JNTU B.Tech 1st Year Basic 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) Define mean life time of a carrier.
(b) Draw the forward and reverse bias characteristics of a p – n junction diode and explain them qualitatively.
(c) Compare the merits and demerits of H.W. Rectifier, Full Wave Rectifier and Bridge rectifier. [2+8+6]
2. (a) Draw the circuit of transistor in the CE configuration and sketch the output characteristics and indicate the active, saturation and cut off regions.
(b) Define ? and ? of a transistor.
(c) Draw a family of common source drain characteristics of an n-channel JFET and explain the shape of these curves qualitatively. [6+4+6]
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) Explain how the negative feedback helps in reducing the output impedance of an amplifier. Derive an expression for the output impedance of the negative feedback amplifier in terms of the output impedance and gain of the amplifier without feedback and feedback factor.
(b) An amplifier has a gain of 1000 and output impedance of 10 k when no feedback is employed. Determine the value of feedback factor required to have an output impedance of 600 when negative feedback is employed. [10+6]
5. (a) Why phase shift through the R-C feed back network of R-C phase shift oscillator is to be 1800? Explain.
(b) What are the limitations of R C-Phase shift oscillators?
(c) Draw the circuit of Colpitts Oscillator and explain the working of it. [5+3+8]
6. (a) Briefly explain “Thermal Expansion timers”.
(b) Draw sequence Timer Welding Circuit and explain its operation. [6+10]
7. (a) Giving basic set up, explain the principle of Induction heating.
(b) Draw and explain piezo electric generator circuit using Hartley oscillator for generation of Ultrasonic waves. [8+8]
8. (a) Explain the dual slope A-to-D converter technique with the help of block diagram.
(b) What are the various general purpose registers in 8085? Explain. [10+6]