Question Paper: Basic Electronics Engineering (BXE) : Question Paper Apr 2013 - First Year Engineering (Semester 2) | Pune University (PU)
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## Basic Electronics Engineering (BXE) - Apr 2013

### First Year Engineering (Semester 2)

TOTAL MARKS: 50
TOTAL TIME: 2 HOURS
(1) Solve Q.1 or Q.2, Q.3 or Q.4, Q.5 or Q.6, Q.7 or Q.8
(2) Assume suitable data, if necessary.

### Answer any one question from Q1 & Q2

1 (a) Sketch IR and VO w. r .t time for the network shown in fig. A. Assume both the diodes are silicon type with Vf=0.7 V

(6 marks) 1 (b) For a BJT as a switch why CB and cc configurations are not preferred.(2 marks) 1 (c) Explain how Ri and Ro affect the performance of the BJT voltage amplifire.(4 marks) 2 (a) Explain with V-I characteristics the working of zener diode as voltage regulator.(6 marks) 2 (b) In the voltage amplifire shown in Fig B, Vs=100m V Rs=50 Ω
(i) Calculate input voltage Vi if the input resistance Ri is 600 Ω
(ii) What should be the value of Ri to get Vi=75 mV.

(6 marks)

### Answer any one question from Q3 & Q4

3 (a) In fig. C if Va=+2V Vb=+4V
Ra=Rb=R1 = 1K Ω and Rf=3 k Ω determine the voltage V1 at non-inverting terminal of OP-AMP and out voltage V0

(4 marks) 3 (b) Draw the block diagram of full adder using two half adder, explain its working with proper expression for sum and carry.(6 marks) 3 (c) Explain how EX-OR gate can be used as an invertor.(2 marks) 4 (a) With neat waveform explain IC555 in astable mode.(6 marks) 4 (b) Implement the following logic expression with minimum number of NAND gate
(i) y1=B(D +C D)
(ii) y2=AB+CD+B C
(6 marks)

### Answer any one question from Q5 & Q6

5 (a) Explain in detail, the selection criteria for transducer.(6 marks) 5 (b) Explain in detail
i) construction of TRIAC
ii) characteristics of TRIAC
iii) modes of oper Ation
(7 marks)
6 (a) Explain with block diagram an electronic weighing machine.(6 marks) 6 (b) Explain the construction of DIAC w.r.t
i) Characteristics
ii) Application
(7 marks)
7 (a) What is the importance of modulation index. Draw the AM waveform for
i) Liner modulation
ii) Over modulation
iii) Modulation index = 0
(8 marks)
7 (b) Explain the basic structure of mobile phone system.(5 marks) 8 (a) With respect to FM explain
i) Frequency deviation
ii) Modulation index
iii) Deviation ratio
iv) Frequency spectrum of FM
(8 marks)
8 (b) Write a note on co-axial cable and optical fibre cable.(5 marks)