This set of Analog Circuits Multiple Choice Questions & Answers (MCQs) focuses on “Clapp Oscillator”.

1. Clapp oscillator is an ___________

a) LC oscillator

b) RC oscillator

c) RL oscillator

d) Crystal oscillator

View Answer

Explanation: Clapp oscillator is a colpitts oscillator which has an extra capacitor series with an inductor. Hence it is an LC oscillator, with 3 capacitors and one single inductor to set its frequency, and the clap circuit is often used as a variable frequency oscillator, by making one capacitor variable.

2. Which type of feedback is used in clapp oscillator?

a) Positive feedback

b) Negative feedback

c) No feedback is used

d) Both positive and negative feedback

View Answer

Explanation: Positive feedback is present in the clap oscillator, where in the three capacitors form a voltage divider which determines amount of feedback being applied to transistor input.

3. When constructing variable frequency oscillator among clapp oscillator and colpitts oscillator which one is preferred?

a) Colpitts oscillator

b) Clapp oscillator

c) Both of them have equal preference

d) None of them preffered

View Answer

Explanation: The stray third capacitor in the clap oscillator doesn’t have a negative effect and the frequency obtained is instead more stable and accurate than colpitt oscillator, hence the clap oscillator is preferred for a variable frequency oscillator.

4. In clapp oscillator voltage is divided by using __________

a) Resistors

b) Capacitors

c) Inductors

d) Voltage dividing circuits are not used

View Answer

Explanation: In clap capacitor voltage divider circuit is achieved by capacitor because it is a modified version of colpitts oscillator.

5. In a clapp oscillator with three capacitor C_{1}, C_{2}, C_{3}, C_{1} is used as upper capacitor in voltage divider, C_{2} is used as lower capacitor in voltage divider and C_{3} is the third capacitor. For perfect operation which of these capacitor should have minimum value?

a) C_{1}

b) C_{2}

c) C_{3}

d) All of them are equal

View Answer

Explanation: In a Clapp oscillator C

_{3}is much smaller than C

_{1}and C 2as a result, the equivalent capacitance C is approximately equal to C

_{3}. For perfect operation C

_{3}should have minimum value.

6. In a clapp oscillator with three capacitor C_{1}, C_{2}, C_{3}, C_{1} is used as upper capacitor in voltage divider, C_{2} is used as lower capacitor in voltage divider and C_{3} is the third capacitor. The frequency of operation will be close to (Assume C_{1} parallel C_{2} is C_{3}).

a)

b)

c)

d)

View Answer

Explanation: Since equivalent capacitance is close to C

_{3}and equation is similar to colpitts oscillator.

7. In a clapp oscillator with three capacitor C_{1}, C_{2}, C_{3}, C_{1} is used as upper capacitor in voltage divider, C_{2} is used as lower capacitor in voltage divider and C_{3} is the third capacitor. For perfect operation of clapp oscillator value of C_{3} should be __________

a) Equal to C_{1}

b) Equal to C_{2}

c) Equal to C_{1} parallel C_{2}

d) Very small

View Answer

Explanation: For perfect operation of clapp oscillator value of C

_{3}should be C

_{1}parallel C

_{2}.

8. In a clapp oscillator with three capacitor C_{1}, C_{2}, C_{3}, C_{1} is used as upper capacitor in voltage divider, C_{2} is used as lower capacitor in voltage divider and C_{3} is the third capacitor. Inductance used in the circuit is L. The frequency of operation will be __________

a)

b)

c)

d)

View Answer

Explanation: The frequency of operation is given . Here effective capacitance is equal to C parallel C

_{2}parallel C

_{3}.

9. In the following oscillator which one is more accurate?

a) Colpitts oscillator

b) Clapp oscillator

c) Hartley oscillator

d) Simple LC oscillator

View Answer

Explanation: The stray third capacitor in the clap oscillator doesn’t have a negative effect and the frequency obtained is instead more stable and accurate than colpitt oscillator.

10. What will be the clapp oscillator frequency if the C_{1}, C_{2}, C_{3} of clap oscillator is 1μF, 1μF, 2μF respectively and inductance is 1μH?

a) 0.1MHz

b) 0.4MHz

c) 1MHz

d) 4MHz

View Answer

Explanation: Frequency of clap oscillator is = 3.9 x 10

^{5}ie approximately 0.4MHz.

Therefore, frequency is equal to .

**Sanfoundry Global Education & Learning Series – Analog Circuits.**

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