I B.Tech - Regular Examinations, June 2009
First Year
ELECTRONIC DEVICES AND CIRCUITS- SET NO: 1
(Regulation 2007)
Time : 3 hours |
Maximam Marks:80 |
Answer any FIVE Questions
1. What are the main parts of the CRT? Explain briefly with neat sketch.
2. (a) Short notes on LED voltage drop and current.
(b) Write short notes on Multi colour LED.
3. (a) Draw the circuit diagram of HWR. Explain its working. What is the frequency
of ripple in its output.
(b) A HWR circuit supplies 100mA d.c to a 250
load. Find the d.c output
voltage, PIV rating of a diode and the r.m.s. voltage for the transformer
supplying the rectifier.
4.Derive an Eber’s Moll equation for a transistor.
5.(a) Explain the criteria for fixing operating point.
(b) List out the different types of biasing methods.
6.A transistor used in a CC Circuit as shown in Figure 6. has the following set of h
parameters.
hic = 2 K
, hfc = -51, hrc = 1, hoc = 25 × 10-6
Find the values of input and output resistances, current and voltage gains of the
amplifier stage. Use the approximate analysis.
7.Enumerate the effects of negative feedback on the various characteristics of the
amplifier.
8.(a) Define:
i. Damped Oscillation.
ii. Un Damped oscillation.
(b) Why an LC tank circuit,once excited, does not produce sustained oscillation?
Explain it briefly?
(c) Give the two Bark Hansen condition required for sinusoidal oscillations to be
sustained.
(d) What are the factors which affect the frequency stability of an oscillator?
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