Standard Electrical and Electronic Symbols and Drawing Identification

Vocabulary flashcards covering electrical and electronic symbols, component functions, and circuit diagram types based on Information Sheets 4.2-2 and 4.3.2.

Block Diagram

A diagram created by analyzing a system, breaking it into meaningful subsystems drawn as individual blocks to portray flow and interaction between them.

Schematic Diagram

Commonly referred to as the electronic technician’s or engineer’s shorthand, it uses standardized symbols to represent circuits and configurations in a concise manner.

Wiring Diagram

The most common form of electrical wiring diagram where components are represented by pictorials and lines represent the physical wiring of the circuit.

Pictorial Diagram

A diagram that concentrates on the components in the circuit rather than an accurate representation of the circuit layout; it is considered the least useful main electrical wiring diagram.

Reference Designations

Letters assigned to electronic components where the letter signifies the type of component and the number distinguishes it from others of the same type.

Cell

A source of electricity that supplies electrical energy where the larger terminal on its symbol is positive ($+$).

Battery

A source of electricity defined strictly as two or more cells joined together.

Fuse

A safety device that will 'blow' (melt) if the current flowing through it exceeds a specified value.

Transformer

Two coils of wire linked by an iron core used to step up (increase) or step down (decrease) AC voltages via a magnetic field with no electrical connection between the coils.

Earth (Ground)

A connection to earth which for many electronic circuits represents the $0V$ (zero volts) of the power supply.

Resistor

A component that restricts the flow of current, such as to limit the current passing through an LED or for use in a timing circuit.

Rheostat

A type of variable resistor with 2 contacts usually used to control current, such as adjusting lamp brightness or motor speed.

Potentiometer

A type of variable resistor with 3 contacts usually used to control voltage, which can convert position/angle to an electrical signal.

Capacitor

A component that stores electric charge, used in timing circuits or as a filter to block DC signals while passing AC signals.

Inductor (Coil, Solenoid)

A coil of wire which creates a magnetic field when current passes through it and can convert electrical energy to mechanical energy.

Diode

A device which only allows current to flow in one direction.

Zener Diode

A special diode which is used to maintain a fixed voltage across its terminals.

Light Emitting Diode (LED)

A transducer which converts electrical energy to light.

Bipolar Junction Transistor (BJT)

A semiconductor device that amplifies current and can be used with other components to make an amplifier or switching circuit.

Relay

An electrically operated switch that allows a low voltage circuit (e.g., $9V$) to switch a high voltage circuit (e.g., $230V$ AC).

Oscilloscope

An instrument used to display the shape of electrical signals and measure their voltage and time period.

LDR (Light Dependent Resistor)

A transducer which converts brightness (light) to resistance.

Thermistor

A transducer which converts temperature (heat) to resistance.

NOT Gate

Also called an inverter, its output is the inverse (opposite) of its input; the 'o' on the output symbol means 'not'.

AND Gate

A logic gate where the output is true only when all its inputs are true.

OR Gate

A logic gate where the output is true when at least one of its inputs is true.

B+ Line

The top line in a schematic diagram layout, representing the highest voltage in the circuit.

Galvanometer

A very sensitive meter used to measure tiny currents, usually $1mA$ or less.