CONTROL SYSTEMS

Code No: R05220205 Set No. 1
II B.Tech II Semester Regular Examinations, Apr/May 2008
CONTROL SYSTEMS
( Common to Electrical & Electronic Engineering, Electronics &
Communication Engineering, Electronics & Instrumentation Engineering,
Electronics & Control Engineering, Electronics & Telematics and
Electronics & Computer Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Explain the traffic control system concepts using open loop as well as closed
loop system.
(b) Why is negative feedback invariably preferred in closed loop systems? [8+8]
2. (a) Reduce the given block diagram (figure 2a)and hence obtain the transfer func-
tion C(s)
R(s) .
Figure 2a
(b) Explain the need of signal flow graph representation for any system. [10+6]
3. (a) What is meant by time response? Explain about
i. Steady- state response
ii. Transient response
(b) A unity feed-back system is characterized by an open loop T.F G(s) = K
s(s+10)
Determine the gain K so that the system will have a damping ratio of 0.5. For
this value of K , determine Ts, Tp and Mp for a unit step input. [6+10]
4. (a) Define the term root locus and state the rule for finding out the root locus on
the real axis?
(b) Calculate the angle of asymptotes and the centroid for the system having
G(s)H(s) = K(s+3)
s(s+2)(s+4)(s+5)
(c) For G(s)H(s) = K
s(s+1)(s+3) , find the intersection point of the root locus with
the jω - axis? [4+6+6]
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Code No: R05220205 Set No. 1
5. Sketch the Bode plots for a system
G(s) = 15(s+5)
s(s2+16s+100)
Hence determine the stability of the system. [16]
6. Write short notes:
(a) Comparision of polar & Nyquist plots
(b) Applications of Nyquist criterion. [8+8]
7. (a) What is compensation? what are the different types of compensators?
(b) What is a lag compensator, obtain the transfer function of lag compensator
and draw pole-zero plot?
(c) Explain the different steps to be followed for the design of compensator using
Bode plot? [3+3+10]
8. Obtain the two differential state representation for the system with transfer func-
tion.
y(s)
u(s) = 2
S3+6S2+11S+6 . [16]
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Code No: R05220205 Set No. 2
II B.Tech II Semester Regular Examinations, Apr/May 2008
CONTROL SYSTEMS
( Common to Electrical & Electronic Engineering, Electronics &
Communication Engineering, Electronics & Instrumentation Engineering,
Electronics & Control Engineering, Electronics & Telematics and
Electronics & Computer Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Define transfer function and what are its limitations? [6+10]
(b) Find the transfer function of the following system: Shown in figure 1b.
Figure 1b
2. (a) Reduce the given block diagram (figure 2a) and hence obtain the transfer
function C(s)
R(s)
Figure 2a
(b) Explain the working principle of synchro receiver with neat sketch. [10+6]
3. (a) What are generalized error constants? State the advantages of generalized
error coefficients?
(b) For a first order system, find out the output of the system when the input
applied to the system is unit ramp input? Sketch the r(t) and c(t) and show
the steady state error. [8+8]
4. (a) What are the necessary conditions to have all the roots of the characteristic
Equation in the left half of s-plane?
(b) What are the difficulties in RH stability crititerion? Explain ,how you can
over come them? [4+12]
5. (a) State the advantages & limitations of frequency domain analysis
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Code No: R05220205 Set No. 2
(b) Sketch the Bode plot s of
G(s) = 28.5e−0.1s
s(1+s)(1+0.1s)
Hence find gain cross over frequency. [6+10]
6. (a) What is “Nyquist Contour”?
(b) A system is given by
G(s) = 4s+1
s2(s+1)(2s+1) Sketch the Nyquist plot & hence determine the stability
of the system. [2+14]
7. (a) What is compensation? what are the different types of compensators?
(b) What is a lag compensator, obtain the transfer function of lag compensator
and draw pole-zero plot?
(c) Explain the different steps to be followed for the design of compensator using
Bode plot? [3+3+10]
8. Obtain the two differential state representation for the system with transfer func-
tion.
y(s)
u(s) = 2
S3+6S2+11S+6 . [16]
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Code No: R05220205 Set No. 3
II B.Tech II Semester Regular Examinations, Apr/May 2008
CONTROL SYSTEMS
( Common to Electrical & Electronic Engineering, Electronics &
Communication Engineering, Electronics & Instrumentation Engineering,
Electronics & Control Engineering, Electronics & Telematics and
Electronics & Computer Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Write the important differences between open loop and closed loop systems
with suitable examples.
(b) Obtain the transfer function X0(s)
X1(s) of the following system. Shown in figure 1b.
[8+8]
Figure 1b
2. (a) State and explain mason’s gain formula for the signal flow graph.
(b) What are differences between block diagram reduction and signal flow graph
reduction? [8+8]
3. (a) How steady ?state error of a control system is determined? How it can be
reduced?
(b) Determine the error coefficients and static error for G(s) = 1
s(s+1)(s+10) ,
H(s) = s + 2 . [8+8]
4. (a) What are the necessary conditions to have all the roots of the characteristic
Equation in the left half of s-plane?
(b) What are the difficulties in RH stability crititerion? Explain ,how you can
over come them? [4+12]
5. (a) Define frequency response.
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Code No: R05220205 Set No. 3
(b) Discuss the advantages & disadvantages of frequency response analysis.
(c) Bring out the correlation between time response & frequency response and
hence show that the correlation exists for the range of damping ratio 0 <ζ< 0.707.
[2+6+8]
6. (a) What is “Nyquist Contour”?
(b) A system is given by
G(s) = 4s+1
s2(s+1)(2s+1) Sketch the Nyquist plot & hence determine the stability
of the system. [2+14]
7. Design a lead compensator for unity feed back system whose open loop transfer
function G(S) = K
S(S+1)(S+5) to satisfy the following specifications.
(a) velocity error constant KV  50
(b) Phase margin  200. [16]
8. (a) Obtain the state model of the system whose transfer function is given as.
Y (s)
V (s) = 10
S3+4S2+2S+1
(b) Consider the matrix A compute eAt? [8+8]
A =  0 1
−2 − 3 
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Code No: R05220205 Set No. 4
II B.Tech II Semester Regular Examinations, Apr/May 2008
CONTROL SYSTEMS
( Common to Electrical & Electronic Engineering, Electronics &
Communication Engineering, Electronics & Instrumentation Engineering,
Electronics & Control Engineering, Electronics & Telematics and
Electronics & Computer Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Explain the basic components of control systems?
(b) Find the transfer function for the system given figure 1b:
Figure 1b
where, M is the mass of the system. [6+10]
K is the spring deflection
B is the coefficient of viscous damping.
2. (a) Reduce the given block diagram (figure 2a) and hence obtain the transfer
function C(s)
R(s)
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Code No: R05220205 Set No. 4
Figure 2a
(b) Explain the need of Mason’s gain formula for any system reduction. [10+6]
3. (a) Define type and order of a control system and hence find the type and order
of the following systems?
i. G(s)H(s) = 100
s(s2+4s+200)
ii. G(s)H(s) = 200
s2(s2+10s+200)
iii. G(s)H(s) = 4(s2+10s+100)
s(s+3)(s2+2s+10)
iv. G(s)H(s) = 200
(1+01s)(1+0.5s)
(b) The unit step response of a second order linear system with zero initial state
is given by c(t) = 1 + 1.25e−6tSin(8t − tan−1 1.333). Determine the damping
ratio, un damped natural frequency of oscillations and peak overshoot? [8+8]
4. (a) Define the the following terms
i. absolute stability
ii. marginal stability
iii. conditional stability
(b) By means of RH criterion determine the stability of the system represented
by the characteristic equation S4 + 2S3 + 8S2 + 4S + 3 = 0
(c) State the advantages of RH Stability criterion? [6+6+4]
5. (a) Derive the expressions for resonant peak & resonant frequency and hence
establish the correlation between time response & frequency response.
(b) Given ζ = 0.7 & ωn = 10 r/s find resonant peak, resonant frequency & Bandwidth.
[10+6]
6. (a) With respect to a function q(s) “Every s-plane contour which does not pass
through any singular points of q(s) has a corresponding contour in q(s) plane”
Elaborate.
(b) What is the effect of adding a zero at origin to the to the open loop transfer
function on polar plot? [8+8]
7. (a) What is compensation? what are the different types of compensators?
(b) What is a lag compensator, obtain the transfer function of lag compensator
and draw pole-zero plot?
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Code No: R05220205 Set No. 4
(c) Explain the different steps to be followed for the design of compensator using
Bode plot? [3+3+10]
8. (a) The system is represented by the differential equation
y¨+ 5y˙ + 6y = u
Find the transfer from state variable representation.
(b) Consider the RLC network shown in figure 8b. Write the state variable representation.
[16]
Figure 8b
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ANALOG COMMUNICATIONS

Code No: R05220405 Set No. 1
II B.Tech II Semester Regular Examinations, Apr/May 2008
ANALOG COMMUNICATIONS
( Common to Electronics & Communication Engineering and Electronics &
Telematics)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) With necessary expressions, waveforms and spectrums, Explain AM for an
arbitrary baseband signal m(t).
(b) The output power of an AM transmitter is 1KW when sinusoidally modu-
lated to a depth of 100%. Calculate the power in each side band when the
modulation depth is reduced to 50%. [10+6]
2. (a) Draw the circuit diagram for balanced ring modulator and explain its operation
indicating all the waveforms and spectrums.
(b) In an AM-SC system, modulating signal is a single tone sinusoid 4 cos 2 103t,
which modulates a carrier signal 6 cos 2106t. Write the equation of modu-
lated wave. Plot the two sided spectrum of the modulated wave. Calculate
the amount of power transmitted. [8+8]
3. (a) Describe the time domain band-pass representation of SSB with necessary
sketches.
(b) Find the percentage of power saved in SSB when compared with AM system.
[12+4]
4. (a) Explain the operation of the balanced slope detector using a circuit diagram
and draw its response characteristics. Discuss in particular the method of
combining the outputs of the individual diodes. In what way is this circuit an
improvement on the slope detector and in turn what are the advantages?
(b) Compute the bandwidth requirement for the transmission of FM signal having
a frequency deviation 75 KHz and an audio bandwidth of 10KHz. [12+4]
5. Explain how S/N ratio is a figure of merit incase of performance of a communication
channel. [16]
6. (a) Draw the block diagram of an SSB - SC transmitter employing sideband sup-
pression filter and explain.
(b) Why are limiters and preemphasis filters used in FM radio. [16]
7. (a) With the aid of the block diagram explain TRF receiver. Also explain the
basic superheterodyne principle.
(b) List out the advantages and disadvantages of TRF receiver. [16]
8. (a) Describe the synchronization procedure for PAM, PWM and PPM signals.
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Code No: R05220405 Set No. 1
(b) Discuss about the spectra of PWM and PDM signals. [16]
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Code No: R05220405 Set No. 2
II B.Tech II Semester Regular Examinations, Apr/May 2008
ANALOG COMMUNICATIONS
( Common to Electronics & Communication Engineering and Electronics &
Telematics)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) What are the main objectives of a communication system design? What are
the primary resources of any communication system.
(b) The RC load for a diode envelope detector consists of a 1000 pF capacitor
in parallel with a 10-K
 resistor. Calculate the maximum modulation depth
that can be handled for sinusoidal modulation at a frequency of 10 KHz if
diagonal peak clipping is to be avoided.
(c) A broadcast AM transmitter radiates 50 KW of carrier power. What will be
the radiated power at 85 % of modulation and what is the side band power?
[6+6+4]
2. Considering the modulating and carrier waves as sinusoids, Explain the single tone
modulation and demodulation of DSB-SC wave with necessary expressions, wave-
forms and spectrums and explain how only one side band is necessary for transmis-
sion of information. [16]
3. A synchronous detection of SSB signal shows phase and frequency discrepancy.
ConsiderS(t) =
N
P
i=1
cos [(ωct) cos(ωit + i) − sin(ωct) sin(ωit + i)]is an SSB signal.
The signal is multiplied by the locally generated carrier cosωct and then passed
through a low-pass filter.
(a) Prove that the modulating signal can be completely recovered if the cut-off
frequency of the filter is fN < fo < 2fc.
(b) Determine the recovered signal when the multiplying signal is cos[ωc + ].
(c) Determine the recovered signal when the multiplying signal is cos[(ωct+
ω)t].
Give
 << i where ωc = 2fc,
ω = 2Q
f. [16]
4. Explain demodulation of FM signal with the help of PLL. [16]
5. Compare noise performance of PM and FM system. [16]
6. (a) Draw the block diagram of an SSB - SC transmitter employing sideband sup-
pression filter and explain.
(b) Why are limiters and preemphasis filters used in FM radio. [16]
7. (a) Explain the working of TRF receiver with its block diagram.
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Code No: R05220405 Set No. 2
(b) A TRF receiver is turned to 1000 KHz AM radio broadcast signal by a variable
tuned circuit with 1 KHz bandwidth. Find the bandwidth when receiver is
returned to 1550 KHz and 550 KHz. Determined the recovered baseband. [16]
8. (a) Describe the generation and demodulation of PPM with the help of block
diagram and hence discuss its spectral characteristics.
(b) Define and distinguish between PTM and PAM schemes. Sketch and explain
their waveform for a single tone sinusoidal input signal. [16]
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Code No: R05220405 Set No. 3
II B.Tech II Semester Regular Examinations, Apr/May 2008
ANALOG COMMUNICATIONS
( Common to Electronics & Communication Engineering and Electronics &
Telematics)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Draw the one cycle of AM wave and calculate the modulation index of it in
terms of Vmax and Vmin voltages.
(b) A modulating signal consists of a symmetrical triangular wave having zero dc
component and peak to peak voltage of 12V. It is used to amplitude modulate
a carrier of peak voltage 10V. Calculate the modulation index and the ratio
of the side lengths L1/L2 of the corresponding trapezoidal pattern.
(c) The rms antenna current of an AM transmitter is 10 A when un-modulated and
12 A when sinusoidally modulated. Calculate the modulation index. [6+6+4]
2. (a) Explain about the quadrature null effect of coherent detector.
(b) In DSB-SC, suppression of carrier so as to save transmitter power results in
receiver complexity - Justify this statement. [8+8]
3. (a) Why SSB transmission is the preferred than DSB-SC?
(b) i. Prove that the signal s(t) =
NP
i=1
cos [(ωct) cos (ωit + i) − sin (ωct) sin (ωit + i)]
is an SSB signal (fc >> fN), where ωc = 2fc, carrier angular frequency
and ωi = 2fi is modulating angular frequency. Identify the side band.
ii. Obtain an expression for missing side band.
iii. Obtain an expression of the total DSB-SC signal. [4+12]
4. (a) Describe generation of FM carrier by Transistor reactance modulator with
necessary diagrams.
(b) Compare the phasor diagram of narrow band FM signal and AM signal and
discuss about the similarities and differences of the two signals. [8+8]
5. (a) Derive the expression for figure of merit of AM system for large case.
(b) Given an analog base band communication system with additive white noise
having power spectral density 
2 and a distorting channel having the frequency
response. The distortion is equalized by a receiver filter having the frequency
response
Hc (w) = 1
1+Jw/w
Heq (w) =  1
Hc(w) 0  |w|  w
0 otherwise
Obtain an expression for the output SNR.
[16]
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Code No: R05220405 Set No. 3
6. (a) Classify radio transmitters based on the type of modulation and Service in-
volved.
(b) Explain AM transmitters with modulation at high carrier power level with the
help of its block diagram. [16]
7. (a) With the aid of the block diagram explain TRF receiver. Also explain the
basic superheterodyne principle.
(b) List out the advantages and disadvantages of TRF receiver. [16]
8. (a) How is PDM wave converted into PPM system.
(b) Explain why a single channel PPM of system requires the transmission of
synchronization signal, where as a single channel PAM or PDM system does
not it. [16]
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Code No: R05220405 Set No. 4
II B.Tech II Semester Regular Examinations, Apr/May 2008
ANALOG COMMUNICATIONS
( Common to Electronics & Communication Engineering and Electronics &
Telematics)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Draw the one cycle of AM wave and calculate the modulation index of it in
terms of Vmax and Vmin voltages.
(b) A modulating signal consists of a symmetrical triangular wave having zero dc
component and peak to peak voltage of 12V. It is used to amplitude modulate
a carrier of peak voltage 10V. Calculate the modulation index and the ratio
of the side lengths L1/L2 of the corresponding trapezoidal pattern.
(c) The rms antenna current of an AM transmitter is 10 A when un-modulated and
12 A when sinusoidally modulated. Calculate the modulation index. [6+6+4]
2. (a) Explain the DSB-SC generation by balanced modulator using diodes.
(b) The modulating signal in an AM-SC system is a multiple-tone signal given by
m(t) = A1 cos ω1t + A2 cos ω2t + A3 cos ω3t. The signal m(t) modulates a
carrier Ac cos ωct. Plot the single-sided spectrum and find the bandwidth of
the modulated signal. Assume that ω3 > ω2 > ω1 and A1 > A2 > A3 . [8+8]
3. (a) Why VSB system is widely used for TV broadcasting - Explain?
(b) An AM transmitter of 1KW power is fully modulated. Calculate the power
transmitted if it is transmitted as SSB.
(c) Calculate the filter requirement to convert DSB signal to SSB Signal, given
that the two side bands are separated by 200HZ. The suppressed carrier is 29
MHZ. [6+4+6]
4. (a) Give the procedure to determine the effective bandwidth of an FM signal.
(b) Which method of FM signal generation is the preferred choice, when the sta-
bility of the carrier frequency is of major concern? Discuss about the method
in detail. [8+8]
5. (a) Find the output SNR in a PM system for tone modulation.
(b) A phase modulation (PM) system, with the modulated wave defined by S (t) =
Ac Cos [2π fct + kpm(t)]
where kp is a constant and m(t) is the message signal. The additive noise n(t)
at the phase detector input is
n(t) = nI(t) cos (2πfc t)−nQ (t) sin 2πfc t Assuming that the carrier-to-noise
ratio at the detector input is high compared with unity, determine
i. the output signal-to-noise ratio and
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Code No: R05220405 Set No. 4
ii. the figure of merit of the system. [16]
6. (a) Classify radio transmitters in detail.
(b) Compare low level modulation and high level modulation of radio transmitters.
[16]
7. (a) Describe the circuit of an FET amplitude limiter, and with the aid of the
transfer characteristic explain the operation of the circuit.
(b) What can be done to improve the overall limiting performance of an FM
receiver ? Explain the operation of the double limiter and also AGC in addition
to a limier. [16]
8. (a) What is the fundamental difference between pulse modulation, on the one
hand, and frequency and amplitude modulation on the other?
(b) What is pulse width modulation? What other names does it have? How is it
demodulated? [16]
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ANTENNAS AND WAVE PROPAGATION

Code No: R05310403 Set No. 1
III B.Tech I Semester Regular Examinations, November 2007
ANTENNAS AND WAVE PROPAGATION
( Common to Electronics & Communication Engineering and Electronics &
Telematics)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Draw the Dual characteristics of an antenna.
(b) Explain the Radiation from Two wire. [8+8]
2. (a) Derive the expressions for electric field in case of short current element and
hence obtain the conditions for the field to be in Franhofer region.
(b) Find the distance from a radiating element with 60Hz current such that radi-
ation and induction fields are equal. [10+6]
3. (a) A linear broadside array consist of 4 identical equal in phase point source with
λ/3 spacing. Calculate and plot the field pattern. Also find the directivity
and beam width.
(b) What is optimum spacing used in parasitic array? Why. [12+4]
4. (a) Write short notes on “Helical Antenna”.
(b) Derive an expression for radiated electric field strength of a traveling wave
radiation of length ‘l’. [8+8]
5. (a) Sketch the current distribution of folded dipole and find out input impedance
when two legs have unequal diameters.
(b) A Parabolic dish provides a power gain of 50dB at 10GHz, with 70% efficiency.
Find out
i. HPBW.
ii. BWFN, diameter. [8+8]
6. (a) Describe the method of measuring the gain and radiation pattern of an an-
tenna.
(b) A standard gain horn antenna with a power gain of 12.5, is used to measure the
gain of a large directional antenna by comparison method. The test antenna
is connected to the receiver and an attenuator adjusted to 23dB in order to
have the same receiver output. Find out the gain of the large antenna. [8+8]
7. (a) Describe the following:
i. Space wave propagation.
ii. Duct propagation.
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Code No: R05310403 Set No. 1
(b) VHF communication is to be established with a 50watt transmitter at 100MHz.
Calculate the LOS distance if the heights of transmitting and receiving an-
tennas are respectively 50m and 10m. Assuming the capture area of the
transmitting antenna is 25sqmts, calculate the field strength at the receiving
neglecting ground reflected wave. [8+8]
8. (a) Discuss the characteristics of F1 and F2 layers.
(b) Discuss the reasons for reduction of field strength in sky wave propagation.
[8+8]
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Code No: R05310403 Set No. 2
III B.Tech I Semester Regular Examinations, November 2007
ANTENNAS AND WAVE PROPAGATION
( Common to Electronics & Communication Engineering and Electronics &
Telematics)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Distinguish between Directive Gain and Power Gain.
(b) An antenna has a radiation resistance of 73 ohms and a lossy resistance of 7
ohms. If the power gain is 20, calculate the directivity and the efficiency of
the antenna. [8+8]
2. (a) Derive an expression for radiance resistance of current element starting from
the expression for radiation fields.
(b) Prove that the impedance of an isolated antenna when used for receiving is
same as when used for transmitting. [8+8]
3. (a) In order to scan the beam of a linear array to 300 off broadside. Calculate the
inner element phase shift required if the elements are spaced at 3 cms and the
frequency is 64 KHz.
(b) What are linear arrays. Compare Broadside array and End fire array. [8+8]
4. (a) Derive an expression for electric field of a Non Resonant antenna of length ‘l’
carrying current.
(b) Sketch and explain the constructional features of a Helical Antenna. [10+6]
5. (a) What is a Parasitic Element? Describe the use of different types of parasites
in TV receiving antennas.
(b) Derive an expression for aperture field distribution of a parabolidal reflector.
[8+8]
6. (a) Describe the method of measuring the gain and radiation pattern of an an-
tenna.
(b) A standard gain horn antenna with a power gain of 12.5, is used to measure the
gain of a large directional antenna by comparison method. The test antenna
is connected to the receiver and an attenuator adjusted to 23dB in order to
have the same receiver output. Find out the gain of the large antenna. [8+8]
7. (a) Define MUF and Critical frequency. Derive the expressions for the same.
What is Secant law?
(b) Describe the Ground wave propagation. [8+8]
8. (a) Derive the field strength of tropospheric wave.
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Code No: R05310403 Set No. 2
(b) Give an account of effect of earths imperfections and roughness. [8+8]
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Code No: R05310403 Set No. 3
III B.Tech I Semester Regular Examinations, November 2007
ANTENNAS AND WAVE PROPAGATION
( Common to Electronics & Communication Engineering and Electronics &
Telematics)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Define the terms:
i. Beam Width
ii. Side Lobe Level
iii. Polarization
iv. Effective Aperture Area.
(b) What is the effective length of an antenna. Determine the effective length of
a half wave dipole antenna. [8+8]
2. (a) Show that the radiation resistance of a small loop is equal to 320π 4(A/λ2)
ohms where A is loop area.
(b) What is Folded Dipole ? Find its Radiation Resistance. [8+8]
3. (a) Explain the procedure for measuring the radiation pattern of a half wave
dipole.
(b) What is the requirement for tapering of arrays.
(c) State the applications of arrays. [8+4+4]
4. (a) State the advantages and disadvantages of Rhombic Antenna.
(b) Draw the radiation pattern for traveling wave antenna for L=λ/2,λ,2 λ,4λ and
8 λ. [8+8]
5. (a) What is a Parasitic Element? Describe the use of different types of parasites
in TV receiving antennas.
(b) Derive an expression for aperture field distribution of a parabolidal reflector.
[8+8]
6. (a) Describe the method of measuring the gain and radiation pattern of an an-
tenna.
(b) A standard gain horn antenna with a power gain of 12.5, is used to measure the
gain of a large directional antenna by comparison method. The test antenna
is connected to the receiver and an attenuator adjusted to 23dB in order to
have the same receiver output. Find out the gain of the large antenna. [8+8]
7. It is defined to establish short wave communication between two points on earths
surface(assumed flat) separated by 1200km. Calculate MUF and angle of take off
1 of 2
Code No: R05310403 Set No. 3
of the transmitted wave from the following: Highest signal frequency returned to
earth after vertically upward propagation=7.2MHz. Virtual height of the ionized
layer=200kms. Deduce the working formula. [16]
8. (a) Distinguish between Radio and Optical horizons. Give the reasons.
(b) Write short notes on M-Curves. [8+8]
⋆ ⋆ ⋆ ⋆ ⋆
2 of 2
Code No: R05310403 Set No. 4
III B.Tech I Semester Regular Examinations, November 2007
ANTENNAS AND WAVE PROPAGATION
( Common to Electronics & Communication Engineering and Electronics &
Telematics)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Define antenna beam width and directivity and obtain the relation between
them.
(b) Calculate the electric field (Erms) due to an isotropic radiator radiating 3KW
power at a distance of 2 Km from it. [8+8]
2. (a) State the following antenna theorems and bring out their importance in an-
tenna measurements :
i. Reciprocity theorem.
ii. Maximum power transfer theorem.
(b) A half wave transmitting antenna radiates 10KW of power at 100MHz.If the
heights of transmitting and receiving antennas are 100m and 9m, calculate the
power received at a distance of 10kms from the transmitting antenna. [8+8]
3. (a) Calculate
i. HPBW
ii. Solid Angle if a linear array having 10 isotropic point source with λ/2
spacing and phase difference δ=900.
(b) Write short notes on Hansen-Wood yard end fire array. [8+8]
4. (a) Distinguish between Traveling wave and Standing wave antennas.
(b) Compare Resonant and Non Resonant antennas.
(c) Explain the working of Rhombic antenna. [4+4+8]
5. (a) Compute the gain, principle beam width and HPBW of a 10m diameter par-
abolic dish with a half wave length dipole feed in focus at 10GHz.
(b) Explain the Cassegrain mechanism in transmission mode. List out the advan-
tages and disadvantages of Cassegrain feed. [8+8]
6. (a) What is an electromagnetic horn antenna? What are its applications? The
length of an E-plane sectoral horn is 15cms. Design the horn dimensions such
that it is optimum at 10GHz.
(b) Calculate the minimum distance required to measure the field pattern of an
antenna of diameter 2m at a frequency of 3GHz. Derive the necessary equa-
tion. [8+8]
1 of 2
Code No: R05310403 Set No. 4
7. (a) Show that Ionosphere act as a variable refractive index medium.
(b) A radio link has to be established between two earth station at a distance of
25000kms. If the height of ionosphere is 200kms and its critical frequency is
5MHz. Calculate the MUF for the given path. Also calculate the electron
density in the ionosphere layer. [8+8]
8. (a) Describe the troposphere and explain how tropospheric ducts can be used for
microwave propagation.
(b) Derive the expression for space wave electric field produced by an antenna at
a distance point, assuming a flat earth. [8+8]
⋆ ⋆ ⋆ ⋆ ⋆
2 of 2

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REMAINING WILL BE UPDATED SOON

EM-2

Code No: R05310204 Set No. 1
III B.Tech I Semester Regular Examinations, November 2008
ELECTRICAL MACHINES-III
(Electrical & Electronic Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Explain the classification of alternators based on rotor used with the help of
neat diagrams.
(b) A 16 pole, 3-, alternator is coupled to a engine running at 375 rpm. It
supplies an IM that has a full load speed of 1450 rpm. Find the slip & number
of poles of the motor. [8+8]
2. (a) Explain the sources of harmonics. What are the various effects of harmonics
on generated emf in an alternator?
(b) Find the RMS value of fundamental & third harmonic EMF per phase for an
alternator having following data: 50 Hz, 3-, 20 poles, 4 slots/pole/phase,
double layer winding with 6 conductors/slot, coil span of 150o, flux per pole:
fundamental is 0.1 wb, third harmonic 17 % of fundamental. All coils of a
phase are connected in series. [8+8]
3. (a) What is the synchronous impedance method? Why the method is called so?
What are the limitations of this theory?
(b) The following table gives the OCC & SCC of a 2 pole, 11kV, 50 Hz, 3- star
connected alternator. The stator resistance between two terminals is 0.2
.
Calculate the regulation at full load current of 125 A at 0.8 pf lagging (by
synchronous impedance method) [6+10]
If 16 20 25 32 45
EOL-kV 4.4 5.5 6.6 7.7 8.8
(where EoL is line voltage at no load)
4. (a) Explain the various methods of synchronization of alternators.
(b) Two similar 4 MVA alternators operate in parallel. The governor of first
machine is such that frequency drops from 50 Hz at no load to 47.5 Hz at full
load. The corresponding drop for second machine is 50 Hz to 48 Hz. [8+8]
i. How will they share a load of 6 MW?
ii. What is the maximum load they can share at UPF without over loading
any generator?
5. (a) A sub-station operating at full load of 1200 kVA supplies a load at 0.7 power
factor lagging. Calculate the permissible additional load at this power factor
and the rating of synchronous condenser to raise the substation power to 0.9
lagging.
1 of 2
Code No: R05310204 Set No. 1
(b) Derive the expression for the maximum power developed by a synchronous
motor. [8+8]
6. (a) Explain the procedure to plot ‘V curves’ & ‘inverted V’ curves for a given
synchronous machine with help of its circles diagrams.
(b) A 2 pole, 50 Hz, 3- turbo alternator is excited to generate a bus-bar voltage of
11 kV on no load. The machine is star connected and the short circuit current
for this excitation is 1000 A. Calculate the synchronizing power per degree
of mechanical displacement of the rotor and the corresponding synchronizing
torque. [8+8]
7. (a) Why single phase motors are not self starting?
(b) Explain the necessary arrangements made to make single phase Induction
motor self starting & with neat diagram explain the operations of same. [8+8]
8. (a) Explain the working principle of reluctance motor.
(b) Compare working of AC series motor & Universal motor. [8+8]
⋆ ⋆ ⋆ ⋆ ⋆
2 of 2
Code No: R05310204 Set No. 2
III B.Tech I Semester Regular Examinations, November 2008
ELECTRICAL MACHINES-III
(Electrical & Electronic Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Explain the differences between stationary armature and rotating armature.
What are the advantages of rotating armature over stationary armature?
(b) A 4 pole alternator has an armature with 25 slots and 8 conductors per slot
and rotates at 1500 rpm and the flux per pole is 0.05 wb. Calculate the EMF
generated, if winding factor is 0.96 and all the conductors in a phase are in
series. [8+8]
2. (a) Explain the effects of harmonics on electrical power system & utility.
(b) Calculate the RMS value of EMF induced per phase of a 10 pole, 3-, 50 Hz,
alternator with 2 slots per pole per phase and 4 conductors per slot in two
layers. The coil span is 150o electrical. The flux per pole has a fundamental
component of 0.12 wb & a 20% of third harmonic component. [8+8]
3. (a) Explain the AT method of finding voltage regulation.
(b) A 1 MVA, 6.6 kV, 3- star connected synchronous generator has a synchronous
reactance of 25
 per phase. It supplies full load current at 0.8 lagging pf and a
rated terminal voltage. Compute the terminal voltage for the same excitation
when the generator supplies full load current at 0.8 leading pf. [8+8]
4. (a) Explain the operational differences in parallel operation of two alternators &
synchroning an alternator to infinite bus bars.
(b) Two star connected alternators supply a load of 3 MW at 0.8 pf lagging and
share the load equally. The excitation of second machine is adjusted so that
it is supplying 150 A at a lagging pf. The synchronous impedances are 0.4 +
j12
/ph& 0.5 + j10
/ph. Find current, power factor, induced EMF and
load angle of each machine. Terminal voltage is 6.6 kV. [8+8]
5. (a) An industrial plant has a load of 800 kW at power factor of 0.8 lagging. It is
desired to purchase a synchronous motor of sufficient capacity to deliver a load
of 200 kW and also serve to correct the over all plant power factor to 0.92.
Assuming that the synchronous motor has an efficiency of 92%, determine its
kVA input rating and power factor at which it will operate.
(b) Explain the load angle characteristics of a synchronous motor. [8+8]
6. A 1000 HP, 6.0 kV, 3-, star connected synchronous motor has a synchronous
impedance of 1.5 +j16
/ph. It is excited to develop an open circuit EMF of 5
kV. Draw the locus diagram of current for loads up to 1250 HP, with constant
excitation. Determine the maximum value of power factor. [16]
1 of 2
Code No: R05310204 Set No. 2
7. (a) Explain the various types of single phase Induction motor.
(b) What is splitting of phases? Why splitting of phase is necessary in single
phase Induction motor. [8+8]
8. Write short notes on following:
(a) AC series motor
(b) Universal motor
(c) Variable reluctance stepper motor
(d) Permanent magnet stepper motor. [4×4=16]
⋆ ⋆ ⋆ ⋆ ⋆
2 of 2
Code No: R05310204 Set No. 3
III B.Tech I Semester Regular Examinations, November 2008
ELECTRICAL MACHINES-III
(Electrical & Electronic Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Derive the expression for the EMF induced in a 3- alternator?
(b) Calculate the no load terminal voltage of a 3-, 8 pole, star connected alter-
nator running at 750 rpm having the following data:
Sinusoidaly distributed flux per pole = 55 mwb, total number of slots on the
armature = 72, conductors per slot = 10, distribution factor = 0.96. Assume
full pitch coils. [8+8]
2. (a) Explain the causes of harmonics? Explain the concept of fictitious poles.
(b) A 10 pole, 3-, 50 Hz, alternator has 8 slots per pole & 6 conductors per slot.
The winding is 7/8 pitch. There are 0.03 wb entering the armature from each
north pole & this flux is sinusoidaly distributed along the air gap. The star
armature coils are connected in series. Determine the open circuit EMF of the
alternator. Find the breadth factor for 3rd & 5th harmonics. [6+10]
3. (a) Explain the various tests conducted on an alternator to find the voltage reg-
ulation of an alternator by Potier triangle method.
(b) The no load excitation of an alternator required to give rated voltage is 1
pu. In a short circuit test with full current flowing in the armature, the field
excitation was 0.85 pu. Determine the approximate excitation that will be
required to give full load current at 0.78 PF leading at the rated terminal
voltage. [8+8]
4. (a) Explain the term synchronization, and hence explain, synchronizing power.
(b) Two identical 3 MVA alternators are running in parallel. The frequency drops
from no load to full load for the two alternators are 50 Hz to 47 Hz and 50 Hz
to 48 Hz respectively. [8+8]
i. How they will share a load of 4000 kW?
ii. What is maximum unity factor load which they can supply jointly supply
without any one of them over loaded?
5. (a) A 3-, synchronous motor observing 60 kW is connected in parallel with a
factory load of 240 kW having lagging pf of 0.8. If the combined load has a
pf of 0.9 lagging, what is the value of leading kVAR supplied by the motor &
at what power factor it is working?
(b) Explain the ‘power factor v/s field current’ & ‘armature current v/s field
current’ characteristics of synchronous motor. [8+8]
1 of 2
Code No: R05310204 Set No. 3
6. (a) Explain the procedure to plot ‘V curves’ with the help of ‘power circle’ &
‘excitation circle’.
(b) Explain the effect of damper winding on the performance of a synchronous
machine. [8+8]
7. (a) Explain the ‘doubly revolving field theory’ related to single phase Induction
motor.
(b) Explain the construction & give the applications of single phase Induction
motor. [8+8]
8. Give at least four applications of each of following:
(a) AC series motor
(b) Universal motor
(c) Variable reluctance stepper motor
(d) Permanent magnet stepper motor. [4×4=16]
⋆ ⋆ ⋆ ⋆ ⋆
2 of 2
Code No: R05310204 Set No. 4
III B.Tech I Semester Regular Examinations, November 2008
ELECTRICAL MACHINES-III
(Electrical & Electronic Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Obtain the expression for the short pitch factor & distributed winding factor?
(b) A 3-, 4 pole, star connected alternator has 60 slots with 2 conductors per
slot. The pitch of the coil is 3 slots less than pole pitch. The flux per pole is
0.125 wb. Calculate the no load terminal voltage if the speed of alternator is
1500 rpm. [8+8]
2. (a) What is armature reaction? Explain armature reaction for different power
factors of load?
(b) Data from tests performed to determine the parameters of a 200 kVA, 480 V,
60 Hz, 3-, stat connected alternator are Voc=480 V, Isc=209.9A for constant
If & for DC test VDC = 91.9 V, IDC=72.8 A (stator). Determine synchronous
impedance & the SCR of the alternator. [8+8]
3. (a) Explain the ‘Zero power factor’ method of finding voltage regulation of an
alternator.
(b) The no load excitation of an alternator required to give rated voltage is 1
pu. In a short circuit test with full current flowing in the armature, the field
excitation was 0.75 pu. Determine the approximate excitation that will be
required to give full load current at 0.866 PF lagging at the rated terminal
voltage. [8+8]
4. (a) Explain the effect of change in excitation on the parallel operation of two
alternators.
(b) Two similar stat connected alternators 3- alternators share a load of 7500
kW equally at 6000 V and 0.8 pf lagging. The synchronous impedance of 2.5
+ j50
/ph. The excitation of second machine is changed, so that it delivers
40 A at a lagging pf. Find: [8+8]
i. Armature current of first machine
ii. EMF of each machine
iii. Power factor of each machine.
5. (a) An industrial load of 4 MW is supplied at 11 kV, the power factor being
0.8 lagging. A synchronous motor is required to meet an additional load of
1103.25 kW and at the same time to raise the resultant power factor to 0.95
lagging. Determine the kVA capacity of the motor and the power factor at
which it must operate. The efficiency of motor is 80 %.
1 of 2
Code No: R05310204 Set No. 4
(b) Explain the various power stages of synchronous motor. What are the various
losses taking place in synchronous motor. [8+8]
6. The effective resistance & synchronous reactance per phase of a 50 Hz, 6.6 kV, 1
MVA, 3-, star connected synchronous motor are 0.5
 & 12
 respectively. Plot
the V curves for this machine when the input is maintained constant at 250 kW.
No load saturation curve: [16]
If 50 100 150 175 200
V 3400 5700 7200 7900 8400
7. (a) Explain the construction & operation of ‘capacitor start and run’ single phase
Induction motor.
(b) Explain ‘double revolving field theory’ of single phase Induction motor. [8+8]
8. With neat diagram explain the construction & working of variable reluctance step-
per motor. Also explain its static & dynamic characteristics. [16]
⋆ ⋆ ⋆ ⋆ ⋆
2 of 2

EM-3

Code No: V3111/R07 Set No. 1
III B.Tech I Semester Regular Examinations, November 2009
ELECTRICAL MACHINES-III
(Electrical & Electronic Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) Explain clearly, the fractional slot winding with all related calculations.
(b) A part of an alternator winding consist of six coils in series, each coil having
an EMF of 10 V RMS induced in it. The coils are placed in successive slots
and between each slot and the next; there is an electrical phase displacement
of 30o. Find the EMF of the six coils in series. [8+8]
2. (a) What are harmonics? Explain how harmonics are present in generated e.m.f
of alternator? What are the effects of hormonics an generated emf?
(b) A star connected 3- alternator has an induced EMF of 400 V between the
lines. Due to presence of third harmonic component, the phase voltage is 244
V. Find the value of
i. Find the value of third harmonic voltage. [10+6]
3. (a) Explain the ‘Zero power factor’ method of finding voltage regulation of an
alternator.
(b) The no load excitation of an alternator required to give rated voltage is 1
pu. In a short circuit test with full current flowing in the armature, the field
excitation was 0.75 pu. Determine the approximate excitation that will be
required to give full load current at 0.866 PF lagging at the rated terminal
voltage. [8+8]
4. A 4 kVA, 3-, 110 V, 50 Hz, star connected alternator has ×d = 3
 & xq = 2
.
The machine is delivering full load current at 0.8 pf lagging at rated voltage. Find
the induced EMF, load angle, maximum power delivered. [16]
5. (a) A 3-, star connected, 440 V, synchronous motor takes a power input of 5472
W at rated voltage. Its synchronous reactance is 10
/ph and resistance is
negligible. If its excitation voltage is adjusted equal to rated voltage of 400
V, compute the load angle, power factor and armature current.
(b) Derive an expression for the synchronizing power developed by a synchronous
motor. [8+8]
6. (a) Explain the importance of ‘power circles’ in determining the characteristics
of a synchronous machine.
(b) Explain the phenomenon of Hunting in synchronous machine? [8+8]
1 of 2
Code No: V3111/R07 Set No. 1
7. The following test results were obtained in case of a 220 V single phase induction
motor:
Free running test: 220V, 5.8 A, 310 W
Blocked rotor test: 120 V, 13.8 A, 530 W
Stator winding resistance = 1.4

Determine the approximate equivalent circuit of motor. [16]
8. (a) Explain the torque-speed characteristics of reluctance motor.
(b) Explain the dynamic characteristic of stepper motor. [8+8]
? ? ? ? ?
2 of 2
Code No: V3111/R07 Set No. 2
III B.Tech I Semester Regular Examinations, November 2009
ELECTRICAL MACHINES-III
(Electrical & Electronic Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) Explain clearly, the fractional slot winding with all related calculations.
(b) A part of an alternator winding consist of six coils in series, each coil having
an EMF of 10 V RMS induced in it. The coils are placed in successive slots
and between each slot and the next; there is an electrical phase displacement
of 30o. Find the EMF of the six coils in series. [8+8]
2. (a) Explain the factors affecting synchronous reactance of alternator.
(b) The SC, OC & DC test data for a star connected 25 kVA, 240 V, 60 Hz,
alternator are (between two terminals):
VOC = 240 V, ISC = 60.2 A - - - - For same field current
VDC = 120.6 V, IDC = 50.4 A
Determine: Synchronous reactance. [8+8]
3. A 3-, 1200 kVA, 2.2 kV, 50 Hz star connected alternator having an effective per
phase resistance of 0.22
 gave the following results: [16]
Field Current (A) 8 10 15 20 25 30 40 50
OC Voltage VL 700 850 1250 1700 1950 2200 2430 2700
SC Current (A) - - 180 240 320 - - -
Find the voltage regulation by MMF method at
(a) 0.8 pf lagging
(b) 0.8 pf leading.
4. A 200 MVA, 11 kV, 3-, star connected alternator is operated at rated speed and
voltage and at no load. A sudden 3- short circuit occurs at its terminals. The pu
reactances are ×d = 1.3, ×
0
d = 0.25 ×
00
d= 0.15 (pu). The initial DC component is
60 % of the initial AC component of current. (Take Td’ = 1 Sec & Td” = 0.05 Sec)
Find:
(a) AC component of current at the instant of short circuit.
(b) Total current at the instant of short circuit.
(c) AC component of current after 1 cycle
(d) AC component of current after 2 sec. [16]
Td’ = 1 Sec & Td” = 0.05 Sec.
5. (a) Explain the ‘V-curves’ & ‘inverted V curves’ of synchronous motor.
1 of 2
Code No: V3111/R07 Set No. 2
(b) A 75 kW, 400 V, 4 pole, star connected synchronous motor has an effective
per phase armature resistance & reactance of 0.04
 & 0.4
 respectively.
Compute the open circuit voltage/ph and mechanical power developed for full
load at 0.8 pf leading. Assume an efficiency of 92.5 %. [6+10]
6. (a) Explain the procedure to plot ‘V curves’ & ‘inverted V’ curves for a given
synchronous machine with help of its circles diagrams.
(b) A 2 pole, 50 Hz, 3- turbo alternator is excited to generate a bus-bar voltage of
11 kV on no load. The machine is star connected and the short circuit current
for this excitation is 1000 A. Calculate the synchronizing power per degree
of mechanical displacement of the rotor and the corresponding synchronizing
torque. [8+8]
7. The constants of a quarter HP, 230 V, 50 Hz, 4 pole single phase IM are as follows:
Stator resistance = 10.0
 ; Stator reactance = 12.8
, Magnetising reactance =
258
,
Rotor resistance referred to stator =11.65
, Rotor reactance referred to stator
=12.8

The total load is such that the machine runs at 3% slip, when the voltage is at 210
V. The iron losses are 35.5 W at 210 V. If mechanical losses are 7 W; Calculate:
(a) Input current
(b) Power developed
(c) Shaft power
(d) Efficiency. [4×4=16]
8. (a) Compare AC series motor & DC series motor. What are the operational
difficulties of each?
(b) Explain the variable reluctance motor principle. [8+8]
? ? ? ? ?
2 of 2
Code No: V3111/R07 Set No. 3
III B.Tech I Semester Regular Examinations, November 2009
ELECTRICAL MACHINES-III
(Electrical & Electronic Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) What are the various terms related with windings? Explain each of them with
their importance.
(b) A star connected 3-, 6 pole synchronous generator has a stator with 90 slots
& 8 conductors per slot. The rotor revolves at 1000 rpm. The flux per pole
is 40 mWb. Calculate the EMF generated, if all the conductors in each phase
are in series. Assume sinusoidal flux distribution & full pitched coil. [8+8]
2. (a) A 16 pole, 3- star connected alternator has 144 slots. The coils are short
pitched by one slot. The flux per pole is  = 100 sin  + 30 sin 3 + 20 sin
5. Find the harmonics as percentage of phase voltage & line voltage.
(b) Define
i. synchronous reactance
ii. Synchronous impedance and
iii. leakage reactance in an alternator. [10+6]
3. A 3- , 440 V, 50 Hz, delta connected alternator has direct axis & quadrature axis
reactance of 0.12
 and 0.09
 respectively. If the alternator supplies 900 A at 0.8
pf lagging, calculate the following: [8+8]
(a) the excitation EMF, neglecting saliency (Xd = Xq)
(b) the excitation EMF, taking into account the saliency.
Neglect armature resistance.
4. (a) Explain the ‘two bright one dark’ & ‘all dark’ method of synchronization of
alternators.
(b) The EMFs of two alternators are 30006 200 &29006 00 V. Their synchronous
impedances are 2 + j20
/ph & 2.5 + j30
/ph. The load impedance is 10 +
j4
/ph. Find the circulating current. [8+8]
5. (a) An industrial load of 800 kW is supplied at 11 kV, the power factor being
0.71 lagging. A synchronous motor of 400 kVA is installed for an additional
load and improve power factor. The synchronous motor load is 160 kW at
efficiency of 90 %. For synchronous motor operation at rated kVA, calculate
total kVA & resultant power factor.
(b) Obtain the condition for the maximum power developed by a synchronous
motor. [8+8]
1 of 2
Code No: V3111/R07 Set No. 3
6. (a) Explain the procedure to plot ‘V curves’ & ‘inverted V’ curves for a given
synchronous machine with help of its circles diagrams.
(b) A 2 pole, 50 Hz, 3- turbo alternator is excited to generate a bus-bar voltage of
11 kV on no load. The machine is star connected and the short circuit current
for this excitation is 1000 A. Calculate the synchronizing power per degree
of mechanical displacement of the rotor and the corresponding synchronizing
torque. [8+8]
7. (a) The following data pertains to a single phase Induction motor:
No. of poles = 4, Supply voltage = 110, Rated output = 125 W,
Slip = 6%, total full load copper losses = 25 W, Rotational losses =
25W. Calculate the full load efficiency & the rotor copper loss caused by the
backward field. Neglect stator resistance.
(b) Give the comparison between ‘capacitor start-capacitor run’ single phase In-
duction motor & ‘capacitor start-run motor’ single phase Induction motor.
[8+8]
8. (a) Explain how the speed of Universal motor can be controlled.
(b) Explain ‘conductively compensated’ AC series motor & ‘inductively compen-
sated’ AC series motor. [8+8]
? ? ? ? ?
2 of 2
Code No: V3111/R07 Set No. 4
III B.Tech I Semester Regular Examinations, November 2009
ELECTRICAL MACHINES-III
(Electrical & Electronic Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) Explain the construction & working principle of 3- alternator.
(b) One phase of a 3- alternator consist of twelve coils in series. Each coil has an
RMS voltage of 10 V induced in it and coils are arranged in slots so that there
is a successive phase displacement of 10o electrical between the EMFs in each
coil and the next. Find the RMS value of the total phase voltage developed
by the winding. If the alternator has six poles and is driven at 1000 rpm,
calculate the frequency of the EMF generated. [8+8]
2. (a) Explain the factors affecting synchronous reactance of alternator.
(b) The SC, OC & DC test data for a star connected 25 kVA, 240 V, 60 Hz,
alternator are (between two terminals):
VOC = 240 V, ISC = 60.2 A - - - - For same field current
VDC = 120.6 V, IDC = 50.4 A
Determine: Synchronous reactance. [8+8]
3. (a) Explain the assumptions made in calculation of voltage regulation of an alter-
natator by synchronous impedance method.
(b) The following table gives the OCC & SCC of a 2 pole, 6.6kV, 50 Hz, 3- star
connected alternator. The stator resistance between two terminals is 0.02
.
Calculate the regulation at full load current of 350 A at 0.8 pf lagging (by
synchronous impedance method) [6+10]
If 60 80 100 120 140 160 180
EOL-kV 5.3 6.2 6.8 7.2 7.5 7.7 7.9
(where EOL is the line voltage at no load)
4. (a) Why parallel operation of alternators is necessary? What are the advantages
of connecting alternators in parallel?
(b) A 5 MVA, 10kV, 1500 RPM, 3-, 50 Hz alternator is opening on infinite bus
bar. Find synchronizing power per mechanical degree of angular displacement
at: [8+8]
i. No load
ii. Full load at rated voltage & 0.8 power factor lagging. Also find synchro-
nizing torque for a 0.5o mechanical displacement in each case. ×s=20%
5. (a) Justify statement ‘An over excited synchronous motor acts as synchronous
condenser’
1 of 2
Code No: V3111/R07 Set No. 4
(b) A 600 V, 6 pole, 3-, star connected, synchronous motor has a resistance &
reactance of 0.4
/ph & 7
/ph respectively. It takes a current of 15 A at UPF
when operating with a certain field current. With the field current remains
constant, the load torque is increased till the motor draws a current of 50 A.
Find the gross torque developed and the new pf. [8+8]
6. Construct curves showing the relation between armature current v/s field current
& power factor v/s field current for a star connected synchronous motor with a
synchronous reactance of 8.25
/ph and negligible resistance. The machine takes
a constant power input of 800 kWat 6.6 kV. The OC characteristic is as follows: [16]
V (kV) 3 4 5 6 6.6 7 7.5 8
If Amp 16 23 31 41 50 56 69 85
7. (a) Why single phase motors are not self starting?
(b) Explain the necessary arrangements made to make single phase Induction
motor self starting & with neat diagram explain the operations of same. [8+8]
8. (a) Derive torque equation of AC series motor.
(b) Explain the operation of permanent magnet stepper motor. [8+8]
? ? ? ? ?
2 of 2
Code No: V3113/R07 Set No. 1
III B.Tech I Semester Regular Examinations, November 2009
DESIGN OF MACHINE MEMBERS-I
(Mechanical Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. A copper bar 50 mm in diameter is placed with a steel tube 75 mm external diameter
and 50 mm internal diameter of exactly the same length. The two pieces are rigidly
fixed together by two pins 18 mm in diameter, one at each end passing through the
bar and tube. Calculate the stress induced in the copper bar, steel tube and pins
if the temperature of the combination is raised by 50%. Take
Es = 210GN/m2; Ec = 105GN/m2 s = 11.5 × 10−6/oC and c = 17 × 10−6/oC.
[16]
2. A pulley is keyed to a shaft midway between two anti-friction bearings. The bending
moment at the pulley varies from -170N-m to 510N-m and torsional moment in the
shaft varies from 55 N-m to 165 N-m. The frequency of variation of the loads in the
same as shaft speed. The shaft is made cold drawn steel having an ultimate strength
of 540 Mpa and yield strength of 400Mpa. Determine the required diameter for an
infinite life. The stress concentration factor for the keyway in bending and torsion
may be taken as 1.6 and 1.4 respectively. The factor of safety is 1.5. size factor =
0.85 and surface finish factor is 0.85. Assume e = 0.5 2; xy = 0.5y; e = 0.55e.
[16]
3. (a) What is the difference between Caulking and fullering? Explain with the help
of neat sketches.
(b) A double riveted double cover butt joint is made in 12mm thick plates with
18mm diameter rivets. Find the efficiency of the joint for a pitch of 80mm, if
t= 115MPa; = 80MPa; and c= 160Mpa. [6+10]
4. (a) Define the following terms with necessary sketch.
i. Major diameter
ii. Minor diameter
iii. Pitch
iv. Lead.
(b) Derive an expression for the maxim load in a bolt. When a bracket with a
circular base is bolted to a wall by means of four bolts. [8+8]
5. (a) Differentiate between a cotter joint and a knuckle joint.
(b) The cotter joint is commonly used for long pump rods and similar machine
members. Design this joint to support a load varying from 28kN in com-
pression. The material for all the components of the joint is steel with the
allowable stresses in tension, compression and shear as 50N/mm2, 60N/mm2
and 35N/mm2 respectively. [4+12]
1 of 2
Code No: V3113/R07 Set No. 1
6. Compare the weight, strength and stiffness of a hollow shaft of the same external
diameter as that of solid shaft. The inside diameter of the hollow shaft being 0.6
times the external diameter. Both the shafts have same material and length. [16]
7. Design a rigid flange coupling to transmit a torque of 250N-m between two axial
shafts. The shaft is made of alloy steel, flanges out of cast iron and bolts out of
steel. Four bolts are used to couple the flanges. The shafts are keyed to the flange
hub. The permissible stresses are given below:
Shear stress on the shaft=100MPa
Bearing or crushing stress on shaft=250MPa
Bearing stress on keys=250MPa
Shear stress on keys=100MPa
Shearing stress on cast iron=200MPa
Shear stress on bolts=100MPa
After designing the various elements, make a neat sketch of the assembly indicating
the important dimensions. The stresses developed in the various Members may be
checked if thumb rules are used for fixing the dimensions. [16]
8. (a) Under What circumstances, concentric springs are preferred?
(b) A rail carriage weighing 200kN and running at 5 km/hour is brought to rest by
four buffer springs of close coiled helical type during connection with another
carriage which is already at rest. The mean coil diameter is 5 times the wire
diameter. The deflection of each spring is 220mm, to bring the carriage to
rest. Safe shear stress for the spring material is 400N/mm2. Calculate the
maximum load on the spring, diameter of wire and coil, number of turns and
free length of spring. Assume the ends of spring are squared and ground. Take
G= 0.8×104N/mm2. [2+14]
? ? ? ? ?
2 of 2
Code No: V3113/R07 Set No. 2
III B.Tech I Semester Regular Examinations, November 2009
DESIGN OF MACHINE MEMBERS-I
(Mechanical Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) Explain the following methods of reducing stress concentration.
i. Drilled holes
ii. Using large fillet radius.
(b) A hot rolled shaft is subjected to torsional load that varies from 320 Nm clock
wise to 120 Nm anti -clockwise and an applied bending moment at a critical
section varies from 400 Nm to 200 Nm. The shaft is of uniform cross section.
Determine the required shaft diameter. The material has an ultimate strength
of 560 Mpa and yield strength of 420 Mpa. Assume factor of safty to be 2.
[6+10]
2. (a) Illustrate how stress concentration in a component can be reduced.
(b) Determine the size of a piston rod to a total load of having cyclic fluctuations
from 15 kN in compression to 25 kN in tension. The endurance limit is 360
Mpa and yield strength is 400 Mpa. Take impact factor = 1.25, factor of safty
= 1.5, surface finish factor =0.88 and stress concentration factor = 2.25.[8+8]
3. Figure 3 shows a welded joint subjected to an eccentric load of 20 kN. The welding
is only on one side. Determine the uniform size of the weld on the entire length of
two legs. Take permissible shear stress for the weld material as 80 MPa. [16]
Figure 3
4. Determine the size of the bolts and the thickness of the arm for the bracket as
shown in the figure 4, if it carries a load of 40 KN at an anlge of 600 to the vertical.
The material of the bracket and the bolt is same for which the safe stresses can be
assumed as 70,50 and 105 MPa in tension, shear and compression respectively. [16]
1 of 3
Code No: V3113/R07 Set No. 2
Figure 4
5. (a) Design a rectangular sunk key for a shaft of 50mm diameter, transmitting
1200N-m torque. The shear and crushing stresses in the key are limited to 45
and 70MPa respectively.
(b) Make a neat sketch showing two views of a cotter joint and write equations
showing the strength of the joint for the most probable methods of failure.
[8+8]
6. (a) A solid shaft and a hollow shaft are to be equal in torsional strength. The
hollow shaft is to be 10% larger in diameter than the solid shaft. Assuming
that the material of both the shafts to be the same, find the ratio of the weight
of the solid shaft to that of the hollow shaft.
(b) A shaft is supported on two bearings 750mm apart and transmits 15kW at
560 r.p.m. A spur pinion of 150mm diameter is located at 125 mm to the right
of the left bearing and delivers power horizontally to the right. A spur gear of
500mm diameter is located at 150mm to the left of the right bearing and re-
ceives power from below. Determine the shaft diameter, assuming permissible
shear stress for the shaft material as 45MPa. [6+10]
7. Design a bushed -pin type flexible couplings to transmit 25kW at 960rpm.
Use the following stress values:
Shear stress =50MPa(shaft and key)
30MPa(pin)
Crushing stress =90MPa (key)
Bearing pressure=0.45N/mm2(rubber bush). [16]
8. (a) Write short notes on leaf springs
(b) A lift system is provided with cushion springs at the bottom of lift. The lift is
free to fall. Springs are set in parallel. Specify the required number of springs
if the lift has free fall of 1.5m from rest.
Weight of lift = 30kN
2 of 3
Code No: V3113/R07 Set No. 2
Allowable deflection per spring = 370 mm
Number of active turns =15
Spring mean coil diameter =30 mm
Spring wire diameter = 30mm
Modulus of rigidity for spring =80Gpa. [6+10]
? ? ? ? ?
3 of 3
Code No: V3113/R07 Set No. 3
III B.Tech I Semester Regular Examinations, November 2009
DESIGN OF MACHINE MEMBERS-I
(Mechanical Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) Classify the various types Machine Design.
(b) What is the procedure adopted in the design of Machine elements. [6+10]
2. (a) Illustrate how stress concentration in a component can be reduced.
(b) Determine the size of a piston rod to a total load of having cyclic fluctuations
from 15 kN in compression to 25 kN in tension. The endurance limit is 360
Mpa and yield strength is 400 Mpa. Take impact factor = 1.25, factor of safty
= 1.5, surface finish factor =0.88 and stress concentration factor = 2.25.[8+8]
3. Design a longitudinal joint for a 1.25m diameter steam boiler to carry a steam
pressure of 2.5 N/mm2. The ultimate strength of the boiler plate may be assumed
as 420 MPa, crushing strength as 650 MPa and shear strength as 300 Mpa. Take
the joint efficiency as 80%. Sketch the joint with all the dimensions. Adopt the
suitable factor of safty. [16]
4. Determine the size of the bolts and the thickness of the arm for the bracket as
shown in the figure 4, if it carries a load of 40 KN at an anlge of 600 to the vertical.
The material of the bracket and the bolt is same for which the safe stresses can be
assumed as 70,50 and 105 MPa in tension, shear and compression respectively. [16]
Figure 4
5. (a) How is the slipping of the cotter avoided? Explain by two methods.
1 of 2
Code No: V3113/R07 Set No. 3
(b) Design a knuckle joint to transmit 120 kN, with permissible stresses in tension;
shear and compression are 75 Mpa; 60 Mpa and 150 Mpa respectively. [4+12]
6. In axial flow rotary compressor, the shaft is subjected to a maximum twisting
moment of 1500N-m and a maximum bending moment of 3000N-m. Neglecting
the axial load on the shaft, determine the diameter of the shaft, if the allowable
shear stress is 50N/mm2. Assume Kb = 1.5 and Kt = 1.2. If the shaft is to be a
hollow one with di/do=4, what will be the material saving in the hollow shaft. It is
subjected to the same loading and of the same material as the solid shaft. Compare
the torsional stiffness of the two shafts. [16]
7. Design a bushed-pin type flexible coupling for connecting a motor shaft to a pump
shaft, with the following service conditions:
Power to be transmitted=40kW
Speed of the motor shaft=1000rpm
Diameter of motor and pump shafts=45mm
Bearing pressure on the rubber bush=0.7N/mm2
Allowable stress in the pins=60MPa. [16]
8. A diesel engine weighs 800kN and is mounted on 16 springs in order to protect the
building from vibrations. The section of the spring wire is rectangular with side
ratio1.8. One spring has four effective coils and the spring index is 6.
Determine:
(a) Section of the spring so that long side is parallel to the axis of the spring
(b) Deflection under load when engine is stationary
(c) Maximum coil diameter
(d) Shear stress induced if shorter side is parallel to the spring axis. Permissible
shear stress in spring wire material is 300N/mm2 and modulus of rigidity is
0.8×105N/mm2. [16]
? ? ? ? ?
2 of 2
Code No: V3113/R07 Set No. 4
III B.Tech I Semester Regular Examinations, November 2009
DESIGN OF MACHINE MEMBERS-I
(Mechanical Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) Classify the various types Machine Design.
(b) What is the procedure adopted in the design of Machine elements. [6+10]
2. (a) Write Soderberg’s equation and state its application to different type of load-
ings.
(b) Determine the diameter of a circular rod made of ductile material with a
fatigue strength. e=265Mpa and a tensile yield strength of 350 Mpa. The
member is subjected to a varying axial load from Wmin=-300 kN to Wmax=700
kN and has a stress concentration factor=1.8. Use factor of safty as 2.0. [6+10]
3. Design a longitudinal joint for a 1.25m diameter steam boiler to carry a steam
pressure of 2.5 N/mm2. The ultimate strength of the boiler plate may be assumed
as 420 MPa, crushing strength as 650 MPa and shear strength as 300 Mpa. Take
the joint efficiency as 80%. Sketch the joint with all the dimensions. Adopt the
suitable factor of safty. [16]
4. (a) Define the following terms with necessary sketch.
i. Major diameter
ii. Minor diameter
iii. Pitch
iv. Lead.
(b) Derive an expression for the maxim load in a bolt. When a bracket with a
circular base is bolted to a wall by means of four bolts. [8+8]
5. (a) Describe the design procedure of Sleeve & Cotter joint.
(b) Design a cotter joint with two gibs to transmit an axial force of 130 kN. The
permissible stresses are 165 MPa in tension; 100 MPa in shear and 180 M Pa
in crushing. [6+12]
6. The shaft of an axial flow rotary compressor is subjected to maximum torque of
2000N-m and a maximum bending moment of 4000 N-m. The combined shock and
fatigue factor in torsion is 1.5 and that in bending is 2. Design the diameter of the
shaft, if the shear stress in the shaft is 50MPa. Design a hollow shaft for the above
compressor taking the ratio of outer diameter to the inner diameter as 2. What is
the percentage saving in material? Also compare the stiffness. [16]
1 of 2
Code No: V3113/R07 Set No. 4
7. Design and draw protective type of cast iron flange coupling for a steel shaft trans-
mitting 15kW at 200rpm, and having an allowable shear stresses of 40MPa. The
working stress in the bolts should not exceed 30MPa. Assume that the same ma-
terial is used for shaft and key and that the crushing stress is twice the value of its
shear stress. The maximum torque is 25% greater than the full load torque. The
shear stress for cast iron is 14MPa. [16]
8. A semi-elliptical laminated spring is made of no.10.B.W.G. steel 50mm wide. The
length between the supports is 66.25cm and the band is 63 mm wide. The spring
has two full length and five graduated leaves. A central load if 158 kg is carried.
(a) Determine the maximum stress in each set of leaves for an initial condition of
no stress in the leaves.
(b) Draw to half or quarter full size the elevation and plan of the spring
(c) Determine the maximum stress if the initial stress is provided to cause equal
stresses when loaded.
(d) Determine the deflection in parts (a)and (b) respectively. [16]
? ? ? ? ?
2 of 2
Code No: V3121/R07 Set No. 1
III B.Tech I Semester Regular Examinations, November 2009
DIGITAL IC APPLICATIONS
( Common to Electronics & Communication Engineering and Electronics &
Instrumentation Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) Design a CMOS transistor circuit with the functional behavior as
f(x) = (a + b) ( c + d)
Also draw the relevant circuit diagram.
(b) Distinguish between static and dynamic power dissipation of a CMOS circuit.
Derive the expression for dynamic power dissipation. [8+8]
2. (a) Design a TTL three-state NAND gate and explain the operation with the help
of function table.
(b) Compute the maximum fan-out for the following cases.
i. 74LS driving 74F
ii. 74F driving 74AS
iii. 74AS driving 74LS
iv. 74AS driving 74F [8+8]
3. (a) Explain the various data types supported by VHDL. Give the necessary ex-
amples.
(b) Discuss the steps in VHDL design flow. [8+8]
4. Design a logic circuit to detect prime number of a 5-bit input. Write the structural
VHDL program for the same. [16]
5. Design a two-digit BCD adder with logic gates. Using this logic write the VHDL
program. In structural style of modeling. [8+8]
6. Write VHDL program for 8-bit comparator circuit. Using this entity write VHDL
program for 24-bit comparator. Show the additional logic used for this purpose use
structural style or modeling. [16]
7. (a) Define clock skew. Explain how clock skew leads to incorrect outputs in syn-
chronous circuits. Design one logic circuit that minimizes clock skew.
(b) Design an 8-bit universal parallel-in and serial out shift register with a control
input. Shift-left operation with control input 1 and shift-right operation with
control input 0 is to be performed. [8+8]
1 of 2
Code No: V3121/R07 Set No. 1
8. (a) How many ROM bits are required to build a 16-bit adder/subtractor with
mode control, carry input, carry output and two’s complement overflow out-
put? Show the block schematic with all inputs and outputs?
(b) Explain the functional behavior of Static RAM cell. Show the internal struc-
ture of 8x4 static RAM and explain. [8+8]
? ? ? ? ?
2 of 2
Code No: V3121/R07 Set No. 2
III B.Tech I Semester Regular Examinations, November 2009
DIGITAL IC APPLICATIONS
( Common to Electronics & Communication Engineering and Electronics &
Instrumentation Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) Design a 4-input CMOS OR-AND-INVERT gate. Explain the circuit with the
help of logic diagram and function table?
(b) Explain the following terms with reference to CMOS logic.
i. Logic ‘0’ and Logic ‘1’
ii. Noise margin
iii. Power supply rails
iv. Propagation delay [10+6]
2. (a) Mention the DC noise margin levels of ECL 10K family.
(b) A single pull-up resistor to +5V is used to provide a constant-1 logic source
to 15 different 74LS00 inputs. What is the maximum value of this resistor?
How much high state DC noise margin can be provided in this case? [6+10]
3. (a) Write a VHDL Entity and Architecture for a 3-bit synchronous counter using
Flip-Flops.
(b) Explain the use of Packages. Give the syntax and structure of a package in
VHDL. [8+8]
4. (a) Design a logic circuit to detect prime number of a 4-bit input? Write the
VHDL program for the above design?
(b) Design the logic circuit and write a data-flow style VHDL program for the
following function? [8+8]
F(P) = A,B,C,D (1, 5, 6, 7, 9, 13) + d (4, 15)
5. Design a two-digit BCD adder with logic gates. Using this logic write the VHDL
program. In structural style of modeling. [8+8]
6. (a) Write a behavioral VHDL program to compare 16-bit signed and unsigned
integers.
(b) Design a priority encoder with 8 inputs? Write a VHDL program for the same
in structural style. [8+8]
7. Show the logic diagram of 74×175 IC and write VHDL program for this IC in data
flow style. Using this entity develop the program for 16-bit register and show the
corresponding circuit also explain how the register is cleared? [16]
1 of 2
Code No: V3121/R07 Set No. 2
8. (a) Explain how a 4×4 binary multiplier can be designed using 256×8 ROM.
(b) How many ROM bits are required to build a 16-bit adder/subtractor with
mode control, carry input, carry output and two’s complement overflow out-
put? Show the block schematic with all inputs and outputs. [8+8]
? ? ? ? ?
2 of 2
Code No: V3121/R07 Set No. 3
III B.Tech I Semester Regular Examinations, November 2009
DIGITAL IC APPLICATIONS
( Common to Electronics & Communication Engineering and Electronics &
Instrumentation Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) Draw the logic diagram equivalent to the internal structure of CMOS 4-input
NAND gate. Explain the operation with the help of function table.
(b) Compare HC, HCT, VHC and VHCT CMOS logic families with the help of
input specifications and with VCC from 4.5V to 5.5V. [8+8]
2. (a) Draw the circuit diagram of basic CMOS gate and explain the operation.
(b) List out different categories of characteristics in a TTL data sheet. Discuss
electrical and switching characteristics of 74LS00. [8+8]
3. (a) Write a VHDL Entity and Architecture for the following function?
F(x) = a  b  c
Also draw the relevant logic diagram.
(b) Explain the use of Packages Give the syntax and structure of a package in
VHDL [8+8]
4. (a) Explain data-flow design elements of VHDL.
(b) Design the logic circuit and write a data-flow style VHDL program for the
following function. [8+8]
F (X) = A,B,C,D (1, 4, 5, 7, 12, 14, 15) + d (3, 11)
5. A mechanical disk rotates in a circle in different positions. Two successive positions
differ with an angle of 15o . Provide an encoding mechanism for every position of
the disk. The disk in the mechanical system outputs this encoded information to
detect the exact position. Design a decoder with an enable input to identify the
position of the disk. [16]
6. Design an 8×8 combinational multiplier. Determine the worst case propagation
delay. Write a VHDL data flow program for the same. [16]
7. (a) Design a switch debouncer circuit using 74×109 IC. Explain the operation
using timing diagram.
(b) Discuss the logic circuit of 74×377 register. Write a VHDL program for the
same in structural style. [8+8]
1 of 2
Code No: V3121/R07 Set No. 3
8. (a) How many ROM bits are required to build a 16-bit adder/subtractor with
mode control, carry input, carry output and two?s complement overflow out-
put? Show the block schematic with all inputs and outputs?
(b) Design an 8×4 diode ROM using 74×138 for the following data starting from
the first location. [8+8]
B, 2, 4, F, A,D, F,E
? ? ? ? ?
2 of 2
Code No: V3121/R07 Set No. 4
III B.Tech I Semester Regular Examinations, November 2009
DIGITAL IC APPLICATIONS
( Common to Electronics & Communication Engineering and Electronics &
Instrumentation Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
? ? ? ? ?
1. (a) Explain how to estimate sinking current for low output and sourcing current
for high output of CMOS gate.
(b) Analyze the fall time of CMOS inverter output with RL = 100
, VL = 2.5V and CL =
10PF. Assume VL as stable state voltage. [8+8]
2. (a) Mention the DC noise margin levels of ECL 10K family.
(b) A single pull-up resistor to +5V is used to provide a constant-1 logic source
to 15 different 74LS00 inputs. What is the maximum value of this resistor?
How much high state DC noise margin can be provided in this case? [6+10]
3. (a) Write a VHDL Entity and Architecture for a 3-bit synchronous counter using
Flip-Flops.
(b) Explain the use of Packages. Give the syntax and structure of a package in
VHDL. [8+8]
4. (a) What is the importance of time dimension in VHDL and explain its function.
(b) Design the logic circuit and write a data-flow style VHDL program for the
following function. [8+8]
F(X) = A,B,C,D (0, 1, 3, 5, 14) + d (8, 15)
5. (a) Design a 32 to 1 multiplexer using four 74×151 multiplexers and 74X139
decoder.
(b) Realize the following expression using 74×151 IC [8+8]
f(Y ) = AB + BC + AC
6. A simple floating-point encoder converts 16-bit fixed-point data using four high
order bits beginning with MSB. Design the logic circuit and write VHDL data-flow
program. [16]
7. (a) What is the difference between ring counter and Johnson ring counter? Design
a self-correcting 4-bit, 4-state ring counter with a single circulating 0 using
74×194.
(b) Explain how serial data communication is possible using 74×166 as transmitter
and 74×164 as receiver. [8+8]
1 of 2
Code No: V3121/R07 Set No. 4
8. (a) Determine the ROM size needed to realize the logic function performed by
74×153 and 74×139.
(b) Design an 8×8 diode ROM using 74×138 for the following data starting from
the first location. [8+8]
AB, 52, 74, 0F,CA, 9D, 2F,E6
? ? ? ? ?
2 of 2
Code No: V3128 / R07
III B. Tech I Semester Regular Examinations, November 2009
MICROPROCESSORS & INTERFACING
(Common to CSE, IT, ECC & ICE)
Time: 3 Hours Max. Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
*****
1. (a) With a neat diagram explain the architecture of an 8086 microprocessor.
(b) Differentiate between procedures and macros with certain examples.
[10+6]
2. (a) Write an assembly language program in 8086 to add two 16-bit packed BCD
numbers.
(b) Write an assembly language program in 8086 to sort the array of 10 numbers in
ascending order. [8+8]
3. Explain the minimum mode and maximum modes of operation of 8086 with
corresponding timing diagrams. [16]
4. (a) Distinguish between Mode set control word and BSR control word of 8255.
(b) Write an assembly language program in 8086 to generate a symmetrical square
wave with 1KHz frequency? Give the necessary circuit set up with a DAC. [6+10]
5. (a) Discuss in detail about the interrupt structure of 8086.
(b) Describe about the interrupt vector table of Intel processors. [8+8]
6. (a) Discuss the types of serial communication.
(b) Write an 8086 instruction sequence for receiving 50 characters using 8251
USART and store them in the memory. [8+8]
7. (a) What is meant by paging? Explain its advantages and disadvantages.
(b) Explain the procedure of converting linear address into physical address.
[8+8]
8. (a) Discuss various addressing modes of 8051.
(b) Explain in detail about serial port operation in 8051 microcontroller. [8+8]
@@@
Set.No.1
Code No: V3128 / R07
III B. Tech I Semester Regular Examinations, November 2009
MICROPROCESSORS & INTERFACING
(Common to CSE, IT, ECC & ICE)
Time: 3 Hours Max. Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
*****
1. (a) Compare the flag registers of 8085 and 8086.
(b) Explain the different addressing modes of 8086 microprocessor with examples.
[8+8]
2. (a) Write an assembly language program in 8086 to find the maximum in the array of
10 numbers.
(b) Write an assembly language program in 8086 to find the factorial of the given
number. [8+8]
3. (a) Explain the interfacing of static RAMs to 8086 with neat interface diagram.
(b) Explain the need of DMA. Discuss in detail about the DMA data transfer scheme.
[8+8]
4. (a) Explain the modes of operation of 8255 PPI.
(b) Explain about interfacing of a DAC with 8086 using 8255? [8+8]
5. (a) Differentiate between Initialization Command Words and Operation Command
words of 8259.
(b) Discuss about the interrupt priority schemes used in 8259. [10+6]
6. (a) Discuss the serial data transmission standards and their specifications.
(b) Draw and explain the block diagram of 8251. [6+10]
7. (a) Explain the real mode and protected mode operations of 80386 microprocessor.
(b) Compare RISC and CISC processors. [10+6]
8. (a) Draw the architectural diagram of 8051 microcontroller and explain in detail
about each block.
(b) Explain the basic differences between a microprocessor and a microcontroller
[12+4]
@@@
Set. No. 2
Code No: V3128 / R07
III B. Tech I Semester Regular Examinations, November 2009
MICROPROCESSORS & INTERFACING
(Common to CSE, IT, ECC & ICE)
Time: 3 Hours Max. Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
*****
1. (a) Explain the physical address calculation in 8086 microprocessor.
(b) What are the various addressing modes available in 8086 microprocessor and
explain them with examples. [6+10]
2. (a) Write an assembly language program in 8086 to find the sum of first N natural
numbers.
(b) Write an assembly language program in 8086 to display the string “JNTU
KAKINADA” on the screen. [8+8]
3. (a) Explain the maximum mode operation of 8086 microprocessor with
corresponding timing diagrams.
(b) What is DMA? Explain the need for DMA in Microprocessor based systems.
[8+8]
4. (a) Distinguish between Mode set control word and BSR control word of 8255?
(b) Write an ALP in 8086 to generate a symmetrical square wave form with 1 KHz
frequency? Give the necessary circuit setup with a DAC? [8+8]
5. (a) What is the difference between maskable and non-maskable interrupts? Give some
examples?
(b) Discuss about the following control word formats of 8259:
i. Initialization Command Words (ICWs).
ii. Operational Command Words (OCWs) [6+10]
6. (a) Discuss the asynchronous and synchronous data transfer schemes.
(b) Explain the interfacing of 8251 with 8086 with necessary circuit diagram.
[8+8]
7. (a) Explain the architecture of the Pentium processor.
(b) Differentiate RISC and CISC processors. [8+8]
8. (a) Draw the block diagram of 8051 microcontroller and explain its salient features.
(b) Explain the interrupt structure of the 8051 microcontroller. [10+6]
@@@
Set. No. 3
Code No: V3128 / R07
III B. Tech I Semester Regular Examinations, November 2009
MICROPROCESSORS & INTERFACING
(Common to CSE, IT, ECC & ICE)
Time: 3 Hours Max. Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
*****
1. (a) Explain different general purpose registers available in 8086 microprocessor.
(b) Explain different data definition assembler directives in 8086. [8+8]
2. (a) Write an assembly language program in 8086 to sort the given array of numbers in
descending order using bubble sort.
(b) Write an assembly language program in 8086 to display the string “JNTU
KAKINADA” on the screen. [8+8]
3. (a) With a neat block diagram, explain the working of 8257 DMA controller.
(b) Explain the need of DMA. Discuss in detail about DMA data transfer method.
[8+8]
4. (a) Explain the interfacing of stepper motor with 8255.
(b) Write an assembly language program to rotate 200 teeth, 4 pole stepper motor
(i). in clockwise 5 rotations and
(ii). in anticlockwise 5 rotations. [6+10]
5. (a) Describe some important features of 8259 interrupt controller.
(b) Distinguish between Master and Slave mode operation of 8259. [8+8]
6. (a) Discuss the types of serial communication.
(b) With a neat circuit diagram, explain the interfacing of 8251 with 8086.
[6+10]
7. (a) List and explain the new Pentium instructions.
(b) Explain the memory system of the Pentium processor. [8+8]
8. (a) Differentiate microprocessors and microcontrollers.
(b) Explain different addressing modes of 8051 microcontroller with suitable
examples. [6+10]
@@@
Set. No. 4

LDSA

Code No: R05310205 Set No. 1
III B.Tech I Semester Regular Examinations, November 2008
LINEAR AND DISCRETE SYSTEMS ANALYSIS
(Electrical & Electronic Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Obtain the state variable model for a system described by the following dif-
ferential equation.
10d3y
dt3 + 5d2y
dt2 + 2dy
dt + 3y = 20dx
dt + 10x
(b) Determine the state transition matrix for the state matrix.
A =


−1 1 0
0 −1 1
0 0 −2

 [8+8]
2. The input to the circuit of figure 2(a) is a rectified sine wave as shown in figure
2(b).
Determine the current following through 1 ohm resistor. ω = 1 rad/sec. Draw the
magnitude spectrum and find out the nth harmonic of i(θ). [8+4+4]
(a) & (b) Figure 2
3. (a) Show that a periodic signal can be expressed as continuous sum of everlasting
exponentials.
(b) Find the F.T. of
i. δ(t − t0)
ii. rect t/τ. [8+8]
4. (a) Explain the graphical interpretation of convolution with the following func-
tions. As shown in figure 4a.
1 of 2
Code No: R05310205 Set No. 1
Figure 4a
(b) A voltage
−t
e u(t) is applied to a series RC network as shown in figure 4b.
Figure 4b
Find the voltage V0(t) using frequency domain analysis.
5. (a) State and explain the properties of positive real function.
(b) Check whether given polynomial H(s) = 2s4 +5s3 +6s2 +2s +1 is Hurwitz
or not. [8+8]
6. Find the networks for the following functions in one Foster and one Cauer form
(a) Y (s) = (s+1)(s+3)
(s+4)(s+2)
(b) Z(s) = 2(s+0.5)(s+4)
s(s+2) . [2 × 8]
7. (a) The signals m1(t) = 10cos100πt and m2(t) = 10cos50πt are both sampled
with fs = 75 Hz. Show that the two sequences of samples so obtained are
identical.
(b) The signal g(t) = cos10 πt+0.5cos 20 πt is sampled with the interval between
samples is Ts. Find the maximum allowable time for Ts.
(c) Determine the sampling rate for the band pass signal whose centre frequency
fc is 5 fm with a signal band width of 2fm. [5+5+6]
8. How many different sequences have a Z-transform given by
H(z) = 1−2z−1+3z−2
(1−
1
8 z−1+1
4 z−2)(1+1
3 z−1) . [16]
⋆ ⋆ ⋆ ⋆ ⋆
2 of 2
Code No: R05310205 Set No. 2
III B.Tech I Semester Regular Examinations, November 2008
LINEAR AND DISCRETE SYSTEMS ANALYSIS
(Electrical & Electronic Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Develop the state variable model equation for the circuit as shown in figure
1a.
Figure 1a
(b) A system matrix is given by
A =  −1/2
−5/2
1/2
−7/5 
obtain the state transition matrix. [8+8]
2. A rectangular waveform of magnitude 10V,duty ratio 75% and frequency 50Hz
is applied across a resistance of 1ohm in series with an inductance of 100mH.
Determine the steady state current in the circuit. Also find the power and P.F of
the load current. [8+4+4]
3. (a) Use the duality property of F.T, find the transform of
g(t) = A
1+(at)2
(b) Using the superposition and time shifting properties, Find the F.T. of the
signals shown in figure 3b. Sketch the amplitude spectrum assuming τ<< To.
[8+8]
Figure 3b
4. (a) Find the LT of the following functions.
1 of 3
Code No: R05310205 Set No. 2
i. f(t) = Kt K is a real constant >1
ii. f(t) = tδ′(t)
(b) The impulse response of a certain linear system is given by
h(t) =
−2t
e u(t) t  0
= 0 t < 0
using the convolution integral, determining the response y(t) due to the ramp
input
x(t) = 0 t < 0
= t t  0. [8+8]
5. (a) List the properties of positive real function.
(b) A function is given by N(s) = s3+5s2+9s+3
s3+4s2+7s+9 .
Determine the positive realness of the function. [8+8]
6. (a) Given the driving-point impedance function
Z(s) = s(s2+2)
(s2+1)(s2+4)
Synthesize a ladder network of the first Cauer form for this impedance func-
tion.
(b) A network is made up of a series connection of an RL network and RC network.
Assuming that neither of the networks is a short circuit find the location of
poles and also the location of zeros. What is the behavior at the origin and
at infinity? [8+8]
7. Find the mean square value of the output voltage vo(t) of an RC network shown
in figure 7 if the input voltage has a power density spectrum Si(ω) given by
(a) Si (ω)= k
(b) Si (ω)= G2(ω) [gate function with cutoff at ω=1]
(c) Si (ω)= π [δ(ω + 1)+δ(ω − 1)]
In each case, also calculate the power of the input signal. [16]
Figure 7
8. For a causal discrete-time LTI system, if the input x(n) is
x(n) = 1/2n
u(n) − 1/4 1/2n−1
u(n − 1)
Then the output is y(n) = 1/3n
u(n)
(a) Determine the impulse response h(n) and the system function H(z)
2 of 3
Code No: R05310205 Set No. 2
(b) Find the difference equation that characterizes this system. [2 × 8]
⋆ ⋆ ⋆ ⋆ ⋆
3 of 3
Code No: R05310205 Set No. 3
III B.Tech I Semester Regular Examinations, November 2008
LINEAR AND DISCRETE SYSTEMS ANALYSIS
(Electrical & Electronic Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Show that the inductor current iL(t) in the circuit as shown in figure 1a is
given by
iL (t) = −3
1 − 20t/3 −
−20t/3
e 
 u(t).
Figure 1a
(b) A dynamical system is described ... by the differential equation
y + 4y¨+ 5y˙ + 2y = u
show that the state variable formulation is

x˙ 1
x˙ 3
x˙ 2

= 

0 1 0
0 0 1
−2 −5 −4
 x1
x2
x3

+ 

0
0
1

u [8+8]
2. (a) Derive an expression for the effective value of non-sinusoidal periodic waveform.
(b) A periodic current source given by i(t) = 5+3 cos (100t + 45◦)+2 cos (200t − 10◦)
is applied to a parallel RL circuit as shown in figure 2b. Calculate the response
V(t) and average power. [8+8]
Figure 2b
1 of 3
Code No: R05310205 Set No. 3
3. (a) Determine the F.T. of a trapzoidal function and triangular RF pulse f(t) shown
in figure 3(a)i and figure 3(a)ii. Draw its spectrum.
i. Figure 3(a)i
Figure 3(a)i
ii. figure 3(a)ii
Figure 3(a)ii
(b) Show that a normalized Gaussian pulse is its own fourier transform. [8+8]
4. (a) Find the convolution for the signals.
i. x(t) =  1 0 < t < T
0 otherwise
ii. h(t) =  t 0 < t < 2T
0 otherwise
(b) Given LT, how do you obtain its F.T. [8+8]
5. Given z(s) = (s2+Xs)
s2+5s+4
(a) What are the conditions on ‘X’ for Z(s) to be a positive real function?
(b) Find ‘X’ for Re (Z (jω)) to have a second order zero at ω = 0. [8+8]
6. (a) Given the driving point admittance function Y (s) = s(s2+1)(s2+4)
s(s2+2) . Synthesize
ladder network of the first Cauer form.
(b) State and explain Foster’s reactance theorem for LC networks. [8+8]
7. (a) How does flat top sampling differ from impulse sampling? Discuss the merits
and drawbacks of both types of sampling.
(b) Show that the continuous time signal xa(t) = A cos (ωot+φ) can be uniquely
recovered from its sampled version x[n]=xa(nT) if the sampling frequency is
ωs = 2 π/T > 2wo. [8+8]
2 of 3
Code No: R05310205 Set No. 3
8. The output y(n) of a discrete-time LTI system is found to be 2(1/3)nu(n) when the
input x(n) is u(n)
(a) Find the impulse response h(n) of the system.
(b) Find the output y(n) when the input x(n) is 􀀀1
2
n
u(n). [8+8]
⋆ ⋆ ⋆ ⋆ ⋆
3 of 3
Code No: R05310205 Set No. 4
III B.Tech I Semester Regular Examinations, November 2008
LINEAR AND DISCRETE SYSTEMS ANALYSIS
(Electrical & Electronic Engineering)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆
1. (a) Write the state equation for the circuit as shown in figure 1a.
Figure 1a
(b) Find the state response of the system shown in figure 1b.
 x˙ 1
x˙ 2  =  0 1
−1 0  x1
x2  +  0
1 
 x1(0)
x2(0)  =  0
0 
[8+8]
Figure 1b
2. Find the trigonometric form of the following voltage waveform shown figure 2 and
hence compute average power and power factor of the load if voltage is applied to
series RL circuit with R = 1
, L = 1H. [8+4+4]
1 of 3
Code No: R05310205 Set No. 4
Figure 2
3. (a) State and prove the time scaling property of F.T.
(b) Find the fourier transform of the pulse functions shown in figure 3b.
Figure 3b
4. (a) Evaluate the following convolution integrals.
i. u(t) 
−t
e u(t)
ii. u(t)  tu(t)
(b) Find the Inverse LT of the following function
F(s) = S+4
2S2+5S+3 . [8+8]
5. (a) Explain Sturm’s theorem.
(b) Test whether the following function is a positive real function and the poly-
nomials are Hurwitz or not using Sturm’s test.
F(s) = 2s4+7s3+11s2+12s+4
s4+5s3+9s2+11s+6 . [8+8]
6. Indicate which of the following functions are either RC, RL, or LC impedance
functions. Give reasons.
(a) Z(s) = (s+1) (s+3)
s(s+4)
(b) Z(s) = (s+3) (s+7)
(s+2) (s+5)
(c) Z(s) = s2+4s+3
s2+6s+8
(d) Z(s) = s2+5s+6
s2+s . [4 × 4]
2 of 3
Code No: R05310205 Set No. 4
7. For a low pass signal with a bandwidth of 6000Hz, what is the minimum sampling
frequency for perfect reconstruction of the signal? What is the minimum required
sampling frequency if a guard band of 200Hz is required? What is the minimum
required sampling frequency and the value of ‘K’ for perfect reconstruction if the
reconstruction filter has the following frequency response
H(f) =

K, |f| < 7000
K − K(|f| − 7000)/3000, 7000 < |f| < 10000
0, otherwise
. [16]
8. Using the relation anu(n) $ z
z−a , |z| > |a|. Find the Z-transform of the following:
(a) x1(n) = nan−1u[n]
(b) x2(n) = n(n − 1)an−2u[n]
(c) x3(n) = n(n − 1)......(n − k + 1)an−ku[n]. [5+5+6]
⋆ ⋆ ⋆ ⋆ ⋆
3 of 3