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.
Begin the Test
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.