Source text. Published from the recorded source PDF for NEETS Module 7: Solid-State Devices and Power Supplies.
INDEX-1
MODULE 7 INDEX
A
Amplifier classes of operation, 2-21
class A, 2-21
class AB, 2-22
class B, 2-22
class C, 2-22
Applications, semiconductor, 1-3
Atomic structure, semiconductor theory, 1-5
B
Bias, types of, basic transistor amplifier, 2-18
base current (fixed bias), 2-19
combination, 2-20
self-bias, 2-19
Bridge rectifier, 4-10
C
Capacitor filter, 4-12
Classification, transistor fundamentals, 2-2
Combination bias, 2-20
Competition, semiconductor, 1-4
Conduction process, semiconductor theory,
1-12
Configurations, transistor, 2-23
common base, 2-26
common collector, 2-27
common emitter, 2-24
Construction, semiconductor diode, 1-16
Construction, transistor fundamentals, 2-4
Conventional full-wave rectifier, 4-3
Covalent bonding, semiconductor theory, 1-10
Current regulators, 4-35
D
Diode identification, signal diodes, 1-29
Diode maintenance, signal diodes, 1-31
Diode, semiconductor, 1-15
construction, 1-16
diode characteristics, 1-27
PN junction application, 1-23
Diode, semiconductor—Continued
PN junction operation, 1-18
Diodes, 3-2
optoelectronic devices, 3-27
silicon controlled rectifier (SCR), 3-18
TRIAC, 3-24
tunnel, 3-8
varactor, 3-15
Zener, 3-2
Doping process, semiconductor, 1-13
N-type semiconductor, 1-14
P-type semiconductor, 1-14
E
Energy bands, semiconductor theory, 1-8
F
FET, field-effect transistors, 3-38
Filters, power supply, 4-12
capacitor, 4-17
LC capacitor-input, 4-32
LC choke-input, 4-22
resistor-capacitor (RC), 4-30
Fixed bias, 2-19
G
Glossary, AI-1
H
Half-wave rectifier, 1-23
I
Identification, transistor, 2-27
L
LC capacitor-input filter, 4-32
INDEX-2
LC choke-input filter, 4-22
Load regulation, 4-34
M
Maintenance, transistor, 2-31
lead identification, 2-32
precautions, 2-31
transistor testing, 2-33
Microelectronics, 2-37
N
NPN transistor operation, 2-6
O
Optoelectronic devices, 3-27
P
Periodic table of the elements, AII-1
PN junction application, 1-23
diode switch, 1-26
half-wave rectifier, 1-23
PN junction operation, semiconductor diode,
1-15
current flow in the N-type material, 1-18
current flow in the P-type material, 1-18
junction barrier, 1-19
PNP transistor operation, 2-11
Power transformer, 4-3
Practical full-wave rectifier, 4-8
R
Rectifier, 4-4
bridge, 4-10
conventional full-wave, 4-7
half-wave, 4-4
practical full-wave, 4-8
ripple frequency, 4-6
rms, peak, and average values, 4-5
Rectifier diodes, 1-28
Regulators, power supply, 4-35
current, 4-43
Regulators, power supply—Continued
series and shunt voltage regulators, 4-36
Resistor-capacitor (RC) filters, 4-30
Ripple frequency, 4-6
S
SCR, silicon controlled rectifier, 3-18
Self-bias, 2-19
Semiconductor diodes, 1-1
diode identification, 1-29
diode maintenance, 1-31
introduction to solid-state devices, 1-1
rectifier diodes, 1-28
semiconductor applications, 1-3
semiconductor competition, 1-4
semiconductor development, 1-2
semiconductor theory, 1-5
signal diodes, 1-28
summary 1-34
Series and shunt voltage regulators, 4-36
Solid-state devices, introduction to, 1-1
Solid-state power supplies, 4-1
basic power supply, 4-1
troubleshooting, 4-51
Special devices, 3-1
Specifications, transistor, 2-29
T
Theory, semiconductor, 1-5
atomic structure, 1-5
conduction process, 1-12
covalent bonding, 1-10
doping process, 1-13
energy bands, 1-8
Transistors, 2-1
basic transistor amplifier, 2-15
FET (field effect), 3-38
fundamentals, 2-2
identification, 2-30
introduction to, 2-1
maintenance, 2-31
microelectronics, 2-37
specifications, 2-29
UJT (unijunction), 3-34
INDEX-3
TRIAC, 3-22
Troubleshooting power supplies, 4-51
testing, 4-49
Tunnel diode, 3-8
U
UJT, unijunction transistor, 3-34
V
Varactor, 3-15
Voltage multipliers, power supply, 4-45
short circuit protection, 4-50
Voltage regulation, power supply, 4-34
Z
Zener diodes, 3-2
Assignment Questions
Information: The text pages that you are to study are
provided at the beginning of the assignment questions.
1
ASSIGNMENT 1
Textbook assignment: Chapter 1, “Semiconductor Diodes,” pages 1-1 through 1-47.
_________________________________________________________________________________
1-1. Which of the following electronic devices
operates by virtue of the movement of
electrons within a solid piece of
semiconductor material?
1. Transistor
2. Junction diode
3. Solid-state device
4. Each of the above
1-2. Which of the following electronic devices
is a minute piece of semiconductor material
that can produce complete electronic
circuit functions?
1. Zener diode
2. Light-emitting diode
3. Integrated circuit
4. Field effect transistor
1-3. Which of the following terms is used for
the decrease in resistance as the
temperature of the semiconductor
increases?
1. Positive temperature coefficient
2. Negative temperature coefficient
3. Faraday temperature coefficient
4. Zero temperature coefficient
1-4. In addition to rectifying properties,
selenium has the property of being light
sensitive. How is selenium's resistance
affected by light?
1. It decreases with an increase in light
intensity
2. It increases with an increase in light
intensity
3. It remains constant with variation in
light intensity
4. It increases regardless of the variation
in light intensity
1-5. One of the most sensitive elements of
semiconductor materials is galena. Galena
is a crystalline form of what material?
1. Krypton
2. Bismuth
3. Strontium
4. Lead sulfide
1-6. What significant discovery caused a
breakthrough in the development of
semiconductor devices?
1. The junction diode
2. The junction barrier
3. The extrinsic semiconductor
4. The point-contact transistor
1-7. Which of the following devices is
frequently used to regulate power supply
voltages at precise levels?
1. Junction diode
2. Tunnel diode
3. Esaki diode
4. Zener diode
1-8. Which of the following solid-state devices
has both gain and fast-switching
capabilities?
1. Zener diode
2. Tunnel diode
3. Junction diode
4. Point-contact diode
1-9. Which of the following advantages, if any,
does a conventional electron tube have
over a semiconductor device?
1. It is more efficient
2. It has a longer life
3. It is more economical
4. None of the above
2
1-10. When compared to an electron tube, the
semiconductor device has which of the
following limitations?
1. The semiconductor is more sensitive to
temperature
2. The semiconductor is used only in
radar equipment
3. The semiconductor is difficult to adapt
to commercial products
4. Each of the above
1-11. Matter can be found in which of the
following forms?
1. Solid
2. Liquid
3. Gas
4. Each of the above
1-12. A substance that cannot be reduced to a
simpler form by chemical means is called
a/an
1. element
2. mixture
3. compound
4. solution
1-13. An atom is the smallest possible particle
that retains the characteristics of which of
the following substances?
1. An element
2. A mixture
3. A compound
4. A solution
1-14. A molecule is the smallest possible particle
that retains the characteristics of which of
the following substances?
1. An element
2. A mixture
3. A compound
4. A solution
1-15. Which part of the atom has a negative
charge and a small mass?
1. Proton
2. Electron
3. Positron
4. Neutron
1-16. Which part of the atom has a positive
charge and a large mass?
1. Proton
2. Electron
3. Positron
4. Neutron
1-17. Which part of the atom has no electrical
charge?
1. Proton
2. Electron
3. Positron
4. Neutron
1-18. What name is given to the outermost shell
of an atom?
1. First shell
2. M shell
3. Valence shell
4. Subshell
1-19. What term is used to describe an atom
which has more than its normal amount of
electrons?
1. Ion
2. Ionization
3. Positive ion
4. Negative ion
1-20. Which of the following terms is defined as
the process by which an atom gains or
loses electrons?
1. Quanta
2. Ionization
3. Loss of energy
4. Remaining energy
3
1-21. Electrons are NEVER found in which of
the following bands?
1. Energy band
2. Valence band
3. Forbidden band
4. Conduction band
1-22. What determines whether a substance is an
insulator, semi-conductor, or conductor?
1. The separation between the valence
and forbidden bands
2. The separation between the conduction
and valence bands
3. The separation between the conduction
and forbidden bands
4. The separation between the forbidden
band and the energy gap
Figure 1A.—Energy level diagram.
IN ANSWERING QUESTIONS 1-23 AND 1-24,
REFER TO FIGURE 1-A.
1-23. What energy level in figure 1-A is
classified as the best insulator?
1. A
2. B
3. C
4. D
THIS SPACE LEFT BLANK
INTENTIONALLY.
1-24. When the insulator is compared to the
semiconductor, (a) which one requires the
least energy to move an electron and
(b) from which point in the energy level in
figure 1-A does the electron leave in its
travel to the conduction band?
1. (a) Semiconductor (b) Valence band
2. (a) Insulator (b) Valence band
3. (a) Semiconductor (b) Forbidden band
4. (a) Insulator (b) Forbidden band
1-25. Which of the following terms applies to the
process that holds the atom together in a
crystal?
1. Suhl effect
2. Superposition
3. Boundary defect
4. Covalent bonding
1-26. The movement of electrons in a
semiconductor toward the applied voltage
is termed
1. hole flow
2. positive conduction
3. negative conduction
4. electron current flow
1-27. When the theory of semiconductors is
discussed, what term(s) is/are used to
describe the current that flows in the
semiconductor?
1. Hole flow
2. Electron flow
3. Both 1 and 2 above
4. Electromotive flow
1-28. What process takes place within the
semiconductor to cause hole flow?
1. The breaking of covalent bonds
2. The combining of valence bands
3. The flexing of the material
4. The splitting of atoms
4
1-29. A material which has an equal number of
electron-hole pairs and conducting
electrons is known as what type of
semiconductor material?
1. Extrinsic
2. Intrinsic
3. N-type
4. P-type
1-30. The process of adding impurities to crystals
is known by which of the following terms?
1. Charging
2. Doping
3. Honing
4. Processing
1-31. When doping increases the number of free
electrons in a semiconductor, what type of
impurity has been added?
1. E-type
2. N-type
3. O-type
4. P-type
1-32. The semiconductor doping impurities—
arsenic, antimony, and bismuth—are
classified as what type of impurities?
1. Active
2. Neutral
3. Trivalent
4. Pentavalent
1-33. In the P-type semiconductor, what are the
majority carriers?
1. The electrons
2. The holes
3. The inactive atoms
4. The inert atoms
1-34. What is/are the purpose(s) of the PN
junction diode?
1. To rectify only
2. To amplify only
3. To rectify and amplify
4. To switch
1-35. In a schematic diagram of a PN junction
diode, which of the following symbols
represents the cathode (N-type material)?
1. The arrow
2. The circle
3. The vertical bar
4. The horizontal line
1-36. Which of the following alphanumerical
codes correctly identifies the diode, crystal
rectifier number 3, in a circuit?
1. CR3
2. DR3
3. RD3
4. CRD3
1-37. Which of the following is the schematic
symbol of the PN junction diode?
1.
3.
2.
4
1-38. The placing of an impurity on a
semiconductor of the opposite impurity and
fusing the two together produce what type
of semiconductor junction?
1. Grown junction
2. Alloy Junction
3. Barrier junction
4. Intrinsic junction
5
1-39. A perfect bond at the junction of the two
diode materials is important for which of
the following reasons?
1. It is the point at which rectification
takes place
2. It is the point at which amplification
takes place
3. It is the main structural point from
where the diode gets its strength
4. All of the above
1-40. Current flow in a copper wire can be
compared to current flow in what type(s)
of semiconductor material?
1. N-type only
2. P-type only
3. N- and P-type
4. All types
1-41. What is the overall electrical charge of the
N-material in a semiconductor?
1. Zero
2. Some negative value
3. Some positive value
4. Depending upon the balance of
electrons, it will be positive or negative
1-42. What is the overall electrical charge of the
P-material in a semiconductor?
1. Zero
2. Some negative value
3. Some positive value
4. Depending upon the balance of
electrons, it will be positive or negative
1-43. What causes the process called junction
recombination to occur when N and P
materials are joined together?
1. The diffusion of electrons and holes
moving across the junction into the two
materials
2. The generation of heat which causes
the electrons to bombard the holes at
the junction
3. The development of an electrostatic
field on each side of the junction
4. The loss of electrons to the depletion
region
1-44. After the junction recombination process
has reached equilibrium, what is the area
that surrounds the junction called?
1. The anode
2. The free ion space
3. The depletion region
4. The electrostatic field
1-45. A voltage applied to a PN junction so that
it reduces the junction barrier and aids
current flow is what type of bias?
1. Indirect
2. Reverse
3. Forward
4. Direct
1-46. In a forward-biased PN junction, when an
electron leaves the negative terminal of the
battery and enters the N material, it
becomes what type of carrier?
1. Loop
2. Signal
3. Majority
4. Minority
6
1-47. Which of the following illustrations depicts
a properly forward-biased PN junction?
(Note: The number of elements in the
battery indicates the applied voltages.)
1.
2.
3.
4.
1-48. In the PN junction, which of the following
actions will increase the number of
majority carriers and increase current flow
in a forward-biased condition?
1. Increasing the size of the P material
2. Decreasing the size of the P material
3. Increasing battery voltage
4. Decreasing battery voltage
1-49. A voltage applied to a PN junction so that
it will increase the junction barrier and
offer a high resistance to current flow is
called what type of bias?
1. Direct
2. Forward
3. Reverse
4. Indirect
1-50. When the negative terminal of a battery is
connected to the P material, and the
positive terminal is connected to the N
material, what type of bias is being used?
1. Self
2. Forward
3. Reverse
4. Inverse
1-51. What provides you with information
concerning the voltage-current relationship
of a PN junction diode?
1. The body color of the diode
2. The color coded bands on the diode
3. The printed information on the diode
4. The characteristic curve graph of the
diode
THIS SPACE LEFT BLANK
INTENTIONALLY.
7
Figure 1B.—An electronic circuit.
IN ANSWERING QUESTIONS 1-52 THROUGH
1-55, REFER TO FIGURE 1-B.
1-52. What type of circuit is shown in figure
1-B?
1. Full-wave rectifier
2. Half-wave rectifier
3. Clipper
4. Clamper
1-53. With the input shown, which of the
following outputs would be correct?
1.
2.
3.
4.
1-54. Which of the following outputs would be
correct with two alternations of the ac input
signal applied?
1.
2.
3.
4.
1-55. What is/are the purposes(s) of RL?
1. It limits the amount of current flow in
the circuit
2. It develops the output signal
3. Both 1 and 2 above
4. It maintains the proper bias on the
diode
THIS SPACE LEFT BLANK
INTENTIONALLY.
8
Figure 1C
IN ANSWERING QUESTIONS 1-56 AND 1-57,
REFER TO FIGURE 1-C.
1-56. What type of circuit is shown in figure
1-C?
1. Positive half-wave rectifier
2. Negative half-wave rectifier
3. Full-wave rectifier
4. Clipper
1-57. With the input shown in figure 1-C, which
of the following outputs would be correct?
1.
2.
3.
4.
1-58. If the input frequency to a half-wave
rectifier is 120 hertz, what is the output
frequency of the rectified dc?
1. 30 pps
2. 60 pps
3. 120 pps
4. 240 pps
1-59. Why are the units (plates) of the metallic
rectifier stacked?
1. To dissipate heat
2. To be used in more than one circuit
3. To prevent inverse voltage breakdown
4. To handle high current applications
1-60. Which of the following types of rectifiers
replaces the bulky selenium rectifier?
1. Copper-oxide rectifier
2. Half-wave rectifier
3. Metallic rectifier
4. Silicon rectifier
1-61. Signal diodes are used for which of the
following purposes?
1. As mixers
2. As switches
3. As detectors
4. Each of the above
1-62. What type of bias makes a diode act as an
open switch?
1. Direct
2. Reverse
3. Forward
4. Switching
1-63. A standard specification sheet for a diode
contains which of the following
information?
1. A brief description of the diode
2. Major application of the diode
3. Special features of the diode
4. All of the above
9
________________________________________
IN ANSWERING QUESTIONS 1-64 THROUGH
1-66, MATCH THE ELECTRICAL LETTER
SYMBOL FOR RECTIFIER DIODES IN
COLUMN B TO THE DEFINITION IN
COLUMN A.
A. DEFINITIONS
B. SYMBOLS
1-64. The maximum reverse
dc voltage that will not
cause breakdown
1. V R
1-65. The peak current
specified for a given
number of cycles or
portion of a cycle
2. I SURGE
1-66. The average reverse
current at a specified
temperature, usually
60 hertz
3.
4.
IF(AV)
IR(AV)
________________________________________
1-67. A matching pair of diodes is indicated by
which of the following numbers?
1. 2N325
2. 1N325C
3. 2N325M
4. 1N325M
1-68. The number 3N345 identifies which of the
following semiconductors, if any?
1. Diode
2. Transistor
3. Tetrode transistor
4. None of the above
1-69. What type of diode has green, blue, and
orange bands?
1. 1N463
2. 1N572
3. 1N663
4. 1N563
1-70. One of the prime dangers to the
semiconductor diode is heat. Excessive
current generated by heat which eventually
destroys a diode is called
1. junction overload
2. thermal runaway
3. thermoplastic action
4. thermionic emission
1-71. When replacing a diode in a circuit, which
of the following safety precautions should
you observe in removing the diode from
the circuit?
1. Do not pry the diode from the circuit
2. Do not use excessive heat to remove
the diode
3. Do not remove the diode from the
circuit while voltage is applied
4. All of the above
1-72. As you make a front-to-back ratio check of
a diode with an ohmmeter, your first
measurement (forward) is a low resistance
reading, and your second measurement
(reverse) is also a low reading. What
should be your evaluation of the diode?
1. It is open
2. It is shorted
3. It is good
4. It is leaky
1-73. What are normally the front-to-back ratio
of (a) a power rectifier and (b) a signal
diode?
1. (a) 10:1 (b) 50:1
2. (a) 10:1 (b) 300:1
3. (a) 300:1 (b) 10:1
4. (a) 300:1 (b) 50:1
10
1-74. Of the following tests, which is the most
valid for checking a diode?
1. A forward and reverse resistance check
with an ohmmeter
2. The substitution of a new diode for the
questionable one
3. A dynamic electrical check with a
diode test set
4. A forward and reverse resistance check
using two different ohmmeters
11
ASSIGNMENT 2
Textbook assignment: Chapter 2, “Transistors,” pages 2-1 through 2-53.
_________________________________________________________________________________
2-1. What term is used for a semiconductor
that has three or more elements?
1. Diode
2. Transistor
3. Duo-diode
4. Point contact
2-2. The term transistor was derived from
which of the following words?
1. Resistance and capacitance
2. Transformer and resistor
3. Resistor and transformer
4. Transfer and resistor
2-3. What are the three elements of a
transistor?
1. Anode, base, and collector
2. Cathode, base, and collector
3. Emitter, collector, and base
4. Collector, emitter, and cathode
2-4. In a transistor, the flow of current carriers
is controlled by which element(s)?
1. Emitter
2. Collector
3. Both 1 and 2 above
4. Base
2-5. In a transistor schematic, what is
indicated by (a) the angular line with the
arrowhead and (b) the direction of the
arrow?
1. (a)
(b)
Cathode
Direction of current flow
2. (a)
(b)
Base
Direction of current flow
3. (a)
(b)
Emitter
Type of transistor
4. (a)
(b)
Collector
Type of transistor
2-6. Junction transistors have replaced point-
contact transistors for which of the
following reasons?
1. Junction transistors generate less noise
2. Junction transistors handle more
power
3. Junction transistors provide higher
current and voltage gains
4. All of the above
2-7. What is the total number of PN junctions
in a transistor?
1. One
2. Two
3. Three
4. Four
2-8. What are the two junctions of a
transistor?
1. Emitter-base and emitter-collector
2. Emitter-collector and base-collector
3. Emitter-base and collector-emitter
4. Emitter-base and base-collector
2-9. With proper bias applied to a transistor,
what should be the relative resistance of
(a) the emitter-base junction and (b) the
base-collector junction?
1. (a) High (b) low
2. (a) High (b) high
3. (a) Low (b) low
4. (a) Low (b) high
2-10. For normal operation of a transistor, what
is the bias of the (a) emitter-base junction
and (b) base-collector junction?
1. (a) Forward (b) reverse
2. (a) Forward (b) forward
3. (a) Reverse (b) forward
4. (a) Reverse (b) reverse
12
Figure 2A.—Transistor symbology.
IN ANSWERING QUESTIONS 2-11
THROUGH 2-15, REFER TO FIGURE 2-A.
MATCH THE SYMBOL TO THE TERM
GIVEN IN THE QUESTION.
2-11. The symbol for base current.
1. H
2. D
3. C
4. B
2-12. The symbol for collector current.
1. A
2. C
3. G
4. H
2-13. The symbol for emitter current.
1. B
2. C
3. D
4. F
2-14. The symbol for collector voltage supply.
1. C
2. D
3. E
4. F
2-15. The symbol for base voltage supply.
1. E
2. F
3. G
4. H
2-16. In a transistor, what percent of the total
current flows through the emitter lead?
1. 100
2. 98
3. 60
4. 5
2-17. What are the majority current carriers in
(a) the PNP transistor and (b) the NPN
transistor?
1. (a) Holes (b) holes
2. (a) Holes (b) electrons
3. (a) Elements (b) holes
4. (a) Electrons (b) electrons
2-18. How will the transistor currents be
affected if the forward bias provided by
VBB is increased?
1. I B will decrease, IE will decrease, and
IC will decrease
2. I B will increase, IE will decrease, and
IC will decrease
3. I B will increase, IE will decrease, and
IC will increase
4. I B will increase, IE will increase, and
IC will increase
2-19. What device provides an increase in
current, voltage, or power of a signal
without appreciably altering the original
signal?
1. Diode
2. Amplifier
3. Oscillator
4. Power supply
2-20. The resistor that provides forward bias
for the emitter-base junction of a
transistor is indicated by which of the
following symbols?
1. R T
2. R g
3. R L
4. R B
13
2-21. The collector load resistor is represented
by which of the following symbols?
1. R T
2. R g
3. R L
4. R B
2-22. In the quiescent state of a transistor
circuit, what does the symbol VC
indicate?
1. Collector voltage supply
2. Collector voltage
3. Current gain
4. Capacitor voltage
Figure 2B.—A basic transistor amplifier.
IN ANSWERING QUESTIONS 2-23
THROUGH 2-26, REFER TO FIGURE 2-B.
2-23. What is the purpose of CC?
1. To bypass ac signals to ground
2. To couple the input signal to the
amplifier
3. To provide base bias to the preceding
stage
4. To prevent ac variations on the base
2-24. When the positive alternation of the input
signal is applied at point A, what, if
anything, happens to the bias on the base
of the transistor?
1. It increases
2. It decreases
3. It remains at its quiescent value
4. Nothing
2-25. When the positive alternation of the input
signal is applied at point A, what
happens, if anything, to the current
through RL?
1. It increases
2. It decreases
3. It remains at its quiescent value
4. Nothing
2-26. When the signal shown at point A is
applied to the base of Q1, which of the
following signals will be at the output?
1.
3.
2.
4.
2-27. What type of bias keeps the base bias
constant and improves thermal stability?
1. Self-bias
2. Fixed bias
3. Combination bias
4. Each of the above
14
Figure 2C.—A transistor amplifier.
IN ANSWERING QUESTIONS 2-28
THROUGH 2-34, REFER TO FIGURE 2-C.
2-28. Which resistors are fixed biased
resistors?
1. R1 and R L
2. R1 and R3
3. R1 and R2
4. R2 and R3
2-29. Which resistor is self-biased?
1. R1
2. R2
3. R3
4. R L
2-30. Which waveform is the output for a class
AB amplifier with input number 1?
1. A
2. B
3. C
4. D
2-31. Which waveform is the output for a class
A amplifier with input number 2?
1. C
2. D
3. E
4. F
2-32. Which waveform is the output for a class
B amplifier with input number 1?
1. A
2. B
3. F
4. G
2-33. Which waveform is the output for a Class
C amplifier with input number 2?
1. A
2. B
3. C
4. G
2-34. If the circuit is operating as a class A
amplifier, but is being "overdriven,"
which output waveform is correct?
1. A
2. B
3. C
4. D
2-35. Which class of amplifier allows collector
current to flow for a full 360 degrees of
the input signal?
1. A
2. B
3. C
4. AB
2-36. Which class of amplifier allows collector
current to flow for more than 180 degrees
of the input signal but less than 360
degrees?
1. A
2. B
3. C
4. AB
15
2-37. Which class of amplifier has the highest
fidelity and lowest efficiency?
1. A
2. B
3. C
4. AB
2-38. Which class of amplifier has the highest
efficiency?
1. A
2. B
3. C
4. AB
2-39. What are the three transistor
configurations?
1. Common base, common grid, and
common output
2. Common anode, common collector,
and common base
3. Common emitter, common base, and
common collector
4. Common emitter, common base, and
common base
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INTENTIONALLY.
_______________________________________
IN ANSWERING QUESTIONS 2-40
THROUGH 2-45, MATCH THE
TRANSISTOR CONFIGURATIONS LISTED
IN COLUMN B TO THE TRANSISTOR
CIRCUITS SHOWN IN COLUMN A. (NOTE:
ANSWERS IN COLUMN B MAY BE USED
MORE THAN ONCE.)
A. CIRCUITS B. CONFIGURATIONS
2-40.
1.
2.
3.
Common Emitter
Common Base
Common Collector
2-41.
2-42.
2-43.
2-44.
2-45.
_______________________________________
16
2-46. Which of the following is a transistor
configuration that provides a phase
reversal?
1. Common bias
2. Common input
3. Common emitter
4. Common collector
2-47. What is the symbol for input current in a
common-emitter configuration?
1. I E
2. I B
3. IC
4. I T
2-48. What is the symbol for input current in a
common-base configuration?
1. I E
2. I B
3. IC
4. I T
2-49. What term is used to indicate current
gain in a common-emitter configuration?
1. Alpha
2. Beta
3. Gamma
4. X-ray
2-50. What term is used to indicate current
gain in a common-collector
configuration?
1. Alpha
2. Beta
3. Gamma
4. X-ray
2-51. What term is used to indicate current
gain in a common-base configuration?
1. Alpha
2. Beta
3. Gamma
4. X-ray
2-52. Which of the following formulas is used
to figure current gain in a common-
emitter configuration?
1.
3.
2.
4.
2-53. Which of the following formulas is used
to figure current gain in a common-base
configuration?
1.
3.
2.
4.
2-54. Which of the following formulas is used
to figure current gain in a common-
collector configuration?
1.
3.
2.
4.
2-55. The common collector is also referred to
by which of the following terms?
1. Low current gain amplifier
2. Voltage amplifier
3. Emitter follower
4. Grounded emitter
17
2-56. Which of the following conditions
presents the greatest danger to a
transistor?
1. Heat
2. High operating voltage
3. Excessive reverse current
4. Handling of the transistor
2-57. What method for checking transistors is
cumbersome when more than one
transistor is bad in a circuit?
1. Ohmmeter
2. Transistor checker
3. Voltage check
4. Substitution
A. Hybrid IC
B. Monolithic IC
C. Microelectronics
D. Modular Circuitry
E. Integrated Circuit
F. Printed Circuit Board
G. Integrated Circuit Board
Figure 2D.—List of microelectronic terminology.
IN ANSWERING QUESTIONS 2-58
THROUGH 2-62, SELECT FROM FIGURE
2-D THE TERM DEFINED IN THE
QUESTION.
2-58. A broad term used to describe the use of
integrated circuits to miniaturize
electronic equipment.
1. A
2. B
3. C
4. D
2-59. A flat insulating surface upon which
printed wires and miniaturized
components are connected in a
predetermined design and attached to a
common base.
1. A
2. B
3. F
4. G
2-60. An assembly technique in which printed
circuit boards are stacked and connected
to form a module.
1. B
2. C
3. D
4. E
2-61. A device that integrates both active and
passive components of a complete
electronic circuit in a single chip.
1. D
2. E
3. F
4. G
2-62. A plastic card on which integrated
circuits are mounted.
1. A
2. B
3. F
4. G
18
ASSIGNMENT 3
Textbook assignment: Chapter 3, “Special Devices,” pages 3-1 through 3-55.
_________________________________________________________________________________
3-1. What is the total number of connections in
a diode?
1. One
2. Two
3. Three
4. Four
3-2. When the PN-junction diode is reversed
biased, what happens to the majority
carriers?
1. They combine with minority carriers at
the junction
2. They move toward the junction
3. Both 1 and 2 above
4. They move away from the junction
3-3. What causes a small leakage current in a
reverse-biased PN junction?
1. Holes
2. Electrons
3. Minority carriers
4. Majority carriers
3-4. At some potential, as you increase the
reverse bias voltage on a PN junction, the
reverse current increases very rapidly.
What electronic term is given to this
voltage potential?
1. Breakdown voltage
2. Reverse-bias
3. Forward-bias
4. Thermal runaway
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INTENTIONALLY.
3-5. Which of the following is a characteristic
of the Zener diode?
1. A PN-junction diode that operates in
the reverse-bias breakdown region
2. A PN-junction diode that uses the
avalanche effect
3. A PN-junction diode that uses the
Zener effect
4. Each of the above
3-6. What determines whether a solid material
will act as a conductor, a semiconductor,
or an insulator?
1. The energy level of the valence band
2. The energy level of the conductor band
3. The energy difference across the
forbidden gap
4. The actual construction of the valence
electrons
3-7. In comparing a conductor and an insulator,
what is the relative dimension of the
forbidden gap of (a) the conductor and
(b) the insulator?
1. (a) Wide (b) wide
2. (a) Wide (b) narrow
3. (a) Narrow (b) narrow
4. (a) Narrow (b) wide
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19
3-8. What is the "tunneling phenomenon"
within the Zener diode?
1. An action where the minority carriers
tunnel across the junction to form the
current that occurs at breakdown
2. An action where the majority carriers
tunnel across the junction to form the
current that occurs at breakdown
3. An action that separates the
conduction band and the valence band
by a large gap
4. An action that removes all the
electrons from the conduction band
energy level
3-9. Which breakdown theory explains the
action that takes place in a heavily doped
PN junction with a reverse bias above 5
volts?
1. Zener effect
2. Avalanche breakdown
3. Energy band effect
4. Valence band gap crossing
3-10. Which breakdown theory explains the
action that takes place in a heavily doped
PN junction with a reverse bias below 5
volts?
1. Zener effect
2. Avalanche breakdown
3. Energy band effect
4. Valence band gap crossing
3-11. What happens to a Zener diode that has a
reverse bias slightly higher than the
breakdown voltage?
1. The Zener cuts off
2. The Zener acts like a short circuit
3. The Zener acts like an open circuit
4. The Zener conduction does not change
Figure 3A.—Schematic symbols.
IN ANSWERING QUESTIONS 3-12 AND 3-13,
REFER TO FIGURE 3-A.
3-12. Which of the symbols represents a Zener
diode?
1. A
2. B
3. C
4. D
3-13. In what direction does current flow in a
Zener diode?
1. From point 1 to point 2
2. From point 2 to point 1
3. From point 1 to point 2 to point 3
4. From point 3 to point 2 to point 1
3-14. Why is the Zener diode an ideal voltage
regulator?
1. It compensates for low supply voltage
2. It uses an unlimited number of carriers
3. Operating in the breakdown region
does not harm it
4. The voltage across the diode remains
almost constant after breakdown
20
3-15. In the construction of the tunnel diode,
what is the ratio of impurity atoms to
semiconductor atoms?
1. 10,000,000: 1000
2. 1,000:10,000,000
3. 10,000: 100,000
4. 100,000: 10,000
Figure 3B. Tunnel diode characteristic curve.
IN ANSWERING QUESTIONS 3-16
THROUGH 3-18, REFER TO FIGURE 3-B.
3-16. What is/are the most important aspects(s)
of the tunnel diode characteristic curve?
1. The forward-current increase to a peak
with small applied forward bias
2. The decreasing forward current with
an increasing forward bias to a
minimum valley current (IV)
3. The normal increasing forward current
with further increase in the bias
voltage
4. All of the above
3-17. What portion of the characteristic curve is
the region of negative resistance?
1. From point 1 to point 2
2. From point 2 to point 3
3. From point 3 to point 4
4. From point 4 to point 5
3-18. At what area on the characteristic curve
does the tunnel diode perform like a
normal PN junction?
1. From point 0 to point 1
2. From point 1 to point 2
3. From point 2 to point 3
4. From point 3 to point 4
3-19. The varactor operates like which of the
following electronic components?
1. A capacitor
2. An inductor
3. A variable capacitor
4. A variable inductor
3-20. An increase in reverse bias of a varactor
will have what effect on the width of the
depletion region?
1. It will stabilize
2. It will fluctuate
3. It will decrease
4. It will increase
3-21. What happens to the capacitance of a
varactor diode as the reverse bias is
increased?
1. It decreases
2. It increases
3. It remains the same
3-22. In electronic circuits, how is the varactor
used?
1. As a tuning device
2. As a balancing device
3. As an amplifier
4. As a rectifier
3-23. What is/are the basic purpose(s) of the
silicon controlled rectifier (SCR)?
1. To function as a switch
2. To function as a regulator
3. To function as a rectifier
4. All of the above
21
3-24. The SCR is equivalent to what electronic
device?
1. Diode
2. Tetrode
3. Thyratron
4. Beam power tube
3-25. Which of the following circuits uses an
SCR in its electronic circuitry?
1. Computer logic circuit
2. Voltage comparator circuit
3. Antenna power amplifier circuit
4. Each of the above
Figure 3C. The schematic symbol for the SCR.
IN ANSWERING QUESTION 3-26, REFER TO
FIGURE 3-C.
3-26. What is the impedance between points A
and C (a) when the SCR is biased off and
(b) when the SCR is at saturation?
1. (a) Low (b) low
2. (a) Low (b) high
3. (a) High (b) high
4. (a) High (b) low
Figure 3D. A two-transistor circuit.
IN ANSWERING QUESTION 3-27, REFER TO
FIGURE 3-D.
3-27. When a positive current is applied to the
gate lead, what happens to the collector
current of Q1 and Q2?
1. Increases to a value limited only by
the external circuit
2. Increases to a value limited only by
the internal circuit
3. Decreases to a value limited only by
the external circuit
4. Decreases to a value limited only by
the internal circuit
3-28. Once an SCR is turned on by a positive
pulse of current applied to the gate lead,
what action turns the SCR off?
1. Removing the positive pulse from the
gate lead
2. Inserting a negative pulse of current on
the gate lead
3. Reducing the collector current to a
value below that necessary to maintain
conduction
4. Increasing the collector current to a
point that the SCR will go into
saturation and cut off
3-29. What is the total number of terminals in a
TRIAC?
1. One
2. Two
3. Three
4. Four
22
3-30. What is the main difference between the
TRIAC and the SCR?
1. The SCR requires a higher input
voltage than the TRIAC
2. The TRIAC requires a higher input
voltage than the SCR
3. The TRIAC controls and conducts
current during both alternations of an
ac cycle, while the SCR controls and
conducts current during only one
alternation
4. The SCR controls and conducts
current during both alternations of an
ac cycle, while the TRIAC controls
and conducts currents during only one
alternation
3-31. What name is given to a group of devices
that either produce light or use light in
their operation?
1. Optoelectronic
2. Ophthalmology
3. Optokenetic
4. Optometry
3-32. In optoelectronic devices, what do the
initials LED stand for?
1. Low-emitting diode
2. Low-emitting device
3. Light-emitting diode
4. Light-emitting device
3-33. What determines the color of light emitted
by an LED?
1. The type of incandescent bulb used
2. The type of material used
3. The type of bias used
4. The type of fluorescent bulb used
3-34. What is the standard schematic symbol
used to designate LEDs?
1. An incandescent bulb with arrows
pointing toward the light
2. An incandescent bulb with arrows
pointing away from the light
3. A diode with two arrows pointing
toward the cathode
4. A diode with two arrows pointing
away from the cathode
3-35. The circuit symbols for all optoelectronic
devices have arrows pointing either
toward them or away from them. When
the arrows point toward the symbol, what
does this indicate?
1. The device produces light
2. The device uses light
3. The device requires current flow
4. The device produces current flow
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23
Figure 3E. Light-emitting diode.
IN ANSWERING QUESTIONS 3-36 AND 3-37,
REFER TO FIGURE 3-E.
3-36. When a negative voltage is applied to the
proper cathodes in an LED display, a
number is formed. To produce the numeral
5 on an LED display, which of the
following diodes must have a negative
potential on their cathodes?
1. ABCDE
2. ABGED
3. AFGCD
4. AFGBC
3-37. If an LED segment has an "8" displayed
and the negative bias is removed from
diodes F and C, what numeral will be
displayed?
1. 1
2. 2
3. 3
4. 4
3-38. When replacing LED displays, which of
the following methods should you use to
ensure that the replacement display is of
the same type as the faulty display?
1. A visual inspection
2. A check of the schematic symbols
3. Both 1 and 2 above
4. A check of the manufacturer's number
3-39. The photodiode acts as what type of
electronic device?
1. Variable inductor
2. Variable resistor
3. Nonvariable inductor
4. Nonvariable resistor
3-40. When the photodiode is exposed to
an external light, what happens to
(a) resistance and (b) current?
1. (a) Increase (b) decreases
2. (a) Increases (b) increases
3. (a) Decreases (b) increases
4. (a) Decreases (b) decreases
3-41. To conduct, how must a photodiode be
biased?
1. Reverse biased
2. Forward biased
3. Either 1 or 2 above, depending on light
intensity
3-42. Photodiodes are useful in which of the
following applications?
1. Computer card readers
2. Photographic light meters
3. Optic scanning equipment
4. Each of the above
3-43. Which of the following optoelectronic
devices provides increased, conduction for
a given light intensity?
1. LED
2. SCR
3. Phototransistor
4. Phototransformer
3-44. To compensate for ambient light, a
phototransistor must have a total number
of how many leads?
1. One
2. Two
3. Three
4. Four
24
Figure 3F. Solid-state schematic symbols.
IN ANSWERING QUESTIONS 3-45
THROUGH 3-47, SELECT FROM FIGURE 3-F
THE SCHEMATIC SYMBOL IDENTIFIED IN
THE QUESTION.
3-45. Schematic symbol for a photo-diode.
1. A
2. B
3. C
4. D
3-46. Schematic symbol for a two-terminal
phototransistor.
1. A
2. B
3. C
4. D
3-47. Schematic symbol for a three-terminal
phototransistor.
1. A
2. B
3. C
4. D
3-48. Which of the following devices is similar
in operation to a photodiode?
1. Phototransistor
2. Photocell
3. LED
4. SCR
3-49. Which of the following is a typical light to
dark resistance ratio of a photocell?
1. 1: 10
2. 1: 100
3. 1: 1000
4. 1:10,000
3-50. Photocells are used in which of the
following circuits?
1. Controller
2. Oscillator
3. Amplifier
4. Detector
3-51. How should photovoltaic cells be coupled
together to produce a relatively high
voltage?
1. Series coupling
2. Parallel coupling
3. Inductive coupling
4. Mechanical coupling
3-52. What is the total number of terminals in a
unijunction transistor (UJT)?
1. One
2. Two
3. Three
4. Four
3-53. The UJT has which of the following
advantages over the conventional
transistor?
1. Fewer terminals
2. Larger bandpass
3. Less bias is required
4. Increased temperature stability
25
3-54. How does the UJT differ from a
conventional transistor?
1. The UJT has a second base instead of
a collector
2. The UJT has a second emitter instead
of a collector
3. The UJT has two collectors
3-55. When properly biased, what area(s) of the
UJT act(s) as a resistor?
1. The area between base 1 and base 2
2. The area between emitter 1 and emitter
2
3. The area between collector 1 and
collector 2
4. All of the above
3-56. The emitter of the UJT may be compared
to what electronic component?
1. A fully charged capacitor
2. The wiper arm of a variable resistor
3. The collector of a conventional
transistor
4. The secondary winding of a step-down
transformer
3-57. What determines the level of voltage
gradient at the emitter-base material
contact point of a UJT?
1. The bias voltage
2. The manufacturer's specifications
3. The base area of the emitter
4. The voltage potential between base 2
and emitter
3-58. The UJT conducts from base 1 to (a) what
point when it is forward biased and from
(b) what point to bass 2 when it is reversed
biased?
1. (a) Emitter (b) base 1
2. (a) Emitter (b) emitter
3. (a) Base 2 (b) base 1
4. (a) Base 1 (b) emitter
3-59. UJTs may be used in which of the
following circuits?
1. Switching
2. Waveshaping
3. Oscillating
4. Each of the above
3-60. The field-effect transistor (FET) combines
what desired characteristic of the vacuum
tube with the many other advantages of
the transistor?
1. Low output impedance
2. High output impedance
3. Low input impedance
4. High input impedance
3-61. What does the FET use to control the
electrostatic field within the transistor?
1. Current
2. Voltage
3. Low input impedance
4. High input impedance
3-62. The junction field-effect transistor's
(JFET) gate element corresponds very
closely in operation with (a) what part of a
conventional transistor and (b) what part
of the vacuum tube?
1. (a) Emitter (b) cathode
2. (a) Base (b) grid
3. (a) Base (b) cathode
4. (a) Collector (b) plate
3-63. In the JFET, the portion of the bar
between the deposit of gate material is of a
smaller cross section than the rest of the
bar. What does this cross section form?
1. A gate
2. A drain
3. A source
4. A channel
26
3-64. If a P-type material is used to construct the
gate of a JFET, what material should be
used to construct the remaining part of the
JFET?
1. N-type
2. P-type
3. Mica type
4. Junction type
3-65. What is the key to FET operation?
1. The control of the effective cross-
sectional area of the channel
2. The control of the effective cross-
sectional area of the gate
3. Both 1 and 2 above
4. The low input impedance compared
with the high output impedance
3-66. When reverse bias is applied to the gate
lead of a JFET, what happens to
(a) source-to-drain resistance of the device
and (b) current flow?
1. (a) Decreases (b) decreases
2. (a) Decreases (b) increases
3. (a) Increases (b) decreases
4. (a) Increases (b) increases
3-67. What is the "pinch off" voltage of an FET?
1. The voltage required for the FET to
conduct
2. The voltage required to overcome the
FET reverse bias
3. The voltage required to reduce drain
current to zero
4. The voltage required to reduce gate
voltage to zero
Figure 3G. JFET common source amplifier.
IN ANSWERING QUESTIONS 3-68 AND 3-69,
REFER TO FIGURE 3-G.
3-68. What type of transistor is shown in figure
3-G?
1. N channel JFET
2. P channel JFET
3. NPN/channel JFET
4. PNP/channel JFET
3-69. The circuit shown has which of the
following characteristics?
1. Low impedance, high current gain
2. Low impedance, high voltage gain
3. High impedance, high current gain
4. High impedance, high voltage gain
3-70. The MOSFET has which of the following
advantages over the JFET?
1. Less bias
2. Higher input impedance
3. Higher output impedance
4. All of the above
27
3-71. The MOSFET is normally constructed so
that it operates in either the depletion
mode or the enhancement mode. The
depletion mode MOSFET (a) uses what
type of bias and (b) has what type of
doped channel to cause a depletion of
current carriers in the channel?
1. (a) Reverse (b) lightly
2. (a) Forward (b) lightly
3. (a) Reverse (b) heavily
4. (a) Forward (b) heavily
3-72. The enhancement mode MOSFET (a) uses
what type of bias and (b) has what type of
doped channel to enhance the current
carriers in the channel?
1. (a) Reverse (b) lightly
2. (a) Forward (b) lightly
3. (a) Reverse (b) heavily
4. (a) Forward (b) heavily
Figure 3H. A MOSFET schematic symbol.
IN ANSWERING QUESTION 3-73, REFER TO
FIGURE 3-H.
3-73. Which MOSFET element is identified by
the arrow in the schematic symbol shown
in figure 3-H?
1. Substrate
2. Source
3. Drain
4. Gate
3-74. What type metal is used in the
construction of a MOSFET?
1. Oxide
2. Copper
3. Silver
4. Aluminum
3-75. What is the purpose of the shorting spring
in a MOSFET?
1. To shunt the substrate to either the
source or gate during operation
2. To protect the device from static
electricity during replacement
3. To shunt the gates of a dual-gate
MOSFET to make it operate like a
single-gate MOSFET
4. To change the gain characteristics of
the MOSFET
28
ASSIGNMENT 4
Textbook assignment: Chapter 4, “Solid-State Power Supplies,” pages 4-1 through 4-62.
_________________________________________________________________________________
4-1. Which of the following is NOT one of
the four sections of a basic power
supply?
1. Transformer
2. Oscillator
3. Rectifier
4. Filter
4-2. The primary purpose of the transformer
in an electronic power supply is to isolate
the power supply from ground.
1. True
2. False
4-3. What is the primary function of the
rectifier section?
1. To convert dc to ac
2. To convert ac to pulsating dc
3. To increase average voltage output
4. To decrease average voltage output
4-4. What is/are the functions of the filter
section?
1. To eliminate dc voltage
2. To increase the amplitude of ac
3. To convert pulsating dc to steady dc
4. All of the above
4-5. The purpose of a center tap in a
transformer is to provide
1. two separate dc voltages to the
rectifier
2. a step-down voltage to the rectifier
3. pulsating dc to the rectifier
4. two equal voltages from one
transformer
4-6. A diode is an ideal rectifier for which, if
any, of the following reasons?
1. Current flows through the diode in
one direction only
2. Current flows through the diode in
both directions
3. Current will not flow through a diode
4. None of the above
4-7. When the anode of a diode is negative
with respect to the cathode, the diode is
said to be in what state?
1. Conduction
2. Saturation
3. Remission
4. Cutoff
4-8. In a simple half-way rectifier, the diode
will conduct for a maximum of how
many degrees of the 360-degree input
signal?
1. 45
2. 90
3. 180
4. 270
4-9. What term is used to describe current
pulses that flow in the same direction?
1. Average current
2. Secondary current
3. Pure direct current
4. Pulsating direct current
4-10. What is the ripple frequency of a
half-wave rectifier with an input line
frequency of 60 Hz?
1. 30 Hz
2. 60 Hz
3. 90 Hz
4. 120 Hz
29
4-11. In a half-wave rectifier, what is the
average voltage output when the peak
voltage is 300 volts?
1. 190.8 volts
2. 95.4 volts
3. 19.08 volts
4. 9.4 volts
Figure 4A. Complete full-wave rectifier.
IN ANSWERING QUESTIONS 4-12 AND
4-13, REFER TO FIGURE 4-A. ASSUME
THAT THE VOLTAGE ACROSS THE
TRANSFORMER SECONDARY (POINT A -
POINT B) HAS AN RMS VALUE OF 480
VOLTS AC.
4-12. What is the peak value of the voltage
pulse across the load?
1. 169.7 volts
2. 215.8 volts
3. 339.4 volts
4. 480 volts
4-13. What is the average load voltage?
1. 339.4 volts
2. 240 volts
3. 216 volts
4. 189.6 volts
4-14. What is the ripple frequency of a full-
wave rectifier with an input line
frequency of 60 Hz?
1. 30 Hz
2. 60 Hz
3. 90 Hz
4. 120 Hz
4-15. The full-wave rectifier has which of the
following advantages over the half-
wave?
1. Higher average voltage and current
2. Larger number of components
3. Higher value of voltage
4. Better regulation
4-16. What is the average voltage output of a
full-wave rectifier that has an output of
100 volts peak?
1. 3.18 volts
2. 6.36 volts
3. 31.8 volts
4. 63.7 volts
4-17. The primary disadvantage of the
conventional full-wave rectifier is that
the peak output voltage is only one-half
that of the half-wave rectifier.
1. True
2. False
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INTENTIONALLY.
30
Figure 4B. Bridge rectifier.
IN ANSWERING QUESTIONS 4-18 AND
4-19, REFER TO FIGURE 4-B.
4-18. When the voltage across the secondary of
the transformer has the polarity shown,
which of the diodes will conduct?
1. D1 and D3
2. D2 and D4
3. D1 and D2
4. D3 and D4
4-19. When the polarity reverses, which of the
diodes will conduct?
1. D3 and D1
2. D4 and D2
3. D2 and D1
4. D4 and D3
4-20. In filter circuits, inductors are used as
what type of impedance(s)?
1. Shunt impedance to oppose changes
in current
2. Shunt impedances to oppose changes
in voltage
3. Series impedances to oppose changes
in current
4. Series impedances to oppose changes
in voltage
4-21. To retain its charge, the capacitor in a
simple capacitor filter must have a long
charge time constant and a short
discharge time constant.
1. True
2. False
4-22. If you increase the value of a capacitor,
the XC will increase.
1. True
2. False
4-23. To obtain a steady dc output in a simple
capacitor circuit, the capacitor must
charge almost instantaneously to the
value of the applied voltage.
1. True
2. False
4-24. Which of the following factors, if any,
determines the rate of discharge of the
capacitor in a filter circuit?
1. The value of the load resistance
2. The amount of voltage
3. The type of capacitor
4. None of the above
4-25. A half-wave rectifier has an output
frequency of 60 hertz, a filter capacitor
value of 40 microfarads, and a load
resistance of 10 kilohms. What is the
value of XC?
1. 133.3 ohms
2. 26.5 ohms
3. 66.3 ohms
4. 40.0 ohms
31
4-26. A full-wave rectifier has an output
frequency of 120 hertz, a filter capacitor
value of 25 microfarads, and a load
resistance of 10 kilohms.What is the
value of XC?
1. 5.3 ohms
2. 53 ohms
3. 106 ohms
4. 1060 ohms
4-27. What type of filter is the most basic
power supply filter?
1. Capacitor
2. LC choke-input
3. LC capacitor-input
4. RC capacitor-input
4-28. In a circuit with a capacitor filter, how is
the capacitor connected?
1. In series with the load
2. In parallel with the load
3. In series with the input
4. Both 2 and 3 above
4-29. The LC choke-input filter is used
primarily where which of the following
types of regulation is/are important?
1. Frequency
2. Current only
3. Voltage only
4. Voltage and Current
4-30. In an LC choke-input filter circuit, the
capacitor charges only to the average
value of the input voltage. What
component inhibits the capacitor from
reaching the peak value of the input
voltage?
1. The diode
2. The capacitor
3. The filter choke
4. The load resistor
4-31. In an LC choke-input filter, the larger the
value of the filter capacitor, the better the
filtering action. Which of the following
factors represents the major limitation in
obtaining the maximum value of the
capacitor used?
1. Cost
2. Reliability
3. Availability
4. Physical size
4-32. What is the most common range of
values, in henries, for a power supply
choke?
1. 1 to 20
2. 5 to 25
3. 25 to 30
4. 10 to 200
4-33. If the impedance of the choke in an LC
choke-input filter is increased, the ripple
will
1. increase
2. decrease
3. oscillate
4. remain the same
4-34. A full-wave rectifier has an output
frequency of 120 hertz, a filter choke
with a value of 10 henries, and a load
resistance of 10 kilohms. What is the
value of XL?
1. 75 ohms
2. 7.5 ohms
3. 75 kilohms
4. 7.5 kilohms
4-35. The filter capacitor in the LC choke-
input filter is NOT subject to extreme
voltage surges because of the protection
provided by what component?
1. Shunt capacitor
2. Series resistor
3. Load resistor
4. Inductor
32
4-36. Shorted turns in the choke of an LC
choke-input filter may reduce the value
of inductance below the critical value.
When this happens, which of the
following problems may occur?
1. Poor voltage regulation
2. Excessive ripple amplitude
3. Abnormally high output voltage
4. Each of the above
4-37. The use of the RC capacitor-input filter is
limited to which of the following
situations?
1. When the load current is large
2. When the load current is small
3. When the load voltage is large
4. When the load voltage is small
Figure 4C. RC capacitor-input filter.
IN ANSWERING QUESTIONS 4-38 AND
4-39, REFER TO FIGURE 4-C.
4-38. Which of the components will have the
highest failure rate?
1. C1
2. C2
3. R1
4. R L
4-39. Which of the components provides
protection against voltage surges in the
circuit?
1. C1
2. C2
3. R1
4. R L
Figure 4D. LC Capacitor-input filter.
IN ANSWERING QUESTIONS 4-40 AND
4-41, REFER TO FIGURE 4-D.
4-40. Components L1 and C2 form what type
of circuit?
1. Ac voltage doubler
2. Dc voltage doubler
3. Ac voltage divider
4. Dc voltage divider
4-41. If component L1 shorts to the core,
which of the following conditions will
result?
1. Low output ripple frequency
2. Excessive ripple frequency
3. Excessively high output
4. No output
4-42. In a voltage regulator, what percent of
regulation would be ideal?
1. 1 %
2. 5 %
3. 3 %
4. 0 %
33
IN ANSWERING QUESTIONS 4-43
THROUGH 4-45, REFER TO THE
FOLLOWING FORMULA:
4-43. If a power supply produces 30 volts with
no load and 25 volts under full load,
what is the percent of regulation?
1. 5
2. 10
3. 20
4. 30
4-44. If a power supply produces 10 volts with
no load and 9 volts under full load, what
is the percent of regulation?
1. 8
2. 9
3. 10
4. 11
4-45. If a power supply produces 20 volts with
no load and 20 volts under full load,
what is the percent of regulation?
1. 1
2. 2
3. 3
4. 0
4-46. Basic voltage regulators are classified as
either series or shunt. Their classification
is determined by which of the following
factors?
1. The type of regulating device used
2. The type of regulation required
3. The amount of regulation required
4. The position of the regulating device
in relation to the load (RL)
4-47. The simple series voltage regulator was
designed to function as what type of
resistance?
1. Fixed resistance in series with the
load
2. Fixed resistance in parallel with the
load
3. Variable resistance in series with the
load
4. Variable resistance in parallel with
the load
4-48. A series voltage regulator is designed so
that what total percentage of current
flows through the regulating device?
1. 25
2. 50
3. 75
4. 100
4-49. When a series voltage regulator is used to
control output voltages, any increase in
input voltage results in a/an
1. decrease in the voltage drop across
the load resistance
2. increase in the voltage drop across
the Zener diode
3. decrease in the resistance of the
regulating device
4. increase in the resistance of the
regulating device
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34
Figure 4E. Simple shunt voltage regulator.
IN ANSWERING QUESTIONS 4-50
THROUGH 4-52, REFER TO FIGURE 4-E.
4-50. The base-emitter bias across Q1 is
determined by which of the components?
1. R1 and CR1
2. R1 and R S
3. R S and CR1
4. R S and RL
4-51. What, if anything, happens to the
forward bias of Q1 when the input
voltage increases?
1. It increases
2. It decreases
3. Nothing, it remains the same
4-52. When the load current increases and the
output voltage momentarily drops, what,
if anything, happens to the resistance of
Q1?
1. It increases to compensate for the
drop
2. It decreases to compensate for the
change
3. Nothing, it remains the same
4-53. What type of ammeter reading indicates
that current regulator is functioning
properly?
1. Constant
2. Deflection in the negative direction
3. Deflection in the positive direction
4. Fluctuation around the center line
4-54. A major disadvantage of having good
current regulation is that good voltage
regulation is lost.
1. True
2. False
4-55. To maintain a constant current flow
when there is an increase in the load
resistance (RL), variable resistance (RV)
must compensate for this change by
1. increasing its resistance
2. decreasing its resistance
3. remaining the same
4-56. A decrease in the forward bias of a base-
emitter junction has which of the
following effects on the resistance of a
transistor?
1. It increases
2. It deceases
3. It remains the same
4-57. Voltage multipliers are used primarily to
develop what type of voltage?
1. Low voltage where low current is
required
2. Low voltage where high current is
required
3. High voltage where low current is
required
4. High voltage where high current is
required
4-58. The classification of voltage multipliers
depends on which of the following
ratios?
1. Input current to output current
2. Input current to output voltage
3. Output voltage to input voltage
4. Input voltage to output current
35
4-59. A half-wave voltage doubler consists of
what total number of half-wave
rectifiers?
1. One
2. Two
3. Three
4. Four
4-60. If a half-wave rectifier circuit is added to
a half-wave voltage doubler circuit, what
will be the resulting circuit?
1. A voltage doubler
2. A voltage tripler
3. A voltage quadruplet
4. A voltage quintuplet
4-61. Which of the following methods is used
by manufacturers of electronic
equipment to reduce the cost of extensive
wiring?
1. Grounding the output of the power
supply to the chassis
2. Grounding the return side of the
power transformer to the chassis
3. Connecting all components in
parallel
4. Connecting all components in series
4-62. When working on electronic equipment,
the technician should observe which of
the following safety precautions?
1. Make certain that the electronic
equipment is properly grounded
2. Make certain that the test equipment
is properly grounded
3. Make certain that the rubber mats are
in good condition
4. All of the above
4-63. Which of the following is/are the most
widely used check(s) for testing
electronic equipment?
1. Smoke
2. Visual
3. Signal tracing
4. Both 2 and 3 above
4-64. Any connection that is located close to
the chassis or to any other terminal
should be examined for the possibility of
which of the following problems?
1. An open
2. A short
3. A low resistance
4. A high resistance
4-65. Which of the following statements
applies to a transformer that is discolored
or leaking?
1. It is operational
2. It is cracked
3. It is shorted
4. It is open
4-66. As a technician, you notice that a resistor
is discolored and charred. Which, if any,
of the following conditions most likely
caused the damage?
1. Overload
2. Open circuit
3. Ambient temperature
4. None of the above
4-67. You are in the process of energizing a
power supply. You hear a boiling or
sputtering noise and notice smoke
coming from a section of the power
supply. Which, if any, of the following
actions should you take first?
1. Secure the power immediately
2. Examine the problem area
3. Remove the defective component
4. None of the above
4-68. Which, if any, of the following is the
most rapid and accurate method for
testing electronic circuits after
completing visual inspection?
1. Smoke test
2. Current test
3. Signal tracing
4. None of the above