Diode Applications

1. Determine the total discharge time for the capacitor in a clamper having C = 0.01 uF and R = 500 k.
A. 5 ms
B. 25 ms
C. 2.5 ms
D. 50 ms

2. Which element dictates the maximum level of source voltage?

A. VZ
B. IZM
C. IZ
D. None of the above

3. What type of diode circuit is used to clip off portions of signal voltages above or below certain levels?
A. clipper or limiter
B. clamper
C. IC voltage regulator
D. none of the above

4. Each diode in a center-tapped full-wave rectifier is ___ -biased and conducts for ___ of the input cycle.
A. forward, 90º
B. reverse, 180º
C. forward, 180º
D. reverse, 90º

5. What is the voltage measured from the negative terminal of C4 to the negative terminal of the transformer?

A. –10 V
B. –20 V
C. 10 V
D. 20 V

6. The output frequency of a full-wave rectifier is ____ the input frequency.
A. one-half
B. equal to
C. twice
D. one-quarter

7. PIV is which of the following?
A. peak input voltage
B. peak inverse voltage
C. peak immediate voltage
D. positive input voltage

8. Determine the peak value of the current through the load resistor.

A. 2.325 mA
B. 5 mA
C. 1.25 mA
D. 0 mA

9. Determine the peak value of the output waveform.

A. 25 V
B. 15 V
C. –25 V
D. –15 V

10. In a regulated supply, what term describes how much change occurs in the output voltage for a given change in the input voltage?
B. voltage regulator
C. line regulation
D. ripple voltage

11. A short circuit has a ____ drop across its terminals, and the current is limited only by the surrounding network.
A. 5 V
B. 0 V
C. 1 V
D. ∞

12. Determine the peak for both half cycles of the output waveform.

A. 16 V, –4 V
B. 16 V, 4 V
C. –16 V, 4 V
D. –16 V, –4 V

13. What is the peak inverse voltage across each diode in a voltage doubler?
A. Vm
B. 2Vm
C. 0.5Vm
D. 0.25Vm

14. What is the VRRM (PIV rating) for the 1N4001 rectifier diode?
A. 50 V
B. 100 V
C. 200 V
D. 400 V
E. none of the above

15. What type of diode circuit is used to add or restore a dc level to an electrical signal?
A. clipper or limiter
B. clamper
C. IC voltage regulator
D. none of the above

16. Determine ID2.

A. 6.061 mA
B. 0.7 mA
C. 3.393 mA
D. 3.571 mA

17. What is the logic function of this circuit?

A. Positive logic AND gate
B. Positive logic OR gate
C. Negative logic AND gate
D. Negative logic OR gate

18. In a regulated supply, what term describes how much change occurs in the output voltage over a certain range of load current values, from minimum to maximum current?
A. line regulation
B. voltage regulator
C. current regulator

19. Determine the average value of the current through the load resistor.

A. 2.5 mA
B. 0 mA
C. 1.37 mA
D. 1.479 mA

20. What best describes the circuit?

A. Full-wave rectifier
B. Half-wave rectifier
C. Clipper
D. Clamper

21. What is the PIV for each diode in a full-wave center-tapped rectifier? Note: Vp(out) = peak output voltage.
A. Vp(out) – 0.7 V
B. Vp(out) + 0.7 V
C. 2Vp(out) – 0.7 V
D. 2Vp(out) + 0.7 V

22. Determine ID2.

A 29.40 mA
B. 30.30 mA
C. 14.70 mA
D. None of the above

23. Determine the current level if E = 15 V and R = 3 k.

A. 0 A
B. 4.76 mA
C. 5 mA
D. 5 A

24. Determine V2.

A. 3.201 V
B. 0 V
C. 4.3 V
D. 1.371 V

25. If the ac supply is 50 Hz, what will be the ripple frequency out of the full-wave rectifier?
A. 50 Hz
B. 60 Hz
C. 100 Hz
D. 120 Hz

26. How many terminals do the 7800 series fixed positive voltage regulators have?
A. 2
B. 3
C. 4
D. 5 E. none of the above

27. An open circuit can have any voltage across its terminals, but the current is always ____.
A. 5 A
B. 0 A
C. 1 A
D. ∞

28. Determine ID1.

A. 0 mA
B. 29.40 mA
C. 14.70 mA
D. 14.09 mA

29. Refer to the figure given below. Which diode arrangement will supply a negative output voltage?

A. a
B. b
C. c
D. d

30. A silicon diode in a half-wave rectifier has a barrier potential of 0.7 V. This has the effect of
A. reducing the peak output voltage by 0.7 V.
B. increasing the peak output voltage by 0.7 V.
C. reducing the peak input voltage by 0.7 V.
D. no effect.

31. What best describes the circuit?

A. Full-wave rectifier
B. Half-wave rectifier
C. Clipper
D. Clamper

32. Determine the value of the load resistor.

A. RL = 5 k
B. RL = 5.5 k
C. RL = 6 k
D. None of the above

33. Use the information provided here to determine the value of IDQ.

A. 0 mA
B. 4.3 mA
C. 5 mA
D. 10 mA

34. If the ac supply is 60 Hz, what will be the ripple frequency out of the half-wave rectifier?
A. 30 Hz
B. 50 Hz
C. 60 Hz
D. 120 Hz

35. Calculate IL and IZ.

A. 2 mA, 0 mA
B. 4 mA, 2 mA
C. 2 mA, 2 mA
D. 2 mA, 4 mA

36. In the operation of a half-wave rectifier with a capacitor-input filter, the ripple factor can be lowered by ___ the value of the filter capacitor or ___ the load resistors.
A. decreasing, decreasing
B. decreasing, increasing
C. increasing, decreasing
D. increasing, increasing

37. Refer to the figure given below. The probable trouble, if any, indicated by these voltages is

A. one of the diodes is open.
B. a diode is shorted.
C. an open transformer secondary.
D. the filter capacitor is shorted. E. no trouble exists.

38. In a particular problem, which mode has the highest level of IDQ?
A. Ideal
B. Approximate equivalent
C. Exact mode using characteristic curve
D. None of the above

39. Which diode(s) has (have) a zero level current and voltage drop in the ideal model?
A. Si
B. Ge
C. Both Si and Ge
D. Neither Si nor Ge

40. Determine Vo if E1 = E2 = 10 V.

A. 9.3 V
B. 10 V
C. –10 V
D. 0 V

41. The output frequency of a half-wave rectifier is ____ the input frequency.
A. one-half
B. twice
C. equal to
D. none of the above

42. A diode is in the ____ state if the current established by the applied sources is such that its direction matches that of the arrow in the diode symbol, and VD = 0.7 V for Si and VD = 0.3 V for Ge.
A. off
B. on
C. neutral
D. quiescent

43. Determine ID.

A. 0 mA
B. 1.893 mA
C. 2.036 mA
D. 2.143 mA

44. What best describes the circuit?

A. Full-wave rectifier
B. Half-wave rectifier
C. Clipper
D. Clamper

45. In a voltage-multiplier circuit, the number of diodes is directly proportional to the multiplicative voltage factor.
A. True
B. False

46. Rectifiers are commonly used in battery chargers.
A. True
B. False

47. List the categories of clippers.
A. Series
B. Parallel
C. Series and parallel
D. None of the above

48. A silicon diode has a voltage to ground of –117 V from the anode. The voltage to ground from the cathode is –117.7 V. The diode is
A. open.
B. shorted.
C. forward-biased.
D. reverse-biased.

49. Which diode arrangement will supply a positive output voltage?

A. a
B. b
C. c
D. d

50. What is the logic function of this circuit?

A. Positive logic AND gate
B. Positive logic OR gate
C. Negative logic AND gate
D. Negative logic OR gate

51. Determine the current through each diode if E1 = E2 = 0 V.

A. 4.65 mA
B. 9.3 mA
C. 18.6 mA
D. 0.7 mA

52. Refer to the figure given below. If the voltmeter across the transformer reads 0 V, the probable trouble, if any, would be

A. one of the diodes is open.
B. a diode is shorted.
C. an open transformer secondary.
D. the filter capacitor is shorted. E. no trouble exists.

53. Determine the voltage across the resistor.

A. 0 V
B. 0.09 V
C. 0.2 V
D. 0.44 V

54. With this Zener diode in its on state, what is the level of IZ for the maximum load resistance?

A. 0 mA
B. Undefined
C. Equal to IRL
D. IZM