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INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary

Choose the correct answer for the following :-
1 (a) (i) Zener diode can be used for rectification. This statement is ______
(A) True
(B) false
(C) neither true nor false
(D) noe of these
1 M
1 (a) (ii) The maximum efficiency of full wave rectifier is _____
(A) 40.6%
(B) 60.4%
(C) 78.5%
(D) 81.2%
1 M
1 (a) (iii) The knee voltage of a silicon diode is ______
(A) 0.3V
(B) 0.5V
(C) 0.7V
(D) none of these
1 M
1 (a) (iv) If f Hz is the frequency of the input given to a half wave rectifier, the output frequency will be
(A) 2f Hz
(B) f Hz
(C) 3f Hz
(D) 0.5f Hz
1 M
1 (b) Draw and explain the VI-characteristics of a Si-diode and Ge-diode.
6 M
1 (c) With a neat circuit diagram, explain the working principles of full wave bridge rectifier and show that the ripple factor=0.48, and efficiency = 81.2%
10 M

Choose the correct answer for the following :-
2 (a) (i) The current conduction in BJT is because of _____
(A) electrons
(B) holes
(C) both electrons and holes
(D) none of these
1 M
2 (a) (ii) If &alph;=0.95, then the values if ? of transistor is _____
(A) 0.05
(B) 19
(C) 100
(D) 120
1 M
2 (a) (iii) Common collector arrangement is generally used for _____
(A) impedance matching
(B) voltage amplification
(C) current amplifier
(D) none of these
1 M
2 (a) (iv) The current relationship between two current gain in a transistor is _____
$(A) \ \beta =\dfrac {\alpha}{1- \alpha} \\(B) \ \beta=\dfrac {1+\alpha }{1-\alpha}\\(C) \ \beta = \dfrac {1-\alpha}{1+\alpha}\\(D) \ \beta = \dfrac {1+\beta}{\beta}\\$
1 M
2 (b) Draw input and output characteristics of an NPN transistor in common base configuration and explain.
10 M
2 (c) For a Silicon transistor ?dc=0.995, emitter current is 10 mA and leakage current Ico is 0.5?A. Find Ic, IB, &beata; and ICEO.
6 M

Choose the correct answer for the following :-
3 (a) (i) Which of the following factor affects the Q-point stability?
(A) Ico
(B) coupling capacitor
(C) emitter resistor
(D) bypass capacitor
1 M
3 (a) (ii) The inter section of the dc load line with given base current curve is the
(A) h-point
(B) D-point
(C) Q-point
(D) none of these
1 M
3 (a) (iii) For an emitter follower, the voltage gain is ______
(A) unity
(B) greater than unity
(C) less than unity
(D) zero
1 M
3 (a) (iv) The best biasing stability is achieved by using _____ biasing method.
(A) fixed
(B) collectro to base
(C) voltage divider
(D) none of these
1 M
3 (b) Explain the working of collector-to-base bias circuit using an NPN transistor and derive the equation for IB.
8 M
3 (c) Define stability factor and discuss the factor that cuase instability of biasing circuits.
8 M

Choose the correct answer for the following :-
4 (a) (i) FET is a _____ controlled device.
(A) Voltage
(B) Current
(C) Pulse
(D) Power
1 M
4 (a) (ii) PNPN device is an _____
(A) UJT
(B) SCR
(C) MOSFET
(D) MODFET
1 M
4 (a) (iii) _____ used as a relaxation oscillator.
(A) MOSFET
(B) SCR
(C) BJT
(D) UJT
1 M
4 (a) (iv) The intrinsic standoff ratio of UJT _____
(A) eqaul to one
(B) must be less than unity
(C) must be greater than unity
(D) must be zero
1 M
4 (b) Explain the working of two transistor model of an SCR and obtain the expression for the anode current.
8 M
4 (c) Draw the equivalent circuit and VI-characteristics of UJT and explain it.
8 M

Choose the correct answer for the following :-
5 (a) (i) Oscillaor uses ______ type of feedback.
(A) positive
(B) negative
(C) reverse
(D) both A and B
1 M
5 (a) (ii) The frequency of osclillators in an oscillator is given by _____
$(A) \ \dfrac {1}{2\pi LC}\\(B) \ 2\pi LC \\(C) \ 2\pi\sqrt{LC}\\(D) \dfrac {1}{2\pi \sqrt{LC}}\\$
1 M
5 (a) (iii) With negative feedback, the bandwidth of an amplifier _____
(A) decreases
(B) increases
(C) both A and B
(D) constant
1 M
5 (a) (iv) ______ times maximum voltage gain.
(A) 0.707
(B) 7.07
(C) 10
(D) 17.06
1 M
5 (b) Draw the frequency repsonse of an RC-coupled amplifier and explain it. Mention its advantages and disadvantages.
8 M
5 (c) Explain with the help of circuit diagram the working of an RC phase shift oscillator using transistor.
6 M
5 (d) In a transistor colpitts oscillator having tank circuit parameters as c1=0.001 ?F and c2=0.01 ?F if L=5?H, calculate the frequency of oscillations.
2 M

Choose the corect answer for the following :-
6 (a) (i) The gain of the voltage follower is ______
(A) zero
(B) infinity
(C) neagative
(D) unity
1 M
6 (a) (ii) Ideally open loop gain of op-amp is _____
(A) 0
(B) 1
(C) ?
(D) positive
1 M
6 (a) (iii) The CMRR is given by _____
(D) none of these
1 M
6 (a) (iv) Maximum rate of charge of output voltage with time is called _____
(A) CMRR
(B) Slew rate
(C) over rate
(D) none of these
1 M
6 (b) List the characteristics of an ideal-op-amp and draw the three input inverting summer circuit using an op-amp and derive an expression for output voltage.
8 M
6 (c) Draw the basic block diagram of a cathode ray tube and explain its working.
8 M

Choose the correct answer for the following :-
7 (a) (i) Two's compliant of (1001)2 is _____
(A) 1001
(B) 0010
(C) 0111
(D) 1010
1 M
7 (a) (ii) To represent 35 in binary, number of bits required is _____
(A) 6
(B) 5
(C) 4
(D) 33
1 M
7 (a) (iii) Decimal number 37 is represented in BCD by _____
(A) 100111
(B) 00111011
(C) 00110111
(D) 111100
1 M
7 (a) (iv) Over modulation exists when modulation index is _____
(A) 1
(B) 0
(C) >1
(D) <1
1 M
7 (b) Explain the need for modulation.
6 M
7 (c) Convert (A3B)16=( )10 and (247.75)10= ( )2.
4 M
7 (d) (i) Perform (FC02A)16-(D052)16 using 16's complement.
(ii) Subtract (4317.46)8 from (42.345)8 using 8's complement.
6 M

Choose the correct answer for the following :-
8 (a) (i) The expression for half adder carry with input A and B given by _____
(A) A+B
(B) AB
(C) A B
(D) none of these
1 M
8 (a) (ii) The complement of A+B+1 is _____
(A) 0
(B) A+1
(C) AB+1
(D) 1
1 M
8 (a) (iii) ABCD+ABD is equal to _____
(A) ABC
(B) ABC
(C) ABD
(D) ABD
1 M
8 (a) (iv) A+(B+C)=(A+B)+C is _____ law.
(A) associative
(B) commutative
(C) distributive
(D) none of these
1 M
8 (b) Design a full adder circuit and realize, using two half adders.
8 M
8 (c) Simplify the following expression and implement using only NAND gates :
$(i)\ Y=ABC+A\bar{B}C+AB\bar{C}+\bar{A}BC\\(ii) \ Y=\overline{\overline{AB}+\overline {AC}} \\(iii) \ Y=A+\bar{A}B$
8 M

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