Download VTU B-Tech/B.E 2019 June-July 1st And 2nd Semester 18 Scheme 18ELN14 Basic Electronics Question Paper

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18ELN14/24

First Semester B.E. Degree Examination, June/July 2019

Basic Electronics

Time: 3 hrs.

Max. Marks: 100

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Note: Answer any FIVE full questions, choosing ONE full question from each module.

Module-1

1. a. What is semiconductor diode? Explain the different equivalent circuits of diode. (06 Marks)
2. b. Explain the working of photodiode. (05 Marks)
3. c. With a neat circuit diagram and waveforms, explain the working of full wave bridge rectifier. Also derive Vdc and Vrms values for full wave rectifier. (09 Marks)

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OR

1. a. A full wave rectifier uses 2 diodes having internal resistance of 20O each. The transformer rms secondary voltage from centre to each end is 50V. Find Im, Idc, Irms and Vdc if the load is 980O. (06 Marks)
2. b. Explain the functional block diagram of 78xx series voltage regulator. (06 Marks)
3. c. Explain how Zener diode can be used as a voltage regulator. Give detail mathematical analysis. (08 Marks)

Module - 2

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1. a. With a neat circuit diagram explain the working of CMOS inverter. (06 Marks)
2. b. For a N-channel JFET if IDSS = 8mA and Vp = -5V, calculate ID at VGS = -3V and VGS at ID = 3mA. (05 Marks)
3. c. Explain the construction, working and characteristics of N-channel JFET. (09 Marks)

OR

1. a. Explain the working of SCR using two transistor model. (06 Marks)

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2. b. What is commutation in SCR? Explain two types of commutation. (05 Marks)
3. c. Explain the construction, working and characteristics of enhancement type MOSFET. (09 Marks)

Module-3

1. a. What is Op-AMP? List the characteristics of ideal Op-Amp. (06 Marks)
2. b. Explain how Op-Amp can be used as i) Integrator ii) Voltage Follower. (08 Marks)

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3. c. Find the output of the Op-Amp circuit shown in Fig Q5(c) below (06 Marks)

[Image of Op-Amp circuit - Fig Q5(c) would be inserted here]

OR

1. a. Explain the following terms with respect to Op-Amp i) CMRR ii) Slew Rate iii) Output offset voltage iv) Supply voltage Rejection Ratio. (08 Marks)
2. b. Design an Op-Amp circuit to obtain output expression as Vo = — [V1 + 3V2 + 5V3]. (06 Marks)

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3. c. Explain how Op-Amp can be used as differentiator. (06 Marks)

Module_4

1. a. What is feedback amplifier? What are the properties of negative feedback amplifier? (06 Marks)
2. b. Explain how transistor can be used as an amplifier. (06 Marks)
3. c. With a neat circuit diagram and waveforms, explain the working of 555 timers as an oscillator. (08 Marks)

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OR

1. a. Draw the block diagram of voltage series negative feedback amplifier and derive the expression for its voltage gain. (06 Marks)
2. b. Design a RC phase shift oscillator for a frequency of 1 KHz. Draw the circuit diagram with designed values. (06 Marks)
3. c. With a neat circuit diagram, explain the working of Wein Bridge oscillator. (08 Marks)

Module_5

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1. a. Perform the following :

   1. i) Convert (925.75)10 to base-2 and base - 16
   2. ii) Subtract (11011.11)2 from (10101.11)2 using 2's compliment method. (06 Marks)
2. b. With a block diagram explain the working of 3-bit asynchronous counter. (06 Marks)

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3. c. What is multiplexer? Implement 8:1 multiplexer using basic gates. (08 Marks)

OR

1. a. Simplify S = A (B + C) + B (D + C) and realize using basic gates. (05 Marks)
2. b. What is flip-flop? Explain the operation of master slave JK flip flop. (06 Marks)
3. c. Implement full adder using two half adders. (04 Marks)

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4. d. With a block diagram, explain the working of basic communication system. (05 Marks)

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