Electronics & Soldering Glossary

A

Absolute maximum ratings: The limits a part can withstand without being damaged. They are not a range where normal operation is guaranteed, so do not operate near these values. Related guide: How to Read a Datasheet: From Pinout to Absolute Maximum Ratings
Astable: A circuit that keeps oscillating by flipping between two states on its own. Blinking an LED with a 555 timer is the classic example. Related guide: Blinking an LED with a 555 Timer: Astable Circuit Design

B

Breadboard: A test board where you build circuits by plugging in parts without soldering. Handy for experiments, but the contacts are unreliable, so it is not used for finished products. Related guide: Breadboard vs. Perfboard vs. PCB, and Choosing by Stage

C

CMOS: A family of digital logic built from MOSFETs with very low current draw. The 74HC and CD4000 series are typical, and many parts support a wide supply range. Related guide: 74LS and 74HC Logic Gate Basics and Handling Unused Inputs
Cold solder joint: A bad joint where too little heat meant the solder did not melt properly onto the pad and part lead. The surface is rough and bead-shaped, and the contact is unreliable, so the circuit works intermittently. Related guide: Perfboard Soldering Basics: Temperature, Order, and Avoiding Cold Joints
Common anode: A seven-segment type where the anodes of all LEDs are tied to one pin. Connect the common pin to the supply and pull the segment pins Low to light them. Related guide: Driving Seven-Segment (FND) Displays: Common Cathode vs. Common Anode
Common cathode: A seven-segment type where the cathodes of all LEDs are tied to one pin. Connect the common pin to ground and drive the segment pins High to light them. Related guide: Driving Seven-Segment (FND) Displays: Common Cathode vs. Common Anode
Component side: The side where the bodies of the parts sit, the side without pads. In Patterndo, parts are drawn as seen from above. Related guide: Reading a Layout Diagram: Component Side, Copper Side, Coordinates, and Pin Numbers
Contact bounce (chattering): The effect where a switch contact touches and separates several times in a short moment when pressed or released, making the signal jitter. A digital circuit may read one press as several, so it is filtered out with an RC filter or in software. Related guide: Tact Switches and Pull-Up/Pull-Down Resistors
Continuity test: A measurement with a multimeter to check whether two points are electrically connected. Many meters beep when they are. Related guide: How to Choose a Multimeter and Basic Measurement Order
Copper side (solder side): The side with the copper pads, where you solder. It is the opposite of the component side, so it looks left-right mirrored. Also called the solder side. Related guide: Reading a Layout Diagram: Component Side, Copper Side, Coordinates, and Pin Numbers
Current-limiting resistor: A resistor placed in series with a part like an LED, whose current is not limited by itself, to set the current to the value you want. Related guide: LED Current-Limiting Resistors and Brightness Control

D

Datasheet: The specification document provided by a part's manufacturer. It contains the pinout, electrical characteristics, absolute maximum ratings, and typical circuits. Related guide: How to Read a Datasheet: From Pinout to Absolute Maximum Ratings
Decoupling (bypass) capacitor: A small capacitor placed right next to an IC's power pin to reduce momentary dips and noise on the supply. A 100 nF ceramic is typical. Related guide: Power Rails, Grounding, and Decoupling Capacitor Placement
DIP (dual in-line package): An IC package with pins in two parallel rows. A 2.54 mm pin pitch and 7.62 mm between the rows is typical, so it plugs straight into perfboard. Related guide: Reading DIP IC Pin Numbers and Using IC Sockets
DRC (design rule check): Short for design rule check. It automatically finds places that break the rules, such as power shorts, part collisions, exceeded ratings, and polarity errors. Related guide: Reading Diagnostics (DRC) Messages and Fixing Them
Duty cycle: The fraction of one signal period that is High. At 50%, the on time and off time are equal. Related guide: Blinking an LED with a 555 Timer: Astable Circuit Design

E

E-series: The geometric sequences of standard values in which resistors and capacitors are sold. E12 has 12 values per decade, E24 has 24, and E96 has 96. Related guide: Reading Resistors: Color Codes and Standard Values (E24)

F

Flux: A substance that removes the oxide film on metal surfaces so solder spreads well. It is often inside solder wire, and also comes as a separate paste or pen. Related guide: Choosing Solder and Flux: Leaded vs. Lead-Free, Thickness, and Storage
Flyback diode: A diode connected in reverse across a coil load such as a relay or motor to absorb the high-voltage spike produced when the current is cut off. Related guide: Driving Motors, Relays, and Solenoids: Transistors and Flyback Diodes
Forward voltage (Vf): The voltage across a diode or LED when it starts to conduct. A common silicon diode is about 0.6–0.7 V and a red LED about 2 V. Related guide: How to Use Diodes and Zener Diodes

G

Gerber file: Manufacturing data in a standard format sent to a PCB fabricator. It holds the copper pattern, solder mask, silkscreen, and so on, each as a separate layer. Related guide: From Perfboard to a Custom PCB: Gerber Files and Choosing Specs
Ground (GND): The 0 V point that is the reference for circuit voltages. All parts must share the same ground for signals to be passed on correctly. Related guide: Power Rails, Grounding, and Decoupling Capacitor Placement

H

Hole pitch: The spacing between neighboring holes. Perfboards, DIP ICs, and pin headers almost all standardize on 2.54 mm (0.1 inch).
Hysteresis: A technique that sets different turn-on and turn-off voltages for a comparator, preventing the output from jittering near the threshold. Related guide: Building a Voltage Comparator with the LM358, and Hysteresis

I

I2C: A serial communication method that connects several devices with just two wires, SDA and SCL. Both lines need pull-up resistors. Related guide: I2C Wiring Basics: Pull-Up Values, Addresses, and What to Check When It Fails
IC socket: A holder soldered to the board first so an IC can be plugged in instead of soldered directly. It makes orientation mistakes and replacing a failed chip easier. Related guide: Reading DIP IC Pin Numbers and Using IC Sockets

J

Jumper: A short wire joining two points on the board. Use insulated wire when the distance is too far to bridge with solder or when it has to cross other wiring. Related guide: Wiring Methods Compared: Jumper Wires, Solder Bridges, and Insulated Wire

L

Layout diagram (pattern diagram): A drawing of where to insert each part on a perfboard and how to run the wiring. A schematic shows "what connects to what", while a layout diagram shows "which holes on the board things go in". Also called a perfboard wiring diagram or placement diagram. Related guide: How to Draw a Perfboard Layout: Placing Parts, Wiring, and Jumpers Step by Step
Level shifter: A circuit or module that converts voltage levels between devices with different signal voltages, such as 3.3 V and 5 V. Related guide: Connecting 3.3V and 5V Signals: Level Shifting Methods

M

Monostable: A circuit whose output turns on for a set time each time it is triggered, then returns to its original state. Also called a one-shot timer. Related guide: 555 Timer Monostable Circuit: Turn On for a Fixed Time When a Button Is Pressed

N

Net: A set of points connected at the same electrical potential. Circuit design tools work out nets automatically by following wires and hole connections to show which pins are tied together.
Net alias: Giving a net a readable name such as CLK or RESET. In Patterndo it appears as a label on the wire; it is for display only, so giving two nets the same name does not connect them electrically.
Notch: The half-circle mark cut into one end of an IC body. With the notch at the top, pin 1 is at the lower left, and pin numbers increase counterclockwise. Related guide: Reading DIP IC Pin Numbers and Using IC Sockets

O

Ohm's law: The relationship V = I × R between voltage V, current I, and resistance R. Power is found with P = V × I. Related guide: Reading Resistors: Color Codes and Standard Values (E24)
Open collector: An output type that can only pull to ground and cannot make a High itself. It needs an external pull-up resistor, or the LED or load connected to the supply side.
Operational amplifier (op-amp): An analog IC that amplifies the voltage difference between two inputs by a very large factor. The LM358 and LM324 are typical, used as comparators or amplifiers. Related guide: Building a Voltage Comparator with the LM358, and Hysteresis
Oscilloscope: An instrument that draws on screen how a voltage changes over time. It lets you see fast signals that a multimeter cannot. Related guide: Oscilloscope Basics: When You Need One and What to Look At

P

Pad: The round copper ring around a hole. Solder sticks here and connects the part lead electrically.
Perfboard: A general-purpose board with holes at regular intervals and no printed circuit pattern. You insert parts and solder on the back to build the circuit you want yourself. Also called a prototyping board. Related guide: What Is Perfboard? Types and How to Choose
Pin header: A connector with pins lined up at 2.54 mm spacing. Used to plug a development board into a board or to attach wires. Related guide: Mounting a Development Board on Perfboard: Header Sockets and Power Separation
Polarity: The + and − orientation of parts that have a direction. Electrolytic capacitors, diodes, LEDs, and ICs will not work or will fail if connected backwards. Related guide: Capacitor Types, Polarity, and Reading Values
Pull-down resistor: A resistor that ties an input pin to ground so it normally stays Low. Pressing the switch connects it to the supply, making it High. Related guide: Tact Switches and Pull-Up/Pull-Down Resistors
Pull-up resistor: A resistor that ties an input pin to the supply (+V) so it normally stays High. Pressing the switch connects it to ground, making it Low. Related guide: Tact Switches and Pull-Up/Pull-Down Resistors

R

Rail: A power line (+V) or ground line (GND) run along the edge of the board to feed many parts in common. Related guide: Power Rails, Grounding, and Decoupling Capacitor Placement
Ratsnest: Thin lines showing pairs of pins that still need to be wired together, as a connection hint. Patterndo's schematic import feature draws these lines. Related guide: Importing a Schematic or Netlist and Using the Ratsnest

S

Seven-segment display (FND): A display with seven bar-shaped LEDs (a–g) and a decimal point arranged to show digits. In Korea it is called an FND. Related guide: Driving Seven-Segment (FND) Displays: Common Cathode vs. Common Anode
Short circuit: A state where two points that should not be connected, such as power and ground, are joined directly and excess current flows. It can damage parts and power supplies. Related guide: It Is Finished but It Does Not Work: A Step-by-Step Checklist
Solder bridge: A state where solder has unintentionally joined two neighboring pads. It is a common cause of shorts, but is sometimes made on purpose to connect adjacent holes. Related guide: Wiring Methods Compared: Jumper Wires, Solder Bridges, and Insulated Wire
Solder wick: A braid of copper wire that soaks up molten solder by capillary action, used to remove solder. Related guide: Desoldering and Rework: Using Solder Wick and a Solder Sucker

T

Time constant (τ): A value for how fast a circuit made of a resistor and capacitor follows a change, τ = R × C. After one τ it has reached about 63% of its final value. Related guide: Understanding RC Time Constants and Capacitor Charging
Tolerance: The range by which the actual value may differ from the marked value. ±5% on a resistor means a 1 kΩ resistor may be anywhere from 950 to 1050 Ω. Related guide: Reading Resistors: Color Codes and Standard Values (E24)
Transistor (BJT): A semiconductor device that switches or amplifies a large collector current with a small base current. There are NPN and PNP types, depending on current direction. Related guide: Transistor Switch Circuits and Pinout Pitfalls
TTL (transistor–transistor logic): A family of digital logic built from bipolar transistors. The 74LS series is the best-known example, and it runs on 5 V. Related guide: 74LS and 74HC Logic Gate Basics and Handling Unused Inputs

V

VCC: The name for the positive supply terminal of an IC or circuit. In a 5 V circuit it means +5 V; in CMOS it is also written VDD.
Voltage divider: A way to take only part of the input voltage from the junction of two resistors in series. The output is Vin × R2 / (R1 + R2). Related guide: Designing Voltage Dividers and the Loading Effect
Voltage regulator: A power part that keeps the output at a constant voltage even when the input voltage changes. A 7805 turns its input into 5 V. Related guide: Making 5V from a 9V Battery: Building a 7805 Power Board

Z

Zener diode: A diode that conducts in reverse once the voltage reaches a set value (the Zener voltage), clamping the voltage at that value. Used to make a reference voltage. Related guide: How to Use Diodes and Zener Diodes

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