle. If not, adjust it using the DC offsetting potentiometer d. Set the Voltage magnitude using Vcoarse settings and Vfine adjustments. 6. CRO (CATHODE RAY OSCILLOSCOPE) AND ITS ADJUSTMENTS CRO (Cathode Ray Oscilloscope) is an electronic instrument used to display,observe and analyse the outputs of the circuits. It has two channels two display two different outputs. Each channel has two axis,vertical axis which represents amplitude and horizontal axis which represents time. Values of amplitude and time of the signal are measured by using corresponding amplitude and time knob( which is common for both channels) on the CRO for both channels. 8

9 Fig 5. Cathode Ray Oscilloscope a. Select the right voltage and time scale to get the proper waveform b. For clipper and clamper circuits, observe the waveform in DC mode only c. Set the input waveform mainly for offset setting in DC mode only. d. Before measurement, ensure X & Y are in calibrated mode (if provided externally) e. Ensure that Channel selection and trigger mode are properly set. f. In case of two channels do not mix the signal and ground terminals. 7. MULTI-METER ADJUSTMENTS Fig 6. Multi Meter a. Set the right mode before taking the readings. Wrong mode settings may damage the instrument. b. For current reading, connect the multi-meter in ma (or A) mode to the circuit before switching on the supply. Do not remove the current meter when the supply is on. Check for ac and dc modes as required. 9

10 c. Use the proper probes for the measurement. Wrong cables may damage the instrument. 8. IDENTIFICATION OF TRANSISTOR TERMINALS Fig 7. Transistor Hold the Transistor as shown in Fig 7 given above. From the notch or Tab in the anticlockwise direction, first is Emitter, middle one is Base and the last i.e. third terminal is Collector terminal. 9. VOLTAGE REGULATED POWER SUPPLY (VRPS) ( Dual D.C Power Supply) Fig 8. Voltage Regulated Power Supply VRPS is used to provide D.C power required by the circuit if any and it looks as shown in Fig BREAD BOARD Fig 9. Bread Board Bread Board is apparatus which is used as the base to connect components of the circuit as shown in the Fig 9. Bread Board has connections points which are divided into rows and columns which in turn are internally shorted. 11. After adjusting the input voltage, check the circuit connections before turning the power on. 10

11 12. The ground connections are made properly & ensure that the circuit has one ground. 13. Connect the ground terminal of signal generator and the oscilloscope to the same point. Do not mix the ground point and signal of the two instruments to get the proper readings. 14. Don t pull out the connections with the power supply on. 15. Use only stripper to remove insulation. 16. Don t short the terminals while checking the output at pin terminals. 17. Don t switch on supply to the circuit unless the staff has checked the circuit connections. 11

12 Exercise Number: 1 Title of the Experiment: SERIES AND SHUNT FEEDBACK AMPLIFIER OBJECTIVE (AIM) OF THE EXPERIMENT To design and test the current-series and voltage shunt feedback amplifier and to calculate the following parameters with and without feedback. 1. Mid band gain. 2. Bandwidth and cut-off frequencies. 3. Input and output impedance FACILITIES REQUIRED AND PROCEDURE a) FACILITIES REQUIRED TO DO THE EXPERIMENT: S.NO APPARATUS SPECIFICATION QUANTITY 1. Power supply (0-30)V 1 2. Function Generator (0-20M)Hz 1 3. CRO 1 4. Transistor BC Resistor 6. Capacitor 7. Connecting Wires b) THEORY: Series Feedback Amplifier The current series feedback amplifier is characterized by having shunt sampling andseries mixing. In amplifiers, there is a sampling network, which samples the output and gives to the feedback network. The feedback signal is mixed with input signal by either shunt or series mixing technique. Due to shunt sampling the output resistance increases by a factor of D and the input resistance is also increased by the same factor due to series mixing. This is basically transconductance amplifier. Its input is voltage which is amplified as current. Shunt Feedback Amplifier In voltage shunt feedback amplifier, the feedback signal voltage is given to the base of the transistor in shunt through the base resistor R B. This shunt connection tends to decrease the input resistance and the voltage feedback tends to decrease the output resistance. In the circuit R B appears directly across the input base terminal and output 12

13 collector terminal. A part of output is feedback to input through R B and increase in I C decreases I B. Thus negative feedback exists in the circuit. So this circuit is also called voltage feedback bias circuit. This feedback amplifier is known a transresistance amplifier. It amplifies the input current to required voltage levels. The feedback path consists of a resistor and a capacitor. c) PROCEDURE: 1. Connect the circuit as per the circuit diagram. 2. Keeping the input voltage constant, vary the frequency from 50Hz to 3MHz in regular steps and note down the corresponding output voltage. 3. Plot the graph: Gain (db) Vs Frequency 4. Calculate the bandwidth from the graph. 5. Calculate the input and output impedance. 6. Remove Emitter Capacitance, and follow the same procedures (1 to 5). d) DESIGN PROCEDURE/ DESIGN CALCULATIONS: (i) Series Feedback Amplifier: Without Feedback: V CC = 12V; I C = 1mA; f L = 50Hz; S = 2; R L = 4.7KΩ r e = 26mV = I c V ce = V cc = 2 V E = V CC 10 h ie = h fe r e ; Applying KVL output loop, we get V cc = I E R E + I C R C + V ce ; R C = R L = 4.7KΩ Since I B is very small when compare with I C, I C I E R E = V E ; S = 1 + R B I E R E R B = V B = V CCR 2 R (R 1 +R 2 ) B = R 1 //R 2 R 1 = R 2 = X Ci = h ie//r B 10 C i = 1 2πfX ci X Co = R C//R L 10 C o = 1 2πfX co 13

14 With feedback (Remove the Emitter Capacitor, CE): Feedback factor, β = -RE = Gm = -hfe / (hie + RE) = Desensitivity factor, D = 1 + β Gm = Transconductance with feedback, Gmf = Gm / D = Input impedance with feedback, Zif = Zi D Output impedance with feedback, Z0f = Z0 D (ii) Shunt Feedback Amplifier: Without Feedback: V cc = 12V I c = 1mA; A v = 30; R f = 2.5KΩ; s = 2; r e = 26mV = I c β = 1 R f = h fe = h ie = h fe r e ; V ce = V cc = 2 V E = V CC 10 ; Applying KVL to output loop, we getv cc = I E R E + I C R C + V ce ; R C = Since I B is very small when compare with I C, I C I E R E = V E ;S = 1 + R B I E R E R B = R 1 = R 2 = With feedback: V B = V CCR 2 (R 1 + R 2 ) R B = R 1 //R 2 R O = R C //R f R i = (R B //h ie )R f R m = (h fe (R B //R f )(R C //R f ))/((R B //R f ) + h ie ) Desensitivity factor,d = 1 + βr m X Ci = R if C 10 i = 1 2πfX ci X Co = R of 10 R if = R i D R E = R E //( R B+h ie 1+h fe ) X CE = R E /10 C E = 1 2πfX ce 1 X Cf = R f /10C f = 2πfX cf 14 R of = R o R D mf = R m D C o = 1 2πfX co

15 e) CIRCUIT DIAGRAM: Series Feedback Amplifier: Without Feedback: Series Feedback Amplifier: With Feedback: 15

16 Shunt Feedback Amplifier: Without Feedback: Shunt Feedback Amplifier: With Feedback: 16

17 f) MODEL GRAPH: Series Feedback Amplifier Shunt Feedback Amplifier e) TABULATION: (i) Without Feedback: Frequency (Hz) Vo (Volts) Gain = V0/Vi Gain = 20 log(v0/vi) (db) 17

18 (ii) With Feedback: Frequency (Hz) Vo (Volts) Gain = V0/Vi Gain = 20 log(v0/vi) (db) RESULT: Thus the current series feedback amplifier is designed and constructed and the followingparameters are calculated Pre lab questions: 1) What is feedback? 2) What is positive feedback? 3) Define amplification factor? 4) What is Q-point? Post lab questions: 1) What is the difference between positive feedback and negative feedback? 2) Define Sensitivity? 3) What are the applications of feedback amplifiers? 4) What is the effect of current series feedback amplifier on the input impedance of the amplifier? 5) Mention the properties of negative feedback? 6) Give an example of negative shunt feedback? 7) Define voltage shunt feedback? 8) What is the effect of negative feedback on the bandwidth of an amplifier? 18

19 Exercise Number: 2 Title of the Experiment: DESIGN OF WEIN BRIDGE OSCILLATOR OBJECTIVE (AIM) OF THE EXPERIMENT To design a wein bridge oscillator and to draw its output waveform. FACILITIES REQUIRED AND PROCEDURE a) FACILITIES REQUIRED TO DO THE EXPERIMENT: S.NO APPARATUS SPECIFICATION QUANTITY 1. Power supply (0-30)V 1 2. Function Generator (0-20M)Hz 1 3. CRO 1 4. Transistor BC Resistor 6. Capacitor 7. Connecting Wires b) THEORY: The Wien bridge oscillator employs a balanced wien bridge as the feedback network. Two stage CE amplifier provides 360 phase shift to the signal. So the wien bridge need not introduce any phase shift to satisfy Barkausen criterion. The attenuation of the bridges calculated to be 1/3 at resonant frequency. So the amplifier stage should provide a gain of exactly 3 to make loop gain unity. Since the gain of two stage amplifier is the product of individual stages, overall gain becomes very high. But the gain will be trimmed down to 3 by negative feedback network. The emitter resistors of both stages are kept unbypassed. This provides a current series feedback which ensures the stability of operating point and reduction of gain. Frequency of oscillation is given by f = 1/2πRC c) PROCEDURE: 1. Connections are made as per the circuit diagram 2. Feed the output of the oscillator to a C.R.O by making adjustments in the Potentiometer connected in the positive feedback loop, try to obtain a stable sine 19

20 Wave. 3. Measure the time period of the waveform obtained on CRO. & calculate the Frequency of oscillations. 4. Repeat the procedure for different values of capacitance d) DESIGN PROCEDURE/ DESIGN CALCULATIONS: V cc = 12V; I c = 2mA; V RC = 4.8V; V RE = 1.2V; V CE = 6V; Design of R c : Design of R E : Design of R 1 and R 2 : R C = V RC = 2.4KΩ; I C R E = V RE =600Ω; I E I B = I C h fe = 20µA; Assume the current through R 1 is 10I B and R 2 is 9I B V R2 = V BE + V RE = 1.9V; V R2 = 9I B R 2 ; R 2 = 10.6KΩ; V R1 = V CC V R2 = 10.1V; V R1 = 10I B R 1 ; R 1 = 50KΩ; f=1khz; f=1/2πc c (R 1 //R 2 //h fe R E ) C c = 44μF; The required frequency of oscillation f C = 1 = 10KHz; 2πRC Take R=47KΩ and C=0.01µF; Gain of the amplifier must be 3; Negative feedback factor is given by R E (RE + R 3 ) R E (RE + R 3 ) = 3; R 3 = 12KΩ; f) CIRCUIT DIAGRAM: 20

21 g) MODEL GRAPH: f) TABULATION: Amplitude Time Frequency RESULT: Thus a Wien bridge oscillator is designed and the output waveform is drawn. Frequency Theoretical Practical Pre lab questions: 1) Define oscillator? 2) What is resonant frequency? 3) Define Q-point? 4) Define tuned amplifier? Post lab questions: 1) Statebarkhausen criteria? 2) What are the applications of wein bridge oscillator? 3) What is the efficiency of wein bridge oscillator? 4) How to produce sinusoidal output from wein bridge oscillator? 21

22 Exercise Number: 3 Title of the Experiment: DESIGN OF TRANSISTOR RC PHASE SHIFT OSCILLATOR OBJECTIVE (AIM) OF THE EXPERIMENT To design and construct a RC phase shift oscillator for the given frequency. FACILITIES REQUIRED AND PROCEDURE a) FACILITIES REQUIRED TO DO THE EXPERIMENT: b) THEORY: S.NO APPARATUS SPECIFICATION QUANTITY 1. Power supply (0-30)V 1 2. Function Generator (0-20M)Hz 1 3. CRO 1 4. Transistor BC Resistor 6. Capacitor 7. Connecting Wires In the RC phase shift oscillator, the required phase shift of 180 in the feedback loopfrom the output to input is obtained by using R and C components, instead of tank circuit. Here a common emitter amplifier is used in forward path followed by three sections of RC phase network in the reverse path with the output of the last section being returned to the input of the amplifier. The phase shift Ф is given by each RC section Ф=tanˉ1 (1/ωrc). In practice R-value is adjusted such that Ф becomes 60. If the value of R and C are chosen such that the given frequency for the phase shift of each RC section is 60. Therefore at a specific frequency the total phase shift from base to transistor s around circuit and back to base is exactly 360 or 0. Thus the Barkhausen criterion for oscillation is satisfied. 22

23 c) PROCEDURE: 1. Connections are made as per the circuit diagram. 2. Switch on the power supply and observe the output on the CRO (sine wave). 3. Note down the practical frequency and compare with its theoretical frequency. d) DESIGN PROCEDURE/ DESIGN CALCULATIONS: V cc = 12V; I c = 1mA; A v = 30; R f = 2.5KΩ; s = 2; f=1khz; r e = 26mV = I c β = 1 R f = h fe = h ie = h fe r e ; V ce = V cc = 2 V E = V CC 10 ; Applying KVL to output loop, we get V cc = I E R E + I C R C + V ce ; R C = Since I B is very small when compare with I C, I C I E R E = V E I E ; R B = V B = V CCR 2 (R 1 +R 2 ) R 1 = R 2 = S = 1 + R B R E R B = R 1 //R 2 Gain formula is given by A v = h fer Leff h ie A v = 29; R Leff = R C //R L ; R L = X Ci = ([h ie + (1 + h fe )R E ]//R B )/10 = C i = 1/2πfX Ci X CO = RL eff 10 ; C o = 1/2πfX CO ; C E = R E ; 10 C E = 1/2πfX CE C=0.01µF; f = 1/2πRC 6 R= 23

24 g) CIRCUIT DIAGRAM: h) MODEL GRAPH: g) TABULATION: Amplitude Time Frequency 24

25 RESULT: Thus RC phase shift oscillator is designed and constructed and the output sine wavefrequency is calculated as Frequency Theoretical Practical Pre lab questions: 1) What is oscillator circuit? 2) What are the different types of oscillators? 3) What are the conditions for oscillations? 4) Define frequency loop? Post lab questions: 1) What are the applications of RC phase shift oscillator? 2) Why RC oscillator cannot generate high frequency oscillations? 3) What phase shift does RC phase oscillator produce? 4) How is phase angle determined in RC phase shift oscillator? 5) How can we get a maximum phase angle of 90 0 in RC phase shift oscillator? 25

26 Exercise Number: 4 Title of the Experiment: DESIGN OF LC HARTLEY AND COLPITT OSCILLATOR OBJECTIVE (AIM) OF THE EXPERIMENT To design and set-up the following tuned oscillator circuits using BJT, and determine the frequency of oscillation. (a) Hartley Oscillator (b) Colpitts Oscillator FACILITIES REQUIRED AND PROCEDURE a) FACILITIES REQUIRED TO DO THE EXPERIMENT: b) THEORY: S.NO APPARATUS SPECIFICATION QUANTITY 1. Power supply (0-30)V 1 2. Function Generator (0-20M)Hz 1 3. CRO Transistor BC Resistor 470Ω, 1KΩ10KΩ,33 KΩ 1 6. Capacitor 0.1µf, 470 pf 3 Inductance 100 µh 2 7. Connecting Wires In the Hartley oscillator shown in Figure. Z1, and Z2 are inductors and Z3 is an capacitor. The resistors R and R2 and RE provide the necessary DC bias to the transistor. CE is a bypass capacitor CC1 and CC2 are coupling capacitors. The feedback network consisting of inductors L1 and L2, Capacitor C determine the frequency of the oscillator. When the supply voltage +Vcc is switched ON, a transient current is produced in the tank circuit, and consequently damped harmonic oscillations are setup in the circuit. The current in tank circuit produces AC voltages across L1 and L2. As terminal 3 is earthed, it will be at zero potential. If terminal is at positive potential with respect to 3 at any instant, then terminal 2 will be at negative potential with respect to 3 at the same instant. Thus the phase difference between the terminals 1 and 2 is always 180. In the CE mode, the transistor provides the phase difference of 180 between the input and output. Therefore the total phase shift is 360. The frequency of oscillations is f = 1/2π LC where L= L1 + L2. 26

27 c) PROCEDURE: 1. Connections are made as per the circuit diagram. 2. Switch on the Power Supply and check the D.C conditions by removing the coupling capacitor CC1 or CC2. 3. Connect the coupling capacitors and obtain an output waveform on the CRO. If the o/p is distorted vary 1- KΩ Potentiometer (R3) to get perfect SINE wave. 4. Measure the period of oscillation and calculate the frequency of oscillation. 5. Compare the measured frequency with re-computed theoretical value for the component values connected. d) DESIGN PROCEDURE/ DESIGN CALCULATIONS: Transistor: SL100 Let VCC = 12V; IC = 4.5 ma; VE = 1.2V; VCE =6V; hfe =100. Given VE = 1.2V. Therefore RE = VE / IE VE / IC = ; RE=270Ω Writing KVL for the Collector loop we get, VCC = ICRC + VCE + VE RC = (VCC VCE VE) / IC = ( )V/4mA=1.06K ; RC= 1 K hfe RE = 10R2 Assume R2=2.7KΩ, VB = (Vcc x R2 ) / (R1 + R2) Hence R1 = K ; R1 = 15 K Use CC1= 0.47 F Use CC2= 0.47 F Use CE=47 F Hartley Oscillator Oscillator Frequencyf= cleq. = L1+ L2Assume f = 500 KHz. With L1 = L2 =100μH, we get Leq. = L1+ L2 = 200μH Leq.C=1/(2πf) 2 =(π) -2 x10-12 This gives C = {1/ (π)2 x 200μH} pf 500pF Use C = 470 pf For this capacitance value f= KHz 27

28 Colpitts Oscillator Tank Circuit Design: f 1 C Where 1 C 2 C eq 2 LC eq C 1 C 2 Given Oscillation frequency f =1 MHz Assume C1=C2 = 470 pf Ceq= 235 pf = Then, L 4 2 ( f 2 )C 119 µh Use L = 100 µh, For this value of L, f = 1.04 MHz e) CIRCUIT DIAGRAM: Hartley Oscillator Colpitts Oscillator 28

29 i) MODEL GRAPH: Hartley and Colpitts Oscillator h) TABULATION: Hartley Oscillator Amplitude Time Frequency Colpitts Oscillator 29

30 Amplitude Time Frequency RESULT: Thus oscillator is designed and constructed and the output sine wavefrequency is calculated as Frequency Theoretical Practical Hartley Oscillator Colpitts Oscillator Pre lab questions: 1) What is Hartley oscillator circuit? 2) What is Colpitts oscillator circuit? 3) What is the main function of biasing circuit? 4) Define Tank circuit? Post lab questions: 1) What are the applications of Hartley oscillator? 2) State the advantage and disadvantage of Hartley Oscillator? 3) What is the purpose of bypass capacitor? 4) What are the applications of Colpitts oscillator? 5) State the advantage and disadvantage of Colpitts Oscillator. 30

31 Exercise Number: 5 Title of the Experiment: CLIPPERS AND CLAMPERS OBJECTIVE (AIM) OF THE EXPERIMENT To design and construct a clipper and clamper. FACILITIES REQUIRED AND PROCEDURE a) FACILITIES REQUIRED TO DO THE EXPERIMENT: b) Theory:- S.NO APPARATUS SPECIFICATION QUANTITY 1. Power supply (0-30)V 1 2. Function Generator (0-20M)Hz 1 3. Switching diode 1N DSO Resistor 1KΩ10KΩ 1 6. Capacitor 1µf, 10 µf 3 7. Connecting Wires Clipping circuits are used to remove part of a signal that us above or below some defined reference level. We have already seen an example of Clipper in the half wave rectifier-that circuit basically cuts off everything at the reference level of zero and let only the positive going portion of input waveform through it. Clamping circuits,also known as dc restorers or damped capacitors shift an input signal by an amount defined by an independent voltage source. While clippers limit the part of the input. Signal that reaches the output according to some reference level. The entire input reaches the output in a clamping circuit-it is just shifted so that the maximum or minimum value of the input is clamped to the independent source. c) Procedure: 1 Connections are made as per the circuit diagram. 2 Set input signal voltage(5v,i KHz) using a function Generator 2 Observe the output waveform using A CRO 4 Sketch the observed waveform on the graph. 31

32 d) Circuit diagram e) Model Graph 32

33 33

34 f) Tabular column for clipper: V m = V max = f = 50Hz V min = POSTIVE CLIPPER DC Voltage (V) V max V O V min 2V 4V 6V NEGATIVE CLIPPER DC Voltage (V) V max V O V min 2V 4V 6V g) Tabular column of clamper: V m = 6V f = 50Hz INPUT OUTPUT V max V min V max V min POSITIVE CLAMPER NEGATIVE CLAMPER 34

35 Result: The clipper and clamper input and output voltages have been designed and verified. Prelab Questions 1. Define clippers 2. Define clamper 3. Give some applications of clippers and clampers. Post lab Questions 1. Why clippers and clamper are called wave shaping circuits? 2. The positive clipper can be easily converted to negative clipper by? 3. Give some examples of clippers and clampers? 35

36 Exercise Number: 6 INTEGRATORS AND DIFFERENTIATORS OBJECTIVE (AIM) OF THE EXPERIMENT To design and construct integrator and differentiator FACILITIES REQUIRED AND PROCEDURE a) FACILITIES REQUIRED TO DO THE EXPERIMENT: S.NO APPARATUS SPECIFICATION QUANTITY 1. Power supply (0-30)V 1 2. Function Generator (0-20M)Hz 1 4. DSO Resistor 1KΩ10KΩ 1 6. Capacitor 47nF 3 7. Connecting Wires b) Theory: Filters are important blocks in communication and instrumentation systems. They are widely used in radio receivers, power supply circuits and noise reduction systems. There are four different types of filters. Low pass filters, (which passes low frequency signals and reject high frequency components) Band pass filters, (Which passes signals within a certain frequency range) high pass filters ( Which passes high frequency signals and reject low frequency components) and band reject Filters (Which reject Signals that have frequencies outside a certain band). c) Procedure: 1. Connections are made as per the circuit diagram. 2 Apply 6 Vpp Sinosoidal signal from Function generator 3 Vary the frequency and find the -3 db Frequency. 4 Observe several points above and below the 3dB frequency 5 Measure the output with input frequency several points above the -3dB frequency 36

37 d) Design Procedure Low pass filters : Where For the low pass filter circuit, the transfer function is of the form, V o / V in = 1 / [ 1+ (s/ ω p ) ] ω p = Pole frequency location in radians / sec High pass filters : Where For high pass filter circuit, the transfer function is of the form, V o / V in = S / (ω p + S) ω p = Pole frequency location in radians / sec Design Calculation: Integrator: Using KVL V in (t) = R in + 1/C i dt V O (t) =1/C i dt (using Laplace) (since i dt =I(s)/s) V in (s) = RI(s) + 1/C I(s)/s (1) V O (s) =1/C I(s)/s (2) V O (s) = I(s) 1/C V in (s) RI(s) +1/C I(s)/s Ω p = 1/RC = 1/Ʈ = 1/S+ Ω p = Differentiator: V in (t)= Ri(t) + 1/ C idt V O (t)= Ri(t) V in (s)= RI(s) + 1/C*I(s)/S Vo(s)= RI(s) V in (s) / Vo(s) = I(s) [R+1/SC] / RI(s) V in (s) / Vo(s) = R.SC / SRC+1=SC+1/SC f = 1k Hz, R=5.6 kω, C = 220pf, Ʈ 1 =RC Ʈ 2 =5.6x10 3 x 0.1x10 6 = s Ʈ = 5.6 x 220= Calculation of C: Z 16T ; T=1/f Z R= 5.6 KΩ f=1.5khz RC= C = /K = 2 µf. 37

38 e) Circuit Diagram f) Model Graph Integrator 38

39 Differentiator f) Tabular column Integrator (low pass filter): 39

40 Frequency= T= T on = Measured voltage INPUT V in OUTPUT V out V max V min V pp Differentiator (high pass filter): Frequency= T= T on = Measured voltage INPUT V in OUTPUT V out V max V min V pp Result: Thus the experiment was performed and the ripple factors for half wave Rectifier with and without load and the loadregulation has been calculated. Pre lab Questions 1. Define filter? 2. Give the classification of filter? 3. What is the difference between active and passive filter? Post Lab Questions 1. Give some applications of filters? 2. What do you mean by -3dB cut off frequency? 3. What is all pass filter? 40

41 Exercise Number: 7 Title of the Experiment: DARLINGTON EMITTER FOLLOWER OBJECTIVE (AIM) OF THE EXPERIMENT To design and obtain the frequency response characteristics of Darlington pair amplifier byhardware implementation. FACILITIES REQUIRED AND PROCEDURE a) FACILITIES REQUIRED TO DO THE EXPERIMENT: S.NO APPARATUS SPECIFICATION QUANTITY 1. Power supply (0-30V) 1 2. CRO 1 3. Resistor 4.9KΩ, 1.6MΩ 3 4. Capacitor 0.45nF 2 5 Transistor BC Connecting wires and probes - Req. b) THEORY: Darlington transistor (often called a Darlington pair) is a compound structure consisting of two bipolar transistors (either integrated or separated devices) connected in such a way that the current amplified by the first transistor is amplified further by the second one. This configuration gives a much higher common/emitter current gain than each transistor taken separately and, in the case of integrated devices, can take less space than two individual transistors because they can use a shared collector. Integrated Darlington pairs come packaged singly in transistor-like packages or as an array of devices (usually eight) in an integrated circuit. c) PROCEDURE: Hook up the circuit as shown in the circuit diagram. Switch on the power supply. Set the input trigger using trigger pulse generator. Observe the output waveform in CRO. 41

42 d) CIRCUIT DIAGRAM: e) MODEL GRAPH: f) Tabulation: S.NO FREQUENCY(Hz) VOLTAGE(Vo) GAIN GAIN (in db) Result:Thus the Darlington amplifier is designed and constructed using transistor and itsoutput waveform is plotted. Pre lab Questions: 1. Mention the advantages of Darlington amplifier. 2. What is the main function of a Darlington amplifier? 3. What is the input impedance of Darlington pair amplifier? 42

43 Post lab Questions: 1. Why do you need more than one stage of amplifiers in practical circuits? 2. What is the effect of cascading on gain and bandwidth? 3. What happens to the 3dB frequencies if the number of stages of amplifiers increases? 4. Why we use a logarithmic scale to denote voltage or power gains, instead of using the simpler linear scale? 5. What is loading effect in multistage amplifiers? 43

44 Exercise Number: 9 Title of the Experiment: MONOSTABLE MULTIVIBRATOR OBJECTIVE (AIM) OF THE EXPERIMENT To design and construct monostable multivibrator using transistor and to plot the outputwaveform. FACILITIES REQUIRED AND PROCEDURE a) FACILITIES REQUIRED TO DO THE EXPERIMENT: S.NO APPARATUS SPECIFICATION QUANTITY 1. Power supply (0-30V) 1 2. CRO 1 3. Resistor 4.9KΩ, 1.6MΩ 3 4. Capacitor 0.45nF 2 5 Transistor BC Connecting wires and probes - Req. b) THEORY: Monostable multivibrator has two states which are (i) quasi-stable state and (ii) stable state. When a trigger input is given to the monostable multivibrator, it switches between two states. It has resistor coupling with one transistor. The other transistor has capacitive coupling. The capacitor is used to increase the speed of switching. The resistor R2 is used to provide negative voltage to the base so that Q1 is OFF and Q2 is ON. Thus an output square wave is obtained from monostable multivibrator. c) PROCEDURE: Hook up the circuit as shown in the circuit diagram. Switch on the power supply. Set the input trigger using trigger pulse generator. Observe the output waveform in CRO. d) DESIGN PROCEDURE/ DESIGN CALCULATIONS: V CC = 12V, V BB = 5V, I C = 2mA, V CE(Sat) = 0.2V, f = 1KHz, h fe= R C = V CC V CE(Sat) =5.9KΩ I C 44

45 I B2(min ) = I C2 h fe = Select I B2 > I B2(min ) I B2 = R = V CC V BE(Sat) I B2 T=0.69RC C=T/0.69R= V B1 = V BBR 1 R 1 + R 2 + V CE(Sat)R 2 R 1 + R 2 V BB R 1 R 1 + R 2 = V CE(Sat)R 2 R 1 + R 2 (V B1 is very less) V BB R 1 = V CE(Sat) R 2 R 2 = 10R 1 Let R 1 = 10KΩ, then R 2 = 100KΩ Choose C1 = 25pF. e) CIRCUIT DIAGRAM: 45

46 f) MODEL GRAPH: g) TABULATION: Width (ms) Vc1 T ON (ms) T OFF (ms) Voltage(V) T ON (ms) T OFF (ms) Voltage(V) Vc2 Result:Thus the bistable multivibrator is designed and constructed using transistor and itsoutput waveform is plotted. Pre lab Questions: 1. Define duty-cycle. 2. Give methods for obtaining symmetrical square wave. 3. Why monostable multivibrator is called one-shot vibrator? Post lab Questions: 1. What are the other names of monostable multivibrator? 2. Why monostable multivibrator is called gating circuit? 3. What is the difference between a retriggerable one shot and a nonretriggerable one shot? 46

47 Exercise Number: 10 Title of the Experiment: BISTABLE MULTIVIBRATOR OBJECTIVE (AIM) OF THE EXPERIMENT To design and construct bistable multivibrator using transistor and to plot the outputwaveform. FACILITIES REQUIRED AND PROCEDURE a) FACILITIES REQUIRED TO DO THE EXPERIMENT: S.NO APPARATUS SPECIFICATION QUANTITY 1. Power supply (0-30V) 1 2. CRO 1 3. Resistor 4.9KΩ, 1.6MΩ 3 4. Capacitor 0.45nF 2 5 Transistor BC Connecting wires and probes - Req. b) THEORY: The bistable multivibrator has two stable states. The multivibrator can exist indefinitely in either of the two stable states. It requires an external trigger pulse to change from one stable state to another. The circuit remains in one stable state until an external trigger pulse is applied. The bistable multivibrator is used for the performance of many digital operations such as counting and storing of binary information. The multivibrator also finds an applications in generation and pulse type waveform. c) PROCEDURE: Hook up the circuit as shown in the circuit diagram. Switch on the power supply. Set the input trigger using trigger pulse generator. Observe the output waveform in CRO. 47

48 d) DESIGN PROCEDURE/ DESIGN CALCULATIONS: Frequency of oscillator F=1//2πRC. Assume C and find R to prevent loading of the amplifier by RC networkr1 10R. R C = V CC V CE(Sat) =5.9KΩ I C R < h fe R c R = 1.8MΩ. Let R1 = 10KΩ, C1 = C2 = 50pF e) CIRCUIT DIAGRAM: V CC = 12V, V BB = 12V, I C = 2mA, V CE(Sat) = 0.2V, V BE(Sat) = 0.7Vh fe =315 f) MODEL GRAPH: 48

49 g) TABULATION: Width (ms) Vc1 T ON (ms) T OFF (ms) Voltage(V) T ON (ms) T OFF (ms) Voltage(V) Vc2 Result:Thus the bistable multivibrator is designed and constructed using transistor and itsoutput waveform is plotted. Pre lab questions: 1. Why a astable multivibrator is called a free-running oscillator? 2. Explain the function rest. 3. Define the term duty cycle. Post lab questions: 1. Why does one of the transistors start conducting ahead of other? 2. What finally decides the shape of the waveform for bistable multivibrator? 3. What happened if positive pulse is given to a transistor in bistable multivibrator? 49