# JNTU B Tech 2nd Semester Examinations, Basic Electronics, Apr/May 2008

JNTU B.Tech II Semester Examinations,

Basic  Electronics,

Apr/May 2008

(Metallurgy & Material Technology)

Time: 3 hours Max Marks: 80

All Questions carry equal marks

SET-III

1. (a) Draw the circuit of Bridge rectifier and explain the working of it. Give the advantages and drawbacks of this circuit.

(b) Compare the performance of C, L- section and ? – section filters with reference to the rectifier circuits. [10+6]

2. (a) Draw the circuit of a P N P transistor in CC configuration and give the special features of this type of circuit.

(b) The emitter current IE in a transistor is 2 ma. If the leakage current ICBO is 5 ? a and ?dc = 0.985 calculate the collector current.

(c) Give the applications of J F E T. [6+6+4]

3. (a) Name different methods of turning-on of SCR.

(b) What are the important points to be noted while designing the gate-control circuit of SCR.

(c) Draw and explain the V-I characteristics of SCR. [2+6+8]

4. (a) Distinguish between open-loop or non feedback system and closed-loop or feedback system.

(b) An amplifier with Zi = 1 k has a gain of 1000. Calculate the feedback factor required to reduce the gain to 100 with negative feedback. Also calculate the input impedance of the feedback amplifier. [6+10]

5. (a) Draw the circuit of transistor Colpitts Oscillator and briefly explain the working of it. Derive the expression for frequency of oscillation fo.

(b) Calculate the frequency of oscillation of a transistor Colpitts Oscillator having

C1 = 0.02 ?F, C2 = 0.2 ?F and L = 10 ?H. [10+6]

6. (a) Classify timers according to the function and the techniques used.

(b) Draw the circuit and explain the working of “Magnetic Energy StorageWelder”. [8+8]

7. (a) Give the block diagram of Cathode Ray Oscilloscope (C R O) and explain each block in detail.

(b) Explain the principle of Dielectric Heating.

(c) Explain thermal effects of Ultrasonic waves. [8+4+4]

8. (a) Explain in detail the various addressing modes used in 8085 Microprocessor with examples.

(b) What is a Microprocessor? [12+4]