Electrical Symbols & Electronic Symbols


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

The symbols represent electrical and electronic components.

Table of Electrical Symbols

Symbol Component name Meaning

Wire Symbols

electrical wire symbol Electrical Wire Conductor of electrical current
connected wires symbol Connected Wires Connected crossing
unconnected wires symbol Not Connected Wires Wires are not connected

Switch Symbols and Relay Symbols

SPST switch symbol SPST Toggle Switch Disconnects current when open
SPDT switch symbol SPDT Toggle Switch Selects between two connections
push button symbol Pushbutton Switch (N.O) Momentary switch - normally open
push button symbol Pushbutton Switch (N.C) Momentary switch - normally closed
dip switch symbol DIP Switch DIP switch is used for onboard configuration
spst relay symbol SPST Relay Relay open / close connection by an electromagnet
spdt relay symbol SPDT Relay
jumper symbol Jumper Close connection by jumper insertion on pins.
solder bridge symbol Solder Bridge Solder to close connection

Ground Symbols

earth  ground symbol Earth Ground Used for zero potential reference and electrical shock protection.
chassis symbol Chassis Ground Connected to the chassis of the circuit
common digital ground symbol Digital / Common Ground  

Resistor Symbols

resistor symbol Resistor (IEEE) Resistor reduces the current flow.
resistor symbol Resistor (IEC)
potentiomemer symbol Potentiometer (IEEE) Adjustable resistor - has 3 terminals.
potentiometer symbol Potentiometer (IEC)
variable resistor symbol Variable Resistor / Rheostat (IEEE) Adjustable resistor - has 2 terminals.
variable resistor symbol Variable Resistor / Rheostat (IEC)
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.
capacitor symbol Capacitor
polarized capacitor symbol Polarized Capacitor Electrolytic capacitor
polarized capacitor symbol Polarized Capacitor Electrolytic capacitor
variable capacitor symbol Variable Capacitor Adjustable capacitance

Inductor / Coil Symbols

inductor symbol Inductor Coil / solenoid that generates magnetic field
iron core inductor symbol Iron Core Inductor Includes iron
variable core inductor symbol Variable Inductor  

Power Supply Symbols

voltage source symbol Voltage Source Generates constant voltage
current source symbol Current Source Generates constant current.
ac power source symbol AC Voltage Source AC voltage source
generator symbol Generator Electrical voltage is generated by mechanical rotation of the generator
battery cell symbol Battery Cell Generates constant voltage
battery symbol Battery Generates constant voltage
controlled voltage source symbol Controlled Voltage Source Generates voltage as a function of voltage or current of other circuit element.
controlled current source symbol Controlled Current Source Generates current as a function of voltage or current of other circuit element.

Meter Symbols

voltmeter symbol Voltmeter Measures voltage. Has very high resistance. Connected in parallel.
ammeter symbol Ammeter Measures electric current. Has near zero resistance. Connected serially.
ohmmeter symbol Ohmmeter Measures resistance
wattmeter symbol Wattmeter Measures electric power

Lamp / Light Bulb Symbols

lamp symbol Lamp / light bulb Generates light when current flows through
lamp symbol Lamp / light bulb
lamp symbol Lamp / light bulb

Diode / LED Symbols

diode symbol Diode Diode allows current flow in one direction only - left (anode) to right (cathode).
zener diode Zener Diode Allows current flow in one direction, but also can flow in the reverse direction when above breakdown voltage
schottky diode symbol Schottky Diode Schottky diode is a diode with low voltage drop
varicap diode symbol Varactor / Varicap Diode Variable capacitance diode
tunnel diode symbol Tunnel Diode  
led symbol Light Emitting Diode (LED) LED emits light when current flows through
photodiode symbol Photodiode Photodiode allows current flow when exposed to light

Transistor Symbols

npn transistor symbol NPN Bipolar Transistor Allows current flow when high potential at base (middle)
pnp transistor symbol PNP Bipolar Transistor Allows current flow when low potential at base (middle)
darlington transistor symbol Darlington Transistor Made from 2 bipolar transistors. Has total gain of the product of each gain.
JFET-N transistor symbol JFET-N Transistor N-channel field effect transistor
JFET-P transistor symbol JFET-P Transistor P-channel field effect transistor
nmos transistor symbol NMOS Transistor N-channel MOSFET transistor
pmos transistor symbol PMOS Transistor P-channel MOSFET transistor

Misc. Symbols

motor symbol Motor Electric motor
transformer symbol Transformer Change AC voltage from high to low or low to high.
Electric bell Rings when activated
Buzzer Produce buzzing sound
fuse symbol Fuse The fuse disconnects when current above threshold. Used to protect circuit from high currents.
fuse symbol Fuse
bus symbol Bus Contains several wires. Usually for data / address.
bus symbol Bus
bus symbol Bus
optocoupler symbol Optocoupler / Opto-isolator Optocoupler isolates connection to other board
speaker symbol Loudspeaker Converts electrical signal to sound waves
microphone symbol Microphone Converts sound waves to electrical signal
operational amplifier symbol Operational Amplifier Amplify input signal
schmitt trigger symbol 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 symbol Crystal Oscillator Used to generate precise frequency clock signal

Antenna Symbols

antenna symbol Antenna / aerial Transmits & receives radio waves
antenna symbol Antenna / aerial
dipole antenna symbol Dipole Antenna Two wires simple antenna

Logic Gates Symbols

NOT gate symbol NOT Gate (Inverter) Outputs 1 when input is 0
AND gate symbol AND Gate Outputs 1 when both inputs are 1.
NAND gate symbol NAND Gate Outputs 0 when both inputs are 1. (NOT + AND)
OR gate symbol OR Gate Outputs 1 when any input is 1.
NOR gate symbol NOR Gate Outputs 0 when any input is 1. (NOT + OR)
XOR gate symbol XOR Gate Outputs 1 when inputs are different. (Exclusive OR)
D flip flop symbol D Flip-Flop Stores one bit of data
mux symbol Multiplexer / Mux 2 to 1 Connects the output to  selected input line.
mux symbol Multiplexer / Mux 4 to 1
demux symbol Demultiplexer / Demux 1 to 4 Connects selected output to the input line.


Passive components

Passive components do not need additional power source to operate and can not have gain.

Passive components include: wires, switches, resistors, capacitors, inductors, lamps, ...

Active components

Active components need additional power source to operate and can have gain.

Active components include: transistors, relays, power sources, amplifiers, ...

See also

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