Electronic Instrumentation (EI 333)
Unit -I
1. Draw the pin out A connection diagram of Quad 2-input NAND gate
2. What is the input loading/ fan-out value of the input and output of 54/74s (U.L.)
high / low
input: 1.25 / 1.25
output: 25 / 12.5
3. What is the range over which the DC and AC units can be applied in a Quad 2input NAND gate ?
DC limits: apply over operating temperature range
AC units: Apply at TA= +25C and Vcc=+5.0V
4. What are the various package types in which the Hex inverter is available ?
Packages
Plastic DIP(P)
Ceramic DIP(D)
Flatpak(F)
Package name
9A
6A
31
5. What is the propagation delay of 54/74S Hex inverter?
The propagation delay of 54/74S Hex inverter is given as
Minimum value: 1.0
Maximum value: 3.5
6. Give the military grade for Hex inverter wit open collector output
Vcc= +5.0V10%
TA= -55C to +125C
7. Draw the connection diagram of 54/7406{Hex inverter Buffer/ driver with open
collector, high voltage output}
8. Write some of the DC and AC characteristics of Hex Schmitt Trigger inverter.
Symbol
VT-
54/74
Max Min
Negative going 0.6
1.1
Parameters
54/74LS
Max Min
0.6
1.1
Unit
Conditions
V
Vcc=+5V
Vcc=+5V
threshold
voltage
VT+ - VT-
Hystersis
voltage
IIL
ICCH
ICCL
Input
Current
0.4
V
Vcc=+5V
-1.2
-0.4
mA
36
16
mA
60
21
Vcc=+5V,
Vin= VTVin=gnd,
Vcc=max,
Vin=open
22
22
low
Power Supply
Current
IPLH
IPHL
0.4
Propagation
Delay
nsec
22`
22
9. Draw the pint out B connection diagram of Dual $-input NAND gate
10. What are the absolute maximum ratings over operating, free air temperature range
for Dual 4 input positive NAND gate?
Supply voltage: Vcc=7V
Input voltage: 7V
Operating free air temperature range:
SN54ALS20A: -55C to 25C
SN74ALS20A: 0C to 70C
Storage temperature range: -65C to 150C
11. Write about Dual 4 input positive NAND gates:
-
these devices contain 2 independent 4 input NAND gates.
they perform Boolean functions Y=(ABCD)’ or Y=A’+B’+C’+D’ in
positive logic.
The SN74HC20 is characterized for operation -40C to 85C.
The SN54HC20 is characterized for operation over the full military
temperature range of -55 C to 25 C.
12. Truth table for Dual JK negative edge triggered flip-flop.
Inputs
@ tn
J
K
Outputs
@ tn+1
Q
0
0
1
1
0
1
0
1
Qn
0
1
Qn’
13. Write a note on monostable multivibrator( 54/74121)
The 121 features positive and negative level triggering inputs and complimentary
outputs. Input pin 5 directly activates the Schmitt circuit, which provides temperature
compensated level direction, increases immunity to positive going noise and assures
jitter free response to slowly rising triggers.
When triggering occurs, internal feed back latches the circuit, prevents re-triggering
while the input pulse is in progress and increases immunity to negative going noise.
Noise immunity is typically 1.2 V at input and 1.5V at Vcc.
Maximum duty cycle capability ranges from 67% with 2k resistor to 90% with a
40k resistor. Duty cycles beyond this range tend to reduce output pulse width.
Otherwise, output pulse width follows the relationship Tw=0.69RxCx.
14. Write a short note on digital up/down counter with separate up/down clocks?
(54/74193,54LS/74LS193)
The ‘193 is up/down module – 16 binary counter. Separate counter and count
down clocks are used and in either counting mode, the circuits operate
synchronously. The output change state synchronous with the low to high
transitions on the clock inputs. Separate terminal count up and terminal count
down outputs are provided, which are used as the clocks for subsequent stage
without extra logic, thus simplifying multistage counter designs. Botht the parallel
load(PL) and the master reset(MR) inputs asynchronously override the clocks.
15. What are the 4 distinct modes of operation in the 4 bit bi-directional universal
shift registry?
-
Inhibit clock( do nothing).
Shift right(in the direction QA towards QD)
Shift left(in the direction QD towards QA)
Parallel(broad side) load.
16. What do you know about timer 555?
The NE/SE 555 monolithic timing circuit is a high stable controller capable of
producing accurate time delays or oscillation. Additional terminals are provided
for triggering or resetting. For a stable operation as an oscillator, the free running
frequency and duty cycle are both accurately controlled with 2 external resistors
and 1 capacitor.
17. What is frequency compensated operational amplifier?
The frequency compensated operational amplifier(A741) is a high performance
monolithic operational amplifier constructed using the FAIRCHILD Planner
epitaxial process. It is intended for a wide range of analog applications.
18. Name the factors that makes the A741 ideal for use as a voltage follower.
High common mode voltage range and absence of latch up tendencies make the
A741 ideal for use as a voltage follower.
19. What are the features(advantages) of A741?
No need of frequency compensation.
Short circuit protection.
Offset voltage null capability.
Large common mode and differential voltage ranges.
Low power consumption.
No latch up.
20. Draw the pin diagram of timer 555:
T package
V package
21. Explain about the mode of operation of timer 555 IC.
In the time delay mode of operation, the time is precisely controlled by 1 external
resistor and capacitor. For a stable operation as an oscillator, the free running
frequency and duty cycle are both accurately controlled with 2 external resistors
and 1 capacitor.
22. What are the features of timer 555
Timing from micro seconds through hours.
-
Operates in both astable and monostable modes.
Adjustable duty cycle.
High current output can source or sink 200mA.
Output can drive TTL.
Temperature stability of 0.005% / C.
Normally on and normally off output.
23. What are the application of 555 IC.
precision timing.
pulse generation.
Sequential timing.
Time delay generation.
Pulse width modulation.
Pulse position modulation.
Missing pulse detector.
Are some of the applications of timer 555.
24. Write the absolute maximum ratings of timer 555 IC.
supply voltage: 18V
power dissipation: 600mW.
Operating temperature range
NE555: 0C to 70C
SE555:-55C to 125C
Storage temperature range: -65C to 150C
Lead temperature(soldering,60secs):+300C.
25. Write the absolute maximum ratings of A741.
Supply voltage
A741A, A741, A741E: 22V
A741C:  18V
Differential input voltage: 30V
Input voltage: 15V
Output short circuit duration: indefinite
Pin temperature(soldering)
Metal can, Hermetic DIPS and flat PAK(60secs): 300C
Molded DIPS(10secs): 260C
operating temperature range:
military(A741A, A741): -55C to 125C
commercial(A741E, A741C): 0C to 70C
Electronic Instrumentation-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 nonviewed 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.cathoderay 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 incoherent 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=IR
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
Electronic Instrumentation-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<Vref then the control circuit will reset that particular bit,such a
kind of measurement is completed in 8-clock pulses.
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?




Prescaling
Hetrodyne converter
Transfer oscillator
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:
 Split-screen capability.
 Pre-trigger capability
 Display the stored data in amplitude Vs time period and X-Y
mode are possible.
Limitations:
 Band-width limitations.
Electronic Instrumentation-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
The has twisted numatic structure is that 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
Here cathode and anode
arrangement is used


Gas is used for discharge


Display is in orange color

Incandescent display
They have 7 segment filaments
contain with in a single vacuum
envelope
Instead of neon gas ,vacuum is
present
Display is in any color accord to
our requirement
(18) Difference between X-Y & digital recorders?


Analog X-Y
Servo motor is used
No different color outputs are obtain

Instantaneous relationship between
2 physical quantities can be
recorded
(19) Difference between LCD & LED?


LED
It is a active device that generates
light
PN junction diodes mode of
galliumarsinide phospide





Digital X-Y
Stepper motor is used
Record no of input simultaneously
with different color
It can record or draw grids axis
LCD
It is a passive device that modified
the light by scattering
In twisted neamutaic display the
LCD is sandwiched between 2 pies
of glass
(20) Difference between seven segment & dot matrix display?
Seven segment display
It is used for numeric display
Dot matrix display

 It is used for numeric & alpha
numeric characters
 A segmental display form the digit
 Various matrix display digit to be
to be displayed
displayed
(21) Difference between single point & multipoint recorders?



Single point recorders
Recording single input only
It is recording with respect to time
only
The trace of curve is single
continuous curve



Multi point recorders
Recording several inputs
It recorders variable quantities with
respect to another variable quantity
The trace of curve are multi curves
not in continuous