1A Flashcards
1
Q
The reason for electronic symbols is to represent the ____ ____ of a circuit on a schematic or drawing. This is used to show a technician how the circuit is wired, and how the circuit functions.
A
physical components
2
Q
Wires are conductors (material that allows electricity to
move or flow) used to connect electrical components to
the ___ ___.
A
power source
3
Q
The lines that connect the various components of the
circuit are labeled as ___ or ___.
A
wire or conductor
4
Q
In some situations, a drawing that a technician is looking at will have arrows on the wires. The arrows indicate ____ ____. They show in which direction the signal flow appears to move.
A
signal flow
5
Q
A ____ is used to turn circuit power on and off or to control a circuit.
A
switch
6
Q
Switches can have one or more sets of electrical contacts. Each set of contacts can be in one of two states: closed, meaning the contacts are touching and electricity ____ flow between them, or open, meaning the contacts are not touching and electricity ____ flow between them.
A
can
cannot
7
Q
The mechanism actuating the transition between these two states (closed or open) can be either a ____ (flip switch) or ____ ____ (push button).
A
toggle
spring loaded
8
Q
The toggle switch is used to establish a ____ open or closed state, while the spring-loaded switch is used to establish a ____open or closed state.
A
continuous
momentary
9
Q
The terms pole and throw are used to describe switch contact variations. The term pole can be defined as the number of completely isolated circuits that can be controlled by the ___.
A
switch
10
Q
The term throw refers to the number contacts of closed contact positions that exist per ____.
A
pole
11
Q
The provided picture is what kind of switch?
A
Switch A is a single-pole single-throw (SPST) and is an example of a switch that either opens or closes the circuit, such as a light
switch, or an on-off switch.
12
Q
The provided picture is what kind of switch?
A
Switch B is a single-pole double-throw (SPDT). This is simply an input
from the left side being connected to the top or bottom wires on the right. An example of this switch could be the AM/FM switch on a radio. When the radio is set to AM, the pole connects to the throw on the top, but when the radio is set to FM, the pole connects to the throw on the bottom.
13
Q
The provided picture is what kind of switch?
A
Switch C is double-pole double-throw (DPDT). It is similar in concept to switch B, but it has two poles mechanically tied together (shown with the dashed line). This means that when one pole is moved, they both move. As shown, the two wires on the left are connected to the two top sections on the right. This could be a radio requiring two separate signals to operate. Then when switched, the wires on the left are connected to the two bottom sections. This could represent a second radio system that requires the same two signals.
14
Q
____ and ___ ___ are circuit protection devices designed to protect
the circuit against excessive current.
A
Fuses and circuit breakers
15
Q
Fuses and circuit breakers are ____ by the amount of current and voltage they will handle.
A
rated
16
Q
If current in a circuit gets too high, equipment can be damaged, and a fire can be started. So, a fuse or circuit breaker is added to the
circuit. Both are rated to support a maximum amount of current. (___A is a common rating in homes.)
A
20A
17
Q
If the current exceeds the maximum rating of the fuse or circuit breaker, both devices will cause the circuit to become open, thus _____ the flow of current and protecting the circuit.
A
stopping
18
Q
When the circuit protecting device is a fuse, the excessive current causes an element in the fuse to melt and break. When this happens, the fuse is said to have “____”.
A
blown
19
Q
A circuit breaker serves the same purpose as a fuse, but it works a little differently. When excessive current passes through the circuit breaker, it energizes an electromagnet. The electromagnet is connected to an internal switch. As more current passes
through the circuit breaker, the electromagnet becomes stronger. Eventually, when enough current, the electromagnet is strong enough to cause the internal switch open, which creates a break
in the circuit. When this happens, the circuit breaker is said to have ____ or ____.
A
tripped or popped
20
Q
An advantage of the circuit breaker over the fuse is the ability to use the circuit breaker….?
A
more than once
21
Q
A circuit breaker’s internal switch can be ____ to the closed position after the excessive current condition has been corrected, while the fuse must be replaced, as there is no way to repair the internal element.
A
reset
22
Q
____ are devices that are used to measure voltage, current, and resistance.
A
Meters
23
Q
A ______ measures voltage, which is the difference of potential between a component and a reference point
(typically a ground connection).
A
voltmeter
24
Q
An _____ measures the current flow; however, the circuit will
need to be broken to insert the ____ to get the desired measurement.
A
ammeter
25
An _____ measures the resistance, or opposition to current flow, that a component or group of components create within a circuit.
ohmmeter
26
For convenience and cost reduction, these functions (voltmeter, ammeter, ohmeter) have been rolled into one piece of equipment called a _____.
multimeter
27
There are times when a voltmeter, ammeter, or ohmmeter need to be shown on a schematic diagram. When this happens, the letter or symbol inside the meter symbol identifies the type of meter.
The attached picture represents which device?
Ammeter
28
There are times when a voltmeter, ammeter, or ohmmeter need to be shown on a schematic diagram. When this happens, the letter or symbol inside the meter symbol identifies the type of meter.
The attached picture represents which device?
Voltmeter
29
There are times when a voltmeter, ammeter, or ohmmeter need to be shown on a schematic diagram. When this happens, the letter or symbol inside the meter symbol identifies the type of meter.
The attached picture represents which device?
Ohmmeter
30
____ convert chemical energy into electrical energy, and therefore, are a source of Direct Current voltage (VDC).
Batteries
31
Figure 1-8 shows the symbol for a single cell (left) and a multi-cell (right) battery. The shorter line in the middle of both symbols represents the ____ terminal, and the longer line represents the ____ terminal.
negative terminal
positive terminal
32
_____ convert mechanical energy into electrical energy.
Generators
33
___ ___, also known as alternators, are generally capable of producing a pure sine wave output voltage of constant frequency. They are used to provide electrical power in motor vehicles, in various military and industrial applications, and in the generation of commercial power. Alternators are designed to produce various voltages, frequencies, and phases.
AC generators
34
The following symbol represents what?
Generator
35
___ ___ are simply threaded bolts or screws to which wires can be attached.
Terminal strips
36
The following symbol represents what?
Terminal strips
37
Terminal strips are molded/attached to some type of assembly and are either separated from one another (not touching) or are
connected (touching) with a ___ ___ of some sort.
shorting bar
38
The term ground is used in two ways. One definition of “ground” is as a common point in an electrical circuit from which voltages are measured. This is a ___ ___, which can be a point in a circuit designated by a schematic drawing or technical order (an official government publication that must be adhered to).
reference ground
39
Ground may be compared to a ___ ___; using zero as a reference, we call the numbers to the right side of zero positive numbers and those to the left side of zero negative numbers; zero is the reference point. With “ground” as our reference point, voltages can be positive or negative with respect to ground.
number line
40
The term ground is used in two ways. Another definition of ground is a current ___ ___ to an energy source.
return path
41
The following symbol represents what?
Earth Ground
42
The following symbol represents what?
Chassis Ground
43
The following symbol represents what?
Digital/Common Ground
44
Individual circuits are grounded by chassis/circuit grounds to component frames. The component frames are grounded to the racks that hold them. The racks that hold the equipment are connected to an ___ ___ via the building's or aircraft’s grounding system.
earth ground
45
Sometimes it is not ____ to “ground” your equipment directly to earth. For example, equipment on a vehicle or an aircraft will use the vehicle’s or aircraft’s frame as a “chassis ground”. Figure 1-15
shows a schematic of a chassis ground. Note that each circuit is connected to the chassis in which it operates, and each chassis has its own ground connection.
feasible
46
In the case of an aircraft, upon landing, the frame of the aircraft is grounded to ___ ___ (Figure 1-16) for safety reasons.
earth ground
47
Electrical ground also helps reduce ____ in an audio system. All the grounds in an audio system are connected physically to one point. This prevents stray noise building up between components.
noise
48
A ____ is a passive, two-terminal electrical component that adds electrical resistance (opposition to current flow) as a circuit element.
resistor
49
In electronic circuits, resistors have many uses to include:
Reducing current flow, adjusting signal levels, dividing voltages, biasing active elements, and terminating transmission lines.
50
The symbol for resistance is __.
R
51
Resistance is measured in ___. The symbol for ___ is Ω (omega).
ohms
52
There are four factors that affect how a resistor resists, or opposes, the movement of electricity. They are:
1. Material - used in the resistor's construction
2. Length - of the resistor
3. Cross sectional area - of the resistor
4. Temperature - in which the resistor is operating
53
The resistance offered by a resistor varies directly with the length of the resister. The ___ the resistor, the more resistance it has. The ___ the resistor, the less resistance it has.
longer
shorter
54
Some materials offer more resistance than others. It depends on the
number of ___ ___ present in the material.
free electrons
55
Just like temperature affects your body, so too does temperature
affect how a resistor works. The relationship between change in temperature and change in resistance is called the ___ ___. If an increase in temperature causes the resistance of a material to increase, the material is said to have a positive temperature coefficient. If an increase in temperature causes the
resistance of a material to decrease, the material is said to have a negative temperature coefficient. Most electronic components today have a negative temperature coefficient.
temperature coefficient
56
For resistance, the relationship between the factors is explained by the formula:
57
Electronic equipment uses a wide variety of resistors made of...?
wire, metal film or carbon composition
58
The three basic types of resistors are ____, ____, and ____.
fixed, tapped and variable
59
A ___ resistor is called ___ because the amount of resistance it provides virtually never changes.
fixed resistor
60
Fixed resistors are designed for a specific purpose where the amount of resistance that is required ___ ___.
doesn't change
61
The follow picture depicts what?
Fixed resistor
62
The following picture is a schematic symbol of what?
Fixed resistor
63
___ resistors have taps that allow different resistive values to be selected and set.
Tapped
64
For tapped resistors, since these are installed in an electrical circuit, we must remember to remove (___ ___) power before moving the resistor’s taps or the leads attached to the taps.
turn off
65
The following picture is an example of what?
Tapped resistor
66
The following schematic symbol depicts what?
Tapped resistor
67
_____ resistors have a sliding contact arm, connected to a rotating shaft that can be adjusted to any position on the circular form to vary the resistance or voltage without having to turn off the power.
Variable
68
The two most common types of variable resistors are the ____and the ____. Both allow resistive values to be changed while equipment is in operation.
rheostat
potentiometer
69
The ____ is used in applications that require the adjustment of
current or the varying of resistance in an electric circuit.
rheostat
70
The following picture is an example of what?
rheostat
71
The following schematic symbol depicts what?
rheostat
72
A ____ is used to control or vary the amount of voltage available to a circuit.
potentiometer
73
A device known as a ___ ___ makes it possible to obtain more than one voltage of differing polarities from a single higher voltage source.
voltage divider
74
Any time two components are placed in ___ across a voltage source, a voltage divider has been developed.
series
75
A voltage divider is considered ____ when no external load device is attached or connected.
unloaded
76
An unloaded voltage divider is composed of a number of resistors connected in series with a ___ ___.
power source
77
Current flows from ___ to ___.
negative to positive
78
The ____ is a component that stores energy in an electromagnetic field and opposes a change in current.
inductor
79
It can be used to block AC or pass DC.
inductor
80
The unit of measurement for Inductors
Henry
81
Inductor symbol for the unit of measurement
H
82
Inductors are labeled with an “__” in schematic drawings.
L
83
Inductors are frequently called ___ or ____.
chokes or coils
84
Inductors are constructed by winding a conductor around a core. The conductor is usually solid copper wire coated with ___ ___. This insulation is required because the coiled wire is very close, if not touching, when manufactured. If the coils were all touching, it would defeat the purpose of the coil and therefore would act as if it was just a straight wire.
enamel insulation
85
Inductor type refers to the ___ ___ used.
core material
86
For inductors, frequency and power requirements determine the
conductor ___ and ___ type.
size and core
87
The __-__ inductor is often used in radio frequency (RF) circuits.
air-core
88
The given picture is the schematic symbol of what?
Air-core inductor
89
The ___-___ inductor finds numerous applications in audio frequency (AF) and in power circuits.
iron-core
90
The given picture is the schematic symbol of what?
iron-core inductor
91
The magnetic laws of attraction and repulsion are stated as follows: Like poles ___ each other and unlike poles ___ each other.
repel
attract
92
The region around a magnet where its influence can be felt is called a ___ ___.
magnetic field
93
The total number of lines of force entering or leaving a pole is called its ___ ___.
magnetic flux
94
___ works on the principle that electrical current through a wire generates a magnetic field.
electromagnetism
95
If we wrap that wire around a metal object, we can often magnetize that object. In this way, we have created a ___ field in the electromagnet.
stronger
96
There are two ways to increase the magnetic field strength of an electromagnet:
First, an increase of current in the coil.
Second, insert a soft iron core in the coil of the electromagnet
97
The relationship of the four physical factors that affect inductance (L)
can be expressed by the following formula for single layer coils:
98
An inductor offers an opposition to a change in current flow. In a DC circuit, this opposition to a change occurs ____ when the circuit is turned on or off.
ONLY
99
In an AC circuit, this opposition to a change occurs the ___ ___ current is flowing.
entire time
100
____ is the ease at which a magnetic field will flow through a material.
Permeability
101
____ ____ is defined as the creation of voltage and current within a conductor by varying the magnetic field affecting that conductor.
electromagnetic induction
102
There are three conditions necessary for electromagnetic
induction:
1. A conductor (coil)
2. A magnetic field
3. Relative motion
103
AC current periodically changes ___ as the voltage changes polarity.
direction
104
An inductor opposes both DC (initially) and AC (continuously). Opposition to DC is called ____ and can be measured with an ohmmeter. An inductor’s opposition to AC is called ___ ___ (XL).
resistance
inductive reactance
105
Reactance is also expressed in Ohms, but it ____ be measured with an ohmmeter.
cannot
106
Inductive reactance can be calculated using the formula:
107
As seen in the formula, there are two parameters, or variables, which affect inductive reactance:
They are frequency and inductance.
108
Inductive reactance is directly ____ to frequency or inductance. If frequency or inductance increases, XL will increase. If frequency or inductance decreases, XL will decrease.
proportional
109
In regards to inductive reactance, since XL is an Ohm value, circuit current flow will change. To determine circuit current, we use the Ohm’s Law formula and replace __ with ___. If inductance increases, then XL increases, and the total current in the circuit will decrease. If input frequency decreases, then XL decreases, and total current will increase.
R
XL
110
_____ are electromagnetic devices.
relays/solenoids
111
____ respond to an electrical signal from a remote location by performing an electrical switching operation.
relays
112
Relays are always shown in the ____ condition unless otherwise indicated
de-energized
113
Schematic symbol for a relay is the letter “__”
"K"
114
The given picture displays the schematics for relays. What do the dotted lines represent?
Dotted lines represent electromagnetic link between coil and armature(s)
115
The following schematic displays what kind of relay?
Single Pole
Single Throw (SPST)
Normally Open (NO)
116
The following schematic displays what kind of relay?
Single Pole
Single Throw (SPST)
Normally Closed (NC)
117
The following schematic displays what kind of relay?
Single Pole
Double Throw (SPDT)
1 Normally Open (NO)
1 Normally Closed (NC)
118
The following schematic displays what kind of relay?
Multi-pole
Assorted-throw
119
What are the five mechanical parts to an electromechanical relay?
Armature
Contacts
Core
Spring
Coil
120
The attached picture is of what?
Relay
121
The electrical portion of a relay consists of two circuits:
Primary Circuit
Secondary Circuit
122
The ___ ___ consists of the coil and the core, which forms an electromagnet. When power is applied to the ___ ___, current flows creating a strong magnetic field around the coil.
Primary Circuit
123
The ____ ____ consists of the armature, spring, and the contacts.
Secondary Circuit
124
Movable contact of a relay
Pole
125
The following picture is of what?
Single-pole - one movable contact
126
The following picture is of what?
Double-pole – two movable contacts
127
Number of switch options (relay)
Throw
128
The ____ carries the relay’s movable contact(s).
armature
129
This provides the restraining force need to keep the armature in the normal, or de-energized, position (relay.)
Spring
130
___ are mating surfaces on either side of a gap in a circuit that meet to form a current path (relay.)
Contacts
131
A contact (relay) has two possible states:
Open
Closed
132
___ ___ contacts do not allow current flow when the relay is de‑energized
Normally Open (NO)
133
___ ___contacts provide a current path when relay is de-energized
Normally Closed (NC)
134
The following is a picture of what?
Solenoid relay
135
A solenoid relay is designed so the armature is drawn into a
___ ___. When an electric current is passed through this coil of wire, a magnetic field is created around the coil, and the coil acts as a
magnet. The magnetic field attracts the movable armature (plunger) into the ___ ___.
hollow coil
136
Solenoid relays are ____ built to withstand the impact of the plunger and to handle high current loads.
ruggedly
137
Another use of relays is in a ___ ___. A common use of the ___ ___ is an automobile starter circuit. The low current ignition switch circuit activates a relay, which, upon closing, permits a large current to flow in the starter motor circuit.
starting relay/solenoid
138
The ___ ___ circuit is another use of a relay. Once activated, a ___ ___ will stay energized by its own contacts.
holding relay
139
The last use of a relay we’ll cover is the ___ ___. An ___ ___ is used as a protective device, similar to a circuit breaker with a manual reset.
overload relay
140
The following picture displays what kind of relay?
Basic relay
141
The following picture displays what kind of relay?
Holding relay
142
The following picture displays what kind of relay?
Overload relay
143
The following picture displays what kind of relay?
Overload relay
144
Common uses for this relay are hair dryers, surge protectors, and garbage disposals.
Overload relay
145
This type of relay is commonly used in a clothes dryer, alarm system, or garage door opener.
Holding relay
146
The following is a picture of what?
Transformer
147
A ____ is an Alternating Current (AC) device that is used to transfer electrical power from one circuit to another by means of an electromagnetic field.
Transformer
148
Transformers couple two or more electrical circuits using the principle of ___ ___.
mutual induction
149
Transformers can perform several functions, including:
* Increase (step- up) voltage and decrease current
* Decrease (step-down) voltage and increase current
* Isolate circuits
* Match impedance of different circuits
* Shift phases between circuits
150
Transformers can be classified by what three things?
winding style
frequency range
power application
151
What are the four types of transformers?
1. Power Transformers
2. Audio Frequency Transformers
3. Radio Frequency Transformers
4. Autotransformers
152
The following describes which type of transformer?
Frequencies between 50 to 1600 Hz
Typical line voltages of
110 VAC – 440 VAC
Used in power distribution circuits
Power transformer
153
The following describes which type of transformer?
Frequencies between 15Hz and 20kHz
Audio Frequency Transformer
154
The following describes which type of transformer?
Frequencies – 20kHz to 300GHz
Various uses in RF receivers
Radio Frequency Transformer
155
The following describes which type of transformer?
Primary and secondary circuits use the same winding
Only transformer that will pass DC current
Autotransformer
156
A basic transformer has two separate, but parallel windings. The ____ winding takes power input from the power source. The power is transferred to the secondary winding. The ____ winding supplies output power to the load device.
primary
secondary
157
When it comes to transformers, the construction material of the core depends on the ____ and ____ requirements.
power and frequency
158
Transformers used in ___ ___ and/or ___ ___ circuits have a laminated iron core, consisting of thin sheets of iron that are laminated or varnished.
audio frequency (AF) and/or power frequency
159
Transformers used for ___ ___ have either a powdered iron core, made of iron granules enclosed in a tube, or an air core.
radio frequencies (RF)
160
The following schematic represents what transformer based on the core material?
Air core
161
The following schematic represents what transformer based on the core material?
Powdered iron core
162
The following schematic represents what transformer based on the core material?
Laminated iron core
163
The following schematic represents what kind of transformer?
Basic transformer
164
Transformers are labeled with a __ followed by the
transformer number, such as T1 or T2.
T
165
The basic transformer symbol is two parallel windings, as
illustrated in Figure 1-53. If the primary and secondary
windings are not labeled, it is possible to trace the signal back to
the source to identify the primary from the secondary. The
primary winding is always connected to the power source and
is usually shown on the ___. The secondary winding always
supplies power to the load device and is usually shown on the
___.
left
right
166
The phase relationship between the primary side and the secondary side of a transformer is indicated in schematics by ___ ___.
phase dots
167
What is the phase relationship if the dots are across from one another?
If the phase dots are across from each other the signal felt at the top of the secondary will be in phase with the applied signal at the top of the primary.
168
What is the phase relationship if the dots are opposite of one another?
When the phase dots are opposite, the signal felt at the top of the secondary will be 180 degrees out of phase with the signal felt at the top of the primary.
169
What is the phase relationship if there are no phase dots?
If the symbol has no phase dots drawn, then a phase shift of 180 degrees is always assumed.
170
The attached picture is a schematic for what transformer?
Multiple Secondary
171
The attached schematic and description matches up to what transformer?
Divides the signal amplitude in half
180° out of phase
Center Tapped
172
The attached schematic and description matches up to what transformer?
One winding functions as both primary & secondary winding
Used to step-down (A) or step-up (B) voltage
Autotransformer
173
The attached schematic and description matches up to what transformer?
Slug changes the output voltage of secondary by changing number of flux lines that cut the secondary
Variable
174
Induction requires what three things:
Magnetic Field
Conductor
Relative Motion
175
___ ___ is process of producing a voltage by expanding and/or collapsing a magnetic field.
Electromagnetic induction
176
___ ___ results when either the conductor or the
magnetic field is moving.
Relative motion
177
The requirement for relative motion makes the transformer an ___ device since DC does not provide constant relative motion (changing amplitude and polarity).
AC
178
Current flowing through a coil of wire produces a ___ ___.
magnetic field
179
Previous discussions on inductance revealed that as current flows through a coil of wire it produces a magnetic field which expands and contracts as the current flow increases and decreases. The
movement of that magnetic field will induce a voltage in ___ ___ conductor it cuts across such as another winding. This is the foundation for the operation of transformers, motors, generators, synchros, and servos.
any adjacent
180
Transformers use ____ induction.
mutual
181
Self-induction creates a ___ ____ ___ (CEMF).
counter-electromotive force
182
___ ___ is the inductive interaction between two or more separate windings. It is the principle that makes transformers work and is the action of inducing a voltage in one circuit by varying the
current in some other circuit (interaction).
Mutual Induction
183
The following schematic displays what?
The magnetic field of one coil winding cuts through another winding of the same coil
Induces a Counter Electromotive Force (CEMF) in the conductor
Self Induction
184
The following schematic displays what?
The inductive interaction between two or more windings (coils)
Source voltage moves current through primary coil
Current in primary creates magnetic field
Magnetic field cuts other primary coils causing primary CEMF
Primary magnetic field cuts secondary coil
Creates secondary voltage causing current to flow
Current in the secondary creates a magnetic field
Secondary field interacts with primary field, reducing primary CEMF and increasing primary current flow
Mutual Induction
185
The term step-up only means that voltage or current is being ____ in value from the primary to the secondary.
increased
186
The term step down means the voltage or current is being ____ from the primary to the secondary.
reduced
187
It is very crucial to understand that a transformer only steps up one or the other but ___ ___.
not both
188
The following schematic displays what?
More secondary windings
Increased secondary voltage
Step Up
189
The following schematic displays what?
Fewer secondary windings
Reduced secondary voltage
Step Down
190
Turns Ratio: Step Up/Step Down (transformer)
Very simply, if voltage is stepped up in the secondary, the current is ___ when compared to the primary. If the voltage is stepped down in the secondary, the current is ___ when compared to the primary.
reduced
increased
191
Assuming an ideal transformer, all the power applied to the primary is transferred to the secondary. Power in will always equal power-out. However, the ratio of voltage to current can be varied going from the primary to the secondary. As voltage steps-up, current decreases, and as voltage steps-down, current increases. The ratio of voltage to current transferred depends on the ___ ___ of the transformer.
turns ratio
192
For a ratio of 3:9 or 1:3, the voltage developed on the secondary will be ____ times the voltage applied to the primary
three
193
For a turns ratio of 10:5 or 2:1, the voltage on the secondary will be ___ ___ of the voltage applied to the primary
one half
194
The ___ ___ equation for voltage calculates the voltage of the secondary winding.
turns ratio
195
What is the voltage turns ratio equation?
196
What is the current turns ratio equation?
197
Transformers operate by power transfer. The total power developed by the primary is the ____ as the power developed by the secondary. (P = I x E)
same
198
____ (Z) is the total opposition to AC current flow, which may include resistance, capacitive reactance, and inductive reactance.
Impedance
199
Directly connecting components with different impedances will interfere with power transfer. The solution is to use a transformer to ____ impedances to ensure maximum power transfer. First,
select a transformer with the correct turns ratio to change the voltage and current levels provided by the power supply to those required by the load device. Next, install the transformer between
the mismatched components.
match
200
___ ___ ___ have three primary windings and three secondary windings which produce three output voltages equal in amplitude and 120 degree out of phase with each other.
Three phase transformers
201
They are used in circuits that require high power and/or the three different phases to drive electrical devices. This type of transformer is primarily used in power supplies.
Three phase transformers
202
What are the advantages of three phase transformers?
The biggest advantage of a three-phase transformer is it weighs less and takes up less space than three single phase transformers. A single three-phase transformer also produces less heat than three single-phase transformers producing the same amount of power.
203
What are the disadvantages of three phase transformers?
The disadvantage of a three- phase transformer is that if all three phases are required and one phase burns out, the entire transformer must be replaced.
204
The construction of a three-phase transformer is like the construction of a single-phase transformer. However, in a three-phase transformer, the three primary and three secondary
windings are wound on a ___ ___ ___.
single iron core
205
What is the following symbol: (φ)
The letter phi. Commonly used in physics to represent wave functions in quantum mechanics
206
The phases (φ) of three-phase transformers are labeled:
φA, φB, and φC.
207
The three-phase transformer primary and secondary windings may come in either of two basic configurations, ___ or ____.
delta or wye
208
There are four combinations of connecting the primary and the secondary to meet circuit requirements. The schematic given is which of those combinations?
Delta-Delta
209
There are four combinations of connecting the primary and the secondary to meet circuit requirements. The schematic given is which of those combinations?
Wye-Wye
210
There are four combinations of connecting the primary and the secondary to meet circuit requirements. The schematic given is which of those combinations?
Wye-Delta
211
There are four combinations of connecting the primary and the secondary to meet circuit requirements. The schematic given is which of those combinations?
Delta-Wye
212
Every electronic circuit, no matter how complicated, is composed of no more than three basic electrical properties:
resistance, capacitance, and inductance
213
Resistors oppose current, while inductance and capacitance oppose changes in ___ ___.
circuit conditions
214
The main difference between resistors and reactive components is that a resistor changes electrical energy into heat energy, causing energy to be lost. A reactive component, on the other hand, ___ ___ and returns it back to the circuit.
store energy
215
The following information is describing what?
Component that stores energy in an electrostatic field
Opposes changes in voltage
Blocks DC
Passes AC
Capacitor
216
A capacitor is a component that stores energy in an _____ field and opposes changes in voltage.
electrostatic
217
The amount of energy a capacitor can store is called capacitance and is measured in ___.
Farads (F)
218
What is the symbol for capacitance?
C
219
Since a capacitor reacts to changes in frequency, it is called a ____ component.
reactive
220
Capacitors are widely used in electronic circuits for blocking non-varying ___ while allowing ___ to pass.
DC
AC
221
Capacitors are also used in ____ to tune in to different frequencies.
radios
222
All capacitors consist of two conductive surfaces called plates separated by a non-conductive region called the ____ (insulator).
dielectric
223
Capacitors are generally classified according to the dielectric. The type of the dielectric material used ___ ___ ___ is a determining factor in capacitance.
between the plates
224
_____ is defined as the ability to store an electrical charge, measured as the difference of potential between the two plate areas across an insulator (dielectric).
Capacitance
225
Capacitance is the ability of a capacitor to temporarily ___ electrical energy in the form of an electrostatic field between the plates.
store
226
A positive potential builds up on one of the plates, while a negative potential builds up on the other. The difference between these potentials is the ___ on the capacitor.
charge
227
In a way, a capacitor is a little like a battery. Although they work in completely different ways, capacitors, and batteries both store electrical energy. Inside the battery, chemical reactions produce
electrons on one terminal (negative ions) and absorb electrons on the other terminal (positive ions). However, a capacitor cannot produce ___ ___ like a battery would and only stores (charge)
the electrons.
new electrons
228
The formula for capacitance is...?
229
The schematic symbol given is of what?
Fix Capacitor (set value)
230
The schematic symbol given is of what?
Electrolytic (polarity sensitive)
231
The schematic symbol given is of what?
Variable (adjustable value)
232
Capacitance is directly ____ to the plate area and dielectric constant
proportional
233
Capacitance is ____ ____ to the distance between the plates
inversely proportional
234
The following describes which kind of capacitor?
Polarity sensitive
Very high capacitance
Not named for dielectric type
Disadvantages: leaky current and high power loss
Electrolytic Capacitor
234
The following describes which kind of capacitor?
-Fixed value
-Set during manufacturing
-Different material can be used for different capacitive values
Fixed Capacitor
235
A ____ capacitor is a capacitor whose capacitance may be intentionally and repeatedly changed mechanically or electronically to meet the needs of the circuit.
variable
236
What are the two types of variable capacitors?
Rotor-Stator Type
Compression Type
237
The following schematic is a depiction of what?
Variable Capacitor
238
The following is a picture of what type of capacitor?
Varies by changing area of plates
also known as a variable air capacitor
is commonly used in radio frequency circuits
Rotor-Stator Type
239
The following is a picture of what type of capacitor?
a fine-tuning capacitor
Varies by changing distance between plates
Compression Type
240
What is the time constant formula?
TC = R x C
Where:
TC = Time Constant in seconds
R = Resistance in Ohms
C = Capacitance in Farads
241
The amount of resistance and capacitance in a series circuit determines the time required for a capacitor to charge to a given percentage of the applied voltage. The same holds true for the time
required for a capacitor to discharge. Consistently it takes 5 of these ___ ___ to fully charge and/or discharge a capacitor, making it easy to mathematically represent not only charge/discharge time, but percentage of the same at each point in time. Remember though, these time periods are in fractions of seconds, so to us they appear instantaneous.
time constants
242
As previously stated, capacitors are used to store electrostatic energy, which will then be used in the components connected to it. Capacitors will take a portion of the provided power (DC battery
or AC source) and store it for a short period of time during a phase of operation called ____.
charging
243
Once the capacitor reaches its full capacitance, it stops charging and starts _____ depending on the circuits needs.
discharging
244
What is the difference between direct current operation and alternating current operation?
In DC operation the capacitor will charge to the level of its applied voltage and stop. At that point, it is blocking further current through the circuit due to both the power source and the capacitor having
equal amounts of voltage. With no difference of potential current will not flow.
In AC operation, a capacitor will constantly charge and discharge because AC is continuously changing polarities. The rate at which the capacitor charges and discharges is now controlled by the frequency of the alternating current.
245
The purpose of the ___-___ ___ ___ is to conduct current freely in one direction and oppose current flow in the opposite direction.
Positive-Negative (PN) junction diode
246
This is accomplished by applying a type of voltage, called ____, across the PN junction.
bias
247
Diodes are used as electronic ____ and ____ ____.
switches and variable resistors
248
Diodes as a switch they:
turn current on or off
249
Diodes as a variable resistor they:
increase or decrease current, voltage and/or resistance in a circuit
250
what are the two elements of a diode?
Cathode
Anode
251
The following is a schematic symbol for what?
Diode
252
When looking at the schematic symbol of a diode, the arrowhead represents the _____ (Positive (P-type) material), and the bar
represents the _____ (Negative (N-type) material).
anode
cathode
253
When looking at the schematic symbol of a diode, the arrow always points towards the...?
N-type material (cathode)
254
Current always flows from ___ to ___ in a circuit.
negative to positive
255
Current always flows from negative to positive in a circuit. Therefore, forward bias current always flows ____ the arrowhead (cathode to anode direction). In reverse bias, current does not flow because the diode is acting like an open switch.
against
256
Many types of diodes are available. Although diodes may physically look different, the ____ ____ is the same. The cathode will have an identifying manufacturer’s marking on it, so polarity can be observed when installing or when determining current flow.
schematic symbol
257
Diodes use the designation of ___ or ___ to identify them in a circuit.
CR or D
258
The CR is for ____
Rectifier and D is for ____
Crystal
Diode
259
Manufacturers use a chemical process to create a semiconductor with both a P region and an N region. The process of adding impurities to a semiconductor material is called ____.
doping
260
By doping a semiconductor material with certain chemicals, we create a positive P-type material. By doping a semiconductor material with a different chemical, we create a negative N-type material. We call the area where the P and N regions meet a ____ ____.
junction barrier
261
We call the area where the P and N regions meet a junction barrier. The result is a PN junction diode. The reason this junction barrier is created is to provide an internal contact potential. Controlling this potential across the PN junction makes it possible to control _____.
current
262
Semiconductors are solid crystal materials with a level of electrical conductivity that places them ____ materials called insulators and conductors.
between
263
As the name semiconductor implies, these materials are neither a good conductor nor a good insulator. The reason is...?
because of how current moves through the materials
264
Since diodes are constructed of crystal material, that material needs to be unbalanced so when we apply voltage across it, the electrons will move. Our primary goal is to get current to ____. Our
secondary goal is to control how ____ that current moves. We control current flow by increasing or decreasing the resistance of the diode.
flow
quickly
265
All semiconductor materials have a ____ temperature coefficient of resistance.
negative
266
(Diodes) This means that the temperature and the amount of resistance of the semiconductor material are ___ ___. If the temperature of a PN junction diode increases, more current flows because the resistance has decreased.
inversely proportional
267
(Diodes) What happens with a decrease in temperature? A decrease in ambient (surrounding) temperature causes a ____ in current and an ____ in resistance.
decrease
increase
268
All semiconductors have an operating temperature range determined by how ___ and how ___ their operating environment can be and still function normally.
hot
cold
269
Remember that the purpose of a PN junction diode is to conduct current freely in one direction and oppose current flow in the opposite direction. This is controlled by the resistance of the
junction barrier. The resistance of the junction barrier is controlled by the application of a voltage potential across the PN junction. This voltage is called ___.
bias
270
There are two types of bias: ____, which will allow current flow, and ____, which will prevent current flow.
forward
reverse
271
The initial width of the junction barrier resistance depends on the specific material used in the doping process. This value is set by the manufacturer. The ____ of the junction determines its resistance, similar to the amount of Ohms determines the resistance of a resistor.
width
272
The following schematic and description are of what?
Resistance is small
Diode acts like a closed switch
Positive side of a power source is connected to the P- type material
Negative side of a power source is connected to the N- type material
When FB increases: Resistance decreases, Current flow increases, Voltage on the diode decreases
Forward Bias
273
If the forward bias decreases junction barrier resistance increases and the majority current decreases. If bias is removed, or if the same potential exists on both terminals, current ___ ___ ___.
does not flow
274
If forward bias increases, the junction barrier resistance ____, and the majority current ____.
decreases
increases
275
To reverse bias a PN junction, connect the negative battery terminal to the __-type material and the positive battery terminal to the __-type material (Figure 1-76).
P-type material
N-type material
276
When you reverse bias a PN junction, the barrier resistance and decreases or ____ circuit current.
stops
277
The following schematic and description is explaining what?
Resistance is large
Diode acts like an open switch
Positive side of a power source is connected to the N- type material
Negative side of a power source is connected to the P- type material
When RB increases: Resistance increases, Current flow decreases, Voltage on the diode increases
Reverse Bias
278
When the crystal is subjected to an external source of energy (light, heat, etc.), electron-hole pairs are generated. These electron-hole pairs produced ___ ___ carriers. Under reverse bias conditions; there will be a small amount of current flow due to these minority carriers crossing the junction.
minority current
279
If reverse bias increases, the minority current ____.
increases
280
If the reverse bias decreases, the minority current ____.
decreases
281
If bias is removed, or if the same potential exists on both terminals, current ___ ___ ___.
does not flow
282
As you may recall, a resistor is a ___ device. This means as the voltage across a resistor changes, the current changes by the same rate (multiplying the applied voltage by three, results in three times the current flow).
linear
283
A PN junction diode is a ____ device (as the voltage across a
diode changes, resistance and current do not change by the same rate).
non-linear
284
Applying excessive forward bias can destroy the diode. Refer to point “E” in figure 1-78. As forward bias voltage is increased, forward bias current increases. If this forward bias current becomes too large, the heat generated by this excessive current will cause structural breakdown. You may recall that any time heat is applied to a PN junction, electron-hole pairs are generated (increasing current flow). This increase in current generates more heat and the cycle repeats. We call this process ___ ___.
thermal runway
284
The PN junction diode conducts very little when reverse biased. At point C in Figure 1-78, the reverse bias voltage is 80 volts, and the reverse bias current (minority current) is 100μA. The diode
has 800k Ohms of resistance, which is much larger than the resistance of the same junction with forward bias. This also shows the ____ characteristics of a PN junction diode.
non-linear
285
You will notice that at point D of the curve the current increases rapidly. We call this rapid increase in reverse current ____ ____. When the reverse bias voltage is large enough to cause structure to be broken, a large reverse bias current occurs. These new free electrons collide with the valence band electrons of the germanium crystal atoms, releasing more and more carriers. Because of the heat generated, the cycle will cause destruction of the crystal. Normal operation of a diode is between points D and E in Figure 1-78. Operating beyond these points will cause structure breakdown and can destroy the diode.
avalanche current
286
A ___ ___ ___ or series limiting resistor (RL) (Figure 1-79) is required to be in series with the diode to protect the diode from excessive current or voltage. Since diodes do not provide much resistance, an excessive amount of voltage or current can damage them.
Current limiting resistor
287
The following schematic is of what?
The resistor in series limits the current in the circuit and reduces the voltage to the level required to power the diode.
Current limiting resistor
288
The primary purpose of a Zener diode is to...?
regulate voltage
289
____ is a name given to a family of diodes specially doped to operate within the reverse bias voltage region.
Zener
290
In theory, they can be compared to a variable resistor because as the voltage changes or fluctuates in a circuit, the resistance of the diode adjusts itself to pass the current but block the voltage.
Zener Diode
291
The following schematic and description is for what?
* Regulates voltage
* specially doped to operate within the reverse bias
voltage region.
* they can be compared to a variable resistor
* The schematic for this symbol is the same as a PN junction except it has a crooked bar instead of a straight line
* This diode diode operates opposite of the PN junction diode.
Zener Diode
292
A Zener diode operates ___ of the PN junction diode. Normal operation for a Zener diode is reverse bias. Since the Zener diode is operating in reverse bias, current flows with the arrow (from the anode to the cathode), in the direction the arrow is pointing.
opposite
293
Elements of a Zener diode are identical to a PN junction diode. The Anode is the ____ and P- type material. The Cathode is the ___ ___ and made up of N-type material. It is labeled like a PN junction diode with a CR or D.
arrow
crooked bar
294
When placed in a circuit, Zener diodes must have a series current-limiting resistor to prevent ___ ___ from excessive current.
structural breakdown
295
The “avalanche region” comprises a rapid increase in reverse current
that, unless checked by a current-limiting resistor, may...?
destroy the semiconductor
296
The reverse bias voltage at which the avalanche effect occurs is called the “___ ___ ___” (BVR).
Breakdown Voltage Reverse
297
A ___ ___ ___ is a semiconductor device that emits light when forward biased.
light emitting diode (LED)
298
LEDs are used widely as...?
powers on indicators of current
299
The following schematic and description is what?
A semiconductor that emits light when forward bias
Many uses: Calculators, Digital voltmeters, Frequency counters
LED
300
The most important part of a LED is the semi- conductor ___ located in the center of the bulb.
chip
301
Like a normal diode, it consists of a chip of semiconducting material doped with impurities to create a PN junction. The type of doping used in the manufacturing process determines the specific color of the light emitted by the LED, not by the ___ ___ ___ ___ ___. LEDs are available in red, orange, amber, yellow, green, blue, and white.
coloring of the plastic body
302
When the LED is forward biased it releases energy in the form of
___ or ___. The amount of light given off is directly proportional to the amount of current. LEDs, like any diode, require a series current limiting resistor.
photons or light
303
What are the reasons to use LEDs?
Low-power requirements.
Highly reliable.
Hard to break and extremely durable.
Have an extremely long-life span: typically ten years.
Produces very little heat.
304
LEDs are used to generate alphanumeric characters by connecting them as seven-segment or ___ ___ ___. The seven-segment display consists of seven individual light-emitting diodes contained in one package and arranged in an eight pattern
dot matrix displays
305
W use a ___ to control current.
resistor
306
There was also a way for us to physically control the amount of current using a ____, to provide a variable voltage using a ____, and to stop current using a ____.
rheostat
potentiometer
switch
307
Transistors are semiconductor devices that have ____ or more electrodes.
three
308
What are the three purposes of a transistor?
1. to function as an electronically controlled variable resistor
2. to act like an electronically controlled switch
3. as an amplifier
309
Transistors are components consisting of multiple layers of different semiconductor material. They control current flow ____ using no moving parts.
electronically
310
The following is a schematic of what?
Transistor
311
The transistor is constructed in three layers. The three layers are:
1. Emitter
2. Base
3. Collector
312
Which of the three layers of a transistor is the following describing?
medium size, gives off or “emits” current carriers (either electrons or holes)
Emitter
313
Which of the three layers of a transistor is the following describing?
very small, controls the flow of the current carriers
Base
314
Which of the three layers of a transistor is the following describing?
large, collects the current carriers
Collector
315
There are two PN junctions in each transistor. One PN junction is between the emitter and the base. This is called the ___-___ (EB) junction. The other PN junction is between the collector and the base. This is called the ___-___ (CB) junction
1. Emitter-Base
2. Collector-Base
316
Transistors are classified as ___ (Negative-Positive-Negative) or ___ (Positive-Negative-Positive) according to the arrangement of the N and P type materials.
NPN
PNP
317
The NPN transistor can be compared to two diodes, connected ___-to-____ (Figure 1-87A). The PNP transistor can be compared to two diodes, connected ____-to-____ (Figure 1-87B).
anode-to-anode
cathode-to-cathode
318
The following picture shows what?
Collector Base (CB) Junction
319
The following picture shows what
Emitter Base (EB) Junction
320
The NPN transistor is constructed of a very ___ and lightly doped base region of P-type material separating two ___ doped regions (emitter and collector) of N-type material (Figure 1-88A).
thin
heavily
321
The schematic symbol for a transistor is labeled with a “__”.
Q
322
The emitter is labeled with an ___. The ___ will identify whether the transistor is NPN or PNP.
arrow
323
The base is represented by a ___. The collector is the third lead (Figures 1-89 A & B).
bar
324
The emitter arrow will always point toward __-type material.
N-type
325
The symbol for a PNP transistor will have the arrow pointing ____ the base (Figure 1-89A).
toward
326
The symbol for an NPN transistor will have the arrow pointing ____ from the base (Figure 1-89B).
away
327
Electrons will always flow against the arrow. The PNP transistor current flow will enter the ___ and the ___ and exit out of the ___ (Figure 1-90A).
collect and the base
emitter
328
The NPN transistor current flow will enter the ___ and out of both the ____ and ____ (Figure 1-90B).
emitter
collect and base
329
As previously mentioned in diode theory, ___ was defined as any external DC voltage applied across a PN junction.
bias
330
Since a transistor has two junctions, we need two biases. In order for a transistor to function normally, the following rules apply:
The Emitter-Base (EB) junction must be forward biased.
The Collector-Base (CB) junction must be reverse biased.
331
Forward bias at the EB junction reduces the size of the junction barrier. Therefore, the EB junction has a ___ ___.
low resistance
332
Reverse bias at the CB junction increases the size of the CB junction
barrier. Therefore, the CB junction has a ___ ___.
high resistance
333
Diode theory tells us to expect almost ___ current through a reverse bias junction.
no
334
Diode theory tells us to expect almost no current through a reverse bias junction. This is true in a diode, but not true in the CB junction of a transistor. The very thin base means the free electrons only have a short distance to go to reach the collector. For these two reasons, almost all of the emitter-injected electrons pass through the ___ to the ___.
base to the collector
335
The two outermost operating points of a transistor are called:
saturation and cutoff
336
The following describes which operating point of a transistor?
The point at which a further increase in forward bias does not result in an increase in collector current. The transistor acts like a short or closed switch.
Saturation
337
The following describes which operating point of a transistor?
The point at which a further decrease in forward bias does not result in a decrease in collector current. The transistor acts like an open or open switch.
Cutoff
338
Like diodes, transistors have a ___ temperature coefficient of resistance.
negative
339
The temperature of a transistor and the resistances of its junctions are ___ ___. When the temperature of a transistor increases, its resistance decreases, and the current flow through it increases. The reverse is also true. If the temperature of a transistor decreases, its resistance increases, and the current flow through it decreases. These changes in transistor current can cause changes in the bias voltages, possibly forcing a transistor to go into saturation or cutoff.
inversely proportional
340
Recombination forms EB and CB junction barriers (depletion regions.)
Unbiased NPN transistor
341
An ___ ___ (IC) is a circuit designed to serve a portion or all of an electronics function and consists of transistors, diodes, resistors, and some small capacitors.
integrated circuit (IC)
342
Until ICs were invented, electronic circuits consisted of individual
components called ___ ___.
discrete components
343
The advantages of integrated circuits (IC) over discrete circuits are:
small size
low cost
high reliability
easy to troubleshoot
344
Integrated circuits have some limitations such as:
power limitations, voltage limitations, and component limitations.
345
Integrated circuits have power limitations, what does this mean?
The power limitation results from the small size of the ICs.
346
Integrated circuits have component limitations, what does this mean?
Component limitations refer to the fact that inductors, transformers, and large capacitors are almost impossible to produce on a silicon
chip.
347
Integrated circuits have voltage limitations, what does this mean?
Voltage limitations occur because the insulation between circuit elements is relatively weak due to the components being closely packed in one chip of material.
348
The classes of integrated circuits are:
linear (analog)
digital
mixed
349
The following describes which class of integrated circuits?
____ ICs are considered ___ because the output is proportional to the input. The ____ ICs are amplifiers such as RF, video, servos, operational amplifiers, and voltage regulators. They are widely used in stereos, televisions, and various communications equipment.
Linear
350
The following describes which class of integrated circuits?
____ refers to the electronic circuits that use voltage or current levels. The ____ ICs are switching circuits such as flip-flops, counters, and memories used with computers. Most of the ICs in use today are digital and are widely used in computers and portable calculators to perform arithmetic and decision-making functions. Unlike a linear IC, a ____ IC is basically a switch which is either on or off. In computers and other digital devices, these switches are called gates, which will be studied in a later objective.
Digital
351
The following describes which class of integrated circuits?
Integrated Circuits (ICs) which have both analog circuits and digital circuits combined on a single semiconductor. Digitally controlled sound chips are mixed-signal circuits. With the advent of cellular technology and network technology this category now includes cellular phones and computer networks.
Mixed
