Wiring Cheat Sheet
Tape this above the bench. It answers the five questions every build asks.
Breadboard & Wiring Cheat Sheet
gizmos & gadgets · bench reference v1
Resistor color code
0
Black
1
Brown
2
Red
3
Orange
4
Yellow
5
Green
6
Blue
7
Violet
8
Grey
9
White
Read bands left → right: digit, digit, ×zeros. Red-Red-Brown = 220Ω
LED rules
- ⚡ Long leg = positive (+). Flat side = negative.
- ⚡ Always pair with a resistor (~220Ω at 5V).
- ⚡ Doesn't light? Flip it before you debug anything else.
Arduino Uno pins to know
| 13 | Built-in LED — your first blink |
| ~3 ~5 ~6 ~9 ~10 ~11 | PWM pins (the ~ means fade-able) |
| A0–A5 | Analog inputs — knobs & sensors |
| GND | Ground — every circuit returns here |
| 5V / 3.3V | Power out — check your part first! |
⚠ 5 classic mistakes
- 1.LED in backwards. Long leg goes to +. LEDs are one-way streets.
- 2.No resistor on the LED. It'll work… once. ~220Ω keeps the smoke inside.
- 3.Breadboard rails split in the middle. Power rails on many boards break at the halfway line — jump them.
- 4.No common ground. Two power sources? Their grounds must connect, always.
- 5.Powering motors from the Uno 5V pin. Motors and servos want their own supply — the Uno browns out.
free plan from the Gizmos & Gadgets workshop · @GizmoAndGadgets on YouTube
mistake #6: not printing this sheet