Electrical Symbols | Electronic Symbols | Schematic symbols

Electrical symbols and electronic circuit symbols are used for drawing schematic diagram.

The symbols represent electrical and electronic components.

Symbol

Component name
Meaning

Wire Symbols

Electrical Wire
Conductor of electrical current

Connected Wires
Connected crossing

Not Connected Wires
Wires are not connected

Switch Symbols and Relay Symbols

SPST Toggle Switch
Disconnects current when open

SPDT Toggle Switch
Selects between two connections

Pushbutton Switch (N.O)
Momentary switch – normally open

Pushbutton Switch (N.C)
Momentary switch – normally closed

DIP Switch
DIP switch is used for onboard configuration

SPST Relay
Relay open / close connection by an electromagnet

Jumper
Close connection by jumper insertion on pins.

Solder Bridge
Solder to close connection

Ground Symbols

Earth Ground
Used for zero potential reference and electrical shock protection.

Chassis Ground
Connected to the chassis of the circuit

Resistor Symbols

Resistor (IEEE)
Resistor reduces the current flow.

Potentiometer (IEEE)
Adjustable resistor – has 3 terminals.

Variable Resistor / Rheostat (IEEE)
Adjustable resistor – has 2 terminals.

Trimmer Resistor
Preset resistor

Thermistor
Thermal resistor – change resistance when temperature changes

Photoresistor / Light dependent resistor (LDR)
Photo-resistor – change resistance with light intensity change

Capacitor Symbols

Capacitor
Capacitor is used to store electric charge. It acts as short circuit with AC and open circuit with DC.

Variable Capacitor
Adjustable capacitance

Inductor / Coil Symbols

Inductor
Coil / solenoid that generates magnetic field

Iron Core Inductor
Includes iron

Power Supply Symbols

Voltage Source
Generates constant voltage

Current Source
Generates constant current.

AC Voltage Source
AC voltage source

Generator
Electrical voltage is generated by mechanical rotation of the generator

Battery Cell
Generates constant voltage

Battery
Generates constant voltage

Controlled Voltage Source
Generates voltage as a function of voltage or current of other circuit element.

Controlled Current Source
Generates current as a function of voltage or current of other circuit element.

Meter Symbols

Voltmeter
Measures voltage. Has very high resistance. Connected in parallel.

Ammeter
Measures electric current. Has near zero resistance. Connected serially.

Ohmmeter
Measures resistance

Wattmeter
Measures electric power

Lamp / Light Bulb Symbols

Lamp / light bulb
Generates light when current flows through

Lamp / light bulb

Lamp / light bulb

Diode / LED Symbols

Diode
Diode allows current flow in one direction only – left (anode) to right
(cathode).

Zener Diode
Allows current flow in one direction, but also can flow in the reverse direction when above breakdown voltage

Schottky Diode
Schottky diode is a diode with low voltage drop

Varactor / Varicap Diode
Variable capacitance diode

Light Emitting Diode (LED)
LED emits light when current flows through

Photodiode
Photodiode allows current flow when exposed to light

Transistor Symbols

NPN Bipolar Transistor
Allows current flow when high potential at base (middle)

PNP Bipolar Transistor
Allows current flow when low potential at base (middle)

Darlington Transistor
Made from 2 bipolar transistors. Has total gain of the product of each gain.

JFET-N Transistor
N-channel field effect transistor

JFET-P Transistor
P-channel field effect transistor

NMOS Transistor
N-channel MOSFET transistor

PMOS Transistor
P-channel MOSFET transistor

Misc. Symbols

Motor
Electric motor

Transformer
Change AC voltage from high to low or low to high.

Electric bell
Rings when activated

Buzzer
Produce buzzing sound

Fuse
The fuse disconnects when current above threshold. Used to protect circuit from high currents.

Bus

Contains several wires. Usually for data / address.

Optocoupler / Opto-isolator
Optocoupler isolates connection to other board

Loudspeaker
Converts electrical signal to sound waves

Microphone
Converts sound waves to electrical signal

Operational Amplifier
Amplify input signal

Schmitt Trigger
Operates with hysteresis to reduce noise.

Analog-to-digital converter (ADC)
Converts analog signal to digital numbers

Digital-to-Analog converter (DAC)
Converts digital numbers to analog signal

Crystal Oscillator
Used to generate precise frequency clock signal

⎓
Direct current
Direct current is generated from constant voltage level

Antenna Symbols

Antenna / aerial
Transmits & receives radio waves

Dipole Antenna
Two wires simple antenna

Logic Gates Symbols

NOT Gate (Inverter)
Outputs 1 when input is 0

AND Gate
Outputs 1 when both inputs are 1.

NAND Gate
Outputs 0 when both inputs are 1. (NOT + AND)

OR Gate
Outputs 1 when any input is 1.

NOR Gate
Outputs 0 when any input is 1. (NOT + OR)

XOR Gate
Outputs 1 when inputs are different. (Exclusive OR)

D Flip-Flop
Stores one bit of data

Multiplexer / Mux 2 to 1
Connects the output to  selected input line.

Multiplexer / Mux 4 to 1

Demultiplexer / Demux 1 to 4
Connects selected output to the input line.