Table of Electrical SymbolsSymbolComponent nameMeaning
Wire Symbols
Electrical WireConductor of electrical current
Connected WiresConnected crossing
Not Connected WiresWires are not connected
Switch Symbols and Relay Symbols
SPST Toggle SwitchDisconnects current when open
SPDT Toggle SwitchSelects between two connections
Pushbutton Switch (N.O)Momentary switch - normally open
Pushbutton Switch (N.C)Momentary switch - normally closed
DIP SwitchDIP switch is used for onboard configuration
SPST RelayRelay open / close connection by an electromagnet
SPDT Relay
JumperClose connection by jumper insertion on pins.
Solder BridgeSolder to close connection
Ground Symbols
Earth GroundUsed for zero potential reference and electrical shock protection.
Chassis GroundConnected to the chassis of the circuit
Digital / Common Ground
Resistor Symbols
Resistor(IEEE)Resistor reduces the current flow.
Resistor(IEC)
Potentiometer(IEEE)Adjustable resistor - has 3 terminals.
Potentiometer(IEC)
Variable Resistor / Rheostat(IEEE)Adjustable resistor - has 2 terminals.
Variable Resistor / Rheostat(IEC)
Trimmer ResistorPreset resistor
ThermistorThermal resistor - change resistance when temperature changes
Photoresistor / Light dependent resistor (LDR)Photo-resistor - change resistance with light intensity change
Capacitor Symbols
CapacitorCapacitor is used to store electric charge. It acts as short circuit withAC and open circuit with DC.
Capacitor
Polarized CapacitorElectrolytic capacitor
Polarized CapacitorElectrolytic capacitor
Variable CapacitorAdjustable capacitance
Inductor / Coil Symbols
InductorCoil / solenoid that generates magnetic field
Iron Core InductorIncludes iron
Variable Inductor
Power Supply Symbols
Voltage SourceGenerates constant voltage
Current SourceGenerates constant current.
AC Voltage SourceAC voltage source
GeneratorElectrical voltage is generated by mechanical rotation of the generator
Battery CellGenerates constant voltage
BatteryGenerates constant voltage
Controlled Voltage SourceGenerates voltage as a function of voltage or current of other circuit element.
Controlled Current SourceGenerates current as a function of voltage or current of other circuit element.
Meter Symbols
VoltmeterMeasures voltage. Has very high resistance. Connected in parallel.
AmmeterMeasures electric current. Has near zero resistance. Connected serially.
OhmmeterMeasures resistance
WattmeterMeasures electric power
Lamp / Light Bulb Symbols
Lamp/ light bulbGenerates light when current flows through
Lamp / light bulb
Lamp / light bulb
Diode / LED Symbols
DiodeDiode allows current flow in one direction only (left to right).
Zener DiodeAllows current flow in one direction, but also can flow in the reverse direction when above breakdown voltage
Schottky DiodeSchottky diode is a diode with low voltage drop
Varactor / Varicap DiodeVariable capacitance diode
Tunnel Diode
Light Emitting Diode (LED)LED emits light when current flows through
PhotodiodePhotodiode allows current flow when exposed to light
Transistor Symbols
NPN Bipolar TransistorAllows current flow when high potential at base (middle)
PNP Bipolar TransistorAllows current flow when low potential at base (middle)
Darlington TransistorMade from 2 bipolar transistors. Has total gain of the product of each gain.
JFET-N TransistorN-channel field effect transistor
JFET-P TransistorP-channel field effect transistor
NMOS TransistorN-channel MOSFET transistor
PMOS TransistorP-channel MOSFET transistor
Misc. Symbols
MotorElectric motor
TransformerChange AC voltage from high to low or low to high.
Electric bellRings when activated
BuzzerProduce buzzing sound
FuseThe fuse disconnects when current above threshold. Used to protect circuit from high currents.
Fuse
BusContains several wires. Usually for data / address.
Bus
Bus
Optocoupler / Opto-isolatorOptocoupler isolates onnection to other board
LoudspeakerConverts electrical signal to sound waves
MicrophoneConverts sound waves to electrical signal
Operational AmplifierAmplify input signal
Schmitt TriggerOperates 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 OscillatorUsed to generate precise frequency clock signal
Antenna Symbols
Antenna / aerialTransmits & receives radio waves
Antenna / aerial
Dipole AntennaTwo wires simple antenna
Logic Gates Symbols
NOT Gate (Inverter)Outputs 1 when input is 0
AND GateOutputs 1 when both inputs are 1.
NAND GateOutputs 0 when both inputs are 1. (NOT + AND)
OR GateOutputs 1 when any input is 1.
NOR GateOutputs 0 when any input is 1. (NOT + OR)
XOR GateOutputs 1 when inputs are different. (Exclusive OR)
D Flip-FlopStores one bit of data
Multiplexer / Mux2 to 1Connects the output to selected input line.
Multiplexer / Mux4 to 1
Demultiplexer / Demux1 to 4Connects selected output to the input line.
Electrical and electronic components tableComponent ImageComponent SymbolComponent Name
Wire
Toggle switch
Pushbutton switch
Relay
Jumper
Dip switch
Resistor
Variable resistor / Rheostat
Potentiometer
Capacitor
Variable capacitor
Electrolytic capacitor
Inductor
Battery
Voltmeter
Lamp / Light bulb
Diode
BJT Transistor
MOS transistor
Optocoupler / optoisolator
Electric motor
Transformer
Operational amplifier / 741
Crystal oscillator
Fuse
Buzzer
Loudspeaker
Microphone
Antenna / aerial
Passive componentsPassive components do not need additional power source to operate and can not have gain.Passive components include: wires, switches, resistors, capacitors, inductors, lamps, ...Active componentsActive components need additional power source to operate and can have gain.Active components include: transistors, relays, power sources, amplifiers, ...
What is resistorResistor is an electrical component that reduces the electric current.The resistor's ability to reduce the current is called resistance and is measured in units of ohms (symbol: ).If we make an analogy to water flow through pipes, the resistor is a thin pipe that reduces the water flow.Ohm's lawThe resistor's currentIin amps (A) is equal to the resistor's voltageVin volts (V)divided by the resistanceRin ohms ():
The resistor's power consumptionPin watts (W) is equal to the resistor's currentIin amps (A)times the resistor's voltageVin volts (V):P=IVThe resistor's power consumptionPin watts (W) is equal to the square value of the resistor's currentIin amps (A)times the resistor's resistanceRin ohms ():P=I2RThe resistor's power consumptionPin watts (W) is equal to thesquare value of the resistor's voltageVin volts (V)divided by the resistor's resistanceRin ohms ():P=V2/RResistors in parallel
The total equivalent resistance of resistors in parallelRTotalis given by:
So when you add resistors in parallel, the total resistance is decreased.Resistors in series
The total equivalent resistance of resistors in seriesRtotalis the sum of the resistance values:Rtotal=R1+R2+R3+...So when you add resistors in series, the total resistance is increased.Dimensions and material affectsThe resistance R in ohms () of a resistor is equal to the resistivityin ohm-meters (m) times the resistor's length l in meters (m) divided by the resistor's cross sectional areaAin square meters (m2):
Resistor image
Resistor symbolsResistor (IEEE)Resistor reduces the current flow.
Resistor (IEC)
Potentiometer (IEEE)Adjustable resistor - has 3 terminals.
Potentiometer (IEC)
Variable Resistor / Rheostat (IEEE)Adjustable resistor - has 2 terminals.
Variable Resistor / Rheostat (IEC)
Trimmer ResistorPresest resistor
ThermistorThermal resistor - change resistance when temperature changes
Photoresistor / Light dependent resistor (LDR)Changes resistance according to light
Resistor color codeThe resistance of the resistor and its tolerance are marked on the resistor with color code bands that denotes the resistance value.There are 3 types of color codes: 4 bands: digit, digit , multiplier, tolerance. 5 bands: digit, digit, digit , multiplier, tolerance. 6 bands: digit, digit, digit , multiplier, tolerance, temperature coefficient.Color codes table1st Digit2nd Digit3rd DigitMultiplierToleranceTemperature Coefficient
4bands1234
5bands12345
6bands123456
Black000100
Brown1111011%100 ppm/K
Red2221022%50 ppm/K
Orange33310315 ppm/K
Yellow44410425 ppm/K
Green5551050.5%
Blue6661060.25%10 ppm/K
Violet7771070.1%5 ppm/K
Grey8881080.05%
White999109
Silver10-210%
Gold10-15%
None20%
Resistance calculation of 4 bands resistorR= (10digit1+digit2)multiplierResistance calculation of 5 or 6 bands resistorR= (100digit1+10digit2+digit3)multiplierResistor typesVariable resistorVariable resistor has an adjustable resistance (2 terminals)
PotentiometerPotentiometer has an adjustable resistance (3 terminals)
Photo-resistorReduces resistance when exposed to light
Power resistorPower resistor is used for high power circuits and has large dimensions.
Surface mount(SMT/SMD) resistorSMT/SMD resistors have small dimensions. The resistors are surface mounted on the printed circuit board (PCB), this method is fast and requires small board area.
Resistor networkResistor network is a chip that contains several resistors with similar or different values.
Carbon resistor
Chip resistor
Metal-oxide resistor
Ceramic resistor
Pull-up resistorIn digital circuits, pull-up resistor is a regular resistor that is connected to the high voltage supply (e.g +5V or +12V) and sets the input or output level of a device to '1'.The pull-up resistor set the level to '1' when the input / output is disconnected. When the input / output is connected, the level is determined by the device and overrides the pull-up resistor.Pull-down resistorIn digital circuits, pull-down resistor is a regular resistor that is connected to the ground (0V) and sets the input or output level of a device to ' 0 '.The pull-down resistor set the level to ' 0 ' when the input / output is disconnected. When the input / output is connected, the level is determined by the device and overrides the pull-down resistor.
What is capacitorCapacitor is an electronic component that storeselectric charge. The capacitor is made of 2 close conductors (usually plates) that are separated by a dielectric material. The plates accumulate electric charge when connected to power source. One plate accumulates positive charge and the other plate accumulates negative charge.The capacitance is the amount of electric charge that is stored in the capacitor at voltage of 1 Volt.The capacitance is measured in units ofFarad(F).The capacitor disconnects current in direct current (DC) circuits and short circuit in alternating current (AC) circuits.Capacitor picturesCapacitor symbolsCapacitor
Polarized capacitor
Variable capacitor
CapacitanceThe capacitance (C) of the capacitor is equal to the electric charge (Q) divided by the voltage (V):
C is the capacitance in farad (F)Q is the electric charge in coulombs (C), that is stored on the capacitorV is the voltage between the capacitor's plates in volts (V)Capacitance of plates capacitorThe capacitance (C) of the plates capacitor is equal to the permittivity () times the plate area (A) divided by the gap or distance between the plates (d):
C is the capacitance of the capacitor, in farad (F).is the permittivity of the capacitor's dialectic material, in farad per meter (F/m).A is the area of the capacitor's plate in square meters (m2].d is the distance between the capacitor's plates, in meters (m).Capacitors in seriesThe total capacitance of capacitors in series, C1,C2,C3,.. :
Capacitors in parallel
The total capacitance of capacitors in parallel, C1,C2,C3,.. :CTotal=C1+C2+C3+...Capacitor's currentThe capacitor's momentary current ic(t) is equal to the capacitance of the capacitor,times the derivative of the momentary capacitor's voltage vc(t):
Capacitor's voltageThe capacitor's momentary voltage vc(t) is equal to the initial voltage of the capacitor,plus 1/C times the integral of the momentary capacitor's current ic(t) over time t:
Energy of capacitorThe capacitor's stored energyECin joules (J) is equal to the capacitanceCin farad (F)times the square capacitor's voltageVCin volts (V) divided by 2:EC=C VC2/ 2AC circuitsAngular frequency= 2 f - angular velocity measured in radians per second (rad/s)f - frequency measured in hertz (Hz).Capacitor's reactance
Capacitor's impedanceCartesian form:
Polar form:ZC=XC-90Capacitor typesVariable capacitorVariable capacitor has changeable capacitance
Electrolytic capacitorElectrolytic capacitors are used when high capacitance is needed. Most of the electrolytic capacitors are polarized
Spherical capacitorSpherical capacitor has a sphere shape
Power capacitorPower capacitors are used in high voltage power systems.
Ceramic capacitorCeramic capacitor has ceramic dielectric material. Has high voltage functionality.
Tantalum capacitorTantalum oxide dielectric material. Has high capacitance
Mica capacitorHigh accuracy capacitors
Paper capacitorPaper dielectric material
InductorInductor is an electrical component that stores energy in magnetic field.The inductor is made of a coil of conducting wire.In an electrical circuit schematics, the inductor marked with the letter L.The inductance is measured in units of Henry [L].Inductor reduce current in AC circuits and short circuit in DC circuits.Inductor picture
Inductor symbolsInductor
Iron core inductor
Variable inductor
Inductors in seriesFor several inductors in series the total equivalent inductance is:LTotal=L1+L2+L3+...Inductors in parallelFor several inductors in parallel the total equivalent inductance is:
Inductor's voltage
Inductor's current
Energy of inductor
AC circuitsInductor's reactanceXL=LInductor's impedanceCartesian form:ZL=jXL=jLPolar form:ZL=XL90
DIP SwitchDIP switch definitionDIP switch is an electrical component that is used to disconnect or connect wires in electrical circuit.DIP switch stands for Dual Inline Package.The DIP switch is mostly used in circuit boards for permanent configuration and settings of the circuit like jumpers orsolder bridge.DIP switch settingsThe DIP switch has usually 4 or 8 mini switches that together set a binary word of 4 or 8 bits.DIP switch symbolThe circuit diagram symbol of DIP switch is:
Solder BridgeSolder bridge is an on PCB conductor with two or more separate pieces that acts as a permanent switch.In order to short the solder bridge, you should solder between the two parts of the bridge.In order to disconnect the solder bridge, you should remove the solder bridge by desoldering it.The solder bridge is used for permanent configuration of the circuit.You can use jumper orDIP switchfor the same functionality. The solder bridge is cheaper, but less easy to use, than jumper or DIP switch.Solder bridge symbolThe circuit diagram symbol of solder bridge is:
Electronic Switch SymbolsElectrical & electronic switch symbols of schematic diagram - toggle switch, pushbutton switch, DIP switch, relay, jumper, solder bridge.SymbolNameDescription
SPST Toggle SwitchDisconnects current when open
SPDT Toggle SwitchSelects between two connections
Pushbutton Switch (N.O)Momentary switch - normally open
Pushbutton Switch (N.C)Momentary switch - normally closed
DIP SwitchDIP switch is used for onboard configuration
SPST RelayRelay open / close connection by an electromagnet
SPDT Relay
JumperClose connection by jumper insertion on pins.
Solder BridgeSolder to close connection
Electrical Ground SymbolsElectrical ground symbols of circuit diagram - earth ground, chassis ground, digital ground.SymbolNameDescription
Earth GroundUsed for zero potential reference and electrical shock protection.
Chassis GroundConnected to the chassis of the circuit
Digital / Common Ground
Resistor SymbolsResistor symbols of electrical & electronic circuit diagram - resistor, potentiometer, variable resistor.Table of resistor symbolsResistor (IEEE)Resistor reduces the current flow.
Resistor (IEC)
Potentiometer (IEEE)Adjustable resistor - has 3 terminals.
Potentiometer (IEC)
Variable Resistor / Rheostat (IEEE)Adjustable resistor - has 2 terminals.
Variable Resistor / Rheostat (IEC)
Trimmer ResistorPreset resistor
ThermistorThermal resistor - change resistance when temperature changes
Photoresistor / Light dependent resistor (LDR)Photo-resistor - change resistance with light intensity change
Capacitor SymbolsCapacitor schematic symbols - capacitor, polarized capacitor, variable capacitor.Table of capacitor symbolsSymbolNameDescription
CapacitorCapacitor is used to store electric charge. It acts as short circuit withAC and open circuit with DC.
Capacitor
Polarized CapacitorElectrolytic capacitor
Polarized CapacitorElectrolytic capacitor
Variable CapacitorAdjustable capacitance
Diode SymbolsDiode schematic symbols of electronic circuit - Diode, LED, Zener diode, Schottky diode, photodiode, ...SymbolNameDescription
DiodeDiode allows current flow in one direction only (left to right).
Zener DiodeAllows current flow in one direction, but also can flow in the reverse direction when above breakdown voltage
Schottky DiodeSchottky diode is a diode with low voltage drop
Varactor / Varicap DiodeVariable capacitance diode
Tunnel Diode
Light Emitting Diode (LED)LED emits light when current flows through
PhotodiodePhotodiode allows current flow when exposed to light
Transistor SymbolsTransistor schematic symbols of electronic circuit - NPN, PNP, Darlington, JFET-N, JFET-P, NMOS, PMOS.Table of transistor symbolsSymbolNameDescription
NPN Bipolar TransistorAllows current flow when high potential at base (middle)
PNP Bipolar TransistorAllows current flow when low potential at base (middle)
Darlington TransistorMade from 2 bipolar transistors. Has total gain of the product of each gain.
JFET-N TransistorN-channel field effect transistor
JFET-P TransistorP-channel field effect transistor
NMOS TransistorN-channel MOSFET transistor
PMOS TransistorP-channel MOSFET transistor
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