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Subido el 15 de octubre de 2018 por Isabel L.

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Although we have already studied some electronic devices and some electronic elements, there are the inputs, such as, for example, potentiometer and so on. 00:00:02
We just only have two outputs which are diode and servo motor. The diode is like a bulb, it emits light, but just only when you connect correctly. 00:00:23
Otherwise, it doesn't work. 00:00:49
So, we are going to study the diode. 00:01:02
Firstly, we are going to study the semiconductor materials and in my explanation you can understand 00:01:06
what is a extrinsic semiconductor, what is a diode, its characteristics and its work point. 00:01:33
We are going to talk about some types of diodes and the application of the others. 00:01:45
Well, what is an intrinsic semiconductor? 00:01:53
Semiconductors are material or substance that they are in the nature and they can be conductor 00:02:04
insulators depending on the circumstances. One example of this kind of 00:02:17
substances could be silicon. Silicon has four electrons in the atom 00:02:28
constitution. So to link with other silicon atoms it usually share one 00:02:43
electron with each silicon neighbor as you can see in this picture. So if you 00:02:55
heat or if there is a very energetic life or other kind of energy, it is possible that 00:03:06
one of these links can be broken by energy. 00:03:18
So some electrons are free now and they can move the same way as electrons move in metals. 00:03:27
So it's a conductor substance. 00:03:45
Apart from this, the positive charges is created by holes in the net of silicon. 00:03:50
So not also the electrons can move, but holes can move also. 00:04:02
So there are two types of conduction in this material now. 00:04:16
One by negative churches, electrons, and another one by holes or positive churches. 00:04:24
This can be also explained using the band theory. 00:04:37
In the band theory, the semiconductors are systems with a gap between the conductor band 00:04:45
and the, between balance bands and conduction bands, there is a very small gap. 00:04:53
So it's very easy that the electrons can jump from the balance band to conduction band. 00:05:04
then the material is a conductor material and as as the way as the same way is conductor because 00:05:14
there are holes there are positive churches and there are also negative churches both of them can 00:05:23
move in the in the silicon net but we can we can do this by by replacing a 00:05:31
atom of silicon in the net of silicon by replacing this atom for example if you 00:05:46
replace an silicon atom with a boron atom, boron has one electron less, so it 00:05:57
creates, each boron atom can create a hole in the silicon net and this 00:06:12
substance is a conductor system because the holes can move in the 00:06:20
in the net. On the other hand if you put an atom which has more electrons than 00:06:30
for example an antimonium-1, electrons can move in the net and this is a 00:06:44
semi extrinsic semiconductor type N. Here could be what happens if I have one 00:06:53
part with a p semiconductor and another one with n semiconductors obviously they 00:07:10
tend to return to a combine and eliminate the holes and electrical extra 00:07:26
So there is a current, there is an intrinsic current in this type of device, which is usually called diode. This is a diode loop. 00:07:36
And if you put an external current, obviously, if you connect in the same way, this current can be strengthened. 00:07:52
On the other hand, if you want a current in opposite direction, that only can be possible 00:08:12
if you are if your current is bigger than the intrinsical current and this effect can be drawn 00:08:37
and it's the what's usually called characteristic of a diode the shape of the characteristic is 00:08:47
well it's the same for all of the diodes but the values of this depends on the 00:08:57
type of of the diode depends how many holes and how many electrons it has so 00:09:06
it's a difference however there's always a more or less a saturated zone which is 00:09:19
more or less 0.3 to germanium or 0.37 to silicon which is the 00:09:32
the maximum volta, the saturator of volta. I built a circuit in which there is a diode, 00:09:46
as you can see in this slide. Firstly, you need, obviously, resistance and using the Ohm's law, 00:10:03
So it's very easy to know or to have a relationship between the voltage in the diode and its current. 00:10:17
So you can draw this relationship in the characteristic cube and there is a point which is a junction between two mathematical functions. 00:10:32
This point is usually called working point and it shows the best conditions in which this diode can work. It's current and it's voltage. 00:10:54
and is a characteristic and it's very important to design a circuit with diodes. 00:11:13
There are various types of diodes, obviously, but this is the symbol of a normal diode 00:11:21
and you should connect the positive with the positive and the negative with the negative. 00:11:34
But we can also have lead, which emits light, which is bright. And another which is important also is zener, which you can use connecting with inverse polarity. 00:11:41
The normal diode is usually used in electronics to do rectificators, for example, or it is 00:12:03
also used to show if it has a current, or nowadays it is also used to give light because 00:12:16
is very very cheap and is very environmental friendly uh and so on to do a circuit using a 00:12:29
diode LED you should use 220 ohms resistance and it's really easy to do 00:12:45
that and obviously you you should do in a protoboard we will use diode with the 00:13:02
Arduino board so we will study better 00:13:15
this kind of circuits. It is all for today 00:13:20
Idioma/s:
en
Autor/es:
ISABEL LAFUENTE
Subido por:
Isabel L.
Licencia:
Reconocimiento - No comercial
Visualizaciones:
70
Fecha:
15 de octubre de 2018 - 20:56
Visibilidad:
Público
Centro:
IES JAIME FERRAN
Duración:
13′ 30″
Relación de aspecto:
1.78:1
Resolución:
1920x1080 píxeles
Tamaño:
216.96 MBytes

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