JNTU Basic Electronics Exam Paper Apr-May 2008
JNTU B.Tech II Semester Examinations, BASIC ELECTRONICS, Apr/May 2008
(Metallurgy & Material Technology)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
1. (a) Explain what is meant by mobility of a charge carrier in a solid. Derive an expression for the conductivity of a semiconductor, containing both free electrons and holes, in terms of the concentrations n and p and the mobilities.
(b) Draw the circuit of Bridge rectifier and explain the working of it. [8+8]
2. (a) Sketch typical output characteristics of CE configuration of a NPN transistor.
Explain how ? of the transistor be computed from the above characteristics.
(b) Draw the structure of n-channel J F E T and explain the drain characteristics of it. [8+8]
3. (a) Give the basic construction, schematic structure and circuit symbol of a thyristor.
(b) Give the important features of TRIAC.
(c) Give typical applications of TRIAC. [8+4+4]
4. (a) Discuss with mathematical expressions, how the negative feedback in amplifiers reduces the distortion and increases the band width of the amplifier.
i. voltage gain
ii. output impedance.
iii. Band width of a feedback amplifier with parameters of the internal amplifier as A=250, Z0=30 k , Bandwidth = 50 kHz and having feedback factor ? =0.02. [8+8]
5. (a) Classify oscillators based on
i. output waveform
ii. operating frequencies.
(b) Draw the circuit of Colpitts Oscillator using transistor and explain the working of it. [6+10]
6. (a) Explain the following timers
i. Delay Timer
ii. Internal Timer and
iii. Repeat Cycle Timer.
(b) Explain the following Resistance welding process : [8+8]
i. Spot welding and
ii. Butt welding.
7. (a) Give the measures adopted to reduce undesirable radiation in Induction heating.
(b) Explain one method of generation of Ultrasonic waves. [8+8]
8. (a) Define the terms for D/A converters.
iii. Settling time
iv. Conversion time.
(b) What is the difference between A/D and D/A converter? Give applications of each. [4+12]