University of Mosul
College: Electronic Eng.
Dept.: Communication Eng.
( Third ) Class
Final Exam.
Time: 3 Hours
Date: 12 / 6 / 2010
Lecturer:Mohannad Najeb
Subject: Elect. Instrumentation
Code: EECM10F3062
Answer all questions :
Q 1 : A : For the instrumentation amplifier shown below, the parameters are : ( R3 = R4 = 20 KΩ )
and ( R2 = 100 KΩ ). Resistance ( R1 ) is a series combination of a fixed resistance of ( 1 KΩ )
and a ( 50 KΩ ) potentiometer. Determine the range of the closed loop gain ?
( 4 marks )
B :Describe the following abbreviations : ( Briefly ) ?
DCE , LVDT , IMRR , UART , IRED , GP-IB .
( 6 marks )
-----------------------------------------------------------------------------------------------------------------------------Q 2 : A: A thermistor has a resistance of (4000 Ω ) at the ice point and (800 Ω ) at ( 60 ̊ C ).
Calculate the constants ( a ) and ( b ). Compute the range of resistance to be measured in case
the temperature varies from ( 50 ̊ C ) to ( 100 ̊ C ) ?
( 6 marks )
B :In any frequency counter there are an input signal processing circuit . Describe the circuit
with the aid of schematic diagram ?
( 4 marks )
-----------------------------------------------------------------------------------------------------------------------------Q 3 : A : Tabulate the major differences between parallel and serial data transmission ?
( 5 marks )
B : Sketch a diagram showing the general interface connection and the bus structure of
the ( HP-IB / IEEE-488 ) ?
( 5 marks )
----------------------------------------------------------------------------------------------------------------------------Q 4 : A: Using 5-bit successive approximation A/D convertor with ( 15 V ) reference voltage .
Find the converted output voltage if the applied input voltage is ( 13.65 V ) ?
( 5 marks )
B : Explain the function of the ( IF filter ) in any spectrum analyzer with its effect on the
displayed signal on the screen ?
( 5 marks )
Q 5 : A: In the Wheatstone bridge shown below , with values of bridge elements as follows :
( R1 = 50 Ω , R2 = 500 Ω , R3 = 100 Ω , R4 = 1005 Ω ) . The battery voltage is ( 5 V ) with
neglected internal resistance . The galvanometer has a current sensitivity of ( 20 mm / μ A )
with ( 100 Ω ) internal resistance . Calculate the deflection of the galvanometer caused by
the ( 5 Ω ) unbalance in arm ( bd ) ?
( 6 marks )
B: Explain with the aid of a block diagram the automatic test system to analyze an audio
amplifier ?
( 4 marks )
-----------------------------------------------------------------------------------------------------------------------------Q 6 : Select the more suitable answer for the following sentences :
( Note : Write only the suitable letter clearly , any misleading answer will be neglected ).
( 2 marks for each )
1- An RTD
a- produces a change in resistance for a change in temperature .
b- has a negative temperature coefficient .
c- has a positive temperature coefficient .
d- has a wider temperature range than a thermocouple .
e- answer ( a ) , ( b ) and ( d ) .
f- answer ( a ) , ( c ) and ( d ).
2- In a dual slope digital voltmeter , as the input voltage to be measured increased , the
conversion time is :
a- decreased .
b- increased .
c- remain constant .
c- no relation .
3- The smallest change in a measured value to which the instrument will respond is referred to :
a- resolution .
b- precision .
d- accuracy .
d- sensitivity .
4- The highest speed A/D conversions are made with :
a- counting ADC .
b- flash ADC .
c- successive approximation ADC .
5- The measurement of frequency can be achieved using :
a- Kelvin bridge .
b- Maxwell bridge .
c- Wien bridge .
d- Wheatstone bridge .
University of Mosul
College: Electronic Eng.
Dept.: Communication Eng.
( Third ) Class
Final Exam.
Time: 3 Hours
Date: 12 / 6 / 2011
Lecturer:Mohannad Najeb
Subject: Elect. Instrumentation
Code: EECM11F3062
Answer all questions:Q 1 : A : For the balanced Wheatstone bridge shown below, calculate the value of the unknown
impedance ( Zx )?
( 5 marks )
B : With the aid of a block diagram explain the basic principle and operation of an electronic
frequency counter?
( 5 marks )
--------------------------------------------------------------------------------------------------------------------------Q 2 : A: Suppose you tried to measure the voltage at all three test points with an analog voltmeter
having a sensitivity rating of 20 kΩ/V, set on the 10 volt scale. How much voltage would it
indicate at each test point? How much voltage should it ideally indicate at each test point?
( 5 marks )
B : Describe the input and output transducers that are used for wireless data communication?
( in details with its block diagrams ).
( 5 marks )
-----------------------------------------------------------------------------------------------------------------------------Q 3 : A : A thermocouple produce an e.m.f. equals (10) mV when the measuring head is kept in ice.
Calculate the temperature at the sensor tip, knowing that ( a=3.5x10-2 , b=8.2x10-6 )?
( 5 marks )
B : What are the handshake signals in the IEEE-488 bus system ? How the handshaking between
devices are achieved ? Explain by drawing the timing relationship of signals.
( 5 marks )
Q 4 : A: A dc current of (2)A is measured by analog and digital ammeter. The analog one is on its
(10)A range with a (±1%) accuracy, while the digital one has a (3½) digit display and an
accuracy of ±(0.5+1). Determine the reading accuracy in each case ?
( 5 marks )
B : Isolation technology is considered as one of the signal conditioning function. Describe
it with the advantages . State the hazardous voltages ?
( 5 marks )
-----------------------------------------------------------------------------------------------------------------------------Q 5 : A: What are the functions of the computer in any based system?
Explain and draw a block diagram for the computer based system.
( 5 marks )
B: A meter movement has an internal resistance of (100)Ω and requires (1)mA dc for full scale
deflection. Shunting resistance Rsh=100Ω placed across the movement. Half-wave rectification
with D1 and D2 forward resistance (400)Ω each and infinite resistance in the reverse direction.
For a (10-V) ac range,calculate : (a) the value of the multiplier Rs.
(b) the voltmeter sensitivity on the ac range.
( 5 marks )
-----------------------------------------------------------------------------------------------------------------------------Q 6 : Select the more suitable answer for the following sentences :
( Note : Write only the suitable letter clearly , any misleading answer will be discarded ).
( 2 marks for each )
1 – A 100 V voltmeter has full-scale accuracy of 5%. At its reading of (50) V will give an error of:
(a) 10%
(b) 5%
(c) 2.5%
(d) 1.25%
2 - A moving coil permanent magnet ammeter can be used to measure:
(a) D.C. current only
(b) A.C. current only
(d) voltage by incorporating a shunt resistance
(c) A.C. and D.C. currents
(e) none of these
3 – In CRT the focusing anode is located :
(a) between pre-accelerating and accelerating anodes
(b) after accelerating anodes
(c) before pre-accelerating anodes
(d) none of above
4 – The level of the input signal displayed on the spectrum analyzer screen can be controlled by:
(a) IF filter
(c) RF input attenuator
(e) both (b) and (c)
(b) IF gain
(d) both (a) and (b)
(f) both (a) and (c)
5 – The effect of outer magnetic field surrounding the measurement devices can be considered as:
(a)
(c) gross error
random error
(b) systematic error
(d) instrumental error.
University of Mosul
College: Electronic Eng.
Dept.: Communication Eng.
( Third ) Class
Subject: Elect. Instrumentation
Answer all questions:-
Final Exam.
Time: 3 Hours
Date: 30 / 5 / 2012
Lecturer:Mohannad Najeb
Code: EECE12F33052
Q 1 : A : An emitter follower transistor with current gain 150 and base emitter voltage 0.7 V is used
in transistor voltmeter. Determine the value of the series resistance Rs that should be used to
arrange the meter whose resistance Rm= 100 Ω to measure input voltage Vin= 2.7 V with input
resistance Rin=100 KΩ.
( 5 marks )
B : With the aid of timing diagram, explain the hand shaking process between two devices
( talker and listener ) through the GP-IB ?
( 5 marks )
--------------------------------------------------------------------------------------------------------------------------Q 2 : A: The circuit shown below is an ammeter-voltmeter method used to measure the value
of unknown resistance. Given: internal resistance of the voltmeter, Rv =125 KΩ, and a
Negligible ammeter resistance, the reading of voltmeter and ammeter were:
180 V , 6 mA respectively. Calculate :
1- The apparent resistance.
2- The actual resistance.
3- The percentage loading error.
( 5 marks )
B : In a Maxwell bridge, given Z1 is a parallel combination of a resistor of value ( 0.2 )KΩ and a
capacitor of value ( 5 )µF, Z2 = 0.5 KΩ , Z3 = 0.4 KΩ and Z4 is the series combination of a
resistor of value ( 1 )KΩ and an inductor of value ( 1 )H. The bridge is operated at
ω = 1000 rad/s sinusoidal source. Is the bridge balanced?
( 5 marks )
-----------------------------------------------------------------------------------------------------------------------------Q 3 : A: An analog and digital multimeters were used to measure a 15 A dc. The analog instrument on
its 20 A range, and its specified error is ± 2.5%. The digital meter has 3½ digit display with error
±(0.7+1). Determine the percentage error in each case. Which meter is more accurate?
( 5 marks )
B: What does the isolation amplifier provide? Describe the general construction. (Briefly).
Mention its types only.
( 5 marks )
-----------------------------------------------------------------------------------------------------------------------------Q 4 : A : Draw a complete block diagram for two of the following instruments:
1- Ramp – type DVM.
2- Universal frequency counter.
3- Swept frequency spectrum analyzer.
( 5 marks )
B : Specify the types of instruments that are used for signal analysis. (Briefly)
( 5 marks )
-----------------------------------------------------------------------------------------------------------------------------Q 5 : A: A strain gauge is bonded to a beam which is 12 cm long and has a cross-sectional area of
3.8 cm2. The unstrained resistance and gauge factor of the strain gauge are 220 Ω and 2.2
respectively. On the application of load the resistance of the gauge changes by 0.015 Ω.
If the modulus of elasticity for steel is 207 GN/m2, calculate:
1- The change in length of the steel beam.
2- The amount of force applied to the beam.
( 5 marks )
B :Classify the following transducers as they are ( input or output, passive or active, analog
or digital ).
Thermocouple , LVDT , IRED , Ultrasonic receiver , Tacho generator.
( 5 marks )
-----------------------------------------------------------------------------------------------------------------------------Q 6 : Select the more suitable answer for the following sentences :
( Note : Write only the suitable letter clearly , any misleading answer will be neglected ).
( 2 marks for each )
1 – The allowed voltages in RS-232 are:
(a) Logic 1 > +3V and logic 0 < -3V.
(c) Logic 1 < -15V and logic 0> +15V.
(b) Logic 1 < -3V and logic 0 > +3V.
(d) Logic 1 > +15V and logic 0 < -15V.
2 - A voltmeter has 100 divisions on 0-100V range. One tenth of each division can be read with
certainty. The resolution of the meter is:
(a) 0.1 V
(b) 0.01 V
(c) 1.0 V
(d) 1.01 V
(e) none of these .
3 – A moving current ammeter has a fixed shunt of (0.02)Ω resistance. If the coil resistance of the
meter is (1000)Ω, a potential difference of (500)mV is required across it for full deflection.
Under this condition, the current in shunt branch would be:
(a) 2.5 A
(b) 0.25 A
(c) 25 A
(d) 0.025 A
4 – Frequency can be measured using:
(a) Maxwell bridge.
(c) Kelvin bridge.
(b) Wheatstone bridge.
(d) Wien bridge.
5 – The principle of operation of LVDT is based on variation of:
(a) Self inductance.
(b) Reluctance.
(c) Mutual inductance.
(d) Permeance.
University of Mosul
College: Electronic Eng.
Dept.: Communication Eng.
( Third ) Class
Final Exam. (3rd Attempt)
Time: 3 Hours
Date: 15 / 10 / 2012
Lecturer:Mohannad Najeb
Subject: Elect. Instrumentation
Code: EECE12G33052
Answer all questions:Q 1 : A : The four arms of a Maxwell’s capacitance bridge at balance are:
arm ab, an unknown inductance L1, having an inherent resistance R1; arm bc, a non inductive resistance of ( 1000 ) Ω ; arm cd, a capacitor of ( 0.5 ) F in parallel with a
resistance of ( 1000 ) Ω; arm da, a resistance of ( 1000 ) Ω. Derive the equations of balance for
the bridge and determine the value of R1 and L1.
( 6 marks )
B : In order to achieve any measurement process , the process should have several items,
Specify them ?
( 4 marks )
--------------------------------------------------------------------------------------------------------------------------Q 2 : A: Define the circuit shown below? State its operation , then sketch the waveforms for both
input ( Vc ) and output ( Vout ) of the amplifier.
( 5 marks )
B : Draw a complete block diagram showing the major components in a spectrum analyzer?
( 5 marks )
-----------------------------------------------------------------------------------------------------------------------------Q 3 : A : A ( 25 ) mA full-scale current meter with an internal resistance of ( 100 )Ω is available for
constructing an ac voltmeter with a voltage range of ( 200 )Vrms . Using four diodes in a
bridge arrangement , where each diode has forward resistance of ( 500 )Ω and an infinite
reverse resistance . Draw the circuit diagram then calculate :
1- The necessary series-limiting resistance for the ( 200 )Vrms range?
2- The dc and the ac sensitivities?
3- The average or dc voltage for the input ( 200 )Vrms ?
( 5 marks )
B : Explain the principle of operation of the Fourier- transform spectrum analyzer.
( 5 marks )
-----------------------------------------------------------------------------------------------------------------------------Q4:A:
( 5 marks )
B : Describe the IEEE-488 (HP-IB) devices according to their behavior or operation in
the system ? Give an example of each device
( 5 marks )
Q 5 : A: What is the duty of the time base in a frequency counter ? What it provides?
Draw a block diagram for a simple frequency counter.
( 4 marks )
B:
.
( 4 marks )
-----------------------------------------------------------------------------------------------------------------------------Q 6 : Select the more suitable answer for the following sentences :
( Note : Write only the suitable letter clearly , any misleading answer will be neglected ).
( 2 marks for each )
1 – The effect of surrounding magnetic field on measurement devices can be considered as :
a) Random error
b) Systematic error
c) Gross error
d) Instrumental error
2 – If the spectrum of the measured signal and the noise were both overlapped. The required signal
conditioning technique to be applied to separate them is :
a) Filtering
b) Averaging
c) Modulation
d) Autocorrelation
3 – The three handshaking lines which control the passage of data in IEEE-488 interface bus are :
a) DAV , SRQ and REN
c) NDAC , DAV and EOI
b) NRFD , DAV and ATN
d) DAV , NRFD and NDAC
4 – In a 3½ digit voltmeter, the largest number that can read is :
a) 0999
b) 1999
c) 4999
d) 9999
5 – A sinusoidal voltage of rms value 10 V is applied to a D`Arsonval movement connected in
series with a half-wave rectifier. It will show a reading of :
a) 9 V
b) 10 V
c) 4.5 V
d) 7.7 V
University of Mosul
College: Electronic Eng.
Dept.: Communication Eng.
( Third ) Class
2nd Final Exam.
Time: 3 Hours
Date: 15 / 9 / 2011
Lecturer:Mohannad Najeb
Subject: Elect. Instrumentation
Code: EECM11G3062
Answer all questions:Q 1 : A : In the full wave rectifier circuit using d`Arsonval meter shown below, with the following
parameters Ein=10 Vrms , Rsh=500Ω , Rm=500Ω , Ifs=1mA and diode forward resistance
( Rd=50Ω ) . Calculate:
1- The value of the multiplier ( Rs ).
2- The a.c. sensitivity.
3- The d.c. sensitivity.
( 5 marks )
B : Draw a complete block diagram for a temperature measurement system specifying all the
elements of the system?
( 5 marks )
--------------------------------------------------------------------------------------------------------------------------Q 2 : A: For the circuit shown below, calculate:
1- The actual value of (VRB)?
2- The measured value of ( VRB ) if the voltmeter used has an internal resistance Rm=10 KΩ?
3- The percentage error in voltage value due to loading effect of the voltmeter?
( 5 marks )
B : What are the advantages of the statistical analysis in a measurement process?
How it can be performed? State briefly its processes?
( 5 marks )
-----------------------------------------------------------------------------------------------------------------------------Q 3 : A : For an ideal 8-bit A/D converter with reference voltage (5) volt. Find the peak input voltage
if the SNR of the digitized output signal is (70) dB?
( 4 marks )
B : Calculate the common mode gain (in dB) for an operational amplifier having AVD=80 dB
and CMRR=60 dB.
( 3 marks )
C : A (2)A full scale PMMC type DC ammeter has a voltage drop of (100)mV at (2)A.
Describe how you can convert this meter into a (10)A full scale DC ammeter?
( 3 marks )
----------------------------------------------------------------------------------------------------------------------------Q 4 : Describe the following terms :(Briefly)
1- Guarantee errors.
2- Cable fault locator instrument.
3- IF filter function in the spectrum analyzer.
4- The advantages of oscilloscope probes.
5- Linearization as one of the signal conditioning functions.
( 10 marks )
-----------------------------------------------------------------------------------------------------------------------------Q 5 : A: A voltage of ( 8 ) Volt is to be measured using a dual slope digital voltmeter. Find the total
Conversion time of the meter knowing that the internal A/D converter has ( 12 ) Volt reference
Voltage and ( 15 ) msec constant integration time?
( 4 marks )
B: In a strain gauge transducer, the change in wire resistance is measured by means of Wheatstone
bridge. Draw its circuit diagram then derive the equation of the output voltage.
( 6 marks )
-----------------------------------------------------------------------------------------------------------------------------Q 6 : Select the more suitable answer for the following sentences :
( Note : Write only the suitable letter clearly , any misleading answer will be neglected).
( 2 marks for each )
1- The closeness with which an instrument reading approaches the true value of the variable being
measured is referred to it's:
(a) Sensitivity.
(b) Accuracy.
(c) Resolution.
(d) Precision.
2- The basic components of a digital voltmeter are:
(a) A/D converter and a counter.
(c) D/A converter and a counter.
(b) A/D converted and a rectifier.
(d) Ramp generator and counter.
3- The temperature coefficient of the thermocouple transducer is:
(a) Positive.
(b) Negative.
(c) Depends on the combination of the metal used.
4- Frequency can be measured using:
(a) Maxwell bridge.
(c) Kelvin bridge.
(b) Wheatstone bridge.
(d) Wien bridge.
5- A d.c. voltmeter has sensitivity of (1000) ohm/volt. When it measures half full scale in (100) V
range, the current through the voltmeter is:
(a) 100 mA.
(b) 1 mA.
(c) 0.5 mA.
(d) 50 mA.
University of Mosul
College: Electronic Eng.
Dept.: Communication Eng.
( Third ) Class
Final Exam. / 2nd Attempt
Time: 3 Hours
Date: 21 / 9 / 2010
Lecturer:Mohannad Najeb
Subject: Elect. Instrumentation
Code: EECM10G3062
Answer all questions :
Q 1 : A : The Voltmeter – Ammeter method was used to measure the value of a resistor. The voltmeter
reading was ( 115 )V on the ( 200 ) V scale, and the ammeter reading was ( 24 ) mA on the
( 50 ) mA scale . Both meters were guaranteed to be accurate within ( ±2 ) percent of full scale
deflection .
Calculate : 1- The indicated value of the resistor ?
2- The limits within which you can guarantee the results ?
( 5 marks )
B :Describe the following abbreviations :
RS-232 , CRT , DAC , VCO , RVDT .
( 5 marks )
-----------------------------------------------------------------------------------------------------------------------------Q 2 : A: Given a square wave oscillator with input capacitor ( 1 ) μF and a feedback resistor ( 10 ) kΩ.
Determine the frequency of oscillation , pulse period , pulse width and duty cycle ?
( 6 marks )
B :In Murray loop test , the fault was located at a distance of (1350) m far away from the
instrument. The Wheatstone bridge was in equilibrium with R1=200 Ω , and R2=400 Ω .
Find the length of the tested cable ?
( 4 marks )
-----------------------------------------------------------------------------------------------------------------------------Q 3 : A : A parallel plate capacitive transducer uses plates of (500)m2 area and (0.2)mm separation between
them. Calculate :
1- The value of the capacitance when the dielectric is air . ( permittivity = 8.85x10-12 F/m)
2- The change in capacitance if a linear displacement reduces the distance between the plates
to (0.18) mm.
3- The ratio of per unit change of capacitance to per unit change of displacement.
( 6 marks )
B : Draw a block diagram for an angular velocity measurement system . Specify all the
elements of the measurement system on the diagram ?
( 4 marks )
----------------------------------------------------------------------------------------------------------------------------Q 4 : A: An ideal 8-bit A/D converter with (Vref = 5 V) is used to convert a (150)mVp sinusoidal
signal . Determine signal to noise ratio of the digitized output?
( 4 marks )
B : Given a sensor signal with ( 0 – 100 ) Hz bandwidth , explain in details ( with diagrams )
how the modulation can be used to eliminate the effect of ( 50 ) Hz noise ?
( 6 marks )
Q 5 : A: Determine the different range values of this multi-range voltmeter ?
( 6 marks )
B: Sketch a block diagram showing the elements of a computer based instrumentation ?
( 4 marks )
-----------------------------------------------------------------------------------------------------------------------------Q 6 : Select the more suitable answer for the following sentences :
( Note : Write only the suitable letter clearly , any misleading answer will be neglected ).
( 2 marks for each )
1- The span from the smallest to the largest detected measured value is referred to :
a- Resolution
b- Accuracy
c- Dynamic range
d- Sample rate
2- The type of amplifier used to amplify small signals that are riding on large common mode
voltages is :
a- Isolation amplifier
b- Instrumentation amplifier
c- Operation amplifier
d- Current mode amplifier
3- In any measuring system, the ground loops which are generated due to improper grounding
can be eliminated using :
a- Isolation amplifiers
b- Filters
c- Multiplexers
d- Differential amplifiers
4- As the pointer of measuring instrument is far away from the full scale, the percentage error
of that reading is :
a- Decreases
b- Increases
c- Constant over the entire range
d- No relation
5- In the spectrum analyzer, the IF signal must be converted to a baseband or video signal, so it
can be digitized and then viewed on the analyzer display. This can be done using :
a- IF filter
b- A/D converter
c- IF gain
d- Envelope detector .