DipIETE – CS (OLD SCHEME)

Code: DC02 Subject: FUNDAMENTALS OF ELECTRONICS

Time: 3 Hours Max. Marks: 100

NOTE: There are 9 Questions in all.

· Question 1 is compulsory and carries 20 marks. Answer to Q.1 must be written in the space provided for it in the answer book supplied and nowhere else.

· Out of the remaining EIGHT Questions, answer any FIVE Questions. Each question carries 16 marks.

· Any required data not explicitly given, may be suitably assumed and stated.

Q.1 Choose the correct or the best alternative in the following: (210)

a. What is the value of the knee voltage for silicon p-n junction?

(A) 0.5 V. (B) 0.7 V.

(C) 0.4 V. (D) 0.8 V.

b. In which region the zener diode is operated?

(A) Forward characteristics region (B) None

(C) Breakdown region (D) Reverse region

c. A practical voltage source is considered to be a good voltage source when its internal impedance is _________ in comparison to external load impedance.

(A) high (B) low

(C) equal (D) None of the above.

d. What is the value of collector current, if the emitter current in the transistor is 1 mA?

(A) 1 mA (B) 2 mA

(C) 3mA (D) 4 mA

e. How the base of transistor is doped?

(A) Heavily. (B) Lightly.

(C) Moderately. (D) None.

f. The fastest logic family is ________.

(A) TTL (B) DTL

(C) ECL (D) RTL

g. What is the value of alpha?

(A) Less than one. (B) More than one.

(C) Unity. (D) None.

h. The voltage gain of a practical op-amp is of the order of _____________.

(A) 10⁵ (B) 10²

(C) 1 (D) 10

i. What is the type of FET transistor?

(A) Bipolar (B) Dipolar

(C) None (D) Unipolar

j Which statement is correct for Demorgan’s theorem?

(A) A+B=A .B (B) A . B=A+B

(C) None (D) A . A=A+A

Answer any FIVE Questions out of EIGHT Questions.

Each question carries 16 marks.

Q. 2 a. What do you mean by active and passive components? What are the various types of resistors and capacitors? (4+4)

b. Determine the current through 6 Ω resistance connected across points A and B terminals in the electric circuit as shown in Fig.1 using       Thevenin’s theorem. (8)

Q.3 a. What is intrinsic semiconductor? Describe the effect of temperature on the conductivity of intrinsic semiconductor. Where does the Fermi-Level lie in these semiconductors? (3+3+2)

b. With the help of energy level diagram explain the differences between insulator, semiconductor and conductor. (8)

Q.4 a. With the help of suitable diagram explain the V-I characteristics of p-n junction Diode. (8)

b. What is zener diode? Draw its characteristics and label different regions. (8)

Q.5 a. What are the three configurations of a transistor? Which configuration gives highest input impedance and no voltage gain? How alpha and beta are related to each other? (2+3+3)

b. For a certain transistor collector current is 20 mA and current gain factor is 50. Determine emitter current. (8)

Q. 6 a. With the help of suitable diagram describe the operation of N-channel JFET. (9)

b. What is the merits of IC’s over Discrete component? (7)

Q. 7 a. Minimize the four variable logic function

f (A,B,C,D) = . .

. . . . using K map. (9)

b. What is an oscillator? Explain the essential parts of an oscillator. (7)

Q. 8 a. With the help of suitable circuit diagram explain working of op-amp as an integrator. (8)

b. Write short Note on the following:

( i) Direct coupled transistor logic.

(ii) Differential Amplifier. (4+4)

Q. 9 a. What are the universal logic gates? Draw the truth table of each gate. (8)

b. Show that:

1. ABC + ABC + ABC = A (B+ C)

2. AB+ABC+AB+ABC=B+AC. (8)