Basic Electronics - Dec 2015

First Year Engineering (C Cycle) (Semester 2)

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 the V-I characteristics of a silicon diode.(8 marks) 1 (b) What is a rectifier? With a neat circuit diagram and waveforms, explain the working of full wave rectifier.(8 marks) 1 (c) A full wave rectifier with a load of 1 kΩ. The ac voltage applied to the diode is 200-0-200 V, if diode resistance is neglected. Calculate:
i) Average dc current;
ii) Average dc voltage.(4 marks) 10 (a) With a block diagram, explain typical cellular mobile unit.(5 marks) 10 (b) What is ISDN? Explain services of ISDN.(6 marks) 10 (c) Explain advantages and applications of optical fibres.(5 marks) 10 (d) Give the comparison between AM and FM.(4 marks) 2 (a) Draw and explain the input and output characteristics of common emitter configuration.(8 marks) 2 (c) Explain full wave rectifier with capacitor filter with necessary waveforms.(7 marks) 3 (a) With a neat circuit diagram, explain the voltage divider bias circuit by giving its exact analysis.(8 marks) 3 (b) For the base bias circuit for npn transistor, find I_B, I_C and V_CE if R_C=2.2 KΩ, R_B=470 KΩ. V_CC=18 V, h_fe=100. Draw the dc load line and Q point.(8 marks) 3 (c) What is op-amp? List the ideal characteristics of an op-amp.(4 marks) 4 (a) Define for an op-amp (i) CMRR, (ii) Slew rate, (iii) PSRR.(6 marks) 4 (b) Show how an op-amp can be used as integrator. Derive an expression for its output.(6 marks) 4 (c) For the circuit shown in Fig. Q4(c). Calculate the output voltage. (4 marks) 4 (d) What is voltage follower? Explain.(4 marks) 5 (a) Convert:
i) (35.45)₁₀ =( )₂.
ii) (475.25)₈=( )₁₀
iii) (3FD)₁₆ = ( )₂.(6 marks) 5 (b) State and prove DeMorgan's theorems.(6 marks) 5 (c) Show that: [ i) Aoverline{B}C + B + Boverline{D}+ ABoverline{D} + overline{A}C = B+C \ ii) overline{overline{AB}+overline{A}+AB}=0 \ iii) AB+A(B+C)+B(B+C)=B+AC ](6 marks) 5 (d) What are universal gates?(2 marks) 6 (a) Realize two input EX-OR gate using only NAND gates.(5 marks) 6 (b) Design full adder and implement it.(7 marks) 6 (c) Subtract (111001)₂ from (101011)₂ using 2's complement method.(4 marks) 6 (d) Realize OR gate using diodes and explain.(4 marks) 7 (a) Define flip flop. Explain R-S flip flop.(5 marks) 7 (b) With neat block diagrams, explain architecture of 8085 microprocessor.(10 marks) 7 (c) List the difference between microprocessor and microcontroller.(5 marks) 8 (a) What is transducer? Distinguish between active and passive transducer.(5 marks) 8 (b) With a neat sketch, explain construction and working of LVDT.(7 marks) 8 (c) Explain the working of photo voltaic transducer.(8 marks) 9 (a) What is modulation? What is the need of modulation?(5 marks) 9 (b) A 500, W, 1MHz carrier is amplitude modulated with a sinusoidal signal of 1 kHz. The depth of modulation is 60%. Calculate the bandwidth, power in the sidebands and the total power transmitted.(7 marks) 9 (c) Define AM. Draw the AM signal and its spectrum. Derive the necessary expression for AM.(8 marks)