Understanding Electrical and Electronic Symbols: Free A Comprehensive Guide

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Introduction to Electrical and Electronic Symbols

Electrical and electronic symbols are the universal language of the engineering and technology world. They serve as essential tools for professionals, engineers, technicians, and hobbyists to communicate, design, and understand electrical and electronic systems. In this blog post, we will explore the most common electrical and electronic symbols, their meanings, and their applications.

Electrical Symbols

  1. Basic Electrical Symbols:
  • Resistor: Represents a passive two-terminal electrical component used to limit the flow of electric current.
  • Capacitor: A device used to store and release electrical energy.
  • Inductor: Symbolizes a coil of wire that generates a magnetic field when current flows through it.
  1. Switches:
  • SPST (Single-Pole, Single-Throw) Switch: A simple on/off switch.
  • SPDT (Single-Pole, Double-Throw) Switch: A switch with one input and two possible outputs.
  • DPDT (Double-Pole, Double-Throw) Switch: A switch with two inputs and two possible outputs.
  1. Connectors:
  • Terminal Block: Used to connect wires together.
  • Fuse: Represents a protective device that interrupts electrical flow in the event of overcurrent.
  • Ground Symbol: Denotes a connection to ground, typically for safety.
  1. Power Sources:
  • Battery: Represents a voltage source.
  • AC Voltage Source: Represents an alternating current power source.
  • DC Voltage Source: Represents a direct current power source.

Electronic Symbols

  1. Diodes:
  • Light Emitting Diode (LED): Indicates a diode that emits light when current flows through it.
  • Zener Diode: Represents a diode that maintains a constant voltage across its terminals.
  • Schottky Diode: Symbolizes a diode with low voltage drop.
  1. Transistors:
  • NPN Transistor: Denotes a bipolar junction transistor with an N-type material between two P-type materials.
  • PNP Transistor: Represents a bipolar junction transistor with a P-type material between two N-type materials.
  • Field Effect Transistor (FET): Symbolizes a transistor that controls current flow using an electric field.
  1. Integrated Circuits:
  • Operational Amplifier (Op-Amp): Represents an electronic amplifier with two input terminals and one output terminal.
  • Microcontroller: Symbolizes a compact computer on a single chip, used for controlling electronic systems.
  • Digital Logic Gates: Include symbols for AND, OR, NOT, XOR, and other logic gates.
  1. Sensors:
  • Temperature Sensor: Represents a device used to measure temperature.
  • Photoresistor: Symbolizes a light-dependent resistor.
  • Proximity Sensor: Denotes a sensor that detects the presence or absence of an object.

Applications

Understanding these symbols is crucial for a wide range of applications:

  1. Circuit Design: Engineers and designers use symbols to create and represent electrical and electronic circuits.
  2. Troubleshooting: Technicians rely on these symbols to diagnose and repair electrical and electronic systems.
  3. Education: Students and enthusiasts learn about electrical and electronic systems by studying these symbols.
  4. Manufacturing: Electronics manufacturers use these symbols in the production of devices and components.

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

SymbolComponent nameMeaning
Wire Symbols
electrical wire symbolElectrical WireConductor of electrical current
connected wires symbolConnected WiresConnected crossing
unconnected wires symbolNot Connected WiresWires are not connected
Switch Symbols and Relay Symbols
SPST switch symbolSPST Toggle SwitchDisconnects current when open
SPDT switch symbolSPDT Toggle SwitchSelects between two connections
push button symbolPushbutton Switch (N.O)Momentary switch – normally open
push button symbolPushbutton Switch (N.C)Momentary switch – normally closed
dip switch symbolDIP SwitchDIP switch is used for onboard configuration
spst relay symbolSPST RelayRelay open / close connection by an electromagnet
spdt relay symbolSPDT Relay
jumper symbolJumperClose connection by jumper insertion on pins.
solder bridge symbolSolder BridgeSolder to close connection
Ground Symbols
earth  ground symbolEarth GroundUsed for zero potential reference and electrical shock protection.
chassis symbolChassis GroundConnected to the chassis of the circuit
common digital ground symbolDigital / Common Ground 
Resistor Symbols
resistor symbolResistor (IEEE)Resistor reduces the current flow.
resistor symbolResistor (IEC)
potentiomemer symbolPotentiometer (IEEE)Adjustable resistor – has 3 terminals.
potentiometer symbolPotentiometer (IEC)
variable resistor symbolVariable Resistor / Rheostat (IEEE)Adjustable resistor – has 2 terminals.
variable resistor symbolVariable 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 with AC and open circuit with DC.
capacitor symbolCapacitor
polarized capacitor symbolPolarized CapacitorElectrolytic capacitor
polarized capacitor symbolPolarized CapacitorElectrolytic capacitor
variable capacitor symbolVariable CapacitorAdjustable capacitance
Inductor / Coil Symbols
inductor symbolInductorCoil / solenoid that generates magnetic field
iron core inductor symbolIron Core InductorIncludes iron
variable core inductor symbolVariable Inductor 
Power Supply Symbols
voltage source symbolVoltage SourceGenerates constant voltage
current source symbolCurrent SourceGenerates constant current.
ac power source symbolAC Voltage SourceAC voltage source
generator symbolGeneratorElectrical voltage is generated by mechanical rotation of the generator
battery cell symbolBattery CellGenerates constant voltage
battery symbolBatteryGenerates constant voltage
controlled voltage source symbolControlled Voltage SourceGenerates voltage as a function of voltage or current of other circuit element.
controlled current source symbolControlled Current SourceGenerates current as a function of voltage or current of other circuit element.
Meter Symbols
voltmeter symbolVoltmeterMeasures voltage. Has very high resistance. Connected in parallel.
ammeter symbolAmmeterMeasures electric current. Has near zero resistance. Connected serially.
ohmmeter symbolOhmmeterMeasures resistance
wattmeter symbolWattmeterMeasures electric power
Lamp / Light Bulb Symbols
lamp symbolLamp / light bulbGenerates light when current flows through
lamp symbolLamp / light bulb
lamp symbolLamp / light bulb
Diode / LED Symbols
diode symbolDiodeDiode allows current flow in one direction only – left (anode) to right (cathode).
zener diodeZener DiodeAllows current flow in one direction, but also can flow in the reverse direction when above breakdown voltage
schottky diode symbolSchottky DiodeSchottky diode is a diode with low voltage drop
varicap diode symbolVaractor / Varicap DiodeVariable capacitance diode
tunnel diode symbolTunnel Diode 
led symbolLight Emitting Diode (LED)LED emits light when current flows through
photodiode symbolPhotodiodePhotodiode allows current flow when exposed to light
Transistor Symbols
npn transistor symbolNPN Bipolar TransistorAllows current flow when high potential at base (middle)
pnp transistor symbolPNP Bipolar TransistorAllows current flow when low potential at base (middle)
darlington transistor symbolDarlington TransistorMade from 2 bipolar transistors. Has total gain of the product of each gain.
JFET-N transistor symbolJFET-N TransistorN-channel field effect transistor
JFET-P transistor symbolJFET-P TransistorP-channel field effect transistor
nmos transistor symbolNMOS TransistorN-channel MOSFET transistor
pmos transistor symbolPMOS TransistorP-channel MOSFET transistor
Misc. Symbols
motor symbolMotorElectric motor
transformer symbolTransformerChange AC voltage from high to low or low to high.
bell symbolElectric bellRings when activated
buzzer symbolBuzzerProduce buzzing sound
fuse symbolFuseThe fuse disconnects when current above threshold. Used to protect circuit from high currents.
fuse symbolFuse
bus symbolBusContains several wires. Usually for data / address.
bus symbolBus
bus symbolBus
optocoupler symbolOptocoupler / Opto-isolatorOptocoupler isolates connection to other board
speaker symbolLoudspeakerConverts electrical signal to sound waves
microphone symbolMicrophoneConverts sound waves to electrical signal
operational amplifier symbolOperational AmplifierAmplify input signal
schmitt trigger symbolSchmitt 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 oscillator symbolCrystal OscillatorUsed to generate precise frequency clock signal
Direct currentDirect current is generated from constant voltage level
Antenna Symbols
antenna symbolAntenna / aerialTransmits & receives radio waves
antenna symbolAntenna / aerial
dipole antenna symbolDipole AntennaTwo wires simple antenna
Logic Gates Symbols
NOT gate symbolNOT Gate (Inverter)Outputs 1 when input is 0
AND gate symbolAND GateOutputs 1 when both inputs are 1.
NAND gate symbolNAND GateOutputs 0 when both inputs are 1. (NOT + AND)
OR gate symbolOR GateOutputs 1 when any input is 1.
NOR gate symbolNOR GateOutputs 0 when any input is 1. (NOT + OR)
XOR gate symbolXOR GateOutputs 1 when inputs are different. (Exclusive OR)
D flip flop symbolD Flip-FlopStores one bit of data
mux symbolMultiplexer / Mux 2 to 1Connects the output to  selected input line.
mux symbolMultiplexer / Mux 4 to 1
demux symbolDemultiplexer / Demux 1 to 4Connects selected output to the input line.
Electrical and Electronic Symbols

Conclusion

Electrical and electronic symbols are the building blocks of modern technology. They enable us to communicate complex circuit designs, troubleshoot issues, and understand the inner workings of electronic systems. Whether you’re an electrical engineer, a hobbyist, or just someone interested in technology, having a good grasp of these symbols is essential for success in the field of electronics.

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