How A Breadboard Works

Before you get started building any circuits, it’s important to know how a breadboard works so you actually understand what is going on as opposed to just plugging wires in holes and not knowing why.

The Humble Breadboard

If you have a breadboard in front of you, why not take it out and look at it.

You will notice that there are a lot of holes in the middle part of the breadboard and some holes that run down the sides of the breadboard. By taking the backing off the breadboard and looking at the underneath you can really see how the breadboard is structured. (No need to do this in real life we have a picture)

By looking at the picture above you can see that the holes on the sides of the breadboard are connected vertically. These are called the power rails and are indicated by the red arrows in the picture.

Normally you just have one wire per power rail that supplies the power. For example if you had a battery with a red (positive) wire and a black (negative) wire you would put the red wire on the red (positive) rail and the black wire on the blue (negative) rail. This then means that if there is something on the breadboard that needs power, like an Arduino for example, you can easily power it by running positive and negative wires to the nearest power rail.

Let’s look at this idea using pictures:

Let’s start out with just the breadboard:


Now let’s connect a battery to one of the power rails:

This means that all of the holes on the red rail are connected to the red (positive) power cable of the battery. The same goes for all of the holes on the blue rail being connected to the black lead of the battery.

Take a look at this image which further illustrates this point:

The reason the breadboard is made this way is that it makes powering things on the breadboard really easy. For example let’s add an Arduino nano to the breadboard and take a look at where the power pins are:

If you zoom in an look at the bottom row on pins on the Arduino. At the far right there are two pins labelled GND and VIN. GND is the negative power connection which should be connected to the negative power rail. VIN is the positive power connection and should be connected to the positive power rail.

This is what it looks like to connect the Arduino pins to the correct power rails:

In the above picture we have used the power rails but also the main middle part of the breadboard. Let’s go over how the middle part works.

In the middle section of the breadboard you will see a trench or dip that runs down the center of the breadboard. The reason this is here is so that you can plug in integrated circuits (ICs) and PCBs  with two rows of pins.

Take a look at the image below to show how the middle section pins are connected. The trench divides the middle into two halves as shown:

If we come along an place down an arduino, the pins on the top of the Arduino will be connected to the rows on the top half of the breadboard. The pins on the bottom of the Arduino will be connected to rows on the bottom half of the breadboard.

We can now easily connect wires to any pin on the Arduino by placing the wire in the same row as the pin. The exact hole in the row doesn’t matter as long as it is the same row it will work.


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