ELECTRONIC AND INSTRUMENTATION
Part B
UNIT I
1. Explain Q meter and derive the relation for Q?
Refer Page Num: 165 (Cooper)
2. With neat block diagram explain Vector Impedance meter?
Refer Page Num: 174 (Cooper)
3. Explain Vector voltmeter with neat block diagram?
Refer Page Num: 178 (Cooper)
4. With necessary diagrams explain Electronic Multimeter
Refer Page Num: 140 (Cooper)
5. Explain DC ammeters and DC voltmeters?
Refer Page Num: 57-63 (Cooper)
6. Explain True RMS responding voltmeter?
Refer Page Num: 139 (Cooper)
UNIT II
1. Explain Sine wave generator?
Refer Page Num: 246 (Cooper)
2. With neat diagrams explain pulse and square wave generators?
Refer Page Num: 268 (Cooper)
3. Explain Harmonic distortion analyzer?
Refer Page Num: 286 (Cooper)
4. With neat diagrams explain Spectrum Analyzer?
Refer Page Num: 291 (Cooper)
5. Explain audio frequency signal generation and function generator?
Refer Page Num: 279 & 277 (Cooper)
UNIT III
1. Explain General purpose oscilloscope
Refer Page Num: - 187 Cooper & (784,785,786) Sawhney
2. Explain vertical and Horizontal deflection plates?
Refer Page Num: Vertical deflection systems – (203) cooper
Horizontal deflection systems – (213-217 )Cooper
3. Expalin storage oscilloscopes?
Analog Storage – (821 -825) Sawhney
Digital Storage – ( 825-827) & fig 21.59 Sawhney
4. Explain sampling oscilloscope?
Refer page num: (233-235) Cooper
5. Explain Oscilloscope techniques?
Refer page num: (221-226) Cooper
6. Expalin dual trace and dual beam oscilloscopes?
Refer page num: (815,816) Sawhney
UNIT IV
1.Explain Digital method for measuring frequency
Refer Page Num: (1295 – 1297) Sawhney
2.Explain period measurement, ratio and multiple ratio measurement?
Refer Page Num: 1299,1300, 1301) Sawhney
3.With neat diagram explain Ramp type digital voltmeter?
Refer Page Num: (1304, 1305) Sawhney
4.Explain integrating and dual slope integrating type DVM?
Refer Page Num: (116-118)Kalsi
5.Explain successive approximation type DVM?
Refer Page Num: (122-125) Kalsi
6.With neat block diagrams explain Digital multimeter and Digital panel meter?
Refer class notes and Xerox
UNIT V
1.Explain in detail Dataloggers?
Refer Page Num: (623-627) Kalsi
2.Explain segmental and dotmatrix display?
Refer Page Num: (42-47) Kalsi
3.Explain X-Y recorders with neat diagram?
Refer Page Num: (1315,1316) Sawhney
4.Explain direct recording using magnetic tape recorder?
Refer notes
5.Explain FM and PDM recording?
Refer to notes & Xerox
6. Write a detailed note on Electrostatic and electromagnetic interference & earth loops?
Refer notes.
Thursday, October 22, 2009
EI 1302(2 MARKS) UNIT V
Unit V
1. Classify the recorders used in instrumentation?
Recorders may be classified as
Analog recorders
Digital recorders
Analog recorders classified as
Graphic recorders
Oscillographic recorders
Magnetic recorders
Digital recorders are classified as
Incremental recorders
Synchronous recorders
2. What are the basic components present in magnetic recorders?
Basic components of magnetic recorders are
Recording head
magnetic tape
Reproducing head
tape transport mechanism and
conditioning devices
3. State the principle of FM recording?
In the FM recording the carrier frequency fc is modulated by the input signal. FM recording uses the variation of frequency to carry the required information instead of varying the amplitude the modulated signal is then recorded using the recording head in normal way the reproducing head reproduced signal is passed through FM demodulator, low pass filter to get original signal
4. What are the advantages of digital data recording?
• recorder and another amplifier in reproducer to condition signal
• The digital data recorders have high accuracy
• They are insensitive to speed of magnetic tape
• The process of recording digitally coded number is simple it requires amplifier in The information can be directly fed to computer for processing and control
• Nonlinearity and distroction problems do not exit
5 What are the advantages of LCD?
• Power consumed is of the order of few micro watt
• The LCD The response time of LCD’ stypiccally range between 10 and 100ns
• They has twisted numatic structure, very small voltage, typically >10v, are sufficient to align the molecules.
6 What are the applications of X-Y recorders?
• Speed-torque characteristics of motor
• Regulation of power supply.
• Plottingcharacterstics of active devices such as vacuum tubes, transistor, rectifiers, diodes.
• Plotting stress strain curves, hysterics curve etc...
• Electrical characteristics of material such as resistance Vs temperature
7 Explain paper drive and chart speed mechanism?
Paper drive system:
The paper drive system should move the paper at uniform speed Aspiring wound mechanism may be used in most recorders asynoshronous motor is used for driving the paper
Chart speed:
Chart speed is a term used to express the rate at which the recording paper in a strip chart recorders it is expressed in in/s or the period of the recorded signal can be calculated as
Period = time/cycle
= time base/chart speed
8 What is data logger & mention its application?
In industries and process plants data logger are becoming very popular so as to monitor display ,measure, store and control different process variable data is nothing but output from different transducer and log means permanent storage of this data the data logger handle digital information hence it require fast ,accurate analog to digital conversion technique.
9 Name the methods of recording?
Direct recording.
FM recording
PDM recording
Digital tape recording
10 State the purpose of play back amplifier in digital recorder?
The playback amplifier raises the voltage level and shortens the rise time.
11 What is Non return zero?
The magnetic tape is magnetically saturated either in positive or in negative direction in NRZ format for logic 1 representation there is no change in flux binary number 10101100 is represented by NRZ format as shown
12 What is the principle of nixie tube?
Non planner display is the nixie tube it is a gaseous glow tube having a set of electrode, each shaped in the form of digit. The selected electrodes are surrounded by a gaseous discharge or glow when the digit it is selected the electrode are stacked one behind the other and hence the various digit appear in different planes in the readout
13 Explain cold cathode display?
They are also known as neon gas discharge displays when a negative voltage is applied to a gas, the gas molecules breakdown and discharge takes place
14 State the primary function of magnetic recorders?
Used for a high frequency signal recording
in these recorders data is in a way that it can be reproduced in electrical form any time
15. State the principle of magnetic Recorder?
The principle of magnetic tape recording in a way that it can be reproduced in electrical form any time
The principle of magnetic tape recording is when a magnetic tape is passed through a recording head the signal to be recorded appears as some magnetic pattern on the tape this magnetic pattern is in accordance with the variation of signal recording current . The recorded signal can be reproduced back by passing the same tape through a reproducing head where the voltage is induced corresponding to the magnetic pattern on the tape.
16 Define multiplexed display?
By time sharing the decoder used for driving the digital digits, it is possible to considerably reduce the count of the components and interconnection in display system, input in BCD form applied to latch &their output are fed to single BCD to seven segment decoder at any instant how ever only one of the digit is displayed as selected by the decoder output from the scan controller
17) Difference between cold cathode &incandescent display?
Cold cathode display Incandescent display
• Here cathode and anode arrangement is used • They have 7 segment filaments contain with in a single vacuum envelope
• Gas is used for discharge • Instead of neon gas ,vacuum is present
• Display is in orange color • Display is in any color accord to our requirement
(18) Difference between X-Y & digital recorders?
Analog X-Y Digital X-Y
• Servo motor is used • Stepper motor is used
• No different color outputs are obtain • Record no of input simultaneously with different color
• Instantaneous relationship between 2 physical quantities can be recorded • It can record or draw grids axis
(19) Difference between LCD & LED?
LED LCD
• It is a active device that generates light • It is a passive device that modified the light by scattering
• PN junction diodes mode of galliumarsinide phospide • In twisted neamutaic display the LCD is sandwiched between 2 pies of glass
(20) Difference between seven segment & dot matrix display?
Seven segment display Dot matrix display
• It is used for numeric display • It is used for numeric & alpha numeric characters
• A segmental display form the digit to be displayed • Various matrix display digit to be displayed
(21) Difference between single point & multipoint recorders?
Single point recorders Multi point recorders
• Recording single input only • Recording several inputs
• It is recording with respect to time only • It recorders variable quantities with respect to another variable quantity
• The trace of curve is single continuous curve • The trace of curve are multi curves not in continuous
1. Classify the recorders used in instrumentation?
Recorders may be classified as
Analog recorders
Digital recorders
Analog recorders classified as
Graphic recorders
Oscillographic recorders
Magnetic recorders
Digital recorders are classified as
Incremental recorders
Synchronous recorders
2. What are the basic components present in magnetic recorders?
Basic components of magnetic recorders are
Recording head
magnetic tape
Reproducing head
tape transport mechanism and
conditioning devices
3. State the principle of FM recording?
In the FM recording the carrier frequency fc is modulated by the input signal. FM recording uses the variation of frequency to carry the required information instead of varying the amplitude the modulated signal is then recorded using the recording head in normal way the reproducing head reproduced signal is passed through FM demodulator, low pass filter to get original signal
4. What are the advantages of digital data recording?
• recorder and another amplifier in reproducer to condition signal
• The digital data recorders have high accuracy
• They are insensitive to speed of magnetic tape
• The process of recording digitally coded number is simple it requires amplifier in The information can be directly fed to computer for processing and control
• Nonlinearity and distroction problems do not exit
5 What are the advantages of LCD?
• Power consumed is of the order of few micro watt
• The LCD The response time of LCD’ stypiccally range between 10 and 100ns
• They has twisted numatic structure, very small voltage, typically >10v, are sufficient to align the molecules.
6 What are the applications of X-Y recorders?
• Speed-torque characteristics of motor
• Regulation of power supply.
• Plottingcharacterstics of active devices such as vacuum tubes, transistor, rectifiers, diodes.
• Plotting stress strain curves, hysterics curve etc...
• Electrical characteristics of material such as resistance Vs temperature
7 Explain paper drive and chart speed mechanism?
Paper drive system:
The paper drive system should move the paper at uniform speed Aspiring wound mechanism may be used in most recorders asynoshronous motor is used for driving the paper
Chart speed:
Chart speed is a term used to express the rate at which the recording paper in a strip chart recorders it is expressed in in/s or the period of the recorded signal can be calculated as
Period = time/cycle
= time base/chart speed
8 What is data logger & mention its application?
In industries and process plants data logger are becoming very popular so as to monitor display ,measure, store and control different process variable data is nothing but output from different transducer and log means permanent storage of this data the data logger handle digital information hence it require fast ,accurate analog to digital conversion technique.
9 Name the methods of recording?
Direct recording.
FM recording
PDM recording
Digital tape recording
10 State the purpose of play back amplifier in digital recorder?
The playback amplifier raises the voltage level and shortens the rise time.
11 What is Non return zero?
The magnetic tape is magnetically saturated either in positive or in negative direction in NRZ format for logic 1 representation there is no change in flux binary number 10101100 is represented by NRZ format as shown
12 What is the principle of nixie tube?
Non planner display is the nixie tube it is a gaseous glow tube having a set of electrode, each shaped in the form of digit. The selected electrodes are surrounded by a gaseous discharge or glow when the digit it is selected the electrode are stacked one behind the other and hence the various digit appear in different planes in the readout
13 Explain cold cathode display?
They are also known as neon gas discharge displays when a negative voltage is applied to a gas, the gas molecules breakdown and discharge takes place
14 State the primary function of magnetic recorders?
Used for a high frequency signal recording
in these recorders data is in a way that it can be reproduced in electrical form any time
15. State the principle of magnetic Recorder?
The principle of magnetic tape recording in a way that it can be reproduced in electrical form any time
The principle of magnetic tape recording is when a magnetic tape is passed through a recording head the signal to be recorded appears as some magnetic pattern on the tape this magnetic pattern is in accordance with the variation of signal recording current . The recorded signal can be reproduced back by passing the same tape through a reproducing head where the voltage is induced corresponding to the magnetic pattern on the tape.
16 Define multiplexed display?
By time sharing the decoder used for driving the digital digits, it is possible to considerably reduce the count of the components and interconnection in display system, input in BCD form applied to latch &their output are fed to single BCD to seven segment decoder at any instant how ever only one of the digit is displayed as selected by the decoder output from the scan controller
17) Difference between cold cathode &incandescent display?
Cold cathode display Incandescent display
• Here cathode and anode arrangement is used • They have 7 segment filaments contain with in a single vacuum envelope
• Gas is used for discharge • Instead of neon gas ,vacuum is present
• Display is in orange color • Display is in any color accord to our requirement
(18) Difference between X-Y & digital recorders?
Analog X-Y Digital X-Y
• Servo motor is used • Stepper motor is used
• No different color outputs are obtain • Record no of input simultaneously with different color
• Instantaneous relationship between 2 physical quantities can be recorded • It can record or draw grids axis
(19) Difference between LCD & LED?
LED LCD
• It is a active device that generates light • It is a passive device that modified the light by scattering
• PN junction diodes mode of galliumarsinide phospide • In twisted neamutaic display the LCD is sandwiched between 2 pies of glass
(20) Difference between seven segment & dot matrix display?
Seven segment display Dot matrix display
• It is used for numeric display • It is used for numeric & alpha numeric characters
• A segmental display form the digit to be displayed • Various matrix display digit to be displayed
(21) Difference between single point & multipoint recorders?
Single point recorders Multi point recorders
• Recording single input only • Recording several inputs
• It is recording with respect to time only • It recorders variable quantities with respect to another variable quantity
• The trace of curve is single continuous curve • The trace of curve are multi curves not in continuous
EI (2 MARKS) UNIT IV
Unit IV
1.Explain the principle of ramp type DVM?
The operating principle isto measure the time taken by a linear ramp to change the input level to ground level and viceversa.
2.Explain the principle of dual slope DVM?
The input voltage is integrated over a fixed time period.After the fixed time period the input voltage is disconnected and a negative input is connected.The output will have a negative slope which is constant and proportional to magnitude of input voltage.
3.Explain the principle of successive approximation type DVM?
The principle of sucessive approximation type DVM is similar to that of measuring the weight of an unknown quantity by using a balance
Ie: At each stage Vin is compared with the reference input.If Vin>Vref then the control circuit set that particular bit and Vref jumps to half of the reference voltage
If Vin
4.Explain the principle of digital frequency meter?
The signal whose frequency to be measured is converted to trigger pulses and applied continuously to an AND gate at one of the input terminal and at the other input terminal a pulse signal is applied.This pulse signal should have a suitable time period.pulses occurring at the output during this time interval is counted and this corresponds to the frequency to be measured.
5.Name the attenuation techniques used for high frequency measurement?
Ø Prescaling
Ø Hetrodyne converter
Ø Transfer oscillator
Ø Automatic divider
6.State the advantage of dual slope integrating type DVM over ramp type DVM?
In ramp techniques,superimposed noise can cause large errors.In dual ramp technique,noise is averaged out by the positive and negative ramps using the process of integration.
7.What is automatic polarity?
In a microprocessor based DMM the counter sends two clock signals to the programming unit,one just before the end of integration period and the one just after the end of integation period.The first signal is used by the polarity detector,hence to determine the polarity of the input signal .This is called automatic polarity.
8.Draw the simple sample and Hold circuit?
9.What is sample and Hold circuit?
Sample and hold circuit is one which is used to convert analog signal to digita signal.
10.Draw the output waveform of a sample and hold circuit?
11.State the advantage of successive approximation method?
The main advantage of SAR DVM is that is very fast.At the best it takes ‘n’ clock pulse to produce ‘n’ bit result.The SAR method is more faster than counter method.
12.State the drawbacks of Ramp-type DVM?
In ramp type DVM noise present in the input signal will cause a lot of errors in the output.
13.Define LCR meter?
LCR meter is an instrument which is used to measure inductance,capacitance and resistance.
14.Define ‘Q’?
Q= Ratio of inductance(or) capacitive resonance
Resistance
15.What is the basic principle of a digital storage oscilloscope?
The basic principle in a digital storage oscilloscope is the conversion of analog input signal into a digital form using A/D converter and then this digital signal
Is stored in the oscilloscope’s memory.
16.Draw the basic circuit for a ‘Q’ meter?
17.What’s the principle of the ’Q’ meter and state its use?
The Q meter is an instrument designed to measure some electrical properties of coils and capacitors.
18.Draw the block diagram of a digital storage oscilloscope?
19.Define sampling rate in a digital storage oscilloscope?
In a digital storage oscilloscope the A/D sample clock determines howoften the ADC takes a sample.This rate is called sample rate and is expressed in samples per second.
20.State the advantages and limitations of digital storage oscilloscope?
Advantages:
Ø Split-screen capability.
Ø Pre-trigger capability
Ø Display the stored data in amplitude Vs time period and X-Y mode are possible.
Limitations:
Ø Band-width limitations.
EI 1302 (2 MARKS) UNIT III
Unit III
1. Name the components of a time domain oscilloscope?
The time domain oscilloscope contains the following component blocks,
o Display device
o vertical amplifier
o Time base
o Horizontal amplifier
o Trigger or sync circuit
o Gate amplifier
o Power supply
2. Describe about the classifications of oscilloscope?
Classification based on frequency
a)Low frequency oscilloscope
b)High frequency oscilloscope
c)Sampling Oscilloscope
Classification based on CRT used
a)Standard phosphor oscilloscope
b)storage oscilloscope.
3. Explain the classification of CRT?
According to the number of independent electron beams and tube the CRT is classified as:
a) single beam CRT
b) dual beam CRT
c) multi beam CRT
According to the deflection technique used:
a) electro magnetic CRT
b) electro static CRT
In electrostatic CRT again classifications can be made according to the design in deflection plates as:
a) parallel plate CRT
b) bent plate CRT
c) segmented plate CRT
d) distributed plate CRT
According to the acceleration given:
a) monoaccelerator CRT
b) postaccelerator CRT
According to the target decay characteristics:
a) standard CRT
b) storage CRT
c) variable persistence CRT
4. What is meant by Aluminising a CRT and explain its advantage?
Aluminizing a CRT is depositing a thin layer of aluminium on the non-viewed side of the phospher screen . it has 3 major functions,its original function was to build-up of charges on the phospher,which tends to slow down the electron and limit brightness.also aluminizing serves to reduce light scatter when beam hits the phosphor.with the aluminized layer,the light emitted back into the tube is reflected again towards the viewer and thus increases the brightness.the aluminium layer acts as a heat sink for the phospher and thus materially reduces the danger of phospher burning.
5. What is scan angle?
It is the number of screen divisions which can be scanned,fullscreen scan is often achieved before the beam intercepts the deflection plate itself.it is one of the significant parameter of electrostatic tube.
6. Describe about writing speed?
Photographic writing speed is a measure of the fastest deflection rate of a single beam trace that is just barely vivible on film,it is affected not only by CRT parameters such as density of beam current,accelerating voltage,and phospher , but also by parameters such as light filters,camera lenses and film speed and sensitivity.cathode-ray tube writing speed is typically given in centimeter/microsecond.
7. What are graticules?
Graticules are scale markings on or near the CRT screen to aid the user in display analysis by calibrating beam deflection. The number of scale divisions multiplied by the appropriate switch settings gives the amplitude difference and time duration between any two points on an observed waveform. Three kinds of graticule system are in use
o External Graticule
o Internal Graticule
o Projected Graticule
8. What is fading positive?
The stored pattern eventually degrades, primarily because ions generated by flood gun electrons charge other regions of the storage surface and the entire display consequently appears to be written. This is called fading positive.
9. Define the technique used in sampling oscilloscope?
Sampling device samples the signal amplitude at regulated intervals and synthetically reproduces the sampled signal. These signals are presented on the CRT as a series of dots.
10. State the prime advantage of peak responding voltmeter?
When no ac pre-amplification is required the rectifying diode and the storage capacitor may be taken out of the instrument and placed in the probe.
11. Define coherent and incoherent sampling?
If the input voltage is sampled at equal interval, this type of sampling is known as coherent sampling.It is primarily used when the waveform must be preserved for visual presentation or phase measurement
If the input voltage is sampled at irregular interval that have no relationship to any of the frequency components of the input signal, this type of sampling is known as in-coherent sampling. It is used in voltmeters due to meter sensitivity, accuracy and broad frequency range of a sampling instrument.
12. Define wave analyzer and name its type?
A wave analyzer is an instrument designed to measure the relative amplitudes of single frequency components in a complex or distorted waveform. The types of wave analyzer are
Frequency selective wave analyzer
Heterodyne wave analyzer
13. Name any two application of wave analyzer?
Fields of electrical measurement and sound
Vibration analysis
14. What are the drawbacks of tuned circuit harmonic analyzer?
The two major drawbacks are
At low frequency very large values of L & C are required and their physical size becomes rather impractical
Harmonics of the signal frequency are often very close in frequency so that it becomes extremely difficult to distinguish between them.
15. Name the major components of fundamental suppression harmonic distortion analyzer?
Input circuit
Impedence converter
Rejection amplifier
Metering circuit
Power supply
16. Define the technique for noise generation?
The method for generating noise is to use a semiconductor noise diode which delivers frequencies in a band roughly extending from 80-220 KHz.
17.What are the important features of an instrumentation amplifier?
Selectable gain with high gain accuracy and gain linearity
Differential input capability with high gain common mode rejection
High stability of gain with low temperature co-efficient
Low DC offset anf drift errors referred to input
Low output impedence
18. State the principle of Q-meter.
Principle of Q-meter is based on series resonance; the voltage drop across the coil is Q times the applied voltage
At resonance XL = XC and
EL= I XL ;
EC= I XC ;
E = I R
Q = X L / R = X C / R = EC / E
19. State the principle of Lock-in amplifier?
The lock in amplifier is basically a band pass filter amplifier that overcomes the Q limitations of conventional circuits.
20. Name the front panel controls used in signal generator?
Frequency selector
Frequency multiplier
Amplitude multiplier
Variable amplitude
Symmetry control
Amplitude
Function Switch
Output
Sync
On-Off Switch
1. Name the components of a time domain oscilloscope?
The time domain oscilloscope contains the following component blocks,
o Display device
o vertical amplifier
o Time base
o Horizontal amplifier
o Trigger or sync circuit
o Gate amplifier
o Power supply
2. Describe about the classifications of oscilloscope?
Classification based on frequency
a)Low frequency oscilloscope
b)High frequency oscilloscope
c)Sampling Oscilloscope
Classification based on CRT used
a)Standard phosphor oscilloscope
b)storage oscilloscope.
3. Explain the classification of CRT?
According to the number of independent electron beams and tube the CRT is classified as:
a) single beam CRT
b) dual beam CRT
c) multi beam CRT
According to the deflection technique used:
a) electro magnetic CRT
b) electro static CRT
In electrostatic CRT again classifications can be made according to the design in deflection plates as:
a) parallel plate CRT
b) bent plate CRT
c) segmented plate CRT
d) distributed plate CRT
According to the acceleration given:
a) monoaccelerator CRT
b) postaccelerator CRT
According to the target decay characteristics:
a) standard CRT
b) storage CRT
c) variable persistence CRT
4. What is meant by Aluminising a CRT and explain its advantage?
Aluminizing a CRT is depositing a thin layer of aluminium on the non-viewed side of the phospher screen . it has 3 major functions,its original function was to build-up of charges on the phospher,which tends to slow down the electron and limit brightness.also aluminizing serves to reduce light scatter when beam hits the phosphor.with the aluminized layer,the light emitted back into the tube is reflected again towards the viewer and thus increases the brightness.the aluminium layer acts as a heat sink for the phospher and thus materially reduces the danger of phospher burning.
5. What is scan angle?
It is the number of screen divisions which can be scanned,fullscreen scan is often achieved before the beam intercepts the deflection plate itself.it is one of the significant parameter of electrostatic tube.
6. Describe about writing speed?
Photographic writing speed is a measure of the fastest deflection rate of a single beam trace that is just barely vivible on film,it is affected not only by CRT parameters such as density of beam current,accelerating voltage,and phospher , but also by parameters such as light filters,camera lenses and film speed and sensitivity.cathode-ray tube writing speed is typically given in centimeter/microsecond.
7. What are graticules?
Graticules are scale markings on or near the CRT screen to aid the user in display analysis by calibrating beam deflection. The number of scale divisions multiplied by the appropriate switch settings gives the amplitude difference and time duration between any two points on an observed waveform. Three kinds of graticule system are in use
o External Graticule
o Internal Graticule
o Projected Graticule
8. What is fading positive?
The stored pattern eventually degrades, primarily because ions generated by flood gun electrons charge other regions of the storage surface and the entire display consequently appears to be written. This is called fading positive.
9. Define the technique used in sampling oscilloscope?
Sampling device samples the signal amplitude at regulated intervals and synthetically reproduces the sampled signal. These signals are presented on the CRT as a series of dots.
10. State the prime advantage of peak responding voltmeter?
When no ac pre-amplification is required the rectifying diode and the storage capacitor may be taken out of the instrument and placed in the probe.
11. Define coherent and incoherent sampling?
If the input voltage is sampled at equal interval, this type of sampling is known as coherent sampling.It is primarily used when the waveform must be preserved for visual presentation or phase measurement
If the input voltage is sampled at irregular interval that have no relationship to any of the frequency components of the input signal, this type of sampling is known as in-coherent sampling. It is used in voltmeters due to meter sensitivity, accuracy and broad frequency range of a sampling instrument.
12. Define wave analyzer and name its type?
A wave analyzer is an instrument designed to measure the relative amplitudes of single frequency components in a complex or distorted waveform. The types of wave analyzer are
Frequency selective wave analyzer
Heterodyne wave analyzer
13. Name any two application of wave analyzer?
Fields of electrical measurement and sound
Vibration analysis
14. What are the drawbacks of tuned circuit harmonic analyzer?
The two major drawbacks are
At low frequency very large values of L & C are required and their physical size becomes rather impractical
Harmonics of the signal frequency are often very close in frequency so that it becomes extremely difficult to distinguish between them.
15. Name the major components of fundamental suppression harmonic distortion analyzer?
Input circuit
Impedence converter
Rejection amplifier
Metering circuit
Power supply
16. Define the technique for noise generation?
The method for generating noise is to use a semiconductor noise diode which delivers frequencies in a band roughly extending from 80-220 KHz.
17.What are the important features of an instrumentation amplifier?
Selectable gain with high gain accuracy and gain linearity
Differential input capability with high gain common mode rejection
High stability of gain with low temperature co-efficient
Low DC offset anf drift errors referred to input
Low output impedence
18. State the principle of Q-meter.
Principle of Q-meter is based on series resonance; the voltage drop across the coil is Q times the applied voltage
At resonance XL = XC and
EL= I XL ;
EC= I XC ;
E = I R
Q = X L / R = X C / R = EC / E
19. State the principle of Lock-in amplifier?
The lock in amplifier is basically a band pass filter amplifier that overcomes the Q limitations of conventional circuits.
20. Name the front panel controls used in signal generator?
Frequency selector
Frequency multiplier
Amplitude multiplier
Variable amplitude
Symmetry control
Amplitude
Function Switch
Output
Sync
On-Off Switch
EI 1302 (2 MARKS) UNIT I
ELECTRONICS INSTRUMENTATION
2 Marks Questions and answers
UNIT-I
1. Define Ayrton shunt or universal shunt?
The universal or ayrton shunt eliminates the possibility of having the meter in the circuit with a shunt. The advantage is gained at the price of a slightly higher overall meter resistance.
2. What is a true RMS responding voltmeter?
Complex waveforms are most accurately measured with an rms-responding voltmeter. This instrument produces a meter indication by sensing waveform heating power, which is proportional to the square of the rms value of the voltage.
3. What are the sources of error in a Q meter?
i) Due to the distributed capacitance or self capacitance Cd
ii) Due to insertion resistor,
iii) Due to self inductance
iv)Conductance of the Q meter.
4. What is a vector impedance meter?
Vector impedance meter makes simultaneous measurements of impedance and phase angle. The magnitude of the impedance is determined measuring the current through the unknown component when a known voltage is applied across it, or by measuring the voltage across the component when a known current is passed through it. The phase angle is found by determining the phase difference between the voltage across the component and the current through the component.
5. What is a power meter?
The electrodynamometer is used extensively used in measuring power. It is used to indicate both dc and ac power for any waveform of voltage and current and it is not restricted to sinusoidal waveforms.
6. State the prime advantage of peak responding voltmeter?
When no ac pre-amplification is required the rectifying diode and the storage capacitor may be taken out of the instrument and placed in the probe.
7.What is meant by basic meter?
The motor action is produced by the flow of a small amount of current through a moving coil which is positioned in a permanent magnetic field.
8.What is the main purpose of the multiplier?
The main purpose of the multiplier is to limit the current through the movement so that the current does not exceed the full scale deflection current.
9.What is meant by full scale deflection current?
Full scale deflection current is defined as the amount of current required to deflect the basic meter to full scale.
10.What are the factors in choosing an analog voltmeter?
a)input impedance,
b)Voltage ranges,
c)Decibels,
d)Sensitivity versus bandwidth,
e)Battery operation
11.What are the general requirements of a shunt?
` a) The temperature coeff of the shunt and instrument should be low.
b)The resistance of the shunt should not vary with time.
c)It should have a low thermal emf.
12.Define Q meter?
Q meter is defined as the power dissipated in the element to the power stored in the element.
13.What is the principle operation of Q meter?
The operation is based on the characteristics of a series resonant circuit.
The voltage across the capacitor or the coil is equal to the applied voltage times the Q of the circuit.
14.What is a vector voltmeter?
A vector voltmeter measures the amplitude of a signal at two points in a circuit and simultaneously measures the phase difference between the voltage waveforms at these points.
15.List the applications of vector voltmeter?
a)Insertion loss
b)Filter transfer functions
16.Write the components of a vector voltmeter?
a)Two RF to IF converters
b)Automatic phase control unit
c)Phase meter circuit
d)Voltmeter circuit
17.Where can we use decibels?
For measurements covering a wide range of voltages , the use of the decibels can be very effective.
18.Define current ratio?
It is defined as the ratio of primary current to the secondary current.
19. What is Digital Panel Meter (DPM)?’
Digital Panel Meters are available in a wide variety of special purpose functions. They have a readout range from the basic 3 digit (999 counts) to high precision 43/4 digit ones. They accept inputs like dc voltage, line voltage, strain gauge bridges, RTDs, thermocouples and frequency inputs.
20. What is the principle of digital frequency meter?
The signal whose frequency is to be measured is converted into a train of pulses, one pulse for each cycle of the signal. The number of pulses occurring in a definite interval of time is then counted by an electronic counter. Since each pulse represents the cycle of the unknown signal, the number of counts is a direct indication of the frequency of the signal.
21. What is ratio and multiple ratio measurement?
The ratio measurement involves the measurement of the ratio of two frequencies. The measurement method used is a period measurement. In multiple ratio measurements the period of the low frequency signal is extended by a factor of 10, 100 etc by using DDAs.
22. What is the purpose of IEEE 488 bus?
The purpose of IEEE488 bus is to provide interfacing between programmable instruments. There are many instrumentation systems in which interactive instruments, under the command of a central controller, provide superior error-free results when compared with conventional manually operated systems.
2 Marks Questions and answers
UNIT-I
1. Define Ayrton shunt or universal shunt?
The universal or ayrton shunt eliminates the possibility of having the meter in the circuit with a shunt. The advantage is gained at the price of a slightly higher overall meter resistance.
2. What is a true RMS responding voltmeter?
Complex waveforms are most accurately measured with an rms-responding voltmeter. This instrument produces a meter indication by sensing waveform heating power, which is proportional to the square of the rms value of the voltage.
3. What are the sources of error in a Q meter?
i) Due to the distributed capacitance or self capacitance Cd
ii) Due to insertion resistor,
iii) Due to self inductance
iv)Conductance of the Q meter.
4. What is a vector impedance meter?
Vector impedance meter makes simultaneous measurements of impedance and phase angle. The magnitude of the impedance is determined measuring the current through the unknown component when a known voltage is applied across it, or by measuring the voltage across the component when a known current is passed through it. The phase angle is found by determining the phase difference between the voltage across the component and the current through the component.
5. What is a power meter?
The electrodynamometer is used extensively used in measuring power. It is used to indicate both dc and ac power for any waveform of voltage and current and it is not restricted to sinusoidal waveforms.
6. State the prime advantage of peak responding voltmeter?
When no ac pre-amplification is required the rectifying diode and the storage capacitor may be taken out of the instrument and placed in the probe.
7.What is meant by basic meter?
The motor action is produced by the flow of a small amount of current through a moving coil which is positioned in a permanent magnetic field.
8.What is the main purpose of the multiplier?
The main purpose of the multiplier is to limit the current through the movement so that the current does not exceed the full scale deflection current.
9.What is meant by full scale deflection current?
Full scale deflection current is defined as the amount of current required to deflect the basic meter to full scale.
10.What are the factors in choosing an analog voltmeter?
a)input impedance,
b)Voltage ranges,
c)Decibels,
d)Sensitivity versus bandwidth,
e)Battery operation
11.What are the general requirements of a shunt?
` a) The temperature coeff of the shunt and instrument should be low.
b)The resistance of the shunt should not vary with time.
c)It should have a low thermal emf.
12.Define Q meter?
Q meter is defined as the power dissipated in the element to the power stored in the element.
13.What is the principle operation of Q meter?
The operation is based on the characteristics of a series resonant circuit.
The voltage across the capacitor or the coil is equal to the applied voltage times the Q of the circuit.
14.What is a vector voltmeter?
A vector voltmeter measures the amplitude of a signal at two points in a circuit and simultaneously measures the phase difference between the voltage waveforms at these points.
15.List the applications of vector voltmeter?
a)Insertion loss
b)Filter transfer functions
16.Write the components of a vector voltmeter?
a)Two RF to IF converters
b)Automatic phase control unit
c)Phase meter circuit
d)Voltmeter circuit
17.Where can we use decibels?
For measurements covering a wide range of voltages , the use of the decibels can be very effective.
18.Define current ratio?
It is defined as the ratio of primary current to the secondary current.
19. What is Digital Panel Meter (DPM)?’
Digital Panel Meters are available in a wide variety of special purpose functions. They have a readout range from the basic 3 digit (999 counts) to high precision 43/4 digit ones. They accept inputs like dc voltage, line voltage, strain gauge bridges, RTDs, thermocouples and frequency inputs.
20. What is the principle of digital frequency meter?
The signal whose frequency is to be measured is converted into a train of pulses, one pulse for each cycle of the signal. The number of pulses occurring in a definite interval of time is then counted by an electronic counter. Since each pulse represents the cycle of the unknown signal, the number of counts is a direct indication of the frequency of the signal.
21. What is ratio and multiple ratio measurement?
The ratio measurement involves the measurement of the ratio of two frequencies. The measurement method used is a period measurement. In multiple ratio measurements the period of the low frequency signal is extended by a factor of 10, 100 etc by using DDAs.
22. What is the purpose of IEEE 488 bus?
The purpose of IEEE488 bus is to provide interfacing between programmable instruments. There are many instrumentation systems in which interactive instruments, under the command of a central controller, provide superior error-free results when compared with conventional manually operated systems.
EI1302 (2 MARKS) UNIT II
ELECTRONIC AND INSTRUMENTATION
UNIT II
1. What is signal generator?
It is an instrument which provides several different output waveforms including sine wave, square wave, triangular wave,
2. What are the requirements of signal generator?
The requirement of signal generator is,
a) The output frequency of signal generator should be very stable
b) The amplitude of the output signal must be stable.
3 .What are the advantages of standard signal generator?
The advantages are,
a)The output is stable
b)The output voltage can be controlled according to the requirement.
4. Define duty cycle?
Duty cycle is defined as the ratio of average value of a pulse over one cycle to peak value.
5.Define risetime and fall time?
Rise time is the time required for the pulse to increase from 10% to 90% of its normal amplitude.
Fall time is the time required for the pulse to decrease from 90% to 10% of its maximum amplitude.
6.What are the requirements of pulse generator?
a)The pulse should have minimum distortion,
b)The pulse generator can be used to trigger pulses.
7.Define wave analyzer and name its types?
A wave analyzer is an instrument designed to measure the relative amplitudes of single frequency components in a complex or distorted waveform.
Its types are,
a)Frequency selective wave analyzer
b)Heterodyne wave analyzer
8.What is the principle of heterodyne wave analyzer?
It is a RF range analyzer works on the principle of mixing. In this type wave analyzer, the input signal is heterodyned to a higher intermediate frequency by an internal local oscillator.
9.Name the applications of wave analyzer?
Wave analyzer is used in
a)Fields of electrical measurement and sound,
b)Vibration analysis
10.What is spectrum analyzer?
Spectrum analyzer is an instrument which graphically provides energy distribution of a signal as a function of the frequency on its CRT.
11.What is meant by harmonic distortion?
The distortion caused due to non-linear behaviour of the circuit elements is called harmonic distortion.
12.What are the advantages of harmonic distortion analyzer?
a)The harmonic distortion generated within the instrument itself which may cause in total harmonic distortion measurement is very small and neglected.
b)The selectivity requirements are not severe because only the fundamental frequency component must be suppressed.
13.Write the advantages of audio frequency signal generator?
a)Stable and simple operation,
b)Low distortion,
c)Good amplitude stability
14. What is pulse preshoot?
The pulse pre shoot is the deviation prior to reaching the base line at the start of the pulse.
15.What is ringing?
Ringing is the positive and negative distortion excluding overshoot.
16.What is pulse repetition rate?
The pulse repetition rate is the reciprocal of pulse period and it is measured in termed in units of frequency.
17.What are the advantages of wide band sweep generator?
a)Very popularity used to determine the frequency response of the amplifiers and other systems.
b)A wide range of frequencies can be generated.
18.What is meant by settling time?
Settling time is the period needed for pulse ringing to be within a specified percentage if the pulse amplitude, measured from 90% point of the leading edge.
19.Define pulse drop or sag?
Sag is defined as the fall in pulse amplitude within time. Pulse rounding is the curved portion of the pulse at the leading and trailing edge.
20.What is meant by linearity?
Linearity of the pulse is the deviation of the edge from the straight line drawn through the10% and 90% points expressed as percentage of amplitude of pulse.
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