Alternating current (AC): Current in which there is a change in the direction
in which electrons flow. See also direct current (DC).
Amplitude: How much voltage is in an electrical signal.
Anode: Positive terminal of a diode. See also cathode.
Auto-ranging: A feature that some multimeters offer that automatically sets a
test range. See also multimeter.
AWG (American Wire Gauge): See wire gauge.
Bandwidth: With an oscilloscope, the highest frequency signal that you can
test with any reliability, measured in megahertz (MHz).
Battery: A power source that uses electrochemical reaction to create a positive
voltage at one terminal and a negative voltage at another. Two different
types of metal are placed in a type of chemical to produce the power.
Biasing: Applying a small amount of voltage to the base of a transistor. This
partially turns on the transistor.
Bipolar: A common IC type. See also integrated circuit.
Breadboard: Also referred to as a prototyping board or solderless breadboard.
Plastic boards in a variety of shapes, styles, and sizes that have columns of
holes. A line of metal connects these holes electrically. By plugging components
into these holes and connecting them with wire, you can build a circuit.
See also soldered breadboard.
Cable: Sets of two or more wires that are protected by an outer insulation
layer. The common power cord is an example of a cable.
Capacitance: The ability to store electrons. You measure capacitance in
farads.
Capacitor: A component in a circuit providing the property of capacitance.
See also electrolytic capacitor, ceramic capacitor, tantalum capacitor.
Cathode: The negative terminal of a diode. See also anode.
Ceramic capacitor: One of the most common types of capacitor. This type is
used for smaller values of capacitance. See also capacitor.
Circuit: Wires that connect components in such a way that a current flows
through the components and returns to the source.
Closed circuit: A circuit with connected wires, so that current is able to flow.
See also open circuit.
Closed position: The position of a switch in which current can flow. See also
open position.
CMOS: A type of IC that is very sensitive to ESD. See also integrated circuit,
static electricity.
Cold solder joints: A bad joint. These happen when solder doesn’t flow properly
around metal parts.
Commutator: A device that changes the direction of electric current in a
motor or generator.
Components: The parts you use in electronics projects, such as a capacitor
or resistor.
Conductor: A material through which electricity moves freely.
Connector: Metal or plastic receptacles on equipment into which you can fit
cable ends.
Continuity: A multimeter test of whether a circuit is intact between two
points. See also multimeter.
Current: The flow of an electrical charge.
Cycle: That portion of an AC waveform where the voltage goes from its lowest
point to the highest point and back again. This cycle repeats again and again
until you turn off the signal.
Decoder: An IC that takes information transmitted by either infrared or radio
remote signal and translates it into output signals. See also encoder, integrated
circuit.
Desolder pump: A piece of equipment that sucks up excess solder by using a
vacuum.
Diode: A device that limits the flow of current to one direction, thereby converting
alternating current to direct current.
Direct current (DC): A type of current in which the electrons move only from
the negative terminal through the wires to the positive terminal in one direction.
A battery generates direct current.
Double-pole, double-throw switch (DPDT): A type of switch with two input
connections and four output connections.
Double-pole, single-throw switch (DPST): A type of switch with two input
connections and two output connections.
Double-pole switches: A type of switch with two input connections.
DPDT: See double-pole, double-throw switch.
DPST: See double-pole, single-throw switch.
Dual inline package (DIP): A commonly used integrated circuit plastic package;
used in breadboards and circuit boards used by hobbyists.
Electricity: The movement of electrons through a conductor.
Electrolytic capacitor: One of the most common types of capacitor. This type
is used for larger values of capacitance. See also capacitor.
Electromagnet: A type of wire coiled around a piece of metal (usually an iron
bar). When current runs through the wire, the metal is magnetized. Shut off
the current, and the metal loses its magnetic quality.
Electromotive force: An attractive force which you measure in volts. This
force exists between positive and negative charges.
Electron: A negatively charged particle. See also proton.
Encoder: An IC that codes information to be transmitted by either infrared or
radio remote signal. See also decoder, integrated curcuit.
ESD (electrostatic discharge): See static electricity.
Farad: The unit of measurement for capacitance. (A microfarad is one millionth
of a farad.) See also capacitor.
Flathead: A type of screw with a flat head and single slot; the screwdriver
used with a flathead screw.
Flux: A waxy substance used to make molten solder flow around components
and wire, assuring a good joint.
Frequency: A way to measure how often an AC signal repeats. The symbol for
frequency is f.
Gain: The amount that a signal is amplified. To calculate this, divide the voltage
of the signal coming out by the voltage of the incoming signal.
Gauge: See wire gauge.
Ground: A connection in a circuit used as a reference for 0 (zero) volts.
H-bridge: A circuit or IC used to control the power to DC motors. See also
integrated circuit.
Heat sink: A piece of metal used to protect components. The sink is attached
to the component and draws off heat to prevent destroying the component.
Hertz (Hz): The measurement used for the number of cycles per second that
occur in alternating current.
High pass filter: A circuit that allows signals above a certain frequency to
pass through. See also low pass filter.
High signal: In digital electronics, a signal at a value of higher than 0
(zero) volts.
I: The symbol used for current.
IC: See integrated circuit.
Impedance: In an electrical current, a measurement of opposition to the flow
of alternating current.
Inductance: Ability to store energy in a magnetic field (measured in Henries).
Inductors: Components that provide the ability to store energy in a magnetic field for a circuit.
Infrared temperature sensor: A type of sensor that measures temperature
electrically.
Insulator: A substance that electrons are unable to move through freely.
Integrated circuit (IC): A component (in the form of a chip) that contains several smaller components, such as resistors, capacitors, and transistors.
Inverter: A type of logic gate with a single input. See also logic gate.
Inverting mode: What happens when an op amp flips an input signal to produce an output signal. See also operational amplifier.
Jack: A type of connector. See also connector.
kohm: 1000 ohms. See also ohm.
Live circuit: A circuit with voltage applied.
Logic gate: An integrated circuit that uses input values to determine output
value based on certain rules.
Low pass filter: A circuit that allows signals below a certain frequency to pass
through. See also high pass filter.
Low signal: In digital electronics, a signal at or near 0 (zero) volts.
lug: A metal protrusion, usually with a hole in the center, into which you can
feed wire and solder it to various components.
Microcontroller: A programmable circuit.
Multimeter: A testing device that measures things such as voltage, resistance,
and amperage.
N-type semiconductor: A semiconductor to which contaminants are added.
This causes it to have more electrons than a pure semiconductor.
Ohm: A unit of resistance. The symbol for ohm is Ω. See also resistance.
Ohm’s Law: The equation that you use to calculate voltage, current, resistance,
or power.
Open circuit: A circuit in which a wire is disconnected. Therefore, no current
is able to flow. See also closed circuit.
Open position: A switch position that stops current from flowing. See also
closed position.
Operational amplifier: Also called op amp. An integrated circuit that contains
transistors and other components. An op amp provides uniform amplification
over a wider range of frequencies than a single-transistor amplifier.
Oscillator: A circuit that generates waveforms. See also waveform.
Oscilloscope: An electronic device used to measure voltage, frequency, and
other parameters for waveforms.
P-type semiconductor: A semiconductor to which contaminants are added
that cause it to contain fewer electrons than a pure semiconductor.
Pad: Contact points on a circuit board used to connect components.
Phillips: Both a screw with a plus-shaped (+) slot in its head and the screw driver that you use with that type of screw.
PN junction: The interface of two regions that contain boron and phosphorus
adjacent in a semiconductor. Transistors and diodes contain pn junctions.
See also transistor, diode.
Potentiometer: A variable resistor that allows for continual adjustment of
resistance. This adjustment can range from virtually 0 (zero) ohms to a maximum value.
Power: The measure in watts of the amount of work that electric current
does while running through an electrical component.
Proton: A positively charged particle. See also electron.
Prototyping board: See breadboard.
Pulse: A signal that rapidly alternates between high and low.
Pulse width modulation: A way to control the speed of a motor by turning
voltage on and off in quick pulses. When the on intervals are longer, the motor goes faster.
R: The symbol for resistance.
RC (resistance/capacitance) time constant: A formula to calculate the time
required to charge a capacitor to two-thirds or discharge it to one-third of its
capacity.
Relay: A device that performs like a switch. It closes or opens a circuit,
depending on the voltage that you supply.
Resistance: The measurement of the ability of electrons to move through any
material.
Resistor: A component of a circuit that reduces the amount of electrons that
flow through the circuit.
Rosin flux remover: An after-soldering cleaner that removes any remaining
flux so that it doesn’t oxidize your circuit.
Schematic: A drawing that shows 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 sensors: A type of sensor that measures temperature
electrically.
Sensors: Electronic components that sense a particular condition, such as
heat or light.
Series circuit: A circuit in which current runs through each component in
sequence.
Short circuit: What happens when two wires are connected and current goes
through them, resulting in the circuit not being completed.
Sine wave: An signal that switches from a high voltage to a low voltage, back
to the high voltage, and then repeats this cycle with a smooth sinesoidal
(curvy) waveform until it’s shut off.
Single-pole, double-throw switch (SPDT): A type of switch in which one wire goes into the switch and two wires leave the switch.
Single-pole switches: A type of switch with one input wire.
Slide switch: A switch that you slide forward or backward to turn an electronic device on or off.
Solar cell: A semiconductor that generates a current when exposed to light.
Solder sucker: A tool used to remove excess solder. The sucker uses a spring loaded vacuum.
Solder wick: Also called solder braid. A device that you use to remove difficult-
to-reach solder. The solder wick is a copper braid that absorbs solder
more easily than the tin plating on most components and printed circuit
boards.
Soldered breadboard: A breadboard on which you solder components. See
also breadboard.
Soldering: The method that uses small globs of molten metal — solder — to
hold components together.
Soldering iron: See soldering pencil.
Soldering pencil: A wand-like tool used to apply solder.
Solderless breadboard: See breadboard.
Solid wire: A single-strand wire. See also stranded wire.
SPDT: See single-pole, double-throw switch.
Spike: See voltage spike.
Square wave: An signal that switches from a high voltage to a low voltage,
back to the high voltage, and then repeats this cycle with a square-shaped waveform until it’s shut off.
Static electricity: A form of current that remains within an insulating body after you remove the power source. Lightning is an example of static electricity.
Stranded wire: Two or three small bundles of very fine wires wrapped within
insulation. See also solid wire.
Stray capacitance: What happens when electric fields occur between wires or leads in a circuit because they are placed too close together. In this condition, energy is stored unintentionally.
Tantalum capacitor: A type of capacitor used when the circuit can’t accommodate
a large range of capacitance value variation. See also capacitor.
Terminal: A piece of metal to which you hook up wires (for example, a battery terminal).
Thermistor: A resistor that changes its resistance value when the temperature
changes.
Thermocouple: A sensor that measures temperature electrically.
Tinning: The process of heating a soldering tool to full temperature and applying a small amount of solder to the tip. This prevents solder from sticking to the tip.
Tolerance: The variation in the value of a component due to the manufacturing
process that is allowable, typically expressed as a range.
Traces: On a circuit board, the wires that run between pads to electrically
connect components.
Transistor: A semiconductor that controls the flow of electric current.
V: The symbol for voltage. Also can represented by E.
Variable capacitor: A capacitor that includes two or more metal plates that
are separated by air. If you turn the knob, you change the capacitance of a
device. See also capacitor.
Variable coil: A coil of wire that surrounds a movable metal slug. When you
turn the slug, you change or vary the inductance of the coil.
Variable resistor: See potentiometer.
Voltage: Attractive force between positive and negative charges.
Voltage divider: The voltage drops in a circuit that produce voltage lower
than the supply voltage at certain points in the circuit.
Voltage drop: The lowering of voltage that occurs when voltage pulls electrons
through resistors (or any other component) and the component uses
up a portion of the voltage.
Voltage spike: A brief increase in voltage.
Watt hour: A unit of measure for energy; the ability of a device or circuit to
do work.
Waveform: Voltage fluctuations such as those that appear in a sine wave or
square wave. See also oscilloscope, sine wave, square wave.
Wire: A long strand of metal, usually made of copper, used to make connections
in electronics projects. Electrons travel through the wire, conducting
electricity.
Wire clips: An adhesive-backed piece of plastic with a clip used to secure
wires.
Wire gauge: A system used to measure the diameter of wire.
