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.

dual-inline package

DIP. A popular type of integrated circuit packaging that has two rows of external connecting terminals.

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.

field effect transistor

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.

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.

integrated circuit

A miniaturized electronic circuit that combines a variety of components like transistors, resistors, capacitors, and diodes all into one incredibly small piece.

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.

printed circuit board

PCB. Semiconductor devices are often mounted on PCBs because the electrical paths on a PCB are perfect for the needs of most semiconductors.

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.

quad 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.

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.