Jawaharlal Nehru Technological University Kakinada 2008 B.Tech Electrical and Electronics Engineering PULSE AND DIGITAL CIRCUITS - Question Paper

( Common to Electrical & Electronic Engineering and Electronics &
Instrumentation Engineering)
Time: three hours Max Marks: 80
ans any 5 ques.
All ques. carry equal marks
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1. (a) discuss about RLC Ringing Circuit
(b) discuss RC double di?erentiator circuit. [8+8]
2. (a) T=1000  sec
V= 10 V
Duty cycle = 0.2
i. Sketch waveform with voltage levels at steady state ?gure 2(a)iii
ii. Forward and reverse direction tilt
iii. Af / Ar
Figure 2(a)iii
(b) Write a short note on non- linear wave shaping. [12+4]
3. discuss the subsequent
(a) Storage and transition times of the diode as a switch
(b) Switching times of the transistor. [8+8]
4. What is a monostable multivibrator? discuss with the help of a neat circuit di-
agram the principle of operation of a monostable multivibrator, and derive an
expression for pulse width. Draw the wave forms at collector and Bases of both
transistors. [16]
5. (a) De?ne sweep time and restoration time of a voltage time base waveform. What
is the di?erence ranging from sweep and sawtooth waveforms?
(b) In the transistor bootstrap circuit, Vcc = 25V, VEE = - 15V, R = 10kO, RE
= 15kO, RB = 150 kO, C= 0.05 F, C1 = 100 F. The gating waveform has
a duration TG =300 Sec. The transistor parameters are hie = 1.1 kO, hre =
2.5 × 10-4
kO, hfe = 50, hoe = 1/40
1 of 2Code No: 07A30401 Set No. 3
i. Draw the waveforms of ic, and vo, labeling all current and voltage levels.
ii. What is the slope fault of the sweep?
iii. What is the sweep speed and the maximum value of the sweep voltage?
iv. What is the retrace time Tr for C to discharge completely?
v. compute the recovery time T1 for C1 to recharge completely. [16]
6. (a) With the help of a circuit diagram and waveforms, discuss frequency division
of an astable multivibrator with pulse signals.
(b) The relaxation oscillator, when running freely, generates an output signal of
peak - to - peak amplitude 100V and frequency one kHz. Synchronizing pulses
are applied of such amplitude that at every pulse the breakdown voltage is
lowered by 20V. Over what frequency range may the sync pulse frequency be
varied if one : one synchronization is to result? If five : one synchronization is to be
found (fP /fS = 5), over what range of frequency may the pulse source be
varied? [16]
7. (a) discuss the operation of a 6 - diode gate.
(b) Write the applications of sampling gates.
(c) Brie?y define the chopper ampli?er and sampling scope. [16]
8. (a) Compare the Resistor Transistor logic and Diode Transistor logic families
(b) discuss the wired AND logic with the help of circuit diagram.
[8+8]
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2 of 2Code No: 07A30401 Set No. 4
II B.Tech I Semester Regular Examinations, November 2008
PULSE AND DIGITAL CIRCUITS
( Common to Electrical & Electronic Engineering and Electronics &
Instrumentation Engineering)
Time: three hours Max Marks: 80
ans any 5 ques.
All ques. carry equal marks
? ? ? ? ?
1. (a) find the response of RC high pass cirucit for an exponential i/p lignal
(b) A square wave whose peak-to-peak valve is IV, exterds I 0.5V w.r.t. to ground.
The half period is O.iSec this voltage impressed upon an RC di?erentating
circuit whose time constant is 0.2 sec. Determine the maximum and minimum
valves of the l/p voltages int eh steady state. [8+8]
2. (a) The input voltage vi to the 2 level clipper shown in ?gure 2a varies linearly
from 0 to 75 V. Sketch the output voltage vo to the identical time scale as the
input voltage. presume Ideal diodes.
Figure 2a
(b) discuss positive peak voltage limiters beneath reference level. [12+4]
3. (a) discuss with relevant diagram the different transistor switching times
(b) discuss the storage and transition times of the diode as a switch. [8+8]
4. discuss about different switching conditions of Schmitt trigger. [16]
5. (a) elaborate the methods of generating a time base waveform? discuss every
method.
(b) Derive the expression Mathematical relationship ranging from sweep speed error,
Displacement fault and transmission fault for an exponential sweep circuit.
[16]
6. (a) define frequency division employing a transistor a stable multivibrator with
waveforms.
(b) define frequency division employing a transistor monostable multivibrator
with waveforms. [8+8]
1 of 2Code No: 07A30401 Set No. 4
7. (a) define the working of a 4 diode gate with necessary diagrams and equa-
tions.
(b) For the 4 diode gate, RL = RC = 100k O and that R2 = 2kO, RF = 50O.
For Vs = 25V, calculate gain A, Vmin and (Vc)min . calculate (Vn)min for V
= Vmin.
[16]
8. (a) De?ne positive and negative logic system
(b) De?ne fan-In, fan-out
(c) Draw and discuss the circuit diagram of a diode OR gate for positive logic.
[4+4+8]
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2 of 2

Earning:   Approval pending.