1. How many NAND gates required to implement AB+CD+EF
ANS . 4
2. Transparent latch is seen in which type of flip flop
ANS . D flip-flop.
3. Odd parity generator uses which logic?
1. Digital 2.Analog 3. Sequential 4.none NMOS pass logic
1. Digital 2.Analog 3. Sequential 4.none NMOS pass logic
4. One question based on Ripple counter.
5. Which diagram corresponds to D-flip-flop?
6. Which type of ADC is fastest? ANS -flash/Parallel
7. Which one of the following is fastest read/writable memory?
1. PROM 2. EEPROM 3. Flash 4.none
1. PROM 2. EEPROM 3. Flash 4.none
8. In array programming which one is used
1. SISD 2. PISD 3. MISD 4. None
1. SISD 2. PISD 3. MISD 4. None
SISD Single input single data Von Neumann architecture, MISD Multiple input single data
9. DSP uses the computer architecture derived from- 4 options. I don’t remember.
10. Solve ∫(t2∂(t-2)dt ?
11. they given the Bargraph and asked to find the voltage from it?
12. find laplace transform of e-2t? ANS - 1/s+2.
13. Which one of the following is correct-4 options i dont remember?
14. Given VSWR=2 find reflection coefficient? ANS -1/3
15. There are 2 seats to fill in a office a wife and husband came for the interview. For overall competition the probability of a wife to get selected is 1/7. The probability of husband to be selected is 1/5. Then find the probability of either wife/husband to get selected?
16. given matrix 4 -3 -3
1 0 1
-5 -5 x find x?
1 0 1
-5 -5 x find x?
17. Find the differential equation of y=Ae3x+Be2x ?
18. one problem based on determination of resistance and one on inverting and non inverting Amplifier.
19. two Questions based on capacitor and one question based on inductance?
20. The Unit step signal is given to inductance what is the output?
21. what is the difference b/w switch and HUB?
1. switch avoids flooding 2. HUB stops broadcasting.
1. switch avoids flooding 2. HUB stops broadcasting.
22. one question related to Energy signal and time signal (Depending on ampitude and Phase)?
23. a question related to switch to find resistance if switch is closed?
24. Aquestion based on SI and GE?
25. one question based on Enhancement MOSFET?
26. problem to find Iceo?
27. what is the advantage of using 4 diodes in Bridge rectifier compared to full wave rectifier?
28. Question related to PIV of bridge rectifier compared to Full wave rectifier?
29. Which one of the following has high I/p impedance
1. CC 2. CB 3. CE 4. None
1. CC 2. CB 3. CE 4. None
30. one question based on FET And JFET?
31. where does operating point located in B type power amplifier?
32. which type of power amplifier is used in satellite communication
1.Amplitron 2. Klystron 3. Magnetron 4. TWT
1.Amplitron 2. Klystron 3. Magnetron 4. TWT
33. de-emphasis is used to
1. Attenuate low signals.
2. Attenuate High signals.
3.Attenuate middle signals.
4. none.
1. Attenuate low signals.
2. Attenuate High signals.
3.Attenuate middle signals.
4. none.
34. Envelope detector is an .....? Ans- Asynchronous detector.
35. Which one of the following produce modulated signal as i/p signal?
1. FM 2. PM 3. AM 4. None
1. FM 2. PM 3. AM 4. None
36. they asked to find the gain? Given o/p power and i/p power.-4 options
37. Asked a question from EMfield on HEBD something.. i dont rem...
38. find the modulous of 1+cosA+isinA?
ISRO PAPER ON 28th DECEMBER AT CHENNAI
Written test pattern
1. What is characteristic gas constant
a) Cp / Cv b) Cp*Cv c) Cp-Cv d) Cp+Cv
2. If three pipes are in series having dia 450,550 and 650, and thier diameters are 200,250,300 respectively. If we replaced the three pipes with equivalent pipe have length 750 mm then what could be the diameter of the equivalent pipe.
Ans: To solve this problem caluculator is necesssary. The formula is Leqv/D5eqv = L1/D15+ L2/D25+ L3/D35 How we can calculate with out calculater.
3. A rod is subjected to 18000 Nm torque and max permissible shear stress is 60 N/mm2. Calculate the diameter of the Rod.
Ans: Torque T= (∏*D3*fs)/16
4. 10 questions are from Pshysics Ex: A car moving with a uniform acceleration covers 30mt in 5 sec. And next in 5 seconds covers 50 mt with another uniform acceleration. What is acceleration fo the car.
5. Only few qusetions from Thermodynamics
6. What is the parallel flow heat exchanger and answer are with Symbols of Temperature diagrams.
7. No Apptitude and Reasoning.
8. Some questions are from Production, Heat Transfer, FM, Metrology.
9. They didn't touch Management questions.
Mostly all qusetions are from Basics. All the best for all who are intresetd to write ISRO and other compitative exams. Be prepair well. Presently Mechanical and Civil have good opportunities.So study well.
ISRO PAPER ON 10TH AUGUST, 2008
1)Moore
2) Which of the following filter has steep roll-off characteristics?
(A) Butterworth filter (B) Chebyshev filter (C) Bessel filter (D)--
ans: B
3)The architecture of DSP processor---------
(A) Havard (B) Von neumann (C)...(D)..
ans: A
4)If the input frequency to a 6 stage ripple counter is 1000MHz then output frequency at 6th stage_______
5)Minimum number of 2 input NAND gates required to realise the fn. AB'+CD'+EF'
ans: 6
6)What will exit() fn. in C will do?
7) go to command in C will cause the program to jump to----
ans: Label
8)VSWR is given then asked to find out reflection coefficient
9)The relation between power in FM signal and modulation index--------
10)If two signals are AM modulated with modulation indices of 0.3 and 0.4 what will be the modulation index of combined signal?
ans: Calculate using 1/M=(1/m1)+(1/m2)
11)If n stage pipelining is used in a processor, then what will be the speed improvement over non pipelined processor?
(A) same (B) n (C) n! (D) 2n
12) One circuit is given (That was a Voltage Doubler using op-amp) and asked to Identify that...
13) Which one of the following memory has fastest write time?
(A) Flash (B) EEPROM (C) EPROM (D) None of these
14) In EEPROM data is stored in____
(A) Cross coupled Latch (B) Capacitor (C) floating gate transistor (D)--
15) Which technology is faster?
(A) Bipolar (B) MOS (C)CMOS (D) .. ECL
16)Memory access time, cache access time , hit ratio are given, Asked to find out Average memory access time
17) If the probability of getting a job for A is 1/3 and the probability of getting a job for B is 1/4 then the probability of getting a job for A or B will be____?
18)One transfer fn As4 + Bs3 + Cs2 +D=0 (I don't remember the values of A,B,C,D ) is given, Asked to find out whether the system is____
(A) Stable (B) Unstable (C) Marginally Stable
19) For implementing D flip flop using RS flip flop, the extra component needed is____
(A)AND gate (B) OR gate (C) NOT gate (D) NOR gate
20)The output of an 8 bit DAC is 1Volt when the input is 00110010, then the full scale output of the same DAC will be____
ans: 5.1 V (Hint: 1/50*255)
21)FastestADC is___
(A) SAR (B) sigma- delta (C) flash (D)...
22)The operating point of Class-B amplifier will be at_____
(A) exactly at cut-off region (B) inside saturation region (C) inside cut-off region (D) middle of active region
23)For an N bitADC , the number of comparators needed___
(A) N (B) 2N (C) 2N -1 (D) 2N-1 2 power of N-1
24)De-emphasis circuit is used for_______
ans: Attenuating high frequency components
25)The laplace transform of e-2t _____
Ans: 1/(s+2)
26)The magnitude of 1+cos x+j sin x____
Ans: 2 cos (x/2)
27) A circuit is given in which the capacitor (1uF) is initially charged to 12V , At t = 0, one switch is closed so that another capacitor of capacity 1.5uF comes in parallel with the first capacitor, then in steady state what will be the voltage across them? ( Visualize the circuit , as I can not draw the circuit since the editor is not supporting it)
28)Alpha of a transistor=0.99, Ico=1uA, Ie=1 mA, Ic=?
29)If the input given to an inductor is delta(t) (ie: =1 when t=0 and ,=0 otherwise) then the current will be___
(A) infinity (B) -infinity (C) 1 (D) 0
30) For implementing Band pass filter using High pass filter (Cutt off freq=Fh) and Low pass filter (cutt off freq= Fl)_____
(A)Fh=Fl (B) Fh>Fl (C) Fh
Ans: Fh
31)In the Enhancement type MOSFET the gate to source voltage Vs drain current characteristics will be____
Ans: Drain current Increases as Vgs increases in active region
32)In a johnson counter, How many state have to be changed to increment the count from 0100 to 0111?
33)Odd parity generator is____
Ans: XNOR gate
34)A circuit using op-amp was given, the question was to calculate output offset voltage___
Ans: Vo(off)=Vin(off)*(1+Rf/R1)
35
(A) Digital filter (B) Analog filter (C) Can be Analog or digital (D) RC filter
Written test pattern
1. What is characteristic gas constant
a) Cp / Cv b) Cp*Cv c) Cp-Cv d) Cp+Cv
2. If three pipes are in series having dia 450,550 and 650, and thier diameters are 200,250,300 respectively. If we replaced the three pipes with equivalent pipe have length 750 mm then what could be the diameter of the equivalent pipe.
Ans: To solve this problem caluculator is necesssary. The formula is Leqv/D5eqv = L1/D15+ L2/D25+ L3/D35 How we can calculate with out calculater.
3. A rod is subjected to 18000 Nm torque and max permissible shear stress is 60 N/mm2. Calculate the diameter of the Rod.
Ans: Torque T= (∏*D3*fs)/16
4. 10 questions are from Pshysics Ex: A car moving with a uniform acceleration covers 30mt in 5 sec. And next in 5 seconds covers 50 mt with another uniform acceleration. What is acceleration fo the car.
5. Only few qusetions from Thermodynamics
6. What is the parallel flow heat exchanger and answer are with Symbols of Temperature diagrams.
7. No Apptitude and Reasoning.
8. Some questions are from Production, Heat Transfer, FM, Metrology.
9. They didn't touch Management questions.
Mostly all qusetions are from Basics. All the best for all who are intresetd to write ISRO and other compitative exams. Be prepair well. Presently Mechanical and Civil have good opportunities.So study well.
ISRO PAPER ON 10TH AUGUST, 2008
1)
2) Which of the following filter has steep roll-off characteristics?
(A) Butterworth filter (B) Chebyshev filter (C) Bessel filter (D)--
ans: B
3)The architecture of DSP processor---------
(A) Havard (B) Von neumann (C)...(D)..
ans: A
4)If the input frequency to a 6 stage ripple counter is 1000MHz then output frequency at 6th stage_______
5)Minimum number of 2 input NAND gates required to realise the fn. AB'+CD'+EF'
ans: 6
6)What will exit() fn. in C will do?
7) go to command in C will cause the program to jump to----
ans: Label
8)VSWR is given then asked to find out reflection coefficient
9)The relation between power in FM signal and modulation index--------
10)If two signals are AM modulated with modulation indices of 0.3 and 0.4 what will be the modulation index of combined signal?
ans: Calculate using 1/M=(1/m1)+(1/m2)
11)If n stage pipelining is used in a processor, then what will be the speed improvement over non pipelined processor?
(A) same (B) n (C) n! (D) 2n
12) One circuit is given (That was a Voltage Doubler using op-amp) and asked to Identify that...
13) Which one of the following memory has fastest write time?
(A) Flash (B) EEPROM (C) EPROM (D) None of these
14) In EEPROM data is stored in____
(A) Cross coupled Latch (B) Capacitor (C) floating gate transistor (D)--
15) Which technology is faster?
(A) Bipolar (B) MOS (C)
16)Memory access time, cache access time , hit ratio are given, Asked to find out Average memory access time
17) If the probability of getting a job for A is 1/3 and the probability of getting a job for B is 1/4 then the probability of getting a job for A or B will be____?
18)One transfer fn As4 + Bs3 + Cs2 +D=0 (I don't remember the values of A,B,C,D ) is given, Asked to find out whether the system is____
(A) Stable (B) Unstable (C) Marginally Stable
19) For implementing D flip flop using RS flip flop, the extra component needed is____
(A)
20)The output of an 8 bit DAC is 1Volt when the input is 00110010, then the full scale output of the same DAC will be____
ans: 5.1 V (Hint: 1/50*255)
21)Fastest
(A) SAR (B) sigma- delta (C) flash (D)...
22)The operating point of Class-B amplifier will be at_____
(A) exactly at cut-off region (B) inside saturation region (C) inside cut-off region (D) middle of active region
23)For an N bit
(A) N (B) 2N (C) 2N -1 (D) 2N-1 2 power of N-1
24)De-emphasis circuit is used for_______
ans: Attenuating high frequency components
25)The laplace transform of e-2t _____
Ans: 1/(s+2)
26)The magnitude of 1+cos x+j sin x____
Ans: 2 cos (x/2)
27) A circuit is given in which the capacitor (1uF) is initially charged to 12V , At t = 0, one switch is closed so that another capacitor of capacity 1.5uF comes in parallel with the first capacitor, then in steady state what will be the voltage across them? ( Visualize the circuit , as I can not draw the circuit since the editor is not supporting it)
28)Alpha of a transistor=0.99, Ico=1uA, Ie=1 mA, Ic=?
29)If the input given to an inductor is delta(t) (ie: =1 when t=0 and ,=0 otherwise) then the current will be___
(A) infinity (B) -infinity (C) 1 (D) 0
30) For implementing Band pass filter using High pass filter (Cutt off freq=Fh) and Low pass filter (cutt off freq= Fl)_____
(A)Fh=Fl (B) Fh>Fl (C) Fh
Ans: Fh
31)In the Enhancement type MOSFET the gate to source voltage Vs drain current characteristics will be____
Ans: Drain current Increases as Vgs increases in active region
32)In a johnson counter, How many state have to be changed to increment the count from 0100 to 0111?
33)Odd parity generator is____
Ans: XNOR gate
34)A circuit using op-amp was given, the question was to calculate output offset voltage___
Ans: Vo(off)=Vin(off)*(1+Rf/R1)
35
(A) Digital filter (B) Analog filter (C) Can be Analog or digital (D) RC filter
.Here are some question:1. If sampling frequency doubles thena) Quantization noise decreasesb) Quantization density decreasesc) Quantization noise increasesd) Quantization density increases 2. Two signals of 2GHz and 4GHz are frequency modulated on same carrier 10 GHz. Find the ratio of frequency deviation if band widths of both are equal.a ) 1:2 b)2:1 c) 1:1 d) 1:43. Gray code of 111 is4. 3X512+7X64+5X8+3 then value in binary form contains _______ number of 1?s.a) 7 b) 6 c) 9 d) none5. The 2?s compliment of decimal number 19 in 8-bit system is6) The high gain codes area) Turbo codes b) BCH codes c) R-S codes7) BCH codes are of the type________a) Convolutional type b) c)8) Time constant of LC circuit isa) L/R b) L/R2 c) RL9) If R is doubled and C is halved then frequency of series RLC circuit is10) The solution for the equation (D2+4) y=sin2x More question would be posted ASAP. All the best. Edutalk India
ISRO PAPER ON 22nd APRIL AT helo friends, i appeared for ISRO written examinatiom on 22april,2007 for the post of Scientist Engineer.
paper was totally technical.Questions which i remembered are as follows:-
1) output resistance of ideal OP AMP is:-
a) 0 b) 1 c) infinite d) very high
2) waveguide acts as:-
a) LPF b) HPF c) BPF d) BRF
3) quality factor of series
a) increase in R b) decrease in R c) doesn't depends on R d) none of these
4) energy stored in capacitor is given by:
a) CV b) 0.5CV c) CV2 d) 0.5CV2
5) CMRR of an OP AMP is given as 80db and Ad is 20000.Value of Acm will be:-
a) 4 b) 8 c) 2 d) 1
some basic questions were based upon digital electronics,ckt. analysis,antenna theory,zener doides.
Basically all the questions were either based on formulas or simple logic.I have attempted approx. 60-65 questions,osme of them are as given below;
1-
2-To calculate the number of RAMchips for a given one: 4 options
3-The correct value of
4-A figure to represent which kind of Flipflop: 4 options
5-A prob. on adder with shift register to identified no. of clock used to show the output (ie1010) 4options
6-Three questions were asked on Zener Diode to evaluate variable resirance,min. passing current & variable supplied voltage. 4 options
7- A problem on line to which passes thru point (-1,2) and making equal intercepts on both axis: 4 options
8-Transformer core requried 4 options with high permiability & low hysteris losses etc. like difft. values
9-To evaluate the prob. to get either of 2 color balls in a bag containg 6 red & 8 black balls 4 options
10-A wire length 2m having restiance 5 ohms, what will be the resitance if its length bcome 2 fold: 4options
. If sampling frequency doubles then
a) Quantization noise decreases
b) Quantization density decreases
c) Quantization noise increases
d) Quantization density increases
2. Two signals of 2GHz and 4GHz are frequency modulated on same carrier 10 GHz. Find the ratio of frequency deviation if band widths of both are equal.
a) 1:2 b)2:1 c) 1:1 d) 1:4
3. Gray code of 111 is
4. 3X512+7X64+5X8+3 then value in binary form contains _______ number of 1’s.
a) 7 b) 6 c) 9 d) none
5. The 2’s compliment of decimal number 19 in 8-bit system is
a) 11101101
6) The high gain codes are
a) Turbo codes b) BCH codes c) R-S codes
7) BCH codes are of the type________
a) Convolutional type b) c)
8) Time constant of LC circuit is
a) L/R b) L/R2 c) RL
9) If R is doubled and C is halved then frequency of series
10) The solution for the equation (D2+4) y=sin2x is
11) Laplace Tramsform of sin3x is
12) The Z-transform for the series is
X [n] = { 7; n= -1
{5 n=0
{ 1 n=1
{0 else
13) The magic Tee is a
a) 4 port tee b) c)
14) The register which holds the address of the next instruction is
a) Program counter b) c)
15) The antenna gain is given by...............?
a16) The satellite is in 630km orbit and transmitting at a frequency 5 MHz, when satellite is on your head the Doppler shift is--------
a) b) c) 0 d)
17) The impedance of a lossless transmission line is
a) √(L/C)
18) A 50Ώline with load impedance 100Ώ the VSWR is
19) In a waveguide measurement, the forward power is 10mW, the reverse power is 1mW then VSWR is _____________
20) Transmitted power is 100W, gain of the transmitter antenna is 30 dB and the path loss is 50 dB then received power is
21) When transmitted power is 100mW and the path loss 100 dBm then received power is
a) -80 dBm
22) When a em wave is incident normally on a perfect conductor then
a) Totally reflected b) partially reflected
c) Totally transmitted d) none.
23) Zsc =100Ώ Zoc =1Ώ then Zo is
a) 1Ώ b) 10Ώ c)___d)__
24) When the operating wavelength of line is λ/4<λ<λ/2, the impedance is
a) Capacitive b) inductive c) ____ D) none
25) The value of L if source is 50V AC of 10 KHz frequency and current is 7.96 A.
a) ____
26) The resonant frequency is 50MHz bandwidth 100 KHz then Q factor is
a) ______ b)_______ c)…..
27)The Q factor of a series
a)……b)……
28) Q value of a parallel
a)……b)….
29) If the lines x+y+3=0, x-2y+7=0, 2x+ky+5=0 are required to be concurrent then the value of k is___ a) ___ b)…..
30) The vectors i-2j+k, 2i+3j-k,R are the complete, then r is given by ______
31) If a satellite revolving with angular velocity w and the velocity is v then
Curl v is _______
a) w b) 2w c) w 2 d) …..
32) If each stage amplifier contains 10dB gain the figure of merit of 2-stages is
Given by ……
33) The maximum rate possible in kbps if F=15 and bandwidth is 4 KHz is…….
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