Electronic Component Symbols — Reference
What the symbols in a schematic mean — name, purpose, and typical use.
Every schematic is a drawing: each symbol stands for a specific part. Here's what the most common ones mean, what the parts do, and where you'll meet them. Symbols follow the European (IEC) style used on this site.
Passive components
Resistor
Limits current, sets voltages.
Every circuit: LED chains, dividers, pull-ups.
Try: Ohm's LawPotentiometer
Adjustable resistor (3 pin).
Volume knobs, trimmers, voltage references.
Try: Voltage DividerCapacitor
Stores charge, blocks DC, filters AC.
Decoupling, filters, timing, smoothing.
Try: RC Time ConstantElectrolytic capacitor
Polarized capacitor — mind the +/−.
Power supply smoothing (large µF values).
Try: Smoothing CapInductor / coil
Stores energy in a magnetic field.
Filters, DC-DC converters, RF circuits.
Try: LC FilterTransformer
Couples AC between two windings.
Mains power supplies, isolation, impedance matching.
Semiconductors
Diode
Conducts one way only (A → K).
Rectification, reverse protection, OR-ing.
Zener diode
Breaks down at a precise reverse voltage.
Voltage references, regulators, clamping.
NPN transistor
Current-controlled switch/amplifier.
Switching loads, amplifying, logic level shifting.
MOSFET
Voltage-controlled switch (G = gate).
Power switching, motor drives, battery protection.
Op-amp
Amplifies the difference of its inputs.
Amplifiers, filters, comparators, buffers.
Sources & power
DC voltage source
Ideal constant-voltage DC source.
Schematic shorthand for supplies and rails.
AC voltage source
Sinusoidal voltage source.
Mains, audio signals, oscillators.
Ground (GND)
Common reference (0 V).
Every circuit — the return path.
Fuse
Protective device — burns open on overcurrent.
Input protection on every power rail.
Switches & misc
SPST switch
Single on/off contact.
Power switches, jumpers, enable lines.
Crystal oscillator
Precise frequency reference (quartz).
MCU clocks, RTCs, radio tuning.
Try: Load Caps