1. What type of voltage is supplied by a rectifier?

Pulsating DC voltage.

2. What type of voltage is usually required by most electronic equipment?

Smooth DC voltage

3. What is the purpose of a filter used in a rectifier circuit?

To smooth out the pulsating DC voltage.

4. What do you call the filter that uses a capacitor as the first component following the rectifier output?

Capacitor input filter.

5. What does a capacitor oppose?

Change in voltage.

6. What do you call the filter that uses a coil as the first component following the rectifier output?

Choke input filter.

7. What does a choke filter oppose?

Change in current.

8. When is the pi filter with the resistor in it mainly used?

Low current applications.

9. What is the symbol for pi?

10. Which is the most common filter configuration found in power supplies?

A pi filter with a coil.

11. What is a filter circuit?

It is a network of resistors and inductors or capacitors.

12. What does “filter” mean in electronics?

To filter means to oppose or reject voltages and currents of certain frequencies while also offering little opposition to or passing of voltages and currents of other frequencies.

13. What do filter circuits block?

Certain frequencies.

14. What does an RL circuit contain?

Both resistance and inductance.

15. What opposes current flow in an RL circuit?

Resistance and inductive reactance.

16. What is impedance?

The total opposition to current flow in RL circuits.

17. What do you call a filter circuit that contains resistance and capacitance?

An RC filter circuit.

18. What is another term for “cut-off frequency”?

Half-power point.

19. If input frequency decreases in an RL circuit, what happens to voltage across the resistor?

Voltage across the resistor increases.

20. What is another name for a high-frequency discriminator?

A low-pass filter.

21. What is a high-pass filter?

A filter that passes high frequencies and discriminates or blocks low frequencies.

22. What is a low-pass filter?

A filter that passes low frequencies and discriminates or blocks the high frequencies.

23. How can a capacitor act as a high-pass filter in one instance and as a low-pass filter in another instance?

It is determined by the capacitor’s position either across a load or in series with a load.

24. What do you call a speaker that produces low-frequency sounds?

A woofer.

25. What type of speaker is wired across a resistor?

A woofer.

26. What is a tweeter used for?

High-frequency sounds.

27. What is the final stage of a power supply?

The voltage regulator circuit.

28. What is the function of the voltage regulator?

It keeps the output voltage at a constant level under varying loads.

29. What are some reasons why voltage might vary in a circuit?

Input line voltage may vary; load on the power supply might change; and components could be old.

30. What is the simplest type of voltage regulator?

A series regulator.

31. Which type of voltage regulator has the regulating device connected in series?

A series regulator.

32. Which regulator has the regulating device connected in parallel with the load?

A shunt regulator.

33. In a shunt regulator, how is the regulating device connected?

In parallel with the load.

34. In a shunt regulator, what is the voltage across the RV plus the voltage across RS equal to?

The total DC voltage from the filter.

35. What is the only adjustment that can be made in a shunt resistor?

Adjustment to the variable resistor.

36. What happens to the voltage drop across RS when there is an increase in current through RS?

The voltage drop across RS will increase.

37. What type of diode is used as an automatic regulating device?

A zener diode.

38. Why is a zener diode used instead of a variable resistor in most regulators?

Because the input voltage of a variable resistor will fluctuate too rapidly to be controlled by hand.

39. What voltage level does a zener diode maintain?

A constant voltage level as long as the zener continues to conduct.

40. What is the output of a zener diode?

Zener voltage.

41. What is the purpose of a voltage divider?

It makes it possible to obtain more than one voltage from a single power source.

42. What is the simplest form of a voltage divider?

A simple series-parallel circuit.

43. What is a voltage divider composed of?

A simple series-parallel circuit with a number of resistors in series with a power source.

44. What formula do you use to determine amps when you know the resistance and voltage?

Ohm’s Law I = E/R

45. What is a no-load condition?

A condition when no load or energy using device is connected to the voltage divider.

46. What changes the output of a voltage divider?

Connecting a load to a voltage divider changes the output.

47. What is the purpose of a bleeder resistor when equipment is turned off.

To provide a discharge path for the filter capacitor voltage.

48. What is bleeder current in a voltage divider?

The small amount of current in a voltage divider that flows through the bleeder resistor and aids in voltage regulation.

49. What type of voltages can be obtained from a single voltage divider?

Both positive and negative voltage.

50. What happens to total output voltage when a load is connected to a voltage divider?

The voltage decreases.

51. What provides the correct amount of voltage and current to operate an electronic system?

A power supply.

52. What is the most common way of connecting the line voltage to a power supply?

By using a standard plug.

53. What are the first two functions of the input stage of the power supply?

To provide a method of coupling the AC line into the power supply and to provide overload protection.

54. What can provide overload protection to a power supply?

A fuse or circuit breaker.

55. How does a fuse provide protection to a circuit?

A fuse will melt, opening the circuit, when it is overheated.

56. What is the advantage of using a circuit breaker instead of a fuse?

A circuit breaker can be reset and used again, but a fuse must be replaced.

57. What are the last two functions of the input stage of a power supply?

To provide an indication that power is on and to provide a means of turning the power on and off.

58. What is the second stage of a power supply?

The conversion stage.

59. Which substage steps up or steps down AC line voltage?

The transformer secondary.

60. What is the purpose of the filter substage?

The filter substage smooths out the pulsating DC into smooth DC.

61. What does the rectifier do in the conversion stage of the power supply?

The rectifier receives the voltage from the transformer secondary and converts it to DC voltage.

62. What are the three substages in the conversion stage of the power supply?

Transformer secondary, rectifier, and filter.

63. What is the last stage in the power supply?

The output stage.

64. What is the basic function of this final stage of the power supply?

Maintain a steady DC output.

65. What are the three stages in a power supply?

Input, conversion, and output.

66. What is the symbol for a fuse?

67. What is the symbol for a circuit breaker?

68. What is the symbol for a standard plug?

69. What do you call a non- rotating device used for producing alternating current from a direct current supply?

Oscillator.

70. Why is the word “non- rotating” used in describing an oscillator?

So the word will not be confused with alternator or generator.

71. How do you refer to something that moves back and forth in a uniform manner?

It is said to oscillate.

72. What conditions must exist for something to oscillate?

There must be a back and forth motion and the period for the back and forth motion must be the same.

73. What are the three essential sections of an oscillator circuit?

Feedback, amplifier, and frequency determining device.

74. Which section of the oscillator develops the desired AC frequency?

The frequency determining device or tank circuit.

75. What does the tank circuit contain?

A capacitor and an inductor.

76. What does the tank circuit have to do to continue oscillating?

It has to have a voltage push.

77. What is another term for positive feedback in an oscillator?

Regenerative feedback.

78. What actually does the oscillating in an oscillator?

The tank circuit.

79. What section of the oscillator amplifies the tank circuit output to a usable level?

The amplifier circuit.

80. Why does the feedback circuit return part of the oscillation output signal back into the tank circuit?

To insure sustained oscillation.

81. What part of the oscillator replaces the energy lost in the tank circuit?

The feedback circuit.

82. What happens if one stage or section of the oscillator fails to function?

It totally disables oscillation.

83. What do you do when you troubleshoot a circuit?

You locate and correct any malfunction in the circuit.

84. What is a short circuit?

A defect in a circuit that permits current to flow around all or part of the load.

85. What has happened to equipment that has malfunctioned?

It does not operate normally.

86. What do we mean by an open circuit?

A circuit that does not provide a complete path for current flow.

87. What is a direct short?

A condition in a circuit that occurs when a conducting material forms a path directly between the terminals of a source.

88. What is a partial short?

A condition that exists when a short circuit bypasses only part of the normal load in a circuit.

89. What is the function of a fuse in a circuit?

A safety device used to protect a circuit and electrical components against excessive amounts of current.

90. How are fuses rated?

In amperes.

91. What has happened to a circuit when a fuse has blown?

The circuit opens.

92. What instruments can be used in locating shorts?

A voltmeter or an ohmmeter.

93. What is the first step in using an ohmmeter?

Make sure the circuit is de- energized.

94. What do we mean by the term “blow fuse”?

When a fuse burns out we say it is blown.

95. What can cause an open circuit?

A blown fuse, dirt on switch contacts, broken wires, or burned out components.

96. What normally causes short circuits?

Broken or cut insulation wires, loose tools, or loose pieces or wire.

97. What is a defective switch?

A switch that is not working correctly.

98. What is an important safety rule for you to remember when you are working on any type of electronic equipment?

Be careful.

99. What causes electric shock?

Electric current flowing through an individual’s body.

100. What is a “hot” wire?

A conductor through which current is flowing.

101. How can an electric shock kill an individual?

By stopping his or her heart, breathing, or both.

102. What could cause an individual’s body to have a low resistance to electric shock?

If his or her skin is moist or there are cuts on his or her body.

103. What is artificial respiration?

A mechanical or manual means or inducing breathing in someone when breathing has stopped.

104. What is the first thing that you must do if you see someone receive an electric shock?

Turn off the high voltage.

105. When would you stop administering artificial respiration?

When the victim starts to breath or when professional medical assistance arrives.

106. Why is it important to have adequate light when you are working on an energized circuit?

So you can see clearly to perform your job.

107. What should you stand on when you work on energized equipment?

A rubber mat, a large piece of canvas or wood.