Here are many of the terms you’ll run into throughout your electronics life. Knowing these terms will help you become fluent in electronics-speak.

alkaline battery:

A type of nonrechargeable battery. See also battery.

alternating current (AC):

Current characterized by a change in direction of the flow of electrons. See also direct current (DC).

ampere:

The standard unit of electric current, commonly referred to as amps. One ampere is the strength of an electric current when 6.241 x 10¹⁸ electrically charged particles move past the same point within a second. See also current, I.

amplitude:

The magnitude of an electrical signal, such as voltage or current.

analog circuit:

A circuit that processes analog signals. See also digital circuit.

analog signal:

A varying voltage or current that constitutes a one-to-one mapping of a physical quantity, such as sound or displacement.

anode:

The terminal of a device into which conventional current (hypothetical positive charge) flows. In power-consuming devices, such as diodes, the anode is the positive terminal; in power-releasing devices, such as batteries, the anode is the negative terminal. See also cathode.

antistatic wrist strap:

A device used to prevent the buildup of static electricity on individuals working on sensitive electronic equipment.

autoranging:

A feature of some multimeters that automatically sets the test range.

AWG (American Wire Gauge):

See wire gauge.

battery:

A power source that uses an electrochemical reaction to produce a positive voltage at one terminal and a negative voltage at the other terminal. This process involves placing two different types of metal in a certain type of chemical. See also alkaline battery, lithium battery, nickel-cadmium (NiMH) battery, nickel-metal hydride (NiCd) battery and, zinc-carbon battery.

biasing:

Applying a small amount of voltage to a diode or to the base of a transistor to establish a desired operating point.

bipolar transistor:

A common type of transistor consisting of two fused pn-junctions. See also transistor.

bit:

Short for binary digit. A digit that has a value of 0 or 1.

breadboard:

Also known as prototyping board or solderless breadboard; a rectangular plastic board (available in a variety of sizes) that contains groups of electrically interconnected contact holes. You plug in components — resistors, capacitors, diodes, transistors, and integrated circuits, for example — and then string wires to build a circuit. See also solder breadboard.

bus strip:

See power rail.

byte:

A grouping of eight bits used as a basic unit of information for storage in computer systems.

cable:

A group of two or more wires protected by an outer layer of insulation, such as a common power cord.

capacitance:

The capability to store energy in an electric field, measured in farads. See also capacitor.

capacitor:

A component that provides the property of capacitance in a circuit. See also capacitance.

cathode:

The terminal of a device from which conventional current (hypothetical positive charge) flows. In power-consuming devices, such as diodes, the cathode is the negative terminal; in power-releasing devices, such as batteries, the cathode is the positive terminal. See also anode.

circuit:

A complete path that allows electric current to flow.

cladding:

An extremely thin sheet of copper that you glue over a base made of plastic, epoxy, or phenol to make a printed circuit board.

closed circuit:

An uninterrupted circuit through which current can flow. See also open circuit.

closed position:

The position of a switch that allows current to flow. See also open position.

cold solder joint:

A defective joint that occurs when solder doesn’t properly flow around the metal parts.

commutator:

A device used to change the direction of electric current in a motor or generator.

component:

A part used in a circuit, such as a battery or a diode.

conductor:

A substance through which electric current can move freely.

connector:

A metal or plastic receptacle on a piece of equipment (a phone jack in your wall, for example) that a cable end fits into.

continuity:

A type of test you perform with a multimeter to establish whether a circuit is intact between two points.

conventional current:

The flow of hypothetical positive charge from positive to negative voltage; the reverse of real current. See also real current.

current:

The flow of electrically charged particles. See also ampere, I.

desoldering pump:

See solder sucker.

digital circuit:

A circuit that processes digital signals. See also analog circuit.

digital signal:

A pattern consisting of just two voltage or current levels representing binary digital data.

diode:

A semiconductor electronic component consisting of a pn-junction that allows electric current to flow one way more easily than the other way. Diodes are commonly used to convert alternating current to direct current by limiting the flow of current to one direction.

direct current (DC):

A type of current in which the electrons move in only one direction, such as the electric current generated by a battery.

double-pole, double-throw (DPDT) switch:

A type of switch that has two input contacts and four output contacts. It is a dual on/on switch that behaves like two SPDT switches acting in sync.

double-pole, single-throw (DPST) switch:

A type of switch that has two input contacts and two output contacts. It is a dual on/off switch that behaves like two SPST switches acting in sync.

DPDT:

See double-pole, double-throw (DPDT) switch.

DPST:

See double-pole, single-throw (DPST) switch.

earth ground:

A direct electrical connection to the earth. See also ground.

electric current:

See current.

electrical signal:

The pattern over time of an electrical current. Often, the way an electrical signal changes its shape conveys information about something physical, such as the intensity of light, heat, or sound, or the position of an object, such as the diaphragm in a microphone or the shaft of a motor.

electricity:

The displacement of electrons along a conductor.

electromagnet:

A temporary magnet consisting of a coiled wire around a piece of metal (typically, an iron bar). When you run current through the wire, the metal becomes magnetized. When you shut off the current, the metal loses its magnetic quality.

electromotive force:

An attractive force between positive and negative charges, measured in volts.

electron:

A negatively charged subatomic particle. See also proton.

ESD (electrostatic discharge):

See static electricity.

fillet:

A raised area formed by solder.

floating ground:

A circuit ground that isn’t connected to earth ground.

flux:

A wax-like substance that helps molten solder flow around components and wire and ensures a good joint.

frequency:

A measurement of how often an AC signal repeats, measured in cycles per second, or hertz (Hz). The symbol for frequency is f. See also hertz (Hz).

gain:

The amount that a signal is amplified (the voltage of the signal coming out divided by the voltage of the signal coming in).

gauge:

See wire gauge.

ground:

A connection in a circuit used as a reference (0 volts) for a circuit. See also earth ground.

heat sink:

A piece of metal that you attach securely to the component that you want to protect. The sink draws off heat and helps prevent the heat from destroying the component.

helping hands clamp:

Also called a third-hand clamp; adjustable clips that hold small parts while you’re working on projects.

hertz (Hz):

The measurement of the number of cycles per second in alternating current. See also frequency.

high signal:

In digital electronics, a signal at or near 5 volts (typically 3–5 V) that represents one of two binary states.

I:

The symbol for conventional current, measured in amperes (amps). See also ampere, current.

IC:

See integrated circuit (IC).

inductance:

The capability to store energy in a magnetic field (measured in henrys). See also inductor.

inductor:

A component that provides the property of inductance to a circuit. See also inductance.

infrared temperature sensor:

A kind of temperature sensor that measures temperature electrically.

insulator:

A substance through which electric current is unable to move freely.

integrated circuit (IC):

Also known as a chip; a component that contains several miniaturized components, such as resistors, transistors, and diodes, connected in a circuit that performs a designated function.

inverter:

Also known as a NOT gate; a single-input logic gate that inverts the input signal. A low input produces a high output, and a high input produces a low output. See also logic gate.

inverting mode:

A process by which an op amp flips an input signal to produce the output signal.

jack:

A type of connector. See also connector.

joule:

A unit of energy.

lithium battery:

A lightweight disposable battery that generates about 3 volts and has a higher capacity than does an alkaline battery. See also battery.

live circuit:

A circuit to which you’ve applied voltage.

logic gate:

A digital circuit that accepts input values and determines which output value to produce based on a set of rules.

low signal:

In digital electronics, a signal at or near 0 volts (typically 0–2 V) that represents one of two binary states.

microcontroller:

A programmable integrated circuit.

multimeter:

An electronics testing device used to measure such factors as voltage, resistance, and current.

negative temperature coefficient (NTC) thermistor:

A resistor whose resistance decreases with a rise in temperature. See also resistor, thermistor.

nickel-cadmium (NiCd) battery:

The most popular type of rechargeable battery. Some NiCad batteries exhibit the memory effect, requiring that they be fully discharged before they can be recharged to full capacity. See also battery.

nickel-metal hydride (NiMH) battery:

A type of rechargeable battery that offers higher energy density than does a NiCd rechargeable battery. See also battery.

nominal value:

The stated value of a resistor or other component. The real value can vary up or down from the nominal value based on the tolerance of the device. See also tolerance.

N-type semiconductor:

A semiconductor doped with impurities so that it has more free electrons than a pure semiconductor.

ohm:

A unit of resistance; its symbol is Ω. See also R, resistance.

Ohm’s Law:

An equation that defines the relationship between voltage, current, and resistance in an electrical circuit.

open circuit:

A type of circuit in which a wire or component is disconnected, preventing current from flowing. See also closed circuit.

open position:

The position of a switch that prevents current from flowing. See also closed position.

operational amplifier (op amp):

An integrated circuit containing several transistors and other components. In many applications, it performs much better than an amplifier made from a single transistor. For example, an op amp can provide uniform amplification over a much wider range of frequencies than can a single-transistor amplifier.

oscillator:

A circuit that generates a repeating electronic signal.

oscilloscope:

An electronic device that measures voltage, frequency, and various other parameters for varying waveforms.

pad:

A contact point on a printed circuit board used for connecting components.

Phillips:

Both a screw with a plus-sign-shaped (+) slot in its head and the screwdriver used with it.

piezoelectric effect:

The capability of certain crystals, such as quartz or topaz, to expand or contract when you apply voltage to them or to produce voltage when you squeeze or move them.

pn-junction:

The point of contact between a P-type semiconductor, such as silicon doped with boron, and an N-type semiconductor, such as silicon doped with phosphorus. The pn-junction is the foundation for diodes and bipolar transistors. See also bipolar transistor, diode.

positive temperature coefficient (PTC) thermistor:

A device whose resistance increases with a rise in temperature. See also resistance, thermistor.

potentiometer:

A variable resistor that allows for the continual adjustment of resistance from virtually zero ohms to a maximum value.

power:

The measure of the amount of work that electric current does while running through an electrical component, measured in watts.

power rail:

A series of interconnected electrical contact holes in a column of a solderless breadboard that is intended to be used for power distribution. Also known as bus strip.

precision resistor:

A type of resistor with low tolerance (the allowable deviation from its stated, or nominal, value). See also nominal value, tolerance.

proton:

A positively charged subatomic particle. See also electron.

prototyping board:

See breadboard.

P-type semiconductor:

A semiconductor doped with impurities so that it has fewer free electrons than a pure semiconductor.

pulse:

A burst of current or voltage, usually beginning with an abrupt rise and ending with an abrupt fall.

pulse-width modulation:

A method of controlling the speed of a motor that turns voltage on and off in quick pulses. The longer the on intervals, the faster the motor.

R:

The symbol for resistance. See also ohm, resistance.

RC time constant:

A calculation of the product of resistance and capacitance that defines the length of time it takes to charge a capacitor to two-thirds of its maximum voltage or to discharge it to one-third of its maximum voltage.

real current:

The flow of electrons from a negative to a positive voltage. See also conventional current.

relay:

A device that acts like a switch in that it closes or opens a circuit depending on the voltage supplied to it.

resistance:

A measure of a component’s opposition to the flow of electric current, measured in ohms. See also ohm, R.

resistor:

A component with a fixed amount of resistance that you can add to a circuit to restrict the flow of current. See also resistance.

rosin flux remover:

A detergent used after soldering to clean any remaining flux to prevent it from oxidizing a circuit. Available in a bottle or spray can.

schematic:

A drawing showing how components in a circuit are connected.

semiconductor:

A material, such as silicon, that has some of the properties of both conductors and insulators.

semiconductor temperature sensor:

A kind of temperature sensor that measures temperature electrically.

sensor:

An electronic component that senses a condition or an effect, such as heat or light, and converts it into an electrical signal.

series circuit:

A circuit in which the current runs through each component sequentially.

short circuit:

An accidental connection between two wires or components allowing current to pass through them rather than through the intended circuit.

single-pole, double-throw (SPDT) switch:

A type of switch that has one input contact and two output contacts. It switches the input between two choices of outputs. It is also known as an on/on or changeover switch.

single-pole, single-throw (SPST) switch:

A type of switch that has one input contact and one output contact. It is also known as an on/off switch.

60/40 rosin core:

Solder containing 60% tin and 40% lead (the exact ratio can vary a few percentage points) with a core of rosin flux. This type of solder is ideal for working with electronics. See also solder, soldering.

slide switch:

A type of switch where you slide the switch forward or backward to turn something (such as a flashlight) on or off.

solar cell:

A type of semiconductor that generates a current when exposed to light.

solder:

A metal alloy that is heated and applied to two metal wires or leads and allowed to cool, forming a conductive joint. See also 60/40 rosin core, soldering.

solder breadboard:

A breadboard on which you solder components in place. See also breadboard.

soldering:

The method you use in your electronics projects to assemble components on a circuit board to build a permanent electrical circuit. Rather than using glue to hold things together, you use small globs of molten metal, or solder. See also solder.

soldering iron:

A wand-like tool that consists of an insulated handle, a heating element, and a polished metal tip used to apply solder.

soldering pencil:

See soldering iron.

solderless breadboard:

See breadboard.

solder sucker:

Also known as a desoldering pump; a tool consisting of a spring-loaded vacuum used for removing excess solder.

solder wick:

Also known as solder braid; a device used to remove hard-to-reach solder. The solder wick is a flat braid of copper that works because the copper absorbs solder more easily than the tin plating of most components and printed circuit boards.

solid wire:

A wire consisting of only a single strand.

SPDT:

See single-pole, double-throw (SPDT) switch.

SPST:

See single-pole, single-throw (SPST) switch.

static electricity:

Charge that builds on or within an object and remains stationary until a path is provided for the charge to flow. Lightning is a form of static electricity.

strain relief:

A device that clamps around a wire and prevents you from tugging the wire out of the enclosure.

stranded wire:

A metal wire consisting of several fine wires twisted together into a bundle that is wrapped in insulation.

stray capacitance:

Energy that’s stored in a circuit unintentionally when electric fields occur between wires or leads that are placed too close together.

terminal:

A piece of metal to which you hook up wires (as with a battery terminal).

thermistor:

A resistor whose resistance value varies with changes in temperature.

thermocouple:

A type of sensor that measures temperature electrically.

third-hand clamp:

Also called helping hands clamp; a small, weighted clamp that holds parts while you solder.

tinning:

The process of heating up a soldering tool and applying a small amount of solder to the tip to prevent solder from sticking to the tip.

tolerance:

The variation from the nominal value of a component due to the manufacturing process expressed as a percentage. See also nominal value.

trace:

A wire on a circuit board that runs between the pads to electrically connect the components.

transistor:

A semiconductor device that’s commonly used to switch and amplify electrical signals.

V:

The symbol for voltage, also represented by E. See also voltage.

variable capacitor:

A capacitor whose capacitance can be dynamically altered mechanically or electrically. See also capacitance, capacitor.

variable inductor:

A coil of wire surrounding a movable metal slug. By turning the slug, you change the inductance of the coil.

variable resistor:

See potentiometer.

voltage:

An attractive force between positive and negative charges.

voltage divider:

A circuit that uses voltage drops to produce voltage lower than the supply voltage at specific points in the circuit.

voltage drop:

The resulting lowering of voltage when voltage pulls electrons through a resistor (or other component), and the resistor absorbs some of the electrical energy.

wire:

A long strand of metal, usually made of copper, that you use in electronics projects to conduct electric current.

wire gauge:

A system of measurement of the diameter of a wire.

zinc-carbon battery:

A low-quality, disposable battery. See also battery.