 MORE IN Electronic Instrumentation
VTU Electronics and Communication Engineering (Semester 3)
Electronic Instrumentation
June 2015
Total marks: --
Total time: --
INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary

1 (a) Define the following with examples:
i) Accuracy
ii) Precision
iii) Resolution
iv) Significant figures.
8 M
1 (b) With a schematic, explain a true RMS voltmeter.
6 M
1 (c) Calculate the value of the multiplier resistor for a 50V RMS ac range on the voltmeter as shown in Fig. Q1(c). 6 M

Give the working principle of following:
2 (a) (i) V-F type DVM
6 M
2 (a) (ii) Successive approximation.
6 M
2 (b) Explain the principle, construction and working of a digital frequency meter.
8 M

3 (a) Draw the basic block diagram of an oscilloscope and explain the functions of each block and mention the advantages of negative HV supply.
10 M
3 (b) Explain dual trace oscilloscope with a neat block diagram.
10 M

4 (a) Explain the need for a delayed time base oscilloscope. Draw the block diagram of a delayed time base, and explain how it operates.
10 M
4 (b) With block diagram, explain the operation of an analog storage oscilloscope.
10 M

5 (a) Explain the operation of conventional standard signal generator with the help of block diagram.
6 M
5 (b) Write a brief note on function generator.
4 M
5 (c) Explain the operation of a sweep frequency generator with the help of a suitable block diagram. Mention its applications.
10 M

6 (a) Explain the operation of the Maxwell's bridge, with a neat circuit diagram. Derive an expression for unknown values of resistance and inductance. What are the limitations of Maxwell's bridge?
10 M
6 (b) Explain the operation of the capacitance comparison bridge, with a neat circuit diagram and derive the necessary equations.
6 M
6 (c) A capacitance comparison bridge is used to measure a capacitance impedance at a frequency of 2kHz. The bridge constant at balance are C3=100μF, R1=10KΩ, R2=50KΩ, R3=100KΩ. Find the equivalent series circuit of the unknown impedance.
4 M

7 (a) List at least five advantages of electrical transducer.
5 M
7 (b) Explain the method of measuring displacement using LVDT with a suitable diagram. State the advantages and disadvantages of LVDT.
10 M
7 (c) Write a note on differential output transducers.
5 M

8 (a) Write a note on photo transistor.
5 M
8 (b) List at least five classifications of digital displays.
5 M
8 (c) Explain the operation of the measurement of power by means of bolometer bridge, with the suitable circuit.
10 M

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