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How a breadboard works

The few rules that explain every breadboard layout.

Why use a breadboard?

A breadboard lets you connect electronic parts without soldering. Metal clips under the holes join some holes together, so pushing two leads into the same connected group joins them electrically.

Which holes are connected?

• Columns of five: on the virtual board, holes a–e in the same column are connected, and so are f–j in that column.
• The centre gap: the two halves are not connected to each other. Chips straddle the gap so each pin gets its own column.
• Power rails: the long + and − strips run the whole length of the board, so every hole along a rail is the same connection.

Your first circuit: an LED with a resistor

1. Place a Battery across the rails (for example 9 V).
2. Place a Resistor from the positive rail to an empty column.
3. Place an LED from that column to the negative rail. The anode (first tap) faces the resistor.
4. Press Run and read the current at the top of the screen.

Choosing the resistor

An LED drops a fixed voltage (about 1.9 V for red in the simulator) and the resistor takes the rest. Ohm’s law gives R = (Vsupply − Vled) ÷ I. With 9 V, a red LED and a target of 10 mA: (9 − 1.9) ÷ 0.010 = 710 Ω. A 680 Ω resistor gives about 10 mA; 1 kΩ gives about 7 mA — a bit dimmer but still safe.

Common mistakes

• Parts placed in different columns, so the loop is never closed.
• An LED fitted backwards (it stays dark).
• No current-limiting resistor. The simulator warns you, and a real LED would fail.
• Both ends of a part in the same connected group, which shorts it out.

Open the Breadbit simulator