Solderless breadboard

Solderless breadboards are a common way to prototype many kinds of circuits. They allow you to quickly make electrical connections between through hole parts, wired components, DIP chips, and prototyping breakout boards. When you’re done, you can take all the parts out and reuse them, including the breadboard.

For this article, I’ll be specifically describing the BB830 breadboard from BusBoard Prototype Systems, which is a good quality, reliable breadboard that’s not frustrating to use. However, there are a wide variety of breadboards that are very similar, but may have different lengths or configuration for the power rails.

Physical overview

The breadboard is a rectangular piece of plastic. On the top side there is a roughly 2mm notch-shaped valley running down the middle. For the BB830 specifically, there are tabs that stick out from the edge of the breadboard, and indentations on the opposite edge that match these tabs. Other breadboards may lack the tabs.

On the top, on both sides of the valley, there is a grid of small squarish holes. These holes are spaced .1 inch (2.54mm) apart.

Orientation

For this description, we’ll orient the breadboard so the valley is perpendicular to you, and the tabs are on the left (if your breadboard has no tabs, don’t worry about it). I’ll use the word “row” to describe arrangements of holes that run left to right, and “column” to describe range of holes that run in the perpendicular (near to far) direction.

Hole configuration

Using a fine-pointed object like a stylus, you can explore the holes on the top of the breadboard. The main part of the breadboard comprises two grids of evenly-spaced holes on both the left and right side of the central valley. This grid is 5 holes wide to the left, and 5 holes wide to the right. Each of these rows of 5 form one electrical connection point, so that anything plugged into one of the 5 holes in a row will be connected to anything else plugged into that row. The rows on either side of the valley are not connected to each other, so that you can plug in a component (like a DIP IC) that straddles the valley and h not have to connect opposing pins together.

The BB830 has 63 rows of holes on each side, meaning there are a total of 630 connection points in this central area, and since each row of 5 is electrically connected there are 126 separate electrical points.

On both the left and right of the central grid, separated by a flat strip, there are columns of holes. These are 2 holes wide, and on the BB830 they are in groups of 5 rows. These are the so-called “power rails”. These four columns (two on each side) are the “power rails”, they are set up so that the whole column is connected together within the breadboard, meaning that if you power one of the holes in a column you can tap into any other hole in the column to get power. The columns are not connected to each other, or to the corresponding column on the opposite side, so you could use a different power supply for both the left and right rails, or jumper them together.

These are labeled visually but it’s just a guideline. If you’re sharing your prototype with sighted engineers, following the label can help prevent mishaps. On the left side, the outer and leftmost column is labeled + for the positive rail. The inner column is labeled -. Then on the right side, the left (inner) column is + and the right (outer) column is -. So from left to right the rails are plus, minus, plus, minus.

Variations for other breadboards

The number of rows varies a lot between breadboards.

Some very small breadboards have no power rails.

Many breadboards have disconnected power rails, meaning that the groups of power holes are not necessarily connected all down the line, so you need to insert jumpers to extend the power rail. This is sometimes marked visually by a broken line on the breadboard, or you can test it using a multimeter or continuity tester. This is mostly a huge annoyance and one of the reasons why I recommend the BB830 over $2 breadboards from AliExpress.

Many breadboards have power rails that are labeled differently.

Basic usage tips

• Most important: Double check your power connections, and which column you’re plugging into. Remember that all the pins in a row are connected, so if you’re making multiple different circuit nodes they need to be arranged in different rows.
• Wiring: I recommend buying flexible breadboard jumpers, which are wires with male pins on both ends. You can easily plug one end into one row and another end into another row. Solid core wire that has been stripped at the end works fine, provided it’s not too fat or thin (20-22 AWG works great). However, stranded wire will not work and will be very frustrating.
• Bigger components: To connect to things that don’t fit into the breadboard, you can use an alligator clip lead with one of your jumpers. Clip one end of the alligator to the jumper, plug the jumper into the board, clip the other end to the component lead.
• Microchips: DIP style through-hole chips can be inserted so they span the central valley. Make sure the pins are straight and push in gently, so that you don’t bend or break off the delicate pins.
• Breakout boards: Breakout boards are often designed to have 2 parallel rows of pins, so you can insert them like a microchip.
• Female connectors: Some components (e.g. servos) have connectors with the right spacing of .1 inch, but they’re female. You can connect them to a breadboard by sticking jumper wires into the end of the connector, and inserting the other end into the breadboard. Or you can insert a strip of breakaway male header pins into the breadboard.