Malvino Chapter 23

Chapter 23 

1 . An oscillator always needs an amplifier with 
a. Positive feedback 
b. Negative feedback 
c. Both types of feedback 
d. An LC tank circuit 

2. The voltage that starts an oscillator is caused by 
a. Ripple from the power supply 
b. Noise voltage in resistors 
c. The input signal from a generator 
d. Positive feedback 

3. The Wien-bridge oscillator is useful 
a. At low frequencies 
b. At high frequencies 
c. With LC tank circuits 
d. At small input signals 


4. A lag circuit has a phase angle that is 
a. Between 0 and +90 degrees 
b. Greater than 90 degrees 
c. Between 0 and -90 degrees 
d. The same as the input voltage 

5. A coupling circuit is a 
a. Lag circuit 
b. Lead circuit 
c. Lead-lag circuit 
d. Resonant circuit 

6. A lead circuit has a phase angle that is 
a. Between 0 and +90 degrees 
b. Greater than 90 degrees 
c. Between 0 and -90 degrees 
d. The same as the input voltage 

7. A Wien-bridge oscillator uses 
a. Positive feedback 
b. Negative feedback 
c. Both types of feedback 
d. An LC tank circuit 

8. Initially, the loop gain of a Wien-bridge oscillator is 
a. 0 
b. 1 
c. Low 
d. High 

9. A Wien bridge is sometimes called a 
a. Notch filter 
b. Twin-T oscillator 
c. Phase shifter 
d. Wheatstone bridge 

10. To vary the frequency of a Wien bridge, you can vary 
a. One resistor 
b. Two resistors 
c. Three resistors 
d. One capacitor 

11. The phase-shift oscillator usually has 
a. Two lead or lag circuits 
b. Three lead or fag circuits 
c. A lead-lag circuit 
d. A twin-T filter 

12. For oscillations to start ina circuit, the loop gain must be greater than 1 when the phase shift around the loop is 
a. 90 degrees 
b. 180 degrees 
c. 270 degrees 
d. 360 degrees 

13. The most widely used LC oscillator is the 
a. Armstrong 
b. Clapp 
C. Colpitts 
d. Hartley 

14. Heavy feedback in an LC oscillator 
a. Prevents the circuit from starting 
b. Causes saturation and cutoff 
c. Produces maximum output voltage 
d. Means B is small 

15. When Q decreases in a Colpitts oscillator, the frequency of oscillation 
a. Decreases 
b. Remains the same 
c. Increases 
d. Becomes erratic 

16. Link coupling refers to 
a. Capacitive coupling 
b. Transformer coupling 
c. Resistive coupling 
d. Power coupling 

17. The Hartley oscillator uses 
a. Negative feedback 
b. Two inductors 
c. A tungsten lamp 
d. A tickler coil 

18. To vary the frequency of an LC oscillator, you can vary 
a. One resistor 
b. Two resistors 
c. Three resistors 
d. One capacitor 

19. Of the following, the one with the most stable frequency is the 
a. Armstrong 
b. Clapp 
c. Colpitts 
d. Hartley 

20. The material with the piezoelectric effect is 
a. Quartz 
b. Rochelle salts 
c. Tourmaline 
d. All the above 

21. Crystals have a very 
a. Low Q 
b. High Q 
c. Small inductance 
d. Large resistance 

22. The series and parallel resonant frequencies of a crystal are 
a. Very close together 
b. Very far apart 
c. Equal 
d. Low frequencies 

23. The kind of oscillator found in an electronic wristwatch is the 
a. Armstrong 
b. Clapp 
c. Colpitts 
d. Quartz crystal 

24. A monostable 555 timer has the following number of stable states: 
a. 0 
b. 1 
c. 2 
d. 3 

25. An astable 555 timer hasthe following number of stable states: 
a. 0 
b. 1 
c. 2 
d. 3 

26. The pulse width out of a one-shot multivibrator increases when the 
a. Supply voltage increases 
b. Timing resistor decreases 
c. UTP decreases 
d. Timing capacitance increases 

27. The output waveform of a 555 timer is 
a. sinusoidal 
b. triangular 
c. rectangular 
d. elliptical 

28. The quantity that remains constant in a pulse-width modulator is 
a. Pulse width 
b. Period 
c. Duty cycle 
d. Space 

29. The quantity that remains constant in a pulse-position modulator is 
a. Pulse width 
b. Period 
c. Duty cycle 
d. Space 

30. When a PLL is locked on the input frequency, the VCO frequency 
a. Is less than f0 
b. Is greater than f0 
c. Equals f0 
d. Equals fin 

31. The bandwidth of the low-pass filter in a PLL determines the 
a. Capture range 
b. Lock range 
c. Free-running frequency 
d. Phase difference 



Also try:

Malvino Chapter 1
Malvino Chapter 2
Malvino Chapter 3
Malvino Chapter 4
Malvino Chapter 5
Malvino Chapter 6
Malvino Chapter 7
Malvino Chapter 8
Malvino Chapter 9
Malvino Chapter 10
Malvino Chapter 11
Malvino Chapter 12
Malvino Chapter 13
Malvino Chapter 14
Malvino Chapter 15
Malvino Chapter 16
Malvino Chapter 17
Malvino Chapter 18
Malvino Chapter 19
Malvino Chapter 20
Malvino Chapter 21
Malvino Chapter 22
Malvino Chapter 24