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PHE-10
ASSIGNMENT BOOKLET
Bachelor's Degree Programme (B.Sc.)
Electrical Circuits and Electronics
School of Sciences
Indira Gandhi National Open University
Maidan Garhi,
New Delhi-110068
2006
Dear Student,
We hope you are familiar with the system of evaluation to be followed for the Bachelor’s Degree
Programme. At this stage you may probably like to re-read the section on assignments in the
Programme Guide for Elective Courses that we sent you after your enrolment. A weightage of 30 per
cent, as you are aware, has been earmarked for continuous evaluation which would consist of two
tutor-marked assignment for this course. TMA-1 is based on Blocks 1 and 2; TMA-2 is based on
Blocks 3 and 4.
Instructions for Formating Your Assignments
Before attempting the assignment please read the following instructions carefully:
1) On top of the first page of your TMA answer sheet, please write the details exactly in the
following format:
ENROLMENT NO.:……………………………………………
NAME :……………………………………………
ADDRESS :……………………………………………
……………………………………………
……………………………………………
COURSE CODE:
…………………….
COURSE TITLE :
…………………….
ASSIGNMENT NO. ………………….…
STUDY CENTRE: ………………..…..
DATE : ….………………………………………...
PLEASE FOLLOW THE ABOVE FORMAT STRICTLY TO FACILITATE EVALUATION
AND TO AVOID DELAY.
2) Use only foolscap size writing paper (but not of very thin variety) for writing your answers.
3) Leave 4 cm margin on the left, top and bottom of your answer sheet.
4) Your answers should be precise and in your own words. Do not copy answers from study
material.
5) While solving problems, clearly indicate the question number along with the part being solved.
Write units at each step of your calculations as done in the text because marks will be deducted for
such mistakes. Take care of significant digits in your work. Recheck your work before
submitting it.
6) This assignment will remain valid for one year. However, you are advised to submit TMA-1
within 8 weeks and TMA-2 in 12 weeks of receiving this booklet to accomplish its purpose as a
teaching-tool.
We strongly recommend that you should retain a copy of your assignment response to avoid any
unforeseen situation.
You could obtain response to the difficulties you may face in PHE-10 course via e-mail by writing to
[email protected]. Please note that, we donot provide answers to Assignment questions.
We wish you good luck.
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Tutor Marked Assignment-1
Electrical Circuits and Electronics
Course Code: PHE-10
Assignment Code: PHE-10/TMA-1/2006
Max. Marks: 100
Note: This assignment is based on Blocks 1 and 2. Attempt all questions. Marks for each
question are indicated against it.
1. State giving reasons, if the following statements are true or false:
i) Transformer is an active device since it can boost current.
ii) Ideal independent energy sources donot exist.
iii) Q factor of resonant circuit is independent of its band width.
iv) Filter circuit has to contain a reactive element.
v) The energy required to eject an electron from a thermionic emitter is equal to its
band gap energy.
vi) Transport of charge carriers by temperature gradient is most important in case of
semiconductor devices.
vii) Forward biasing of a semiconductor junction diode reduces its band gap energy.
viii) Negative feedback results into instability of a circuit, hence it is used in oscillators.
ix) Ripple factor is a measure of ac in dc.
x) Zener diode is generally used in forward biased condition.
(210)
2. a) Calculate the impedance of a circuit comprising of series combination of R = 50,
C = 2F and L = 50 mH at 10 kHz. Find the resonant frequency of the circuit. (4)
b) Use superposition principle to find the current through R2.
(6)
3. a) Draw a circuit corresponding to admittance
Y
1
1
.
 jC 
R
jL
(2)
b) A 30 cm long wire with 6 resistance is bent to form an equilateral triangle. A battery
of e.m.f. 10V and internal resistance 1 is connected parallel to one of the sides of
this triangle. Draw the circuit of this arrangement. Calculate current in each branch
of the circuit.
(4)
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c)
Draw a circuit of band reject (stop) filter along with the attenuation characteristics.
(4)
4. a) Calculate the value of load inductor and resistor in order to achieve a maximum power
transfer from a source with 2 resistor and 50 F capacitor at 50 Hz frequency. (6)
b) What is the function of grids in the vacuum valves?
(2)
c) What are the advantages of semiconductor devices over vacuum tube devices?
(2)
5. a) Write down the units of transconductance gm, anode resistance rp and amplification
factor  of a vacuum triode amplifier.
(3)
b) Explain with a neat diagram application of p-n junction diode as a peak voltage
detector.
(4)
c) Draw a diagram showing common emitter biasing of a p-n-p transistor. Indicate
polarities of all the bias voltages.
(3)
6. a) Explain the working of p-channel junction field effect transistor with the help of a
suitable diagram.
(5)
b) “Though common collector amplifier has voltage gain lesser than unity, it is
preferred in some electronics applications.” Comment on this statement.
(3)
c) Express the gain (in dB) of a multistage amplifier with individual stage voltage
gains of 100, 50 and 20.
(2)
7. a) Refer to the universal bias shown in Fig. 4.11 of your study material. If Vcc = 10V,
R1 = R2 = RC = RE = 10k, VBE = 0.7V and  = 100, calculate VB, VE, IE, IB, VC and
VCE.
(6)
b) What are the conditions to be fulfilled for a circuit to give sustained oscillations? (4)
8. a) Draw a circuit diagram of phase shift oscillator using n-p-n transistor. Explain,
how the phases of signal vary at different circuit points to achieve positive
feedback in this circuit.
(6)
b) What are the advantages of bridge rectifier over centre tapped full wave rectifier?(2)
c) Why is it necessary to use a filter in a power supply circuit?
(2)
9. a) In a voltage regulator circuit, the output voltage under no load condition is 12V
while under full load it is 11.8V. Over the full range of input voltage variation the
nominal voltage output of 12V varies by 50 mV. Calculate percentage line and
load regulation.
(4)
b) Design a zener voltage regulator shown in Fig. 6.25 of your study material to
give 6V output for input unregulated voltage of 7V. Maximum load current is
50mA. Write down the voltage and power rating of the zener diode. Calculate
the value and power rating of Rs. (consider zener operating current to be 5mA)
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(6)
Tutor Marked Assignment-2
Electrical Circuits and Electronics
Course Code: PHE-10
Assignment Code: PHE-10/TMA-2/2006
Max. Marks: 100
Note: This assignment is based on Blocks 3 and 4. Attempt all questions. Marks for
each question are indicated against it.
1. State with reasons whether the following statements are true or false:
i) Operational amplifier has zero open loop voltage gain.
ii) It is necessary to have bipolar supply for op-amp.
iii) The increase in gain of op-amp circuit increases its frequency range of operation.
iv) Operational amplifier in non-inverting mode cannot amplify negative signals.
v) It is preferable to have highest possible headroom voltage in case of 7800 series of
IC regulators.
vi) Largest decimal number represented by a 2-digit hex number is 99.
vii) AND gate is called universal gate.
viii) All the memory in a calculator is RAM.
xi) Cathode Ray Tube is filled with inert gas.
x) Input impendence of electronic voltmeter is very low.
(210)
2. a)
Write down the specifications of IC you understand by following number coding:
A741MP
(3)
b)
Draw a circuit of a non-inverting amplifier with gain 1 using op-amp. Draw the
output voltage curve for a step input of 5V, if the slew rate of op-amp is 0.5 V/s.
(Use proper scale on time axis to illustrate the effect of slew rate).
(5)
c)
What is the physical significance of CMRR of an op-amp?
(2)
Design and draw the circuit of op-amp integrator with RC time constant
0.10s. Draw the output waveform of this integrator for 10 Hz square wave
input of amplitude 1 V.
(6)
3. a)
b)
4. a)
b)
5. i)
ii)
iii)
iv)
Which characteristics of op-amp will you specifically consider if 1 mV input
signal of 1 MHz frequency is to be amplified? What will be your choice of
values of these parameters?
(4)
Draw a circuit of amplifier of gain 50 using IC 380. Use the non-inverting
terminal as input signal terminal.
(5)
Design and draw the circuit of an adjustable negative voltage regulator with
output voltage range of 10 to 15V.
(5)
Convert decimal 38.437510 in to binary.
What is octal equivalent of 76.4510?
Write ASCII code of “IGNOU B.Sc.”
Divide 110112 by 00112
(2)
(3)
(3)
(2)
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6. a)
b)
Draw a circuit to realize NAND gate using diodes and transistor.
(3)
Reduce the following expression to minimum sum of products.
Y  AB  B C  A B  B C
c)
7. a)
b)
8. a)
Draw a logic circuit to implement the MSP you obtain.
(3)
Design a logic circuit to implement NOR gate using only NAND gates.
(4)
What is race-around condition in R-S flip-flop? Why is it not desired? How this
problem is removed in D flip-flop?
(5)
Design a MOD 6 counter.
(5)
Design a 4-channel op-amp adder to give individual channel gains of 12, 3,
5 and 10.
(4)
b)
What is the maximum size of the memory addressable by 6 address lines?
c)
Draw a circuit of 5-bit DAC. What will be its output voltage for 10101 input? (4)
9. a)
b)
In CRO, how the movement of electron beam across the screen to display
the input signal is achieved?
(2)
(5)
Explain the basic working principle and construction of magnetic field meter. (5)
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