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