Introduction to electronics and communication 2024-25

Question Bank for Introduction to Electronics and Communication (BESCK104C/204C)

Module – 1 POWER SUPPLIES

1. What is Regulated power supply? With neat block diagram, explain the working of DC
power supply. Also mention the principal components used in each block.
(Jul’23–8M, MQP‘22–6M)

2. With a neat block diagram, explain the working of a DC power supply. Also mention the
principal components used in each block. (Nov’23–7M, Aug’22–7M, MQP ‘21–7M)

3. Describe the DC power supply with the help of block diagram. (Nov’23–8M, Jul’23–7M)

4. Draw the block diagram of DC power supply and explain the individual blocks.
(Feb’23–8M)

5. What is a rectifier? What are the different types of rectifiers?

6. Describe half-wave rectifier with circuit diagram and waveforms. (Jul‘23–8M)

7. With appropriate circuit diagram, explain the working of half-wave rectifier. (Nov‘23–8M)

8. A mains transformer having a turn’s ratio of 44:1 is connected to a 220 Vr.m.s .mains
supply. If the secondary output is applied to a half-wave rectifier, determine the peak voltage
that will appear across a load. (Nov‘23–4M)

9. What is the need for reservoir and smooth in g circuits? Explain.

10. Explain the working of a half-wave rectifier with reservoir capacitor along with relevant
waveforms.

11. The R-C smoothing filter in a 50Hzmains operated half-wave rectifier circuit consists of R1=
100 ΩandC1 = 1,000 μF. If 1 V of ripple appears at the input of the circuit, determine the
amount of ripple appearing at the output.

12. A half-wave rectifier is fitted with an R-C smoothing filter comprising R = 200 Ω and C =50
μF. If 2V of 400 Hz ripple appear at the input of the circuit, determine the amount of ripple
appearing at the output.

13. Explain the working of bi-phase full wave rectifier circuit with neat diagram and waveforms.

1 Department of CSE VTU RC MYSORE

 Introduction to electronics and communication 2024-25

(Aug’22–7M, MQP‘21–8M)

14. With appropriate circuit diagram, explain the working of full-wave rectifier. Draw the input
and output waveforms. (Nov‘23–12M)

15. Explain full wave rectifier with necessary circuit diagrams and waveforms. (Jul’23–8M)

16. With a neat circuit diagram, explain the working of a bi-phase rectifier along with relevant
waveforms. Also explain how the output changes when a reservoir capacitor is used.

17. With neat circuit diagram and waveforms explain the working of a full wave bridge rectifier.
(Jul’23–8M, Feb’23–8M, MQP ‘21–8M)
18. With a neat circuit diagram and waveforms, explain the working of bridge rectifier without
filter. (Feb’22–8M)
19. With a neat circuit diagram and waveform, explain the working of bridge rectifier with filter.
(Nov’23–8M)

20. With a neat circuit diagram, explain the working of a bridge rectifier along with relevant
waveforms. Also explain how the output changes when a reservoir capacitor is used.

21. Discuss the need of filter circuit. With circuit diagram and waveforms, brief out The
operation of smoothing filter for full wave rectifiers. (MQP‘22–7M)

22. What is voltage regulator? With neat circuit diagram, explain the operation of a voltage
regulator using Zener diode. (Jul‘23–7M)

23. Draw the circuit diagram of voltage regulation and explain the operation. (Feb‘23–6M)

24. Explain the operation of a simple shunt Zener voltage regulator. (MQP‘21–7M)

25. A 5V zener diode has a maximum rated power dissipation of 500 mW. If the diode is to be
used in a simple regulator circuit to supply a regulated 5 V to a load having a resistance of
400 Ω, determine a suitable value of series resistor for operation in conjunction with a supply
of 9V. (MQP‘22–7M)

26. A 6V zener diode has a maximum rated power dissipation of 500 mW. If the diode is to be
used in a simple regulator circuit to supply a regulated 6 V to a load of 500 Ω, determine a

2 Department of CSE VTU RC MYSORE

 Introduction to electronics and communication 2024-25

suitable value of series resistor for a supply of 12 V. (Nov’23–5M, Feb’22– 6M)

27. If a 9 V zener diode is to be used in a simple shunt regulator circuit to supply a load having a
nominal resistance of 300Ω, determine the maximum value of series resistor for operation in
conjunction with a supply of 15 V.

28. Explain the terms output resistance and voltage regulation with respect to voltage regulator.

29. The following data were obtained during a test carried out on a d.c.power supply:

(i) Load test

Output voltage (no-load) =12V

Output voltage (2Aloadcurrent) =11.5 V

(ii) Regulation test

Output voltage (mains input, 220 V) = 12 V

Output voltage (mains input, 200V) =11.9V

Determine (a) the equivalent output resistance of the power supply and (b) the regulation of
the power supply.
30. The following data were obtained during a load test carried out on a d.c.power supply:
Output voltage (no-load) = 8.5 V
Output voltage (800 mA load)= 8.1 V
Determine the output resistance of the power supply and estimate the output voltage at a load
current of 400 mA.
31. The following data were obtained during a regulation test on a d.c. power supply: Output
voltage (a.c. input: 230 V) = 15 V
Output voltage (a.c.input:190V)=14.6V

Determine the regulation of the power supply and estimate the output voltage when the input
voltage is 245 V.

32. What is voltage multiplier? With circuit diagram, explain the operation of voltage doubler.
(Jul‘23–6M)

3 Department of CSE VTU RC MYSORE

 Introduction to electronics and communication 2024-25

33. With circuit diagram explain the following: Voltage Doubler, Voltage Tripler (MQP‘21–5M)

34. Draw the circuit diagram of voltage doubler and the working operation. (Feb‘23–6M)

35. What is voltage multiplier and mention its applications? With circuit diagram brief out the
operation of voltage tripler circuit. (MQP‘22–7M)

AMPLIFIERS

1. What is an amplifier? Explain the types of amplifier. (Jul‘23–4M)

2. List and describe the main types of amplifiers. (MQP‘21–7M)

3. Classify different types of amplifier. (Jul‘23–8M)

4. With neat block diagram of an amplifiers howing the input and output current and voltages
provide the formula for voltage gain, current and power gain. (Nov‘23–4M)

5. Explain the following terms related to amplifier:

(a) Gain (b) Input resistance (c) Output resistance

6. Define the following with respect to amplifier:

(i) Input resistance (ii) Amplifier gain (iii) Bandwidth (iv) Phase shift (Nov‘23–8M)

7. Describe the terms: Gain, Input resistance, Band width of amplifier. (Jul‘23–5M)

8. An amplifier produces an output voltage of 2V for an input of 50mV.If the input and output
currents in this condition are, respectively, 4 mA and 200 mA, determine: (a) the voltage
gain(b) the current gain(c)the power gain. (Jul’23–4M,Feb‘23–6M)

9. An amplifier produces an output voltage of 5V for an input of 100mV.If the input and output
currents in this condition are 4 mA and 200 mA, find voltage, current and power gains.
(Nov’23–4M)

10. The following measurements were made during at Estonian amplifier:

Vin=250mV,I in=2.5mA,Vout=10V,I out=400mA Determine :(a) the voltage gain (b) the
current gain (c) the power gain (d) the input resistance.

11. An amplifier has a power gain of 25 and identical input and output resistances of 600Ω.

4 Department of CSE VTU RC MYSORE

 Introduction to electronics and communication 2024-25

Determine the input voltage required to produce anoutputof10V.

12. Write a note on frequency response characteristics of an amplifier circuit, clearly mentioning
the half power frequencies. (MQP‘21–6M)

13. Mention the advantages of negative feedback in amplifiers circuits. With relevant equations
and diagram, explain the concept of negative feedback.
(Jul’23–7M, Aug’22 –7M, MQP‘21–7M)

14. Discuss briefly a negative feedback amplifier with block diagram. (Feb‘23–6M)

15. With a neat block diagram, derive the expression for overall gain of a negative feedback
amplifier. (Nov’23–6M,Feb’22–6M)

16. Explain the concept of negative feedback with a neat diagram. Show how negative feedback
stabilizes the overall gain of an amplifier.

17. An amplifier with negative feedback applied has an open-loop voltage gain of 50, and one-
tenth of its output is fed back to the input (i.e. β = 0.1). Determine the overall voltage gain
with negative feedback applied. If the amplifier’s open-loop voltage gain increases by 20%,
determine the percentage increase in overall voltage gain.

18. An amplifier with negative feedback applied has an open-loop voltage gain of 250, and 5%
of its output is fed back to the input. Determine the overall voltage gain with negative
feedback applied. If the open-loop voltage gain increases by 20% determine the new value of
overall voltage gain.

19. An integrated circuit that produces an open-loop gain of 100 is to be used as the basis of an
amplifier stage having a precise voltage gain of 20. Determine the amount of feedback
required.

20. An amplifier produces an open-loop gain of 180. Determine the amount of feedback required
if it is to be operated with a precise voltage gain of 50.

21. What are multi-stage amplifiers? Write different methods used for inter stage coupling.
(Nov’23–6M).

5 Department of CSE VTU RC MYSORE

 Introduction to electronics and communication 2024-25

Module–2 Oscillators
1. What is an oscillator?
2. Explain the concept of positive feedback with a neat diagram. Show how positive
feedback increases the overall gain of an amplifier.
3. An amplifier with a gain of 8 has10% of its output feedback to the input. Determine the
gain of the stage (a) with negative feedback (b) with positive feedback.
4. What is oscillator? And mention the conditions for oscillation. (Feb’23–6M)
5. Explain the Barkhausens’ criteria for oscillations.
6. Explain the operation of three-stage ladder RC network oscillator with neat circuit diagram.
(Jul’23–6M)
7. Listandexplaintheconditionsforsustainedoscillations.Determinethefrequencyof oscillation
of a three-stage ladder network in which C = 10 nF and R = 10 kΩ.
(Nov’23–6M,Jul’23–4M, MQP ’22–6M, Aug’22–6M,MQP‘21–6M)
8. A phase-shift oscillator is to operate with an output at 1 kHz. If the oscillator is based
on a three-stage ladder network, determine the required values of resistance if three
capacitors of 10 nF are to be used.
9. With circuit diagram, explain the operation of a Wien bridge oscillator.
(Nov’23–8M,Feb’23–8M)
10. With a neat circuit diagram, explain the working of Wien bridge oscillator using op-
amp. (Feb’22–6M)
11. Describe Wien bridge oscillator with circuit diagram and formula for frequency of
oscillations. (Jul’23–7M)
12. Explain the Barkhausen criteria for oscillations. In a Wien bridge oscillator, if C1 = C2
= 100nF, determine the frequency of oscillations when R1=R2=1 k Ω. (Jul’23–7M)
13. In a Wien bridge oscillator based on an operational amplifier ,if C1= C2= 100 n F,
determine the output frequencies when (a) R1=R2=1 k Ω and (b) R1=R2=6 k Ω.
14. In a Wien bridge oscillator based on an operational amplifier, C1 = C2 = 22 n F.
Determine the values of R1and R2 required to produce an output at exactly 400 Hz.
15. What are multi vibrators? Mention the different types of it. (Nov’23–8M)
16. With suitable circuit diagram, explain single stage astable multi vibrator using
operational amplifier. (Nov’23–7M, MQP’22– 7M, Aug’22– 7M)
17. Explain the operation of single stage a stable multi vibrator with its circuit diagram.
(Jul’23–7M)

6 Department of CSE VTU RC MYSORE

 Introduction to electronics and communication 2024-25

18. Explain the operation of single stage astable Oscillator with its circuit diagram.
(Feb’23–8M, MQP‘22–7M)
19. Describe the working of a single stage astable oscillator using an op-amp.
(MQP‘21–5M)
20. With a neat circuit diagram and waveforms, describe the operation of crystal
controlled oscillator. (Nov’23–7M, MQP‘22–7M)
21. Write a note on crystal controlled oscillators. (Nov’23–4M)

7 Department of CSE VTU RC MYSORE

 Introduction to electronics and communication 2024-25

Operational Amplifiers
1. What is an operational amplifier? Sketch the circuit symbol for an operational
amplifier. Label each of the connections.
2. What is op-amp? Explain the various parameters of operational amplifier. (Jul‘23–7M)
3. Explain the following parameters of an op-amp:(a) Open-loop voltage gain(b) Closed-
loop voltage gain (c) Input resistance (d) Output resistance
4. Explain the following operational amplifier parameters:
(i)Open-loop voltage gain (ii) Closed-loop voltage gain (iii) Input offset voltage
(iv) Slew rate (Nov‘23–16M)
5. Explain the following terms with reference to operational amplifiers:
(i)Open-loop voltage gain (ii) Input resistance (iii) Input off set voltage (iv) Slew rate
(Jul‘23–8M)
5. Define the following operational amplifiers parameters and write their typical values:
a. Open loop voltage gain ii)Output resistance iii) Slew rate (Feb’23–6M)
6. Define the following with respect to operational amplifiers and write their typical
values:
a. Open loop voltage gain ii)Input offset voltage iii)Full power band width
and iv) Slew rate (Nov’23–8M,Feb’22–8M)
7. During measurements on an operational amplifier under open-loop conditions, an
output voltage of 12 V is produced by an input voltage of 1 mV. Determine the open-
loop voltage gain expressed in dB.
8. An operational amplifier operating with negative feedback produces an output
voltage of
2V when supplied with an input of 400μV. Determine the value of closed-loop voltage
gain.
9. An operational amplifier with negative feedback applied produces an output of 1.5 V
when an input of 7.5 mV is present. Determine the closed-loop voltage gain.
10. An operational amplifier has an input resistance of 2MΩ. Determine the input current
when
An input voltage of 5mV is present.
11. Explain the following parameters of an op-amp: (a) Input offset voltage (b) Full-power
bandwidth (c) Slew rate
12. With the aid of a sketch, explain what is meant by the term ‘slew rate’. Why is this
important?
13. A perfect rectangular pulse is applied to the input of an operational amplifier. If it takes

8 Department of CSE VTU RC MYSORE

 Introduction to electronics and communication 2024-25

4μs
For the output voltage to change from –5V to +5V, determine the slew rate of the
device.
14. A wideband operational amplifier has a slew rate of 15 V/μ s. If the amplifier is used
in a circuit with a voltage gain of 20 and a perfect step input of 100 mV is applied to
its input, determine the time taken for the output to change level.
15. Explain the ideal characteristics of an op-amp. (Jul’23–6M)
16. Write a note on ideal characteristics of an operational amplifier.
(Nov’23–5M, MQP’22–7M)
17. What are characteristics of an ideal operational amplifier? (Jul’23–6M)
18. List and explain the ideal and real characteristics of op-amp.
19. Describe three basic configurations for operational amplifiers. (Jul’23–8M)
20. Explain how capacitors can be added to modify the frequency response of op-amps.
21. An inverting operational amplifier is to operate according to the following
specification: Voltage gain = 100 Input resistance (at mid-band)=10kΩ Lower cut-off
frequency = 250 Hz Upper cut-off frequency = 15 kHz
23.With a neat circuit diagram and waveforms, explain the following op-amp
circuits: Voltage follower (b) Differentiator (c) Integrator (d) Comparator (e)
Summing amplifier

22. Write a note on voltage follower using operational amplifier. (Nov’23–4M)

23. Sketch the circuits of each of the following based on use of op-amp along with input
and output waveforms:

(i) Integrator (ii) Voltage follower (iii) Comparator (Jul’23–7M)

25. Sketch the circuit of each of the following based on the use of operational amplifiers

(a) Comparator (b) a differentiator (c) an integrator (d) Inverting Amplifier.

(Aug’22–6M, MQP‘21–8M)
26. With a neat circuit diagram, explain the working of integrator using op-amp
(Feb’22–6M)

27. Explain a differentiator circuit with wave forms and circuit diagrams. (Jul’23–7M)
28. With circuit diagram and waveform show how operational amplifier can work as a

9 Department of CSE VTU RC MYSORE

 Introduction to electronics and communication 2024-25

comparator. (MQP‘21–6M)
29. Explain the operation of summing amplifier using operational amplifier and write
the output equation. (Feb’23–6M)
30. An inverting amplifier is to be constructed having a mid-band voltage gain of 40, an
input resistance of 5kΩ and a frequency response extending from 20Hz to 20 kHz.
Devise a circuit and specify all component values required.
31. A summing amplifier with two inputs has RF=10kΩ, and RIN (for both inputs) of
2kΩ. Determine the output voltage when one input is at −2V and the other is +0.5V.

10 Department of CSE VTU RC MYSORE