Oscillators - Gibilisco MCQs in Electronics

This is the Multiple Choice Questions (MCQs) in Chapter 25: Oscillators from the book Teach Yourself Electricity and Electronics, 5th edition by Stan Gibilisco. If you are looking for a reviewer in Electronics Engineering this will definitely help you before taking the Board Exam.

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1. Negative feedback in an amplifier:

• A. Causes oscillation.
• B. Increases sensitivity.
• C. Reduces the gain.
• D. Is used in an Armstrong oscillator.

2. Oscillation requires:

• A. A common-drain or common-collector circuit.
• B. A stage with gain.
• C. A tapped coil.
• D. Negative feedback.

3. A Colpitts oscillator can be recognized by:

• A. A split capacitance in the tuned circuit.
• B. A tapped coil in the tuned circuit.
• C. A transformer for the feedback.
• D. A common-base or common-gate arrangement.

4. In an oscillator circuit, the feedback should be:

• A. As great as possible.
• B. Kept to a minimum.
• C. Just enough to sustain oscillation.
• D. Done through a transformer whose wires can be switched easily.

5. A tapped coil is used in a(n):

• A. Hartley oscillator.
• B. Colpitts oscillator.
• C. Armstrong oscillator.
• D. Clapp oscillator.

6. An RF choke:

• A. Passes RF but not dc.
• B. Passes both RF and dc.
• C. Passes dc but not RF.
• D. Blocks both dc and RF.

7. Ferromagnetic coil cores are not generally good for use in RF oscillators because:

• A. The inductances are too large.
• B. It’s hard to vary the inductance of such a coil.
• C. Such coils are too bulky.
• D. Air-core coils have better thermal stability.

8. An oscillator might fail to start for any of the following reasons except:

• A. Low-power-supply voltage.
• B. Low stage gain.
• C. In-phase feedback.
• D. Very low output impedance.

9. An advantage of a crystal-controlled oscillator over a VFO is:

• A. Single-frequency operation.
• B. Ease of frequency adjustment.
• C. High output power.
• D. Low drift.

10. The frequency at which a crystal oscillator functions is determined mainly by:

• A. The values of the inductor and capacitor.
• B. The thickness of the crystal.
• C. The amount of capacitance across the crystal.
• D. The power-supply voltage.

11. The different sounds of musical instruments are primarily the result of:

• A. Differences in the waveshape.
• B. Differences in frequency.
• C. Differences in amplitude.
• D. Differences in phase.

12. A radio-frequency oscillator usually:

• A. Has an irregular waveshape.
• B. Has most or all of its energy at a single frequency.
• C. Produces a sound that depends on its waveform.
• D. Uses RC tuning.

13. A varactor diode:

• A. Is mechanically flexible.
• B. Has high power output.
• C. Can produce different waveforms.
• D. Is good for use in frequency synthesizers.

14. A frequency synthesizer has:

• A. High power output.
• B. High drift rate.
• C. Exceptional stability.
• D. Adjustable waveshape.

15. A ferromagnetic-core coil is preferred for use in the tuned circuit of an RF oscillator:

• A. That must have the best possible stability.
• B. That must have high power output.
• C. That must work at microwave frequencies.
• D. No! Air-core coils work better in RF oscillators.

16. If the load impedance for an oscillator is too high:

• A. The frequency might drift.
• B. The power output might be reduced.
• C. The oscillator might fail to start.
• D. It’s not a cause for worry; it can’t be too high.

17. The bipolar transistors or JFETs in a multivibrator are usually connected in:

• A. Class B.
• B. A common-emitter or common-source arrangement.
• C. Class C.
• D. A common-collector or common-drain arrangement.

NOTE: For questions 18 see Fig.25-11.

18. The arrangement in the block diagram of Fig. 25-11 represents:

• A. A waveform analyzer.
• B. An audio oscillator.
• C. An RF oscillator.
• D. A sine-wave generator.

19. Acoustic feedback in a public-address system:

• A. Is useful for generating RF sine waves.
• B. Is useful for waveform analysis.
• C. Can be used to increase the amplifier gain.
• D. Serves no useful purpose.

20. An IMPATT diode:

• A. Makes a good audio oscillator.
• B. Can be used for waveform analysis.
• C. Is used as a microwave oscillator.
• D. Allows for frequency adjustment of a VCO.

Complete List of Multiple Choice Questions from this Book

Multiple Choice Questions in Teach Yourself Electricity and Electronics

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