EX-604-A Electronic Instrumentation - May 2022 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aList the various parts of CRO. Draw its block diagram and explain the working of all parts of CRO.
   How to answer

   • List CRO parts: CRT, electron gun, deflection system, time base, triggering, amplifiers, power supply
   • Draw block diagram of CRO showing signal flow
   • Explain function of each block: electron gun, horizontal/vertical deflection, sweep generator
   • Explain synchronization and display of waveform on screen
2. 7 Marks
   bHow does the digital oscilloscope differ from the conventional storage oscilloscope using a storage cathode tube?
   How to answer

   • Define storage oscilloscope with storage cathode tube vs digital storage
   • Explain acquisition, storage mechanism in conventional storage tube
   • Explain ADC, memory, processing in digital oscilloscope
   • Compare on basis of bandwidth, storage time, resolution, flexibility
3. 7 Marks
   aExplain the working of dual beam oscilloscope with diagram.
   How to answer

   • State need for dual beam for two simultaneous signals
   • Draw diagram with single CRT with two electron guns / dual trace concept
   • Explain vertical channels, separate time bases and deflection
   • Explain display modes and applications
4. 7 Marks
   bWhat are the sources of errors in bridge circuits? How they can be minimized? Explain.
   How to answer

   • Define bridge balance and error sources: stray capacitance, inductance, frequency, temperature, leads
   • Explain effect of each source on null detection
   • Explain shielding, grounding, Wagner earthing, proper frequency selection
   • Summarize minimization techniques
5. 7 Marks
   aDraw the circuit diagram of Wien bridge. Explain the measurement of frequency with it.
   How to answer

   • Draw Wien bridge with RC series-parallel arms and ratio arms
   • Write balance condition for impedance
   • Derive frequency expression $f = 1/(2\pi RC)$
   • Explain null detection procedure for frequency measurement
6. 7 Marks
   bDescribe the circuit and working of a Q-meter. Explain its application.
   How to answer

   • Draw Q-meter circuit with oscillator, series resonant circuit
   • Explain resonance, voltage magnification principle $Q = V_C/V$
   • Explain measurement procedure for Q, inductance, capacitance
   • List applications in RF component testing
7. 7 Marks
   aWhat is Transducer? Explain primary and secondary transducer with the help of an example.
   How to answer

   • Define transducer as energy conversion device
   • Define primary vs secondary transducer
   • Give example e.g., Bourdon tube + LVDT for pressure
   • Explain role of each stage in measurement chain
8. 7 Marks
   bExplain the theory of strain gauge and derive an expression for gauge factor.
   How to answer

   • Explain strain gauge principle: resistance change with strain
   • Relate $R = \rho l/A$ and differentiate for strain effect
   • Derive gauge factor $G_f = (\Delta R/R)/(\Delta l/l)$
   • Discuss Poisson ratio and piezoresistive terms
9. 7 Marks
   aExplain the construction and working of LVDT.
   How to answer

   • Draw LVDT construction: primary, two secondaries, movable core
   • Explain AC excitation and mutual induction
   • Explain differential output vs core displacement, phase reversal
   • Mention null position and linearity
10. 7 Marks
    bWhat is the importance of Spectrum analyzer? Explain it operation with diagram.
    How to answer

    • State importance: frequency domain analysis, harmonics, noise
    • Draw block diagram: input, mixer, filter, detector, display
    • Explain sweeping and spectrum display operation
    • List applications in communications and testing
11. 7 Marks
    aWhat is Function Generator? Explain its operation with block diagram.
    How to answer

    • Define function generator for sine, square, triangular waves
    • Draw block diagram: integrator, Schmitt trigger, sine shaper
    • Explain frequency and amplitude control operation
    • Mention specifications and uses
12. 7 Marks
    bDescribe with the help of diagram, the working of Beat frequency oscillator.
    How to answer

    • State principle of beat: difference of two RF oscillators
    • Draw diagram with fixed and variable oscillators, mixer, amplifier
    • Explain zero-beat and frequency variation with tuning
    • Mention use as audio signal source
13. 7 Marks
    aDraw the block diagram of digital frequency meter and explain the functions of its each block.
    How to answer

    • Draw blocks: input conditioner, gate, decade counters, clock, display
    • Explain gate time and direct frequency counting
    • Explain function of each block and time-base accuracy
    • Mention resolution and range
14. 7 Marks
    bExplain the theory and working of LCDs. Also explain the advantages of LCDs.
    How to answer

    • Explain LCD principle: liquid crystal polarization and field effect
    • Describe construction: glass plates, electrodes, reflector
    • Explain working with applied voltage and light transmission
    • List advantages: low power, compact, low cost
15. 14 Marks
    Write a short note on any two of the following.

    1. i)Wagener's earthing device
    2. ii)Application of CROs
    3. iii)X-Y recorders
    How to answer

    • Select any two topics from given three options
    • Give principle/diagram and working for each
    • Mention key applications and advantages
    • Conclude with comparison or use-case