# Calicut University Question Papers

```Government Engineering College
Kozhikode-5
Calicut University Previous Year
B.Tech Question Papers
AI 09 Syllabus: S3
(Version 1.00 - 2015-07-08)
Nikhil Narayan
(2010 AEI batch)&lt;nikhil.sopanam(at)gmail(dot)com&gt;
c 2013, 2014, 2015 Mohammed Sadik P. K. Some Rights Reserved.
Copyright Note: The questions included in this file are in public domain (as far as I know). But this implementation, the LATEX source and the corresponding compiled document is copyright under the terms and
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D 30912
(Pages : 2)
Name: ...............................
Reg. No: ...........................
THIRD SEMESTER B.TECH. (ENGINEERING) DEGREE EXAMINATION
OCTOBER 2012
AI09 303—ELECTRONIC CIRCUITS—1
Time: Three Hours
Maximum: 70 Marks
Note: The same Question paper was printed for December 2010 Examination (Code: 10051)
Part A
1. Explain the effect of temperature on the volt-ampere characteristic of a diode.
2. Why do we need filters in a power supply? Under what condition we shall prefer a capacitor
filter?
3. Draw the circuit diagram of a common emitter amplifies with emitter and voltage divider biasing
circuit. Why normally an emitter bypass capacitor is used?
4. Draw the circuit diagram of an RC coupled amplifier using PNP transistor.
5. (a) How does the drain current vary with gate voltage in the saturation region.
(b) How does the trans conductance vary with drain current?
(5 &times; 2 = 10 marks)
Part B
6. Draw two biasing circuits for a JFET or a depletion type MOSFET.
7. What are the important applications of a diode?
8. A full wave rectifier with a center tapped transformer (10–0–10V) supplies a load current of 100
mA. Neglecting the diode forward resistance and secondary winding resistance, find (a) the dc
output voltage (b) PIV of each diode and (c) ripple frequency.
9. Explain the V–I characteristics of UJT. Why it is called a current controlled negative resistance
device?
10. Explain how will you determine h-parameters of a transistor experimentally.
11. Give a circuit diagram of a two-stage transistorized RC coupled amplifier. Also draw the frequency response of the amplifier.
(4 &times; 5 = 20 marks)
Turn over
2
D 30912
Part C
12. (a)
i. What are the different types of inductors? Explain them with their constructional
(5 marks)
features. Give some important applications of inductors.
(5 marks)
ii. Explain briefly about the basic construction of an electrolytic capacitor.
Or
(b)
i. Explain with suitable diagram how a diode can be used as a peak clipper and a base
(5 marks)
clipper as series element and shunt element. Draw a circuit for a slices.
ii. What is the purpose of a clamping circuit? Explain the working of a diode clamper.
(5 marks)
How clamping to a dc level is achieved?
13. (a)
i. Explain the operation of short circuit protection against overload with neat circuit
(5 marks)
diagram.
ii. A 10 V zener diode is used to regulate the voltage across a variable load resistor. The
input voltage varies between 13 and 16 V. The load current (IL ) varies between 10 and
85 mA. The minimum zener current is 15 mA. Find (i) the maximum value of Rs and
(5 marks)
the maximum power dissipated by the zener diode, using the value of Rs .
Or
(b)
i. Draw the circuit diagram of half wave rectifier. Explain its working. What is the
(6 marks)
frequency of ripple in its output?
ii. A full-wave rectifier supplies 0.2 A current at 30 V dc. Find the ripple factor to be
expected when two 100 mF capacitors and a 5 H inductor are used in Pi-filter with a
(4 marks)
50 Hz supply.
14. (a) Develop a low frequency equivalent circuit for a basic common collector amplifier and derive
the relations for the current gain, voltage gain and input resistance in terms of h-parameters.
Make suitable assumptions and simplify the final results. Also justify the name ‘emitter
follower’ for this type of amplifier.
Or
(b)
i. With the help of a suitable circuit diagram, explain the working of a RC coupled
(6 marks)
amplifier. Derive the expression for voltage gain of the amplifier.
ii. Explain with suitable circuit diagram, the operation of transformer coupled transistor(4 marks)
ized amplifier.
15. (a) How a small signal high frequency model is different from a low frequency model? Explain
it briefly.
Or
(b) Draw neatly the circuit diagram of a common source JFET amplifier and explain its working.
D 20629
(Pages : 3)
Name: ...............................
Reg. No: ...........................
THIRD SEMESTER B.TECH. (ENGINEERING) DEGREE EXAMINATION
OCTOBER 2011
AI09 303—ELECTRONIC CIRCUITS—1
Time: Three Hours
Maximum: 70 Marks
Part A
1. What is a PN Junction diode? How its terminals are identified?
2. The Q-factor of a 100 mH inductor is 80. When operated in 400 kHz range. What is the dc
resistance (R0 ) of the inductor?
3. What is the function of a bleeder resistor?
4. Name different types of biasing circuits and give three circuit configurations.
5. How do you set a Q-point in a self-biased JFET?
(5 &times; 2 = 10 marks)
Part B
6. How does the dynamic resistance ‘r’ of a diode vary with (a) Current and (b) Temperature
(c) What is the order of magnitude of ‘r’ for silicon at room temperature and for a dc current of
1mA?
7. A zener diode voltage regulating circuit is shown in Fig. 1. The zener diode used has zener
Voltage (Vz ) of 15V and minimum current Iz (min) of 2&micro;A, a power dissipation of 120 mW and
a zener resistance of 40Ω. If the resistance is 5KΩ and the input voltage varies from 18 to 24V,
find the value of Rs .
IL= 0.1A
β=100
I
Vs
15 - 18V
IB
R
12 V
Vz
Iz
Fig. 1.
8. What are the advantages of a bridge rectifier as compared to a full wave center-tapped rectifier?
Turn over
2
D 20629
9. Compare the relative stability of (a) emitter bias and fixed bias circuit, (b) emitter bias and
voltage divide bias circuits.
10. Explain the essential difference between the RC coupled and direct coupled amplifier.
11. A certain JFET amplifier has gm of 4ms, rd = 10KΩ and RD = 5KΩ. What is the voltage gain?
Assume the source resistance to be zero.
(4 &times; 5 = 20 marks)
Part C
12. (a)
i. A.
B.
C.
ii. A.
Draw the piecewise linear voltampere characteristic of a p-n diode.
What is the circuit model for the ON state?
(6 marks)
The OFF state.
Derive the expression for IC versus IB for a CE transistor configuration in the active
region.
(4 marks)
B. For IB = 0, What is IC ?
Or
(b)
i. A.
B.
C.
ii. A.
B.
Sketch the circuit of a CS amplifier.
Derive the expression for the voltage gain at low frequencies.
What is the maximum value of AV ?
Sketch the cross section of a p-channel enhancement MOSFET.
Show two circuit symbols for this MOSFET.
(6 marks)
(4 marks)
13. (a) Draw the circuit diagram of full wave rectifiers:
i. With center-tap connection and
ii. Bridge connection. Explain their working.
What is the peak inverse voltage of a diode in each case?
Or
(b)
(5 marks)
i. Draw circuit diagram of transistor shunt regulator. Explain it briefly.
ii. A 36V dc voltage is applied through a series resister of 600Ω to a load 300Ω shunted
by a zener diode as shown in Fig. 2. if Vz = 8V and γz = 10Ω.
Find (a) dc Load voltage; (b) Power dissipated in the zener and (c) maximum current,
that a regulator can deliver and still regulate.
3
D 20629
Rs=600Ω
Vs=36V
RL=300Ω
Fig. 2.
14. (a)
(4 marks)
i. Derive an expression for the stability factor of a fixed bias current.
ii. Draw a voltage divider bias circuit and derive an expression for its stability factor.
(6 marks)
Or
(b) Derive the expressions for input resistance, output resistance, current gain and voltage gain
of a common emitter amplifier.
15. (a)
i. What are the biasing schemes available to achieve to achieve the required bias in a
(6 marks)
JFET? Explain any one of the biasing schemes.
ii. A certain JFET has a transconductance (gm ) of 2500&micro;S. With an external drain resis(4 marks)
tance of 2kΩ. Find the value of ideal voltage gain.
Or
(b)
i. Sketch the small signal high frequency circuit of a CS amplifier.
ii. Derive the expression for the voltage gain.
(4 &times; 10 = 40 marks)
D 51037
(Pages : 2)
Name: ...............................
Reg. No: ...........................
THIRD SEMESTER B.TECH. (ENGINEERING) DEGREE EXAMINATION
NOVEMBER 2013
AI09 304—ELECTRICAL ENGINEERING
Time: Three Hours
Maximum: 70 Marks
Part A
1. What are the desirable conditions for DC generators to be connected in parallel?
2. Why is the HV side of a single-phase transformer left open and the open circuit test is performed
by energising the LV side?
3. Why is a single-phase transformer rated in kVA?
4. Give the relationship between the gross mechanical power output and the air gap power in a
three-phase Induction motor.
5. What is meant by creep in an Induction type energy meter?
(5 &times; 2 = 10 marks)
Part B
6. Classify the DC generators and draw the external characteristics of each type of DC generator.
7. Explain the principle of operation of a single-phase transformer and hence derive and expression
for induced emf from its first principles.
8. Discuss the phenomenon of armature reaction in a three-phase alternator for pure inductive load
at the armature terminals.
9. Derive the condition for maximum torque at running condition for a three-phase induction motor.
10. Explain the possible errors that can occur in a moving iron instrument when both AC and DC
quantities are measured.
11. Demonstrate how power can be measured in a three-phase circuit by using two wattmeters.
(4 &times; 5 = 20 marks)
Turn over
2
D 51037
Part C
Answer section (a) or section (b) of each question.
12. (a)
(2 marks)
i. Differentiate Lap and wave windings in a DC machine.
ii. Two DC shunt generators are rated 230 kW and 150 kW, 400 V. Their full load voltage
drops are 3% and 6% respectively. They are excited to no-load voltages of 410 V and
420 V respectively. How will they share a load of 1000 Amps and the corresponding
(8 marks)
bus voltage?
Or
(b)
(2 marks)
i. Compare the advantages of four point starter over three-point starter.
ii. A 10 kW, 250 V shunt motor has an armature resistance of 0.5Ω and a field resistance of
200 W. AT no-load and rated voltage, the speed is 1200 rpm, and the armature current
is 3 Amps. At full load 8 rated voltage, the line current is 47 Amps and because of
armature reaction, the flux is 4% less than its no-load value. What is the full-load
(8 marks)
speed? What is the developed torque at full load?
13. (a) Explain the different methods of cooling adopted in a single-phase transformer. (10 marks)
Or
(b)
(2 marks)
i. What is all day efficiency?
ii. Draw and explain the phasor diagram respecting the relationship between different
voltages and current of a single-phase transformer if the secondary is loaded with pure
(8 marks)
14. (a) Explain in detail the construction of a three-phase Induction motor. Also explain the
(10 marks)
different types of rotor construction.
Or
(b) Explain how does a synchronous motor perform when the excitation current is increased
from zero to rated value with the help of phasor diagram relating the induced voltage and
(10 marks)
the field currents.
15. (a) Explain the kelvins double bridge method of measurement of Low resistance.
(10 marks)
Or
(b) Explain how dissipation factor can be determined accurately with the help of schering
(10 marks)
Bridge.
(4 &times; 10 = 40 marks)
D 20630
(Pages : 3)
Name: ...............................
Reg. No: ...........................
THIRD SEMESTER B.TECH. (ENGINEERING) DEGREE EXAMINATION
OCTOBER 2011
AI09 304—ELECTRICAL ENGINEERING
Time: Three Hours
Maximum: 70 Marks
Part A
1. What is the need for starters for starters used in D.C. motors? Justify your answer.
2. What is the significance of ‘Back emf’ in a shunt motor?
3. Mention the losses that occur in a single phase transformer.
4. Comment on the starting torque of a wound rotor induction motor.
5. Which bridge is suitable for measuring small capacitance? Mention any two special features of
it.
(5 &times; 2 = 10 marks)
Part B
6. A 75kW, 250 V compound dc generator has the following data:
Ra = 0.04Ω
Rsh = 100Ω
Rse = 0.004Ω
Brush contact deep = 1V per brush.
Determine and compare the induced emf in the generator when it is
(a) Long shunt compound and
(b) Short shunt compound.
7. Draw the phasor diagram representing the various currents and voltage in a single-phase transformer when loaded with inductive and capacitive loads.
8. Discuss how constant flux is maintained in a single-phase transformer when the secondary winding is loaded.
9. Explain how the rotor rotates in a three-phase induction motor when a 3-φ supply is given to
the stator terminals.
10. Explain any one starting method for a three-phase synchronous motor.
Turn over
2
D 20630
11. Explain the constructional details of a permanent magnet moving coil type ammeter.
(4 &times; 5 = 20 marks)
Part C
Answer section (a) or section (b) of each question.
12. (a) Explain with appropriate graphs the magnetisation and load characteristics of a dc shunt
generator (self excited) type.
Or
(b) A dc shunt motor rated 10kW connected to 250 V supply is loaded to draw 35 A armature
current running at 1250 rpm. Given Ra = 0.5Ω. Determine the following:
i. Load torque if rotational loss is 500Ω.
ii. Motor efficiency if Rsh = 250Ω.
iii. Armature current for maximum motor efficiency and the maximum efficiency.
What is the corresponding load torque speed?
(10 marks)
13. (a) Explain constructional details of shell and core type transformers.
Or
(b)
i. Derive the emf equation of a single-phase transformer.
ii. Draw the equivalent circuit of a single-phase transformer and explain.
(5 marks)
(5 marks)
14. (a) Explain with neat diagram the construction and principle of working of a three synchronous
motor.
Or
(b)
i. Draw the equivalent circuit of a three-phase induction motor and explain the circuit
parameters.
ii. A 6 pole 50 Hz 3-phase induction motor running on a full load develops a useful torque
of 160 Nm when the rotor emf makes 120 complete cycles per minute. Calculate the
shaft power output. If the mechanical torque lost in friction and that for core-loss is
10 Nm, calculate the
A. Copper loss in the rotor windings.
B. The input to the motor and
C. Efficiency.
The total stator loss is given to be 800 W.
15. (a) Justify that two wattmeters are required to measure three-phase power, with appropriate
equations.
3
D 20630
(b) Explain with suitable diagrams how inductance can be measured in a Maxwell’s bridge in
comparison with a standard variable capacitance. Also discuss the advantage and disadvantages of the Maxwell’s bridge.
(4 &times; 10 = 40 marks)
D 51038
(Pages : 2)
Name: ...............................
Reg. No: ...........................
THIRD SEMESTER B.TECH. (ENGINEERING) DEGREE EXAMINATION
NOVEMBER 2013
AI 09 305—DIGITAL SYSTEMS
Time: Three Hours
Maximum: 70 Marks
Part A
1. What is a parity bit? List its types.
2. Distinguish between PLAs and PALs.
3. State any two advantages of CMOS Logic over other families.
4. State the difference between Mealy and Moore Machine.
5. What are the two types of Asynchronous sequential circuits?
(5 &times; 2 = 10 marks)
Part C
6. State and prove De Morgan’s theorem.
7. Find the Canonical form of f (A, B, C, D) = ABC0 + AB0 D + C0 D + CD0 .
8. Write a brief note on ROM.
9. Explain the operation of a JK flip-flop.
10. Explain the characteristics of ECL Logic.
11. What are cycles and races? How are they avoided?
(4 &times; 5 = 20 marks)
Part C
12. (a) Reduce the following expression using K-Map:
P
P
f (A, B, C, D, E) =
m(0, 2, 4, 15, 21, 27, 29) + d(3, 5, 26).
Or
Turn over
2
D 51038
(b) Minimize:
P
F(A, B, C, D) =
m(0, 1, 5, 7, 8, 9, 10, 11, 14, 15) using Quine McCluskey method.
13. (a) Implement the following function using suitable multiplexers:
P
F(A, B, C, D) =
m(0, 2, 4, 6, 8, 10, 12, 14).
Or
(b) Implement a full adder using suitable decoder and additional logic gates.
14. (a) Design a MOD-5 counter and explain its operation.
Or
(b) Explain the operation of a Monostable Multivibrator and astable Multivibrator.
15. (a) Design a serial adder using Mealy state machine and explain its operation.
Or
(b) Minimize the state table give below:
Present
State
A
B
C
D
E
Next state, Z (Output)
X input
0
1
B, 0
C, 0
B, 0
D, 0
B, 0
C, 0
E, 1
C, 0
B, 0
D, 0
(4 &times; 10 = 40 marks)
D 30914
(Pages : 2)
Name: ...............................
Reg. No: ...........................
THIRD SEMESTER B.TECH. (ENGINEERING) DEGREE EXAMINATION
OCTOBER 2012
AI 09 305—DIGITAL SYSTEMS
Time: Three Hours
Maximum: 70 Marks
Part A
1. Convert 22.2010 to its binary equivalent.
2. Compare 1’s complement and 2’s complement form.
4. Convert JK flip flop into a D flip flop.
5. What is a totem pole output?
(5 &times; 2 = 10 marks)
Part B
6. Write a note on Error detecting Codes.
7. State and prove De Morgan’s theorem.
8. Simplify F = (A + B̄ + C̄)(A + B̄ + C).
9. Design a Binary-Gray decoder.
10. How frequency division is achieved using flip flops? Give the general expression for it.
11. State the condition for state equivalence Give an example.
(4 &times; 5 = 20 marks)
Part C
12. (a) Explain any one Error detecting and Correcting code.
Or
(b) Determine the prime implicants of the function.
P
F(A, B, C, D) = (0, 1, 2, 3, 5, 6, 7, 8, 11, 13).
Turn over
2
D 30914
13. (a) Design an octal to binary encoder.
Or
i. Static RAM.
ii. Dynamic RAM.
14. (a) Design a 3-bit bidirectional shift register.
Or
(b) Explain the features of:
i. TTL
ii. ECL
iii. CMOS
logics.
15. (a) Obtain the transition table and flow table for the given asynchronous sequential circuit.
Or
(b) Design a serial parity generator using the asynchronous FSM technique.
(4 &times; 10 = 40 marks)
D 20631
(Pages : 2)
Name: ...............................
Reg. No: ...........................
FOURTH SEMESTER B.TECH. (ENGINEERING) DEGREE EXAMINATION
OCTOBER 2011
AI 09 305—DIGITAL SYSTEMS
Time: Three Hours
Maximum: 70 Marks
Part A
1. State consensus theorem.
2. Simplify f = AB + BC + B0 C0 .
4. Implement the following function using AND-OR realization: f = ABC + A0 BC0 D.
5. Define fan-in and fan-out.
(5 &times; 2 = 10 marks)
Part B
6. Implement the following function using SOP and POS forms
f (A, B, C) = AB + AC + A0 C0 +A0 B0 + A0 B + AC0
7. Simplify the following function
P
f (A, B, C, D) =
m(0, 1, 2, 3, 5, 7, 8, 9, 11, 12)
9. Design a 2-bit magnitude comparator.
10. Design a 2-bit Asynchronous counter using JK flip flops.
11. Explain the basic principle of partitioning procedure.
(4 &times; 5 = 20 marks)
Part C
Answer section (a) or section (b) of each question.
12. (a) The Hamming Code 101101101 is received. Correct it if any errors. There are four parity
bits and odd parity is used.
Turn over
2
D 20631
Or
(b) Simplify the following function using Quine Mc Cluskey method
P
f (A, B, C, D, E) =
m(0, 1, 2, 3, 5, 7, 9, 12, 15, 17, 21, 25, 27, 29, 30, 31)
13. (a) Design a BCD adder.
Or
(b) What is a race around condition? How it is avoided in Master Slave JK flip flop? Explain.
14. (a) Design a 4-bit universal shifter and explain its operation.
Or
(b) Draw the circuit schematic of a 2-input TTL NAND gate and explain its operation.
15. (a) Draw a sequential circuit for the state diagram shown in figure. Use state assignment rules
for assigning states.
(b) Design a sequence recogniser to detect the sequence 1011.
10053
(Pages : 2)
Name: ...............................
Reg. No: ...........................
THIRD SEMESTER B.TECH. (ENGINEERING) DEGREE EXAMINATION
DECEMBER 2010
AI 09 305—DIGITAL SYSTEMS
Time: Three Hours
Maximum: 70 Marks
Part A
1. Convert binary number 11011.1101 to its decimal equivalent.
2. Express -54 in 2’s complement form.
3. Determine the minimum number of gates required to implement the boolean function (AB + C)
using only 2-input NOR gates.
4. What do you mean by propagation delay?
5. Draw te circuit diagram of a CMOS NAND gate.
(5 &times; 2 = 10 marks)
Part B
6. Reduce boolean expression ABC + ABC̄ + AB̄C + ĀBC.
7. Develop a circuit for the given expression for (A + C)(B̄ + D) using NAND gates.
8. Convert SR flipflop to JK flipflop.
9. Design a combinational logic circuit which will compare two 4 bit numbers A and B and produce
a high output, if A&gt;B and zero if A&lt;B.
10. Design a circuit that will produce a PWM output with 25% duty cycle and frequency of 1 KHz.
11. Design a counter that goes through the states 0, 1, 2, 4, 0 using D flipflop.
(4 &times; 5 = 20 marks)
Part C
Answer section (a) or section (b) of each question.
12. (a) Simplify the following boolean function using Quine-Mc Cluskey method.
P
f (A, B, C, D) =
m(0, 2, 3, 6, 7, 8, 10, 12, 13)
Turn over
2
10053
Or
(b) Reduce the following function using Karnaugh map technique and implement using basic
gates f (A, B, C, D) = ĀB̄D + ABC̄D̄ + ĀBD + ABCD̄.
13. (a) Implement the following Boolean function using 4:1 multiplexer.
P
f (A, B, C, D) =
m(0, 1, 2, 4, 6, 9, 12, 14)
Or
(b) Implement binary to BCD converter using gates.
14. (a) Design a synchronous decade counter using T-flop flop.
Or
(b) Explain with neat diagram the operation of a 4 bit serial in parallel out shift register.
15. (a) Design a synchronous counter using JK-flop flop for 4 → 6 → 7 → 3 → 1 → 4.
Or
(b) Explain the procedure of state minimization using merger graph and merger table.
(4 &times; 10 = 40 marks)
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