Basic Electronics - Jun 2015

First Year Engineering (C Cycle) (Semester 1)

TOTAL MARKS: 100
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks. 1 (a) Draw and explain V-I characteristics of a Germanium Diode.(5 marks) 1 (b) Find the value of the series resistance R, required to drive a forward current of 1.25m through a Germanium diode from a 4.5V battery. Write the circuit diagram showing all the value.(4 marks) 1 (c) With neat diagram explain the working of a half wave rectifier along with relevant waveforms(7 marks) 1 (d) Discuss in brief clipping circuit. Explain the working of positive clipper with neat circuit diagram and relevant waveforms(4 marks) 10 (a) Define Amplitude modulation and derive the expression for AM wave with relevant waveforms. Draw the frequency spectrum(8 marks) 10 (b) With neat diagram , explain the working of telephone system(6 marks) 10 (c) An audio frequency signal 10 sin (2π × 500)t is used to amplitude module a carrier of 50 sin(2π × 10⁵t). calculate
i) Modulation index
ii) Sideband frequencies
iii) Band width
iv) Amplitude of each sideband
v) Total power delivered to a load of 600 Ω
vi) Transmission efficiency(6 marks) 2 (a) Explain the working of a full wave rectifier using 2 diodes with neat diagram. Also derived the expressions for I_dc and I _ms of a full wave rectifier.(10 marks) 2 (b) Discuss in brief clamping circuit. Explain working of a negative clamper.(4 marks) 2 (c) Distinguish between Zener and Avalanche breakdown(6 marks) 3 (a) Calculate the value of I_C , I_E and β_DC for a transistor with α _DC=0.98 and I _B=120μA.(6 marks) 3 (b) For the base circuit V_cd=18V, R_c=2.2KΩ, h_fe =100 and V_BE=0.7 V Find I_B, I _c and V_CE. Draw the DC load line and indicate the Q point.(8 marks) 3 (c) Discuss the ideal characteristics of an operational amplifier(6 marks) 4 (a) Explain the voltage follower circuit using operational amplifier. Mention its importance properties.(5 marks) 4 (b) Design an adder circuit using Op-amp to obtain an output voltage V₀=2 [0.1V₁+0.5V₂+2V₃], where V₁ V₂ and V₃ are input voltage. Draw the circuit diagram.(8 marks) 4 (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(7 marks) 5 (a) With the help of a diode switching circuit and truth table explain the operation of an AND gate and OR gate.(6 marks) 5 (b) State and prove DeMorgan's theorem for three variables.(6 marks) 5 (c) With truth and logical expressions, give the design of a full adder circuit. Realize the circuit using i) Basic gate and ii) NAND gates(8 marks) 6 (a) Performs the following conversions :
i) (1234.56)₈=(?)₁₀ ii) (10110101001.101011)₂=(?)₁₆ iii)(988.86)₁₀=(?)₂ iv)(532.65)₁₀=(?)₁₆ v) (ABCD.EF)_H=(?)8(5 marks) 6 (b) i) Subtract (1000.01)₂ from (1011.10)₂ using 1's and 2's complement method.
ii) Add (7AB,67) ₁₆ with (15C.71)₁₆(5 marks) 6 (c) Design a half adder circuit and realize using Basic gates and NAND gates(5 marks) 6 (d) What are Universal gates? Realise AND and OR gate using universal gates.(5 marks) 7 (a) Distinguish between a Latch and flipflop(4 marks) 7 (b) Explain i) see back effect ii) Peltier effect and iii) Thomson effect(6 marks) 7 (c) Explain the architecture of 8085 microprocessor, with neat diagram(10 marks) 8 (a) Explain the working of LVDT with neat diagram(6 marks) 8 (b) List the difference between a microprocessor and micro controller(8 marks) 8 (c) Explain the working of a R-S flipflop with relevant circuit and truth table(6 marks) 9 (a) What is Modulation? Mention some of the need for modulation in communication system(6 marks) 9 (b) Give the comparison between AM and FM(8 marks) 9 (c) With block diagram, explain the working of cellular mobile communication system(6 marks)