# CEL 1502 ELECTRONICS IV - ELECTRONIC INSTRUMENTATION

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M.Sc. DEGREE (5 YEAR INTEGRATED COURSE) V SEMESTER EXAMINATION IN PHOTONICS,
DECEMBER 2005
CEL 1502 ELECTRONICS IV - ELECTRONIC INSTRUMENTATION
Time: 3 Hours
Maximum marks : 50
PART A
(All questions carry EQUAL marks)
(5 x 2= 10)
1.
(a)
(h)
Explain the three forces involved in the moving system of a deflection instrument.
What is a sampling Oscilloscope?
What is a Lock-in amplifier?
What is a strain gauge?
What is quantization error?
What is Oscilloscope probe compensation?
What is a capacitive transducer?
How microcomputers in instruments are programmed?
PART — B
(A II questions carry EQUAL marks)
(5 x
II.(A)
(a)
(b)
11.(B)
(a)
(b)
40)
Explain the construction of a D'Arsonval meter movement. Explain how it can be used as a
voltmeter and Ammeter.
Calculate the impedance of a have wave rectifier type ac voltmeter in the 0-50V range if it uses
a basic movement with a full scale deflection current of 50 p A. (Ignore diode resistance)
OR
With a block diagram explain the working of a Digital frequency counter? What are the factors
that effect the inherent error in frequency measurement?
Find the period in seconds of a signal if the decimal counting assembly (DCA) reading is 8026
and the time base frequency is IKliz.
2
V.(A) (a)
(b)
V.(B) (a)
(b)
With a neat skletch explain the principles of operation of a LVDT.
An RTD has a resistance of 100 ohms at 0&deg; and 108 ohms at 30&deg;C. Calculate the resistance
of 120&deg;C.
OR
Explain various temperature transducers. Compare their major characteristics.
A 6 bit D/A convertor has a reference voltage of 10V. Calculate the output voltage for the
input words 101101 AND 110010.
I
VI.(A) (a)
(b)
V1.(B) (a)
(b)
Write short notes on
low capacitance probes
(ii)
Shielded cables
(i)
A 100 MHz signal from a source of 50ohms source resistance is to be Connected to a
oscilloscope with attenuation not exceeding 3dB. Calculate the maximum probe capacitance
allowable if the oscilloscope has an input capacitance of lOpf.
OR
Explain how different instruments communicate with each other through GPIB.
Convert the binary number 1001101101 into a hexadecimal number and decimal number 33
into a binary number.
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