Overview
A breadboard holds parts and joins them through metal clips hidden under the holes. Once you know which holes share a clip, reading or building any circuit gets much easier.
The rules
- Terminal strips: each group of five holes in a line across the board (a–e, or f–j) is one connection. The two halves are not joined.
- Centre channel: chips such as the 74HC595 straddle it so that each pin lands in its own strip.
- Power rails: the long lines along the edges, usually marked red (+) and blue (−). On some full-size boards the rails are split halfway along; bridge the gap with a short wire if needed.
Common mistakes
- Both legs of a part in the same strip. They are shorted together and the part does nothing.
- Pushing a button with four legs the wrong way round, so it is either always closed or never connected. Mount it across the centre channel, and use diagonally opposite legs if unsure.
- Forgetting to connect the rails to the Uno's 5V and GND.
- Thick component legs or worn clips giving intermittent contact. If a circuit works only when pressed, move it.
Check with a multimeter
Set the meter to continuity (beep) mode and touch two wires pushed into different holes. A beep means they are connected. This takes seconds and settles any doubt about an unfamiliar board.