Digital electronics:
The field of computers and other computer-controlled
devices. Although they may have analog inputs and outputs, almost all
electronic devices are controlled by digital circuits.Digital electronics is
the foundation of modern computers and digital communications.
Positional notation:
A system of writing numbers in which the position of a digit
affects its value.
Positional notation or place-value notation is a method of
representing or encoding numbers.
Binary Number System:
The binary numeral system, or base-2 number system,
represents numeric values using two symbols, 0 and 1. Or, the binary number
system is a positional notation with a radix of 2.
Octal Number System:
The octal numeral system, or oct for short, is the base-8
number system, and uses the digits 0 to 7.
In octal numerals each place is a power with base 8.
Decimal Number
system:
The decimal number system is a base-10 number system, and
uses digits 0 to 9. In decimal numbers, each place is a power with base-10.
Hexadecimal Number
system:
The Hexadecimal number system is a base-16 number system and
uses digits 0 to 9 and letters A to F.
For example: 2AF is
a Hexadecimal value.
555 timer:
A semiconductor device
that controls various modes of on/off states in electrical systems. The 555
timer is one of the most widely used types of integrated circuits.
Amplification:
The process of
increasing the size or strength of a signal.
Amplifier gain:
The ratio of an output signal's amplitude divided by the
input signal's amplitude. Amplifier gain measures the degree to which a signal
has been strengthened.
amplify
To increase the size or strength of
a signal.
Amplitude:
The maximum height or
depth of a sine wave.
AND:
A logic function where
both A and B must be true to trigger C. AND employs a logic that works similar
to a series circuit.
Anode:
The positive terminal
of an electric current flow.
Antimony:
An element used to
dope silicon to create an N-type semiconductor.
Astable:
A mode in which a 555
timer produces a continuous string of on/off pulses at a preset frequency.
Avalanche
breakdown:
A process that occurs
in a diode when high voltage causes free electrons to travel at high speeds,
colliding with other electrons and knocking them out of their orbits. The
result is a rapidly increasing amount of free electrons.
Avalanche diode:
A specialized diode
that acts as a relief valve for excess voltage. Avalanche diodes are sometimes
used in combination with Zener diodes.
Base:
The input control
terminal of a semiconductor device. Also called a gate.
Bipolar
transistor:
A three-layer
semiconductor device that can conduct current in either direction. Bipolar
transistors provide current gain and voltage amplification in a circuit.
Bistable:
A mode in which a 555
timer changes from 1 to 0 or from 0 to 1 when current is applied. The timer
will remain in the transitioned state until it receives a new input.
Boron:
An element used to
dope silicon to create a P-type semiconductor.
Breakdown:
A condition that
occurs when maximum reverse voltage in a diode is exceeded. Breakdown will
cause a diode to fail and pass a large amount of current in the reverse
direction.
Breakdown voltage:
A term used to
describe the level of AC or DC voltage that results in the failure of a semiconductor
device.
Capacitance:
The ability to store
an electrical charge.
Cathode:
The negative terminal
of an electric current flow.
CMOS:
Complementary
metal-oxide semiconductor. The CMOS IC is the most popular type of digital IC
because of its low power usage and high immunity to noise.
Collector:
The output terminal of
a semiconductor device. Also called a drain.
Common base:
A transistor amplifier
in which the circuit shares the base terminal for both inputs and outputs.
Common collector:
A transistor amplifier
in which the circuit shares the collector terminal for both inputs and outputs.
Common emitter:
A transistor amplifier
in which the circuit shares the emitter terminal for both inputs and outputs.
Complementary
metal-oxide semiconductor (CMOS):
The most popular type
of digital IC because of its low power usage and high immunity to noise.
Demodulate:
To change the
amplitude or frequency of an analog signal.
Depleted region:
The part of a PN
junction in which there are no electrons or holes. The depleted region prevents
current from flowing.
DIAC:
Diode alternating
current switch. A DIAC can conduct current in either direction, but not until
breakdown voltage has been exceeded.
Digital IC:
Digital ICs process
only on/off signals. These devices can be found in microprocessors, memory
chips, and microcomputers.
Diode:
A semiconductor device
that acts as a one-way valve for electrical current.
Diode alternating
current switch (DIAC):
A semiconductor device that can conduct current in either
direction, but not until breakdown voltage has been exceeded.
Diode array:
A group of diodes
arranged in a highly organized manner. Diodes are combined into arrays for
greater efficiency and reliability.
DIP (Dual-inline
package):
A popular type of
integrated circuit packaging that has two rows of external connecting
terminals.
Doping:
The process of changing the conductive properties of silicon
by adding trace amounts of other elements.
Drain:
The output terminal of
a semiconductor device. Also called a collector.
Electrostatic
discharge:
Static electricity
that can damage integrated circuits.
Emitter:
The terminal in a
semiconductor device that is connected to the source supply of voltage. Also
called the source.
ESD (Electrostatic
discharge):
Static
electricity that can damage integrated circuits.
FET (Field effect
transistor):.
A FET is a
semiconductor device that outputs current in proportion to its input voltage.
FETs use a small amount of control current to regulate a larger output current.
Fiber optic:
A filament made of
thin, flexible glass or plastic through which light is transmitted. Optical
fibers are bundled into groups to form fiber optic cable.
Flat pack:
A type of integrated
circuit packaging that is extremely thin and flat. A quad flat pack or QFP has
leads projecting from four sides.
Flip-flop circuit:
A circuit that changes
from 1 to 0 or from 0 to 1 when current is applied.
Forward bias:
A condition in which a
PN junction allows current to flow in one direction only.
Full-wave
rectification:
A type of current
conversion that uses both parts of the AC sine wave, both positive and
negative, to produce a DC output with a single polarity.
Gate:
The input control
terminal of a semiconductor device. Also called the base.
Gate current:
A small amount of
forward-biased current in the middle PN junction of an SCR that controls a
larger amount current flowing through the SCR.
Half-wave
rectification:
A type of current
conversion that uses only one half of an AC waveform to convert into
intermittent DC. This can be the positive half or negative half of an AC wave,
depending on how the diode is connected to the circuit.
Holding current:
The minimum current
which must pass through a semiconductor device in order for it to remain in the
ON state.
Hole:
An extra opening in
the outer orbital shell of an atom into which an electron can move.
IC (Integrated
circuit):
A miniaturized
electronic circuit that combines a variety of components like transistors,
resistors, capacitors, and diodes all into one incredibly small piece.
IEC (The
International Electrotechnical Commission):
An international
organization that prepares and publishes all standards for electrical,
electronic, and related technologies.
Impedance:
Resistance to current
flow in an AC circuit.
Intrinsic
semiconductor:
A type of
semiconductor that has a low level of electron movement at any temperature
above 0°C (32°F). Silicon is an intrinsic semiconductor.
JFET:
Junction field effect
transistor. A solid state device that can be used as an electronically
controlled switch.
Leakage current:
The amount of current
required to keep a device active when it is not operating. Also known as load
current and residual current.
LED (Light
emitting diode):
A semiconductor
device that emits a narrow spectrum of light in a forward direction.
Logic gate:
A programming function
that processes true and false signals.
Low current drop:
A condition that
occurs when the current falls below the minimum value required to operate a
semiconductor device.
Monostable:
A mode in which a 555
timer produces a single pulse for a preset amount of time in response to an
input.
MOSFET:
Metal oxide
semiconductor field effect transistor. A type of transistor that is controlled
by voltage rather than current.
Multivibrator:
A device that controls
various modes of on/off states in electrical systems. A multivibrator behaves
like a pendulum moving back and forth, or a ball bouncing up and down.
NAND:
A logic function where
both A and B must be false to trigger the output. If one input is present, the
output will not be turned on.
NOR:
A logic function where
the output will be triggered if neither A nor B are present.
NOT:
A logic function where
the output will not be triggered if a specified input is present.
N-type
semiconductor:
A type of
semiconductor that moves current by creating extra electrons that are easily
excited into movement.
One-shot:
A series of timer
instructions that creates a delay for only one scan.
OR:
A logic function where
the output is triggered if either A or B are true. OR works similar to a
parallel circuit.
Oscillator:
A device that produces
a continuous string of on/off pulses at a preset frequency.
PCB (Printed circuit board):
Semiconductor devices
are often mounted on PCBs because the electrical paths on a PCB are perfect for
the needs of most semiconductors.
PIN diode:
A specialized diode
that has a layer of intrinsic semiconductor material between the P and N
materials. PIN diodes are also used as photodetectors.
PN junction:
The area in a
semiconductor where P-type and N-type materials are located next to each other.
A PN junction allows current to flow in one direction only.
Polarity:
Having a positive or
negative charge.
P-type
semiconductor:
A type of
semiconductor that moves current by creating holes for the movement of valence
electrons.
Pulsating DC:
A type of DC current
in which half of the original AC signal wave is blocked, so that the resulting
DC signal rises from zero to a maximum, and then returns to zero.
QFP (Quad flat pack):
A type of integrated
circuit packaging that is extremely thin and flat. A QFP has leads projecting
from four sides.
Rectifier:
A device that converts
AC into DC.
Rectify:
To convert into direct
current.
Reverse bias:
A condition in which a
PN junction does not allow current to flow.
Reverse breakdown
voltage:
The amount of reverse
bias that will cause a diode to break down and conduct in reverse.
Reverse firing:
A method of turning
off an SCR by applying negative voltage to the gate. Reverse firing requires a
high amount of gate current.
Sandwich:
A three-layer NPN or
PNP arrangement of semiconductor material.
Schottky diode:
A specialized diode
used in the electronics industry and in radio frequency applications because of
its fast switching speed and high frequency capability.
SCR:
A solid state
switching device that turns current on and off. SCRs use a small amount of
current to switch hundreds of amps without being damaged.
Semiconductor:
A solid state device
that is less conductive than a conductor, but more conductive than an
insulator. The most common semiconductor material is silicon.
signaling
The transmission of electrical
signals.
silicon
An element from which almost all
semiconductors are made.
silicon controlled rectifier
A solid state switching device that
turns current on and off. SCRs use a small amount of current to switch hundreds
of amps without being damaged.
silicon dioxide
A glass-like material that is
naturally an excellent insulator. Silicon dioxide is used as the gate insulating
material in a MOSFET.
single-phase rectifier
A semiconductor device that
converts single-phase AC into DC. In a single-phase rectifier, the sine waves
produced by the AC power supply reach their peak at 90° simultaneously.
solid state
Purely electronic with no moving
parts.
source
The terminal in a semiconductor
device that is connected to the source supply of voltage. Also called the
emitter.
substrate
The surface or medium that serves
as a base for other materials or components.
switching
The process of making or breaking
an electric circuit, or selecting between multiple circuits.
terminal
A connecting point in a circuit to
which a wire can be attached to connect a component.
three-phase electric power
A type of AC power that is
generated with three waveforms that are not in phase with each other.
three-phase rectifier
A type of rectifier that uses a
three-phase AC electric power source to produce a relatively smooth DC.
Three-phase rectifiers provide much smoother DC output voltage than
single-phase rectifiers.
thyristor
A three-terminal semiconductor
switching device. The two main types of thyristors are SCRs and TRIACs.
TO package
Transistor-outline
package. A type of integrated circuit packaging that is cylindrical in shape
and looks like a little can. TO-5
can A commonly used TO package.
transistor
A solid state device that can be
used either as an amplifier or as a switch. There are two basic types of
transistors: bipolar and field effect.
transistor-outline
A type of integrated circuit
packaging that is cylindrical in shape and looks like a little can.
TRIAC
Triode alternating current switch.
A gated switching device that will conduct current in either direction.
triode alternating current switch
TRIAC.
A gated switching device that will conduct current in either direction.
UJT
Unijunction
transistor. A voltage-controlled switch that controls current.
unijunction transistor
UJT.
A voltage-controlled switch that controls current.
valence electron
An
electron found in the outermost orbit of an atom.
varactor diode
A
specialized diode that changes its level of capacitance depending on the level
of reverse bias applied to the diode. Also known as a varicap diode.
varicap diode
A specialized diode that changes its level of capacitance depending on
the level of reverse bias applied to the diode. Also known as a varactor
diode.
zener diode
A specialized diode that is used as a voltage regulator. Zener diodes
maintain voltage at a constant, predefined value when they are subjected to
reverse voltage.
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