Download VTU B-Tech/B.E 2019 June-July 1st And 2nd Semester 2015 June-July 14ELN15 Basic Electronics Question Paper

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USN 14ELN15/25

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First / Second Semester B.E. Degree Examination, June / July 2015

Basic Electronics

Time: 3 hrs. Max. Marks: 100

Note: Answer any FIVE full questions, selecting ONE question from each part.

PART - A

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1. a. Draw and explain V — I characteristics of a Germanium Diode. (05 Marks)
   b. Find the value of the series resistance R, required to drive a forty element of 1.25mA through a Germanium diode from a 4.5V battery. Write the circuit diagram showing all the value. (04 Marks)
   c. With neat diagram, explain the working of a half wave rectifier along with relevant waveforms. (07 Marks)
   d. Discuss in brief clipping circuit. Explain the working of a positive clipper with neat circuit diagram and relevant waveforms. (04 Marks)
2. a. Explain the working of a full wave rectifier using 2 diodes with neat diagram. Also derive the expressions for Idc and Irms of a full wave rectifier. (10 Marks)
   

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   b. Discuss in brief clamping circuit. Explain the working of a negative clamper. (04 Marks)
   c. Distinguish between Zener and Avalanche breakdown. (06 Marks)

PART -B

1. a. Calculate the value of I_C, I_E and ß for a transistor with a = 0.98 and I_B = 120µA. (06 Marks)
   b. For the base bias circuit V_CC = 18V, R_C = 2.2KO, R_B = 470kO, h_fe = 100 and V_BE = 0.7V. Find I_B, I_C and V_CE. Draw the DC load line and indicate the Q point. (08 Marks)
   

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   c. Discuss the ideal characteristics of an operational amplifier. (06 Marks)
2. a. Explain the voltage follower circuit using operational amplifier. Mention its important properties. (05 Marks)
   b. Design an adder circuit using Op amp to obtain an output voltage of V_o = 2[0.1 V₁ + 0.5V₂ + 2V₃], where V₁, V₂ and V₃ are input voltages. Draw the circuit. (08 Marks)
   c. Design a voltage divider bias circuit to operate from a 12V supply with V_CE = 3V, V_E = 5V and I_C = 1mA, V_BE = 0.7V. (07 Marks)

PART - C

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1. a. With the help of a diode switching circuit and truth table explain the operation of an AND gate and OR gate. (06 Marks)
   b. State and prove Demorgan's theorem for three variables. (06 Marks)
   c. With truth table and logical expressions, give the design of a full adder circuit. Realize the circuit using i) Basic gates and ii) NAND gates. (08 Marks)
2. a. Perform the following conversions :
   i) (1234.56)₈ = (?)₁₀ ii) (10110101001.101011)₂= (?)₁₆ iii) (988.86)₁₀ = (?)₂
   

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   iv) (532.65)₁₀ = (?)₁₆ v) (ABCD.EF)₁₆ = (?)₈ (05 Marks)

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6. b. i) Subtract (1000.01)₂ from (1011.10)₂ using l's and 2's complement method. (05 Marks)
   ii) Add (7AB.67)₁₆ with (15C.71)₁₆. (05 Marks)
   

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   c. Design a half adder circuit and realize using Basic gates and NAND gates. (05 Marks)
   d. What are Universal gates? Realise AND and OR gate using Universal gates. (05 Marks)

PART - D

1. a. Distinguish between a Latch and flipflop. (04 Marks)
   b. Explain i) See beck effect ii) Peltier effect and iii) Thomson effect. (06 Marks)
   

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   c. Explain the architecture of 8085 microprocessor, with neat diagram. (10 Marks)
2. a. Explain the working of a LVDT with neat diagram. (06 Marks)
   b. List the difference between a microprocessor and micro controller. (08 Marks)
   c. Explain the working of a R - S flipflop with relevant circuit and table. (06 Marks)

PART -E

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1. a. What is Modulation? Mention some of the need for modulation in communication system. (06 Marks)
   b. Give the comparison between AM and FM. (08 Marks)
   c. With block diagram, explain the working of a cellular mobile communication system. (06 Marks)
2. a. Define Amplitude modulation and derive the expression for AM wave with relevant waveforms. Draw the frequency spectrum. (08 Marks)
   b. With neat diagram, explain the working of a telephone system. (06 Marks)
   

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   c. An audio frequency signal (10 x 500)t is used to amplitude modulate a carrier of 50 sin(2p x 10⁵t). Calculate
   i) Modulation index.
   ii) Sideband frequencies
   iii) Band width.
   iv) Amplitude of each sideband.
   

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   v) Total power delivered to a load of 600O.
   vi) Transmission efficiency. (06 Marks)