Hi, this is Ben Finio with Science Buddies, and this video is an introduction to how to
use a breadboard.
This is a breadboard.
It's a rectangular piece of plastic with a grid of holes that allows you to easily and
quickly build electronic circuits by pushing electronic components into the holes.
For example, simple circuits like this one with a battery and an on/off switch to control
a light.
You can also build more complicated circuits, for example lights that flash automatically,
or robots of all different shapes and sizes.
There are far more examples than we can list in the beginning of this short video.
At this point you might be thinking that this doesn't really look like it has anything to
do with bread.
The name breadboard comes from the early days of electronic circuits when people would literally
use wooden boards with screws or nails driven into them to make electronic connections.
Modern breadboards are made from plastic, and come in all shapes, sizes, and even different
colors.
The most common sizes you will probably see are full-size breadboards, half-size breadboards,
and mini breadboards.
Larger and smaller sizes are available, and many breadboards come with tabs and notches
on the side that allow you to snap two or more of them together, but a single breadboard
will be more than sufficient for most beginner projects.
Let's take a closer look at how a breadboard actually works.
The holes of a breadboard allow you to easily push the leads, or metal legs, of a component
like this LED into them, and then will lightly hold them in place.
This connection is strong enough that the LED won't fall out on its own, but light enough
that if you make a mistake, you can easily pull it out and put it in a new location.
Technically, these are called solderless breadboards because they can make these connections without
using solder, or melted metal, to permanently bond electronic components together.
Let's find out how breadboards can hold onto components without using solder.
If you flip a breadboard over, they come with an adhesive backing that allows you to permanently
stick them onto a project, for example, the breadboard stuck to this robot.
If you remove that backing completely, like I've done with this breadboard here, you expose
a series of metal strips that are inside the breadboard.
These metal strips are what make mechanical and electrical connections to the components
you insert into the breadboard.
We can remove one of these metal strips by pushing it out from the front to see what
it looks like up close.
Each strip is a series of five clips that line up with the holes in the breadboard.
When you push a component into the breadboard, these clips are what's actually grabbing onto
the leads, like you can see here with this LED.
This breadboard is actually made from transparent plastic, so you can see the clips from the
outside.
When you press a lead into one of the holes, it's just getting grabbed onto by one of these
clips.
Let's take a closer look at the writing on the front of your breadboard.
Your breadboard has columns labeled from A through J, and rows that start with one and
go up to a number that depends on the size of the breadboard.
These labels make it easy to follow directions when building a circuit.
For example, all of these holes are in column C, and all of these holes are in row 12.
Hole C12 is where column C intersects row 12.
There are also long strips on either side of your breadboard that are usually labeled
with red and black or red and blue lines, and also a plus or minus sign.
These are called buses or rails, and are used to deliver power to your entire circuit.
Typically, the red one marked with a plus sign will connect to the positive battery
terminal, and the black or blue one marked with a minus sign will connect to the negative
battery terminal.
Some breadboards, like this mini one, do not have power buses at all.
Some full-size breadboards have power buses that run the entire length of the breadboard,
as indicated by the continuous, unbroken red and black lines.
Other ones have power buses that only run half the length of the breadboard, as indicated
by the break in the lines here.
This is convenient if you have a circuit that needs to be powered by two different voltage
levels.
In order to use a breadboard, it really helps to understand how all the holes are connected.
Let's take a look at hole A1 as an example.
Remember that inside the breadboard are sets of five metal clips.
This means that hole A1 is electrically connected to hole B1, hole C1, D1, and E1.
It is not connected to hole A1 because that hole is in a different row and they do not
share the same set of metal clips.
It is also not connected to any of the holes on the other side of the gap in the middle
of the breadboard.
That's holes F1, G1, H1, I1, and J1.
We'll explain more about what this gap means in a little bit.
This diagram shows all of the connections on the breadboard highlighted with yellow
lines.
Each set of five holes forming half a row, that's those on the left in columns A through
E, and those on the right in columns F through J, is electrically connected.
The power buses run vertically on the sides of the breadboard, and are typically connected
over more than five holes, although this can vary from breadboard to breadboard.
The individual power buses are not connected to each other.
Let's take a look at what all this means for a common demonstration circuit with a battery,
a resistor, and an LED.
When I turn the battery pack on, the LED lights up.
Pretty simple.
Now let's zoom in and see how I actually have everything connected on the breadboard.
The battery pack's red lead is connected to the power bus on the right side of the breadboard.
This is connected to a jumper wire that goes to row 5, which then goes to the LED, over
to row 5 on the other side, to a resistor, to the ground bus, and then to the battery
pack's black lead.
This diagram shows how electricity flows through the circuit using yellow arrows.
This is called a closed circuit, or a complete path for electricity to flow.
Remember that on each separate half of the breadboard, the holes in row 5 are electrically
connected to each other.
This means, for example, that I can take the leads of the LED and move them to different
holes in row 5 and it will still light up.
However, if I take the LED and move it to a different row entirely, like row 4 or row
6, it does not light up because there is no path for the electricity to flow.
It has to be in row 5 to have that complete path.
You can also reconfigure the entire circuit.
For example, here I am going to move the LED and the resistor over to the right side of
the breadboard, and then connect the battery pack's negative lead to the ground bus on
this side.
While this looks different, electrically it is the same circuit, so the LED still lights
up.
You can see that in this diagram by tracing the yellow arrows, and noticing that there
is still a closed path for the electricity to flow through the LED.
Now let's take a look at some of the most common mistakes that students make when learning
to use a breadboard.
Here we have the demonstration circuit from the previous part of the video, with a battery,
a resistor, and an LED.
At first glance, everything probably looks fine, but when I turn the battery pack on,
the LED doesn't light up.
You won't know why unless you look closely at the breadboard.
When we zoom in, you can see that one of the LED leads is actually in the wrong row.
Notice how all of the connections are in row 5, except for this lead of the LED which is
in row 4.
Remember that rows 4 and 5 are not electrically connected, so in order for electricity to
have a complete path to flow, we have to move that LED lead over to row 5, and then the
LED will light up.
Every time you build a circuit, you should always double check your wiring to make sure
your connections are in the right place.
Another common mistake is not firmly pushing leads or wires into the breadboard all the
way.
Watch what happens if I pull this jumper wire out slightly so the connection is loose.
The LED will still light up intermittently, but bumping the wire or shaking the breadboard
can easily make the LED go out.
To make sure the connections stay secure, you have to make sure the jumper wire is pushed
firmly into the breadboard on both ends.
The same goes for other components like the LED itself.
You can see that if I pull the LED out slightly, it might look like it's actually pushed into
the breadboard, but it's actually very loose and won't stay lit.
This is because the leads aren't pushed in all the way, so to make sure it stays on,
you have to make sure the LED is pushed firmly into the breadboard, along with the rest of
the components.
The next common mistake will depend on the individual components in the project you're
doing.
Some components have polarity, meaning the direction they are facing matters.
LEDs are a great and very common example.
Notice how if I grab the LED and flip it around, it doesn't stay lit.
If you look closely at an LED, you'll see that the two legs are actually slightly different
lengths.
The longer leg is the positive side, and has to be connected to the battery pack's red
lead.
The shorter leg is the negative side, and needs to be connected to the black lead.
The resistor on the other hand does not have a polarity associated with it, so I can flip
the resistor around and the circuit will still work just fine.
When using a breadboard you'll have to decide what type of jumper wires you want to use,
and there are several different types available.
First are these long, flexible wires that come in many different colors and are usually
sold in packs of at least 10.
The wires themselves are very flexible but they have metal pins attached to their ends
that make them easy to press into the breadboard.
While these wires can be very convenient for simple circuits, they can get very messy for
complicated circuits, and as you add more and more to a breadboard you'll eventually
get a tangled nest of wires that can be very hard to keep track of.
Another option is to buy a jumper wire kit.
This is a small plastic container that comes with many different colors of wire that are
pre-cut to certain lengths.
The ends of these wires are bent down 90 degrees which makes them easy to press into the breadboard
and keep the wire flat, which can make the circuit much neater than the longer, loopier
flexible wires.
The downside of these kits is that they usually only come with one or two lengths for each
color, which can make it difficult to color code your circuit.
The final option is to purchase special spools of wire called hookup wire, and use a tool
called a wire stripper to cut them to length and then strip off some of the insulation
to make your own jumper wires.
You can see here I'm just taking the spool of wire, cutting a short segment of it, then
using the wire strippers to strip insulation off of each end.
When you're done you just have to bend the ends of the wire down, and then you'll be
left with a piece similar to what comes with the jumper wire kit, that easily fits into
the breadboard.
The advantage here is that you can buy several spools of wire of different colors and then
cut them to any length you want so you can color code your circuit.
If you do decide to buy your own hookup wire, you need to make sure you buy solid-core wire
and not stranded wire.
Solid-core wire has wire made of a single solid piece of metal that is very stiff and
easy to push into a breadboard.
Stranded wire is made up of multiple individual smaller strands, kind of like a rope.
This makes the overall wire much more flexible, but the ends are also flexible, and therefore
much harder to push into a breadboard without just bending them.
If you were watching closely earlier in the video, you might have noticed that I actually
violated this rule when I connected the battery pack, which comes with stranded wires.
If you're in a pinch, you don't have access to solid core wire or a soldering iron, you
can take the end of a stranded wire and twist the strands together as tightly as possible,
and that will make it somewhat easier to push into the breadboard, but it's still not the
easiest way to go.
Finally, all this time you might have been wondering what this gap that goes down the
middle of the breadboard is for.
This gap is designed such that integrated circuits, sometimes just called chips, that
come in a dual in-line package, meaning they have two rows of pins, can fit nicely straddling
the middle of the breadboard.
When you have a new chip, you might need to bend the pins together slightly so they'll
fit into the breadboard, but then you just have to line up all of the pins and press
it in firmly, just like you would with any other component.
This works great because now the pins on each side of the chip are each connected to their
own row.
What you don't want to do is put the entire chip just on one side of the breadboard so
it's not straddling the gap.
Remember that the pins in each row on either side of the breadboard are electrically connected
to each other, so if you put a chip in like this, you are shorting out the two pins in
each row.
Integrated circuits come in many different sizes, and they all serve a special purpose,
however all of them will fit directly into a breadboard straddling this middle gap.
You can find a written version of this tutorial, along with other helpful electronics tutorials
like how to use a multimeter and how to strip wire all on our website, www.sciencebuddies.org.
You can also browse our free library of over 1,000 science and engineering project ideas
if you need a project to do for school, at home, or just for fun.