circuit symbols

a tiny cheat-sheet for reading schematics. symbols vary by standard; resistors may be a zig-zag (ANSI) or a rectangle (IEC).

symbolnamenotes
groundreference 0 V
dc sourcebattery/regulator output
\/\/\/resistorlimits current / divides voltage
|‖|capacitortwo plates; polarized variant marks +
▷|diodetriangle → line; conventional current flows from triangle to line. LED adds two arrows out.
⊲+op-amptriangle with +/− inputs (power pins often omitted)
inductorcoil for filtering/energy storage
switchSPST/DPDT variants
▭▭ICmulti-pin rectangle; watch pin 1 mark
BJT / MOSFETtransistorBJT: arrow on emitter; MOSFET: G-D-S with body diode
pro tip: label nets (e.g., VCC, SCL, LED_A) so the schematic reads like a story.