Oscillators MCQ Questions & Answers | Electrical Engineering

21

In Colpitt's oscillator, feedback is obtained ___________

A) By magnetic induction B) By a tickler coil C) From the centre of split capacitors D) None of the above

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Answer & Solution

Answer: Option C

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22

For an oscillator to properly start, the gain around the feedback loop must initially be

A) 1 B) Greater than 1 C) Less than 1 D) Equal to attenuation of feedback circuit

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Answer & Solution

Answer: Option B

Solution:

In order for an oscillator to start and sustain oscillations, the gain around the feedback loop must meet specific criteria. The criteria for proper oscillation are as follows:

The gain around the feedback loop must be equal to or greater than 1.

This means that the gain should be sufficient to compensate for the losses in the feedback loop, so the signal can build up and sustain itself in an oscillatory manner.

Therefore, the correct answer is:

Option B: Greater than 1

23

The Q of the crystal is of the order of ___________

A) 100 B) 1000 C) 50 D) More than 10,000

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Answer & Solution

Answer: Option D

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24

If the crystal frequency changes with temperature, we say that crystal has ___________ temperature coefficient

A) Positive B) Zero C) Negative D) None of the above

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Answer & Solution

Answer: Option A

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25

In a Wien-bridge oscillator, if the resistances in the positive feedback circuit are decreased, the frequency ___________

A) Remains the same B) Decreases C) Increases D) Insufficient data

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Answer & Solution

Answer: Option C

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26

A second condition for oscillations is ___________

A) A gain of 1 around the feedback loop B) No gain around the feedback loop C) The attention of the feedback circuit must be one-third D) The feedback circuit must be capacitive

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Answer & Solution

Answer: Option A

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27

In an LC oscillator, if the value of L is increased four times, the frequency of oscillations is ___________

A) Increased 2 times B) Decreased 4 times C) Increased 4 times D) Decreased 2 times

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Answer & Solution

Answer: Option D

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28

The piezoelectric effect in a crystal is ___________

A) A voltage developed because of mechanical stress B) A change in resistance because of temperature C) A change in frequency because of temperature D) None of the above

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Answer & Solution

Answer: Option A

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