1A Flashcards
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.
physical components
Wires are conductors (material that allows electricity to
move or flow) used to connect electrical components to
the ___ ___.
power source
The lines that connect the various components of the
circuit are labeled as ___ or ___.
wire or conductor
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.
signal flow
A ____ is used to turn circuit power on and off or to control a circuit.
switch
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.
can
cannot
The mechanism actuating the transition between these two states (closed or open) can be either a ____ (flip switch) or ____ ____ (push button).
toggle
spring loaded
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.
continuous
momentary
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 ___.
switch
The term throw refers to the number contacts of closed contact positions that exist per ____.
pole
The provided picture is what kind of switch?
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.
The provided picture is what kind of switch?
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.
The provided picture is what kind of switch?
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.
____ and ___ ___ are circuit protection devices designed to protect
the circuit against excessive current.
Fuses and circuit breakers
Fuses and circuit breakers are ____ by the amount of current and voltage they will handle.
rated
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.)
20A
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.
stopping
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 “____”.
blown
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 ____.
tripped or popped
An advantage of the circuit breaker over the fuse is the ability to use the circuit breaker….?
more than once
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.
reset
____ are devices that are used to measure voltage, current, and resistance.
Meters
A ______ measures voltage, which is the difference of potential between a component and a reference point
(typically a ground connection).
voltmeter
An _____ measures the current flow; however, the circuit will
need to be broken to insert the ____ to get the desired measurement.
ammeter
An _____ measures the resistance, or opposition to current flow, that a component or group of components create within a circuit.
ohmmeter
For convenience and cost reduction, these functions (voltmeter, ammeter, ohmeter) have been rolled into one piece of equipment called a _____.
multimeter
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
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
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
____ convert chemical energy into electrical energy, and therefore, are a source of Direct Current voltage (VDC).
Batteries
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
_____ convert mechanical energy into electrical energy.
Generators
___ ___, 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
The following symbol represents what?
Generator
___ ___ are simply threaded bolts or screws to which wires can be attached.
Terminal strips
The following symbol represents what?
Terminal strips
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
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
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
The term ground is used in two ways. Another definition of ground is a current ___ ___ to an energy source.
return path
The following symbol represents what?
Earth Ground
The following symbol represents what?
Chassis Ground
The following symbol represents what?
Digital/Common Ground
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
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
In the case of an aircraft, upon landing, the frame of the aircraft is grounded to ___ ___ (Figure 1-16) for safety reasons.
earth ground
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
A ____ is a passive, two-terminal electrical component that adds electrical resistance (opposition to current flow) as a circuit element.
resistor
In electronic circuits, resistors have many uses to include:
Reducing current flow, adjusting signal levels, dividing voltages, biasing active elements, and terminating transmission lines.
The symbol for resistance is __.
R
Resistance is measured in ___. The symbol for ___ is Ω (omega).
ohms
There are four factors that affect how a resistor resists, or opposes, the movement of electricity. They are:
- Material - used in the resistor’s construction
- Length - of the resistor
- Cross sectional area - of the resistor
- Temperature - in which the resistor is operating
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
Some materials offer more resistance than others. It depends on the
number of ___ ___ present in the material.
free electrons
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
For resistance, the relationship between the factors is explained by the formula:
Electronic equipment uses a wide variety of resistors made of…?
wire, metal film or carbon composition
The three basic types of resistors are ____, ____, and ____.
fixed, tapped and variable
A ___ resistor is called ___ because the amount of resistance it provides virtually never changes.
fixed resistor
Fixed resistors are designed for a specific purpose where the amount of resistance that is required ___ ___.
doesn’t change
The follow picture depicts what?
Fixed resistor
The following picture is a schematic symbol of what?
Fixed resistor
___ resistors have taps that allow different resistive values to be selected and set.
Tapped
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
The following picture is an example of what?
Tapped resistor
The following schematic symbol depicts what?
Tapped resistor
_____ 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
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
The ____ is used in applications that require the adjustment of
current or the varying of resistance in an electric circuit.
rheostat
The following picture is an example of what?
rheostat
The following schematic symbol depicts what?
rheostat
A ____ is used to control or vary the amount of voltage available to a circuit.
potentiometer
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
Any time two components are placed in ___ across a voltage source, a voltage divider has been developed.
series
A voltage divider is considered ____ when no external load device is attached or connected.
unloaded
An unloaded voltage divider is composed of a number of resistors connected in series with a ___ ___.
power source
Current flows from ___ to ___.
negative to positive
The ____ is a component that stores energy in an electromagnetic field and opposes a change in current.
inductor
It can be used to block AC or pass DC.
inductor
The unit of measurement for Inductors
Henry
Inductor symbol for the unit of measurement
H
Inductors are labeled with an “__” in schematic drawings.
L
Inductors are frequently called ___ or ____.
chokes or coils
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
Inductor type refers to the ___ ___ used.
core material
For inductors, frequency and power requirements determine the
conductor ___ and ___ type.
size and core
The __-__ inductor is often used in radio frequency (RF) circuits.
air-core
The given picture is the schematic symbol of what?
Air-core inductor
The ___-___ inductor finds numerous applications in audio frequency (AF) and in power circuits.
iron-core
The given picture is the schematic symbol of what?
iron-core inductor
The magnetic laws of attraction and repulsion are stated as follows: Like poles ___ each other and unlike poles ___ each other.
repel
attract
The region around a magnet where its influence can be felt is called a ___ ___.
magnetic field
The total number of lines of force entering or leaving a pole is called its ___ ___.
magnetic flux
___ works on the principle that electrical current through a wire generates a magnetic field.
electromagnetism
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
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
The relationship of the four physical factors that affect inductance (L)
can be expressed by the following formula for single layer coils:
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
In an AC circuit, this opposition to a change occurs the ___ ___ current is flowing.
entire time
____ is the ease at which a magnetic field will flow through a material.
Permeability
____ ____ is defined as the creation of voltage and current within a conductor by varying the magnetic field affecting that conductor.
electromagnetic induction
There are three conditions necessary for electromagnetic
induction:
- A conductor (coil)
- A magnetic field
- Relative motion
AC current periodically changes ___ as the voltage changes polarity.
direction
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
Reactance is also expressed in Ohms, but it ____ be measured with an ohmmeter.
cannot
Inductive reactance can be calculated using the formula:
As seen in the formula, there are two parameters, or variables, which affect inductive reactance:
They are frequency and inductance.
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
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
_____ are electromagnetic devices.
relays/solenoids
____ respond to an electrical signal from a remote location by performing an electrical switching operation.
relays
Relays are always shown in the ____ condition unless otherwise indicated
de-energized
Schematic symbol for a relay is the letter “__”
“K”
The given picture displays the schematics for relays. What do the dotted lines represent?
Dotted lines represent electromagnetic link between coil and armature(s)
The following schematic displays what kind of relay?
Single Pole
Single Throw (SPST)
Normally Open (NO)
The following schematic displays what kind of relay?
Single Pole
Single Throw (SPST)
Normally Closed (NC)
The following schematic displays what kind of relay?
Single Pole
Double Throw (SPDT)
1 Normally Open (NO)
1 Normally Closed (NC)
The following schematic displays what kind of relay?
Multi-pole
Assorted-throw
What are the five mechanical parts to an electromechanical relay?
Armature
Contacts
Core
Spring
Coil
The attached picture is of what?
Relay
The electrical portion of a relay consists of two circuits:
Primary Circuit
Secondary Circuit
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
The ____ ____ consists of the armature, spring, and the contacts.
Secondary Circuit
Movable contact of a relay
Pole
The following picture is of what?
Single-pole - one movable contact
The following picture is of what?
Double-pole – two movable contacts
Number of switch options (relay)
Throw
The ____ carries the relay’s movable contact(s).
armature
This provides the restraining force need to keep the armature in the normal, or de-energized, position (relay.)
Spring
___ are mating surfaces on either side of a gap in a circuit that meet to form a current path (relay.)
Contacts
A contact (relay) has two possible states:
Open
Closed
___ ___ contacts do not allow current flow when the relay is de‑energized
Normally Open (NO)
___ ___contacts provide a current path when relay is de-energized
Normally Closed (NC)
The following is a picture of what?
Solenoid relay
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
Solenoid relays are ____ built to withstand the impact of the plunger and to handle high current loads.
ruggedly
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
The ___ ___ circuit is another use of a relay. Once activated, a ___ ___ will stay energized by its own contacts.
holding relay
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
The following picture displays what kind of relay?
Basic relay
The following picture displays what kind of relay?
Holding relay
The following picture displays what kind of relay?
Overload relay
The following picture displays what kind of relay?
Overload relay
The following is a picture of what?
Transformer
The following schematic represents what transformer based on the core material?
Air core
The following schematic represents what transformer based on the core material?
Powdered iron core
The following schematic represents what transformer based on the core material?
Laminated iron core
The following schematic represents what kind of transformer?
Basic transformer
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
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.
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.
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.
The attached picture is a schematic for what transformer?
Multiple Secondary
The attached schematic and description matches up to what transformer?
Divides the signal amplitude in half
180° out of phase
Center Tapped
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
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
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
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
The following schematic displays what?
More secondary windings
Increased secondary voltage
Step Up
The following schematic displays what?
Fewer secondary windings
Reduced secondary voltage
Step Down
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
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
What is the voltage turns ratio equation?
What is the current turns ratio equation?
The three-phase transformer primary and secondary windings may come in either of two basic configurations, ___ or ____.
delta or wye
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
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
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
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
The formula for capacitance is…?
The schematic symbol given is of what?
Fix Capacitor (set value)
The schematic symbol given is of what?
Electrolytic (polarity sensitive)
The schematic symbol given is of what?
Variable (adjustable value)
The following schematic is a depiction of what?
Variable Capacitor
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
The following is a picture of what type of capacitor?
a fine-tuning capacitor
Varies by changing distance between plates
Compression Type
The following is a schematic symbol for what?
Diode
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
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
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
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
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
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
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
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
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
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
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
The following schematic and description is what?
A semiconductor that emits light when forward bias
Many uses: Calculators, Digital voltmeters, Frequency counters
LED
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
The following is a schematic of what?
Transistor
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
The following picture shows what?
Collector Base (CB) Junction
The following picture shows what
Emitter Base (EB) Junction
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
The emitter is labeled with an ___. The ___ will identify whether the transistor is NPN or PNP.
arrow
The base is represented by a ___. The collector is the third lead (Figures 1-89 A & B).
bar
The emitter arrow will always point toward __-type material.
N-type
The symbol for a PNP transistor will have the arrow pointing ____ the base (Figure 1-89A).
toward
The symbol for an NPN transistor will have the arrow pointing ____ from the base (Figure 1-89B).
away
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
