Oscillators and Multivibrators

1. An oscillator is an electronic circuit that converts _____ to AC power at a desired frequency.

a) AC

b) DC ✓

c) RF

d) IF

2. The block diagram of an oscillator does NOT include:

a) Amplifier

b) Feedback network

c) Oscillatory circuit

d) Demodulator ✓

3. Positive feedback in oscillators ensures:

a) Dampened oscillations

b) Sustained oscillations ✓

c) Negative phase shift

d) DC output

4. Which is a sinusoidal feedback oscillator?

a) Astable multivibrator

b) RC phase shift oscillator ✓

c) Sawtooth oscillator

d) Relaxation oscillator

5. The frequency equation for RC phase shift oscillator is:

a) f = 1}{2\pi LC}$

b) f = 1}{2\pi \sqrt{6} RC}$ ✓

c) f = crystal frequency

d) f = 1.44}{(R_1 + 2R_2)C}$

6. Each RC section in RC phase shift oscillator provides a phase shift of:

a) 90°

b) 60° ✓

c) 180°

d) 360°

7. Crystal oscillators use the _____ effect of quartz crystal.

a) Magnetic

b) Piezoelectric ✓

c) Thermoelectric

d) Photoelectric

8. Astable multivibrator produces _____ wave output.

a) Sine

b) Triangle

c) Square ✓

d) Sawtooth

9. Astable multivibrator has:

a) One stable state

b) Two stable states

c) No stable states ✓

d) Three stable states

10. Which oscillator has highly stable frequency output?

a) RC phase shift

b) LC

c) Crystal ✓

d) Astable multivibrator

11. Tuned circuits in oscillators can be formed by:

a) L-C only

b) R-C, L-C, or crystals ✓

c) R-L only

d) Capacitors alone

12. Total phase shift in RC phase shift oscillator (3 RC sections + amplifier) is:

a) 180°

b) 360° ✓

c) 540°

d) 0°

13. Non-sinusoidal relaxation oscillators include:

a) Hartley

b) Crystal

c) Astable multivibrator ✓

d) RC phase shift

14. Frequency of astable multivibrator is approximately:

a) Crystal frequency

b) f =1/0.69 RC✓

c) f = 1/2 pi RC

d) 1 Hz

15. Oscillators are classified by frequency as LF, AF, RF, etc., where RF stands for:

a) Low Frequency

b) Audio Frequency

c) Radio Frequency ✓

d) Intermediate Frequency

16. In crystal oscillator, frequency of oscillations equals:

a) Supply voltage

b) Crystal frequency itself ✓

c) RC values

d) Amplifier gain

17. RC phase shift oscillator is a _____ frequency sine wave oscillator.

a) High

b) Low ✓

c) Radio

d) Audio

18. Astable multivibrator uses _____ transistors connected back-to-back.

a) One

b) Two identical ✓

c) Three

d) Four

19. Feedback in oscillators must be in phase for:

a) Negative feedback

b) Positive feedback ✓

c) No feedback

d) Zero phase

20. Which is NOT a type of sinusoidal oscillator listed?

a) Hartley

b) RC phase shift

c) Crystal

d) Astable multivibrator ✓