Thursday 25 April 2013

R&D SUMMER TRAINING PROGRAM


Hai All,

                  Please find the circular related to
 Summer Training program by R&D Department. For Further details Contact Kishore Sir...


CIRCULAR
All the 2nd Year ECE Students are here by informed that our R&D cell is conducting summer training programs (Hands-on –practice cum certification) in the month of JUNE 2K13 commencing from 01-JUNE-2K13. There is no registration fee. The training program details are as listed below.

1.      PSPICE

2.      EMBEDDED SYSTEMS: MPLAB IDE, KEIL, ECLIPSE, AVR STUDIO by using Atmega, PIC Microcontrollers (on AURUM BOARDS, RTOS BOARDS), and Demonstration of GPS, Zigbee, GSM  based Projects , Wireless controlled(PC< DTMF Robos) etc….

3.      VHDL,VERILOG: using MODELSIM, XILINX (on FPGA,HELIUM BOARDS)

4.      MATLAB: Image Processing, Statistical detection , Signal processing

5.      PCB DESIGN: Orcad for 2-layer PCB

A copy of program details is available in R&D cell notice board. All the  interested candidates can enroll their names with the R&D cell.



D.Kishore                                                                                                                          Principal
R&D member.

Copy to
Academic Director
ECE-HOD
NOTICE BOARD



Tuesday 23 April 2013

Few Transformers viva questions

Hi all,
           
                Please find  few viva questions from transformers.

1.     Define Transformer(T/F)

2. What happens if DC supply is given to transformer?


3. a) On which principle T/F Works.   b) What  is isolation T/F and what is its uses.

4. Why T/F is called constant flux device.
5.     Why T/F is called static piece of device.
6.     Why T/F is called constant power device.
7.     Why T/F is called constant frequency device.
8.     What is ideal and practical T/Fs?
9.     Define primary winding, secondary winding.
10.                        Define LV (Low Voltage) Wdg, HV Wdg.
11.                        What is the Relation between Emf/Turn in primary Wdg, Secondary Wdg?
12.                        Why primary Wdg, Secondary Wdg are interleaved (placed on same leg).
13.                        Why always LV Wdg is placed near by the core.
14.                        What is demagnetizing turns in T/F.
15.                        Define MMF
16.                        What are different types if loads
17.                        Define power factor.
18.                        Define active power, reactive power
19.                        How variation in load is connected to variation of power factor.
20.                        What is the use of Iw, Im,
21.                        What Ro, Xo represents.
22.                         What is turns ratio? Write the value if K for step up, step down isolation T/Fs.
23.                        What is maximum efficiency condition in T/F.
24.                        Where hysteresis loss, eddy current loss occurs in T/F, WHY  they occur, how to minimize them..
25.                        Why Iron losses are called constant loss.
26.                        Why copper losses are called variable losses.
27.                        Why transformer is rated in KVA instead of KW.
28.                        A) Why we need to increase the voltage level
              B) Why need to decrease the voltage level.
29.                        In OC test on T/F what happens if input  supply is given HV Wdg and LV in open circuited.
b) In SC test on T/F what happens if supply is given to LV Wdg and HV winding is  short circuited.
30.  A) How to identify MI, MC instruments
    B) Differentiate MI, MC instruments.
31.   What is LPF wattmeter and UPF watt meter?
32.     (a)What OC test on Transformer gives?
(b) What SC test on transformer gives?
  33.(a) Watt meter reading in OC test Represents ___________
      (b) Watt meter reading in SC test represents____________
34. Define voltage regulation in transformer
35. When can voltage regulation of transformer becomes zero?
36. Type of EMF induced in transformer________
37.what are differences between core type T/f and shell T/f
38.What are power transformers and distribution transformers





Tuesday 16 April 2013

All The Best

Hai  All,

                     I hope all are preparing well for  PEE Second mid.Put your 100% efforts today .this preparation would help you during lab external exam.


Sunday 14 April 2013

PDC BITS




                                                           PDC

                                                                       JNTUH BITS

SECTION-I:   Multiple choice questions

NOTE: Don't think that these bits will be repeated in second mid.Prepare last 4 units concepts well then solve these bits .these bits to cross check your knowledge in subject

1. Bootstrap’s sweep circuit produces _____ type of waveform. [ a]
(a) positive going Ramp (b) negative going Ramp (c) either a or b (d) Both a and b
2. The gate signal is also called as ___________. [c ]
(a) enabling pulse (b) control pulse (c) both a and b (d) either a or b
3. Sampling gates are used in _______. [d]
(a)Multiplexers (b) D to A converters (c) Sample and Hold circuits (d) All the above
4. The variations in phase delay occur due to ____. [c ]
(a) variations in loop gain (b) variations in supply voltage (c) both a and b (d) None
5. Among the logic families, low power dissipation is in _____. [ b]
(a)DTL (b) CMOS (c) TTL (d) ECL
6. Synchronization is said to be with frequency division, if the generators operate at___ [b ]
(a) same frequency (b) different frequency (c) both a and b (d) None
7. Synchronization with symmetrical signals is possible if_______. [c ]
(a) Tp <= T0 (b) Tp >= T0 (c) both a and b (d) either a or b
8. Which of the following logic family has highest fan-out. [ d]
(a) ECL (b) TTL (c) DTL (d) CMOS
9. Among the logic families, Slowest logic family is_____. [c ]
(a)TTL (b)DTL (c)CMOS (d)ECL
10. In Miller circuit, the gain A of the inverting amplifier should be ____. [c ]
(a) unity (b) zero (c) infinite (d) None of the above
11. The time during which the waveform returns to the initial value is called: [b ]
(a)  fall time (b) flyback time (c) rise time (d) delay time

12. The circuit which require an amplifier whose gain is nearly infinity [ b]
a) Boot strap ckt b) Miller ckt c) Phantastron ckt d) Inductor ckt

13. When generators with equal frequencies run in synchronism, the synchronization is said to be on a [ a]
a)     one-to-one basis b) one-to-two basis c) two-to-one basis d) one-to-four basis

14. A Transmission circuit which allows an input Signal to pass through it during a selected interval and blocks it passage outside this time interval is called: [ a]
a) sampling gates b) conventional gates c) non-conventional gates d) logic gates

15. In unidirectional sampling gate the combination of RC forms a [ b]
a)Differentiator b) Integrator c) Coupling elements d) Multivibrator

16. The ratio of maximum deviation to the sweep amplitude is called [ b]
a) Slope error (b) displacement error (c) Transmission error (d) Linear error


17. A capacitor is charged linearly from a constant current source is used to generate [c ]
a)sine wave form (b) pulse wave form (c) time base waveform (d) trapezoidal wave form

18. The several factors which affect phase delay given rise to [ a]
a) Phase jitter b)amplitude jitter c)both amplitude and phase jitter d)frequency jitter

19. The interval of time is selected by means of an externally applied signal termed as:
 [b ]
a) Transient signal b) gating signal c) output signal d)exponential signal

20. Logic gates are the basic elements that make a [ d]
a) analog system b) gating system c) basic system d)digital system


 21.The relation between the slope error, displacement error and transmission error is

22. To get a saw-tooth out put waveform, the restoration time is [ a]
( a ) zero ( b ) rise time ( c ) storage time ( d ) infinity


23. In Miller time base generator, which of the following is used [b ]
(a) an inverting amplifier with a gain of unity (b) an inverting amplifier with a gain of infinity (c) non-inverting amplifier with a gain of unity (d) non-inverting amplifier with a gain of infinity

24. Synchronization with symmetrical signals is possible for [ d]
( a ) Tp = To only ( b ) Tp<To only ( c ) Tp >To only ( d ) both Tp<To and Tp> To

25. The time during which the output increases linearly is called [ a]
( a ) sweep time ( b ) flyback time ( c ) return time ( d ) restoration time

26. The interval of time of transmission of a signal in a sampling gate is selected by means of [ c]
( a ) time delay ( b ) off time of gate ( c ) gating signal ( d ) source signal

27. The following all are disadvantages of unidirectional gate, except [d ]
( a ) interaction between the signal source and control voltage source ( b ) limited used of gate ( c ) slow rise of the control voltage ( d ) little time delay though the gate

28. Which of the following logic gives the complementary outputs? [ d]
( a ) DTL ( b ) RTL ( c ) TTL ( d ) ECL

29. The voltage at the input of a gate which causes a change in the state of the ouput from one logic level to the other is [c ]
( a ) cut-in voltage ( b ) cut-off voltage ( c ) threshold voltage ( d ) peak voltage

30. The high state fan out of a gate is defined at when the [ c]
( a ) input is at logic ‘0’ ( b ) input is at logic ‘1’
( c ) output is at logic ‘1’ ( d ) output is at logic ‘0’

SECTION-II:   Fill in the blanks

1. The ratio of the difference between the input and the output to the input at the end of the sweep time is called  Transmission error

 2. The output of the time base generator is called  Sweep Voltage

3. The gain of a sampling gate is defined as  The ratio of the output voltage to the input voltage during transmission

4.  Ideal sampling gate  is a transmission circuit in which the output is an exact replica of input waveform during a selected time interval and is zero otherwise.

5. The periodic variations in the phase delay are called Phase jitter
6. The range of synchronization increases with increasing  sync signal amplitude

7. The relation between slope error and transmission error is   es=2et

8. Typical noise margin for DTL family is 700mv

9. CML is also called as ECL
10. In a 4-diode sampling gate, minimum value of Vc is given by  Vcmin=Vs [2+Rc / RL]


11.The maximum number of gates that can be driven by any logic gate is called  Fan out

12) If synchronization is achieved with different frequencies, i.e one frequency being n times the other, then it is termed  synchronization with frequency division

13) Two or more generators are said to be running synchronously  if all of them arrive at some point in the cycle at exactly the same instant of time.

14) Sampling gates are used in chopper amplifiers

15) In positive logic system, the higher of the two voltage levels represent logic 1 and lower logic is 0

16) A voltage time base generator is one that provides an output voltage waveform a portion of which exhibits a linear portion with time

17) The ratio of the difference in slope at beginning and end of the sweep to initial value of slope is called  slope error or sweep speed error

18) Sampling gates are classified into two types

19) Chopper often called as modulator

20) A positive logic NOR gate is equivalent to negative logic NAND gate


21).The time required by the sweep voltage to return to the initial value is called

 restoration time, return time or flyback time  

22. Compensating networks used to improve the  linearity of bootstrap circuit

23. The output of a time-base generator is called sweep voltage

24. The range of synchronization decreases with decreasing of sync signal amplitude

25. When generator with equal frequencies run in synchronism, the synchronization is said to be on a one to one basis

26. Bidirectional sampling gates transmit signals in both the polarities

27. The sampling gate is used in sampling scope because the display consists of samples of input waveform

28. The power required by the gate to operated with 50% duty cycle at a specified frequency is called power dissipation

29. High state nose margin of a gate is defined as VOH(min)-VIH(min)

30. The basic TTL gate is NAND gate


                                                                                                  Prepared By
                                                                                                 G.Swathi& Ravali




Saturday 13 April 2013

EMTL BITS





                                                                           EMTL
    
                                                                   JNTUH BITS

                                           SECTION-I:   Multiple choice questions

Note:Don't think that these bots only will be repeated in mid exam.First through the last 4 units concepts well then solve the bits.These bits to cross check your knowledge

 1. For normal incidence of the wave on perfect conductor       [ b]
a) Surface current doesn’t exist b) surface exists  
c) conducting current exiasts d) free charge exists on the surface

2. A standing wave [ d]
a) Progresses with less than light velocity b) progresses with more than light velocity
c) progresses with equal to light velocity d) does not progress.

3. The range of reflection coefficient is [ c]
a) 0 to 1 b) 0 to infinity c) -1 to 1 d) 1 to infinity

4. Electric and magnetic fields which are parallel [d ]
a)Constitute power flow b) constitute infinite power flow
c)constitute unit magnitude power flow d) no power flow.

5. The propagation velocity of TE waves [ a]
a)Depends on frequency b) independent of frequency
c) depends on square of frequency d) varies inversely with frequency.

6. As per the boundary condition, [b ]
a)The normal component of E is continuous across the boundary.
b)The tangential component of E is continuous across the boundary.
c)The tangential component of D is continuous across the boundary.
d)The normal component of H is continuous across the boundary

7. The magnetic field at the surface of a good conductor is 2A/m. The frequency of the field is 600 MHz. The surface r.m.s current density is [c ]
a)0.5 A/m b)0.5 A/m2 c)2 A/m d)2 A/m2

8. If the reflection coefficient is -1/2 then the swr is [ d]
a)Zero b) one c)1/3 d) 3


9. The wave impedance over the cross section of wave guide [d ]
a) Increases with frequency b) decreases with frequency
c) increases exponentially d) constant

10. Hysteresis and eddy current losses in loading coils leads to [c ]
a) Increase in L b) Decrease in L c) Increase in R d) decrease in R



1 1) Which of these is not a correct form of the wave Ex = cos(ωt —βz)? [b ]
(a) Ex = cos(βz-ωt) (b) Ex = cos(ωt —βz-Π/2) (c) Ex = Re[ej(ωt —βz)] (d) Ex = cos(2Πt/T-2Πz/λ)

12) What is the major factor for determining whether a medium is free space, lossless dielectric, lossy dielectric, or good conductor? [ c]
(a) Attenuation constant (b) Constitutive parameters (σ,μ,ε)
(c) Loss tangent (d) Reflection coefficient

13) In a certain medium, E = 10 cos (108t — 3y) ax V/m. What type of medium is it? [ c]
(a) Free space (b) Perfect dielectric (c) Lossless dielectric (d) Perfect conductor

14) For any dielectric material ( σ/ωε) value is [a ]
a)<<1 b)>>1 c)=1 d)zero

15) Given that H = 0.5 e-0.1xsin (106t- 2x) ay A/m, which of these statements are incorrect? [ b]
(a) α = 0.1 Np/m (b)β = - 2 rad/m
(c) ω= 106rad/s (d) The wave is polarized in the z-direction.

16) Which of the following statements is not true of waves in general? [ a]
(a) It may be a function of time only. (b) It may be sinusoidal or cosinusoidal.
(c) It must be a function of time and space. (d) For practical reasons, it must be finite in extent.

17) For a lossy transmission line, the characteristic impedance does not depend on [ b]
(a) The operating frequency of the line (b) The length of the line
(c) The load terminating the line (d) The conductivity of the conductors

18) Which of the following statements are not true of the line parameters R, L, G, and C? [c ]
(a) R and L are series elements. (b) G and C are shunt elements.
(c)G = 1/R (d) LC = με and RG = σε.

19) A lossless transmission line of length 50 cm with L = 10 μH/m, C = 40 pF/m is operated
at 30 MHz. Its electrical length is [c ]
(a) 20λ (b) 0.2λ (c) 108° (d) 40Π


20) Ex = cos(ωt +βz) represents a wave travelling in the __________________ [d ]
(a)-ve x-direction (b)+ve x-direction (c)+ve z-direction (d)-ve z-direction



21. An electromagnetic wave is to pass through an interface separating two media having dielectric constants ε1 and ε2 respectively. If ε1 = 4ε2 , the wave will be totally reflected if angle of incidence is [b ]
( a ) 00 ( b ) 300 ( c ) 450 ( d ) 600


22. The Snell’s law of refraction

23. The instantaneous rate of energy flow per unit area at a point is [a ]
( a ) E x H ( b) ( c ) B D ( d ) ) (2 EHx∇∇

24. When electromagnetic waves are reflected at an angle from a wall, their wavelength along the wall is
[ c]
( a ) shortened because of the Doppler effect ( b) the same as in free space
( c ) greater than in the actual direction of propagation
( d ) same as the wavelength perpendicular to the wall

25. At the cut-off wave length, the wave between the walls of parallel plane guide [d ]
( a ) is travel almost parallel to the axis of the guide
( b ) is travel perpendicular to the axis of the guide
( c ) is travel in zig-zag path ( d ) has no wave motion

26. If the time dependence of voltage is given as e-jwt, then Voe-γz will represent [ b]
( a ) forward travelling wave (b ) backward travelling wave (c ) standing wave (d ) refracted wave
27. A lossless line of length 500m has L=10μH/m and C=0.1pF/m at 1 MHz. The electrical length of the line is
[ c]
( a ) 3600 ( b ) 2700 ( c ) 1800 ( d ) 900

28. For an open circuited line which is not true [b ]
( a ) Zin = -jZo cotβl ( b ) ( c ) 1 −= Γ l 1 = Γ l ( d ) S = ∞


29. Short-circuited stubs are preferred to open-circuited stubs because the latter are [c ]
( a ) more difficult to make and connect
( b ) made of a transmission line with a different characteristic impedance
( c ) liable to radiate ( d ) incapable of giving a full range of reactances

30. For transmission-line load matching over a range of frequencies, it is best to use a [c ]
(a) balun (b) broadband directional coupler (c) double stub (d) single stub of adjustable position



SECTION-II:   Fill in the blanks

1. The frequency at which the wave motion ceases is called  Cutoff frequency.

2. A Lumped load line behaves as a  Low pass filter

3. By inserting inductance in series with the line to increase the inductance is called

 Loading.

4. One neper is =  8.68 dB.

5. A short circuited λ/4 line can be used a  Insulator

6. The range of UHF is 300 MHz to 3 Ghz

7. The loading practice is generally restricted to  Cables only.

8. When a transmission line is shorted, the first voltage minimum occurs at Load

9. The center of smith chart represents  Matched load impedance.

10. Attenuation factor of TEM wave is proportional to  Square root. of frequency.

11.The relation between E and H in any medium is ____________

12) The value of intrinsic impedance of free space is 377Ω

13) In a perfect dielectric medium attenuation constant is  Zero

14) The loss tangent value for a good conductor is  ( σ/ωε)>>1

15) A wave propagating in a conducting medium attenuation constant and phase constant values are_____________

16) The conductivity of silver is 3x106 mho/m.If the skin depth is 1mm,find the frequency?   84.43kHz

17) Write the expression for reflection coefficient of a perfect dielectic surface when the wave incident normal to the boundary.

 TR =(η2-η1)/(η2+η1)

18) The Poynting vector physically denotes the  power density leaving or entering  a given volume in a time-varying field

19) Brewster angle θB when the wave is parallally polarized is

20) Critical angle θc for the total internal reflection is


21. An electromagnetic wave is incident at air-conductor interface. If impedance of the conductor is 120π, the ratio of transmitted and incident electric fields is 2

22. The critical angle for a wave propagating from Teflon ( εr=4) into free space is 30˚

23. The orientation of the electric field with respect to the plane of incidence determines Polarization
of a wave at the interface between two different regions.

24. When the free-space wavelength of a signal equals the cutoff wavelength of the guide, the phase velocity of the signal becomes infinite

25. The wave impedances for waves between parallel planes are functions of frequency

26. A line is of a length ‘l’ has characteristic impedance ‘Zo’. The line is cut into half. The value of characteristic impedance becomes Zo

27. Impedance inversion may be obtained with Quarter  wave line

28. The velocity factor of a transmission line depends on the  dielectric constant of the material used

29. In a transmission line, the attenuation is given as 0.3dB/km. After 10km the power will be  0.5 of  input power

30. In electromagnetic waves, polarization is due to the  transverse  nature of the waves

                                                                                                                       
                                                                                                        Prepared By                                                                                    
                                                                                     Mukesh