BASIC ELECTRONICS JNTU UNIVERSITY PREVIOUS YEAR QUESTION PAPER COLLECTION
BASIC ELECTRONICS JNTU UNIVERSITY PREVIOUS YEAR QUESTION PAPER COLLECTION
BASIC ELECTRONICS
( Common to Mechanical Engineering and Production Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Explain why a semi conductor acts as an insulator at 0o k and why its con-ductivity increases with increase of temperature.
(b) Draw the circuit of Bridge rectifier and explain the working of it. Give its
merits and de-merits. [4+12]
2. (a) Explain why CE configuration is commonly used in amplifier circuits.
(b) Draw the structure of J F E T and explain in detail the effect of gate-source
voltage on the channel when [4+12]
i. No bias
ii. small reverse bias and
iii. large reverse bias such that pinch-off occurs.
3. (a) Draw the basic circuit for obtaining the static V-I characteristics of thyristor.
(b) Draw the V-I characteristics of SCR and account for the shape of the charac-
teristics [6+10]
4. (a) Explain how negative feedback improves the stability of gain of the amplifier
for changes in power supply voltage or change in the parameters of the active
device. What is the condition to achieve the stability of the gain.
(b) Calculate the gain of a negative feedback amplifier with internal gain A =
500 and feed- back factor β = 0.01. If the output impedance of the internal
amplifier is 80 k
, determine the output impedance of the feedback amplifier.
[8+8]
5. (a) Classify oscillators based on
i. output waveform
ii. operating frequencies.
(b) Draw the circuit of Colpitts Oscillator using transistor and explain the working
of it. [6+10]
6. (a) Explain the following type of Timers
i. Electro-mechanical Timers.
ii. Electronic Timers.
(b) List different welding circuits
(c) Explain Projection Welding process. [8+4+4]
1 of 2
Code No: R05220301 Set No. 1
7. (a) List different applications of Ultrasonic Waves and explain the principle and
working of Pulsed-echo Ultrasonic Flow Detector.
(b) Explain the principle of Dielectric heating. [10+6]
8. (a) List various characteristics of A-to-D converter.
(b) Compare three A-to-D conversion techniques. [8+8]
II B.Tech II Semester Regular Examinations, Apr/May 2008
BASIC ELECTRONICS
( Common to Mechanical Engineering and Production Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Explain the concept of “ hole” in a semi conductor.(b) Explain the difference between Ideal Diode and commercial diode with the
help of V-I Characteristics .
(c) Draw the circuit of Half wave rectifier with L- section filter and explain the
working of it. [4+4+8]
2. (a) Explain why CE configuration is commonly used in amplifier circuits.
(b) Draw the structure of J F E T and explain in detail the effect of gate-source
voltage on the channel when [4+12]
i. No bias
ii. small reverse bias and
iii. large reverse bias such that pinch-off occurs.
3. (a) Name different methods of turning-on of SCR.
(b) What are the important points to be noted while designing the gate-control
circuit of SCR.
(c) Draw and explain the V-I characteristics of SCR. [2+6+8]
4. (a) Explain how the negative feedback increases the input impedance and reduces
the output impedance and derive the expressions for input and output im-
pedance of the feedback amplifier.
(b) An amplifier without feedback has a gain of 1200, input impedance of 1.5 k
.
and output impedance of 50 k
. Determine the values of input and output
impedances of feedback amplifier with a feedback factor β of 0.01. [10+6]
5. (a) Why phase shift through the R-C feed back network of R-C phase shift oscil-
lator is to be 1800? Explain.
(b) What are the limitations of R C-Phase shift oscillators?
(c) Draw the circuit of Colpitts Oscillator and explain the working of it. [5+3+8]
6. (a) Name principal types of resistance welding processes and briefly explain them.
(b) Briefly explain the principle of working of any one type of Thermal Timers.
[12+4]
7. (a) Giving basic set up, explain the principle of Induction heating.
(b) Draw and explain piezo electric generator circuit using Hartley oscillator for
generation of Ultrasonic waves. [8+8]
8. (a) Explain the operation of counter type A-to-D converter using D-to-A con-
verter.
(b) Explain various status flags provided in 8085. [10+6]
Code No: R05220301 Set No. 3
II B.Tech II Semester Regular Examinations, Apr/May 2008
BASIC ELECTRONICS
( Common to Mechanical Engineering and Production Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Explain why a semi conductor acts as an insulator at 0o k and why its con-ductivity increases with increase of temperature.
(b) Draw the circuit of Bridge rectifier and explain the working of it. Give its
merits and de-merits. [4+12]
2. (a) Explain why CE configuration is commonly used in amplifier circuits.
(b) Draw the structure of J F E T and explain in detail the effect of gate-source
voltage on the channel when [4+12]
i. No bias
ii. small reverse bias and
iii. large reverse bias such that pinch-off occurs.
3. (a) Name different methods of turning-on of SCR.
(b) What are the important points to be noted while designing the gate-control
circuit of SCR.
(c) Draw and explain the V-I characteristics of SCR. [2+6+8]
4. (a) Draw block diagrams and briefly explain the four types of feedbacks in ampli-
fiers.
(b) An amplifier without feedback has A = 5000, lower cut-off frequency fL =
2.5 Hz, upper cut-off frequency fH= 100 kHz, output resistance R0=2000
.
If negative feed- back in applied to make the output resistance R0f = 600
,
calculate the value of β, voltage gain and half power frequencies of the feedback
amplifier. [8+8]
5. (a) Classify oscillators based on
i. output waveform
ii. operating frequencies.
(b) Draw the circuit of Colpitts Oscillator using transistor and explain the working
of it. [6+10]
6. (a) Draw and explain the heat control circuit for resistance welding.
(b) Compare and contrast the following timers: [8+8]
i. Thermal Timers
ii. Electro-mechanical Timers
iii. Electronic Timers.
7. (a) Explain the application of Induction Heating for
i. Brazing and
ii. Annealing of Brass and Bronze items .
(b) Explain the construction and working of a C R tube with neat diagram [8+8]
8. (a) Explain the operation of counter type A-to-D converter using D-to-A con-
verter.
(b) Explain various status flags provided in 8085. [10+6]
⋆ ⋆ ⋆ ⋆ ⋆
II B.Tech II Semester Regular Examinations, Apr/May 2008
BASIC ELECTRONICS
( Common to Mechanical Engineering and Production Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Explain what is meant by mobility of a charge carrier in a solid. Derivean expression for the conductivity of a semiconductor, containing both free
electrons and holes, in terms of the concentrations n and p and the mobilities.
(b) Draw the circuit of Bridge rectifier and explain the working of it. [8+8]
2. (a) Explain why CE configuration is commonly used in amplifier circuits.
(b) Draw the structure of J F E T and explain in detail the effect of gate-source
voltage on the channel when [4+12]
i. No bias
ii. small reverse bias and
iii. large reverse bias such that pinch-off occurs.
3. (a) Name different methods of turning-on of SCR.
(b) What are the important points to be noted while designing the gate-control
circuit of SCR.
(c) Draw and explain the V-I characteristics of SCR. [2+6+8]
4. (a) Explain the effect of negative feedback on distortion, gain, band-width and
input and output impedances of the amplifier.
(b) In an amplifier an output of 60 V, is obtained for an input signal of 0.6V. This
circuit is now connected to a negative feedback networks such that 20% of the
output voltage goes back to the input side. Calculate the increased value of
input, if we want the same output from the circuit (i.e. 60 V). [8+8]
5. (a) Draw the circuit of transistor Colpitts Oscillator and briefly explain the work-
ing of it. Derive the expression for frequency of oscillation fo.
(b) Calculate the frequency of oscillation of a transistor Colpitts Oscillator having
C1 = 0.02 µF, C2 = 0.2 µF and L = 10 µH. [10+6]
6. (a) Briefly explain “Thermal Expansion timers”.
(b) Draw sequence Timer Welding Circuit and explain its operation. [6+10]
7. (a) Explain the principle of Dielectric heating and List the applications of Dielec-
tric heating.
(b) Explain the use of Ultrasonic waves in Degassing of liquids.
(c) Explain the methods of measurement of frequency using C R O. [6+4+6]
1 of 2
Code No: R05220301 Set No. 4
8. (a) What are the functional units of central processing unit in 8085. Briefly ex-
plain each of them.
(b) What is stack in 8085? What are its functions? [8+8]
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