Hi, my name is Massimo Banzi and
I am one of the co-founders of Arduino.
Welcome to this series of videos
about the Arduino Starter kit.
In this particular video,
we are going to start
learning the basics of all the
components that we are going to use
in the rest of the videos.
What we see here is
is a set of electronic components
and today we are going to
build a very basic circuit.
We are going to use a small LED
connected to a button
and when you press the button,
the LED comes on.
It's a very simple
electronic circuit.
It doesn't involve
our Arduino board at all.
And it is designed for you
to understand all the basic elements
that make
an electronic circuit.
So what is an LED?
An LED is a small source of light.
You can imagine it's
like a light bulb,
but it's more efficient,
because it doesn't generate that much heat.
Because it is an electronic component
based on the semi-conductor.
So LEDs are convenient for us,
because they work at
a small voltage.
They can be powered by a small battery
or the voltage that you
can get from an Arduino board.
So, what’s is a circuit?
A circuit is a series of electronic
components like
this LED
or this button using wires
connected together
Using wires
electricity can flow
through the components
and each component
is either able to transform
the electricity
into something else, like light
like the LED does.
Or for example
the switch
is a component that can
open and close a circuit
when you press on it.
This particular button
that I have in my hand
keeps the circuit closed
until I press the button,
and it closes the circuit.
Closing the circuit is a little bit like
when you open a tap:
you let the electricity
flow through the button.
You can imagine that Electricity
is like water
and the wires that we are using to make
the connection are like pipes.
The source of electricity
is essentially
the equivalent of something
that pushes water
into the pipes.
So the first circuit
that we are going to build
is going to
have the source of electricity
pushing the
current through the wires,
a number of wires
that connect to the button.
Then the button
will open and close the circuit
and when the circuit is closed,
the current will flow through the LED.
and then we will use another component
that I have here, called resistor.
What happens is that
the voltage of our battery
is too high
for the LED that we are using.
Just to give you an idea,
we are going to be
using a source of electricity
operating at 5 volts,
which is the standard voltage
at which the Arduino board operates.
But this LED
is only going to need about 1.7 volts.
So how do we make sure
the LED doesn't take
too much current?
Well, we are going to use a resistor.
And this resistor is going to limit
the amount of current
that flows through the LED,
keeping it at the optimum
amount of voltage and current.
How do we make the connection?
Well, actually
what happens with circuits is that
you can take wires,
and you can wrap them around,
and you can create circuits like that.
But that's not very practical.
If you want to do a lot of experimentation,
if you want to move
components around, if you want
to try different kinds of circuits,
wrapping wires around
is not exactly the best idea.
So what are we going to do?
We are going to use these
components that you see here.
This is called breadboard.
The breadboard
essentially provides a set of
prearranged connections,
and each one of the holes
is actually connected underneath
with a metallic spring.
So when I plug a wire
into the breadboard,
the spring will hold on to the wire
and it will connect to
all the other
holes in the same line of holes.
Let's have a look.
For example,
this line of holes
that I am pointing
to,
they are all connected together.
So if I plug this wire in this hole,
all the holes
in the same column
are going to be connected to this wire.
If I take for example this resistor,
and I plug the resistor
in one hole in the same line,
for example here.
This is ok.
So at the moment, the resistor
and the wire are connected together.
If I move this wire
to the hole next to it,
they are not connected anymore
because only the wires
in the same column
are connected together.
So, to explain this concept better,
I have prepared here
a circuit
that contains
all the basic elements that I
told you about.
This is the resistor,
this is the push button,
this is the LED,
and this is a wire.
So what's missing here
is the source of power.
What the circuit needs
in order to operate
is a source of electricity.
In this case
we are going to use
the Arduino board
as a source of electricity.
The Arduino board can be
powered through a battery
or through a USB connection
as you can see in this particular
situation. We are not going to use
the intelligence
provided by the Arduino board.
We are just going to use
the power
that comes
from the Arduino board
in order to learn
how to build the circuit
on the breadboard.
We are going to connect
this wire
to the other leg of the resistor.
You will notice that
actually the holes
on this side of the breadboard,
they have a different pattern.
Why is this?
Because actually
these two lines of
holes follow a different
connection pattern.
The ones
that cover the main area
of the breadboard
as I said, they are all connected
along the column,
while these
lines
are going
all the way
from one end
to the other.
These are two separate
strips
of holes,
and each one of them is connected
together. So, for example, if I plug
this red wire
at the beginning of this line of holes,
I am actually connecting
5 volts
to every single hole
that you can see
on this line here.
This means that this resistor
is now connected to this hole.
Now I am going to take this black wire
and I am going to plug it in
one of these two holes.
They are marked
GND
GND is the ground.
It also represents the
minus on your battery.
If you look at a battery
normally there's a plus and a minus.
So, 5V
represents the plus on this
ideal battery,
and the minus is
here represented by GND.
So, if i connected
the black wire
to the other line
on the breadboard,
now I have connected
5V to the first line of
holes
and the black wire
to the second line
of holes.
Now if everything is done correctly,
if I pressed the button,
I would connect the resistor
to the LED.
This will complete the circuit
and the LED
will light up.
wow.
Ok,
it's working.
Ok, that was good.
So the ability to convert
the electricity
into another physical phenomenon
that we can actually experience
in the real world
makes the LED a transducer.
The transducer is a component,
which is able to convert
electricity into something else.
or
for example
if there were a component
that would convert the light
back into electricity
that would also be a transducer.
In particular
we call the LED
in this particular situation
an actuator
because it takes electricity
and then turns into something that I
can actually see
in the real world. In this case,
I can see light.
Electricity is invisible to me,
but the LED makes
the electricity visible
by turning it into light.
We have our completed circuit
and I would like to make some
modifications now
to introduce some other concepts.
So what we are looking at here
is a very simple circuit,
where
each component is connected
to the next component
in the circuit,
and then the last connection
goes back to GND.
You can imagine the current flowing
from the red wire,
into the circuit through the resistor,
through the
push button, then in this wire,
then through this LED, another wire
back to ground
So, this is how the circuit is closed.
One of the features of the circuit
is that the elements
we say that are connected in series.
Because one component
comes after the other.
And
we can make the circuit
a little bit more complicated,
because at this moment
we have only one button.
So what happens if I
connect to another button?
I can remove this jumper,
and then I am going to add
another push button,
making sure it's connected
with the LED.
So now, when I press these buttons
nothing happens,
because the circuit is still open.
We have to close the circuit
using one of these wires.
So, I will plug the wire here
I will plug the other wire here.
And if everything works out,
I press the button,
and still nothing happens, why?
Because these two buttons are
connected in series,
so they are one after the other.
If I want to operate the circuit,
I need press both buttons
at the same time.
So look at this,
when I press button number one
and button number two
the current is able to
flow through the circuit.
and when I release
one of the buttons,
the circuit is open
and it stops operating
So what we have learned now is that
if we put
buttons in series,
one after the other,
I need to press all of them in order to
close the circuit
and make the electricity flow.
Inside the push button
there are two pieces of metal.
They are separated by a spring.
When you press the button,
these two pieces of metal,
they come in contact.
and they create an electrical connection,
and the electricity can flow through them.
When you release the button,
the spring pushes the two
pieces of metal away
and it interrupts
the circuit. It opens the circuit.
So you will notice that
the push button has got four legs.
At the moment we used only two.
What are the other two legs doing?
Well, actually
they are internally connected
to the first set of the legs.
So the two legs on this side
of the push button are
internally connected together
and the two legs on
this side of the push button
are internally connected together.
This increases
the number of combinations
that you can use when
you create circuits.
So,
what happens if I
take this jumper
that I used to build this circuit.
I can actually mount it
behind the push buttons.
And the circuit still works.
What you will notice is that
this point of the circuit
and this point of the circuit
are exactly the same.
And here this point
and this point are exactly the same.
So, when I press the button
these two points in the circuit
are connected with these
two points in the circuit.
When I release the button,
only these two points are connected
and these two points are
connected individually,
but there's no connection between
the four of them.
This allows me to try to
create another connection
that we call parallel connection.
The idea is that
we can actually place
one button next to the other
and we can create
two different paths
that the current
can use
to actually flow through.
Let's see what happens
if we put these two
push buttons in parallel?
So what I am gonna do, I am going to use
two jumpers.
I am going to connect
one leg of the first
push button with the
same leg on the second push button
and I am going to do the same for the
remaining contacts,
one and two.
What happens here is that
if I press the button
now the LED comes on.
And if I press the other button,
the other LED comes on.
And if I press both of them,
the LEDs come on at the same time.
So,
what's happening here is that
by creating two different paths
for the current to flow through,
I just need to press one
of the two buttons
for the current to reach the LED
and light up.
If you put the buttons in series,
you need to press
one button and the other button
in order to create light.
And
in this particular configuration,
you need to press one button
or the other button
in order to turn on the LED.
So
in a way, this small circuit
is creating a very basic
logic circuit.
One that has an "and" logic,
you need to press one button
and the other in order to light up
the LED. And the second one is an "or" circuit,
you press one button or the other.
That's all for today.
I hope you enjoyed the tutorial.
And remember: build it, hack it, share it,
because Arduino is you!