The first circuit we will do contains an LED and we will make this LED blink.
Okay.
And to make an LED blink, we will need an LED.
Some wires, but also one resistor.
The resistor is here to lower the amount of current that goes through the LED.
And it's also helping to protect the Gpio so they don't get burnt with too much current.
And for this course we will use one kilo ohm resistors.
It's a very standard value.
And I'm not going to give much details about this value.
But if you want to know more about that you can also find many resources on the internet.
So now that you know what resistor we want to use, then how to know which resistor to pick from the
resistor set that you have.
So maybe the resistors are correctly set per value in the kit you have.
But if it's not the case you will have to read the value from the color.
And here is a table to help you find the value of the resistor with the colors on the resistor.
Usually you will have either four bands or five bands.
Resistor.
And here the first band, the second band and optionally the third band corresponds to a number, the
next one corresponds to a multiplier.
And finally, the last band is for the tolerance or the precision of the resistor.
And for what we will do in this course.
You don't really need to worry about the tolerance.
Okay.
Any value will do.
Usually you will have here plus or -5% or plus -10%.
Here we don't really need to care about the precise value for the resistors.
And here's the example.
With the resistor we're going to use the one kilo ohm resistor.
If you have a four band resistor.
So that's the one on the top here.
You see that the first two bands are going to represent a number.
So here one zero that's ten.
And the third band is going to be here the multiplier.
So to get 1000 you need to multiply ten by 100.
So that's why you have brown black and red.
And then you have the tolerance which can be any color.
It doesn't matter if you have a five band resistor like the one I would show you just in a minute.
Then we will have one zero and zero.
So brown, black and black, those are the first, second and third bands.
And then the multiplier is going to be only ten okay.
Because we multiply 100 by ten to have 1000.
So in this case you have brown black black and brown.
Plus the tolerance.
Okay.
And if you are confused about, well, what side to read the register from, usually all the colors
are you can see closed.
So you have one bin here at each extremity.
But most of the bins will be close to that first value here.
So where you have more space here it corresponds to the tolerance.
So that's how you can correctly read the value.
So here is the resistor that I'm going to be using.
Okay.
So you can see I can read it.
Uh here there is uh so I have five bins I have brown black black brown and then another color for the
tolerance that I don't really care about.
Okay.
So if you can see here that's the resistance I'm going to use.
If you have a five band resistor it should look like this.
And then if you have a four band well you just have brown, black and red coming back to the color code
here.
If you don't have one kilo ohm, don't worry too much.
You can also use 330 or 470 ohm resistors.
So I'm giving those values because they are very common values as well.
And if you have 330, for example, you can see that we first need three and three.
So the first two bands should be orange.
Okay.
And then depends on if it's a four band or five band.
The rest is going to be different.
But you should start with orange and orange.
And if you have a 470 ohm, the first two numbers are four and seven.
So the first two bands should be yellow and violet.
Here.
Purple.
All right.
So that's how you can find a resistor's value.
It's quite easy.
Once you done this once or twice.
It's very easy to find.
And I would just recommend one thing is not going below 330 ohm for the LEDs.
Okay.
One kilo ohm is in fact a pretty high value for an LED with the Raspberry Pi, but it's a nice value
if you want to connect many LEDs, so the total current consumption will not be too high and will not
go beyond the Raspberry Pi's limit, which is 50 milliamp.
So to connect components such as LEDs, the higher the resistor's value, the less current you will
take, and thus you can plug more LEDs and components to your circuit while keeping it safe.
And now that you know which resistor to use, let's build that first circuit with an LED.