What is a breadboard used for?

What is a breadboard used for?

• Prototyping: testing a circuit design before making a permanent version on a printed circuit board (PCB).
• Learning electronics: trying circuits from a lesson or kit, then pulling them apart and building the next one.
• Microcontroller projects: connecting LEDs, buttons, sensors and displays to an Arduino, ESP32 or Raspberry Pi.
• Experimenting: swapping a resistor or sensor in seconds to see what changes.
• Finding faults: rebuilding part of a circuit to check whether it works on its own.

The big advantage is that nothing is permanent. Soldering joins parts with melted metal, which takes time and is hard to undo. On a breadboard, a wrong connection is fixed by pulling a wire out and pushing it in somewhere else.

Why is it called a breadboard?

Early radio and electronics hobbyists really did use wooden boards for cutting bread. As SparkFun explains, they would take the nearest breadboard, hammer in a few nails or thumbtacks, and wrap wires round them to make connections. Today's plastic boards kept the name.

How does a breadboard work?

Under the plastic, a breadboard is lined with strips of springy metal. Each strip joins a group of holes, so anything pushed into the same group is electrically connected. The trick to using one is knowing which holes are joined:

  +  -                                              +  -
  |  |    a  b  c  d  e      f  g  h  i  j          |  |
  o  o  1 o--o--o--o--o      o--o--o--o--o  1       o  o
  o  o  2 o--o--o--o--o      o--o--o--o--o  2       o  o
  o  o  3 o--o--o--o--o      o--o--o--o--o  3       o  o
  |  |                  gap                         |  |
 power rails:         (centre channel)           power rails:
 each column joined                              each column joined
 all the way down                                all the way down

  Row 1, holes a to e: connected     Row 1, holes f to j: connected
  But a to e is NOT connected to f to j across the gap.

• Terminal strips: the main area. Each numbered row is split into two groups of five holes, a to e and f to j. The five holes in a group are joined; different rows are not.
• The centre gap: separates the two halves of every row. Chips straddle it, so each leg gets its own row and the two sides of the chip aren't shorted together.
• Power rails: the long columns down each side, usually marked with a red line for positive (+) and a blue or black line for negative (−). Each rail is joined along its length, so you can take power from anywhere on it. The rails on the left aren't connected to the rails on the right, and on some larger boards each rail is split halfway down.

The holes are 0.1 inch (2.54 mm) apart, the standard spacing for chip legs and pin headers, so parts drop straight in.

How to use a breadboard: your first LED circuit

Lighting an LED is the classic first build. You need a breadboard, an LED, a resistor, two jumper wires and a low voltage supply, such as a 5 V pin on an Arduino.

1. Connect the power rails: one wire from the 5 V pin to the red (+) rail, one from GND to the blue (−) rail.
2. Place the LED across two rows, for example its long leg (positive, the anode) in row 10 and its short leg (the cathode) in row 11. Never put both legs in the same row, or they'd be connected together and the LED would be bypassed.
3. Add the resistor from row 11 to the blue (−) rail.
4. Join row 10 to the red (+) rail with a jumper wire. Current now flows from +, through the LED and resistor, to −, and the LED lights.

Choosing the resistor

The resistor limits the current so the LED doesn't burn out. Say a red LED drops about 2 V and you want about 15 mA. The resistor gets the rest of the 5 V, which is 3 V, so by Ohm's law R = V ÷ I = 3 ÷ 0.015 = 200 Ω. Resistors come in standard values, so pick the next one up, 220 Ω, which gives 3 ÷ 220 = 0.0136 A, about 13.6 mA.

On a Raspberry Pi, the GPIO pins work at 3.3 V instead, so the same LED with a 330 Ω resistor gets (3.3 − 2) ÷ 330 = about 3.9 mA: dimmer, but safe for the Pi. Try one: this question asks you to work out the current through an LED and its resistor.

Before you build, you can try the same circuit safely in our Circuit Builder, which flags a reversed LED and shows the current through every part. The Raspberry Pi course and Microcontrollers course take you from blinking an LED to reading sensors.

Breadboard vs stripboard vs PCB

A common path is to get a circuit working on a breadboard, then copy it onto stripboard or design a PCB once you know it works.

Common breadboard mistakes

• Both legs of a part in one row. The row joins them, so the part is shorted out and does nothing.
• Forgetting the power rail break. On boards with split rails, the bottom half may have no power until you bridge the gap with a wire.
• Assuming the left and right rails are joined. They aren't; add wires if you need power on both sides.
• Putting a chip on one side of the gap. Its legs on each side would be joined row by row. It must straddle the centre channel.
• LED in backwards. The long leg goes towards positive. Reversed, it won't light.
• Wiring while the power is on. Unplug the supply before moving parts.
• Using mains electricity. Breadboards are only for low voltage experiments, such as batteries and USB powered boards.

Read next

Physics · Electricity and magnetismBreadboard simulator: test a circuit before you build itTest a breadboard circuit online before you build it: place LEDs, resistors, switches and sensors, read live voltage and current, and spot mistakes first.