Basic Schematic Symbols | Electronics and Electrical Symbols

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Electrical symbols are a graphical representation of basic electrical and electronic devices or components. These Symbols are used in circuits and electrical diagrams to recognize a component. It is also called a schematic symbol.

Each component has typical functionality according to its operational characteristics.

An electronic circuit or schematic drawing uses a wired path between electronic components to complete the circuit.

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Various national and international standards define electrical and electronic symbols used in circuits. E.g. IEC standard, JIC standard, ANSI standard, IEEE standard, etc.

Though electrical symbols are standardized, they may vary from country to country, or engineering disciplines, based on traditional conventions.

Electrical symbols do not define any function or process unless the circuit is implemented with physically used components. (E.g. the circuit on a breadboard or assembled printed circuit board)

A few electronic symbols that can be used in the circuit diagrams are given below for reference:

ELECTRICAL COMPONENT	DEFINITION	SCHEMATIC SYMBOLS
WIRE SYMBOLS
Electrical wire	A conductor that carries electrical current between components
Connected wires	A wire that is physically linked between components
Not Connected wires	An unused/disconnected wire
Ground Symbols
Earth Ground	Direct connection to Earth for voltage reference
Chassis Ground	Direct connection of all metallic parts of a system
Digital/Common Ground	A shared reference point
Inductor/Coil Symbols
Inductor	A coil that stores energy in a magnetic field when current is passed
Iron Core Inductor	Inductor with a magnetic iron core to increase the inductance
Variable Inductor	Adjustable inductor
Lamp/Light Bulb Symbols
Lamp/light bulb	A device that converts electrical energy to visible light
Switch and Relay Symbols
SPST Toggle Switch	A switch connecting/disconnecting one circuit
SPDT Toggle Switch	A switch connecting one of two circuits
Jumper	A short wire connecting two points in a circuit
DIP Switch	Series of switches in a single compact package
Pushbutton Switch (N.C)	A button connecting the circuit when released
Pushbutton Switch (N.O)	A button connecting the circuit when pressed
SPST Relay/SPDT Relay	SPST relay: An electromechanical switch connecting or disconnecting a circuit SPDT relay: An electromechanical switch connecting one of two circuit
Solder Bridge	A solder connecting two or more pads on a circuit board
Resistor Symbols
Resistor (IEEE)/ Resistor (IEC)	A component opposing the flow of charge
Potentiometer (IEEE)/(IEC)	A variable resistor with three terminals, dividing voltage
Variable Resistor / Rheostat (IEEE)/(IEC)	We can change the electrical resistance using the variable resistor/rheostat
Trimmer Resistor	A small, adjustable resistor for fine-tuning the circuit
Thermistor	A temperature sensing resistor that changes the resistance with temperature
Photoresistor / Light-dependent resistor (LDR)	A resistor changing resistance with light intensity
Capacitor Symbols
Capacitor	A component storing energy in an electric field.
Polarized Capacitor	A capacitor with specific +ve and -ve terminal
Variable Capacitor	A capacitor with adjustable capacitance
Antenna Symbols
Antenna / aerial	A device that converts electrical signals to radio waves for transmission and receives radio waves
Dipole Antenna	A type of antenna consisting of two identical conductive elements, transmitting and receiving radio waves.
Power Supply Symbols
Voltage Source/ Current Source	Voltage source: A device providing constant voltage Current source: A device providing constant current
Battery cell / Battery	A device that stores chemical energy and converts it to electrical energy.
Controlled voltage source/Controlled Current source	Controlled voltage source: A device providing adjustable voltage. Controlled current source: A device providing adjustable current
AC voltage source/Generator	AC voltage source: A device providing AC voltage Generator: A machine converting mechanical energy to electrical energy
Meter Symbols
Voltmeter/Ammeter	Voltmeter: Measures voltage between two points Ammeter: Measures current flowing through a circuit
Ohmmeter/Wattmeter	Ohmmeter: Measures electrical resistance Wattmeter: Measures power consumed by a circuit
Diode/LED Symbols
Diode/Zener Diode	Diode: A semiconductor device that allows the flow of current in one direction Zener diode: Diode that allows reverse current flow
Tunnel Diode/Light Emitting Diode	Tunnel diode: This particular diode exhibits negative resistance Light emitting diode: This particular diode emits light when current flows
Schottky Diode/Varicap Diode	Schottky diode: Fast-switching diode Varicap diode: A Diode in which the internal capacitance varies with the reverse voltage
Photodiode	This particular diode detects light, generating current
Transistor Symbols
NPN Bipolar Transistor/ PNP Bipolar Transistor	NPN: This is a BJT with a negative-positive-negative layer structure. PNP: This is a BJT with a positive-negative-positive layer structure
NMOS/PMOS Transistor	NMOS: This is a field effect transistor with a negative channel PMOS: This is a field effect transistor with a positive channel
JFET-N Transistor/ JFET-P Transistor	JEFT-N: It is a type of junction field effect transistor with a negative channel for switching or amplifying voltage JEFT-P: It is a type of junction field effect transistor with a positive channel for switching or amplifying voltage
Darlington Transistor	It is a compound transistor consisting of two BJTs, amplifying current
Miscellaneous Symbols
Motor/ Transformer	Motor: Converts electrical energy into mechanical energy Transformer: A component that transfers electrical energy from one circuit to another. It changes the voltage levels
Fuse	Device that protects circuits from overcurrent
Electric bell/Buzzer	Generates sound when current flows
Microphone / Loudspeaker	Microphone: Converts sound into electrical signals Loudspeaker: Converts electrical signals into sound
Op-amp /Schmitt trigger	Op-Amp: Used to amplify weak signals Schmitt trigger: A logic gate that converts analog signals to digital
Bus	It helps transfer data between components
Analog-to-digital converter (ADC)	Converts analog signals to digital
Digital-to-Analog Converter (DAC)	Converts digital signals to analog
Optocoupler	Component that helps in transferring electrical signals between isolated circuits
Crystal Oscillator	Used to generate precise clock signals
Logic Gate Symbols
AND/NAND Gate	AND gate: Logical conjunction NAND gate: Inverted AND
XOR Gate/NOT Gate	XOR gate: Logical exclusion NOT gate: Logical negation
OR/NOR Gate	OR gate: Logical disjunction NOR gate: Inverted OR
D flip flop /Multiplexer (MUX) 2 to 1	D flip-flop: Used to store binary data Multiplexer 2 to 1: Selects 1 signal from 2 input signals to send a single output signal.