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That I would have assumed that conductor phenomena there would be a performance with AC and DC commands

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will be discussed.

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Dire times basic led and Xena.

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This is the basic symbol of the road.

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Uh.

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That line indicates that this is the cathode.

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And this is the unbound that is a device that allows current to flow in only one direction.

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There are specialized diodes the light emitting diode under the order that will be discussed later.

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However the basic principle is the same here.

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The current will flow in one direction.

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If current flows flow attempt in the opposite direction the flow will be blocked diode finds.

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Find use and money electronic circuits nowadays.

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Um.

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Now let's see the diode the semiconductor phenomena electrons in a metal frame form a sea of electrons

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that are pitifully free to move about semiconductor materials like silicon and germanium have fuel free

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electrons impurities added to semiconductor material can either add the free electrons or create an

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absence of electrons which has holes.

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So if we looked at this uh small schematic This is the UN type and this is the B type which which has

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holes and type are electrons as you can see here they are equivalent columns excellence and holes.

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This is the castle this.

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This is the anode and this fundamental is that the depletion vision of the junction of the dialogue.

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Consider the part of silicon at the right one side of the bar is daubed with negative material excess

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electrons the cathode while the other side is daubed with a positive material existence all the anode

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in between is a no man's land called the B and junction.

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This is the depletion and the depletion is in this is that the injunction that forms are diode.

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Now if we're locked here consider now applying negative voltage to that anode and I was the voltage

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to the castle.

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If we did that that is reversed reverse bias.

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Meaning no current will flow and this region will be our much wider which means that the four electrons

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will pass or more electrons at all.

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This is the reverse bias of the diode y in this manner.

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If we conducted a negative portion of four electron concerning our buying a positive for the note and

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negative vote to take I thought that it is followed by us meaning current will flow.

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Since this area is minimized and the electrons applied here allow these electrons to go to that junction

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and the positive law applied here allows Hall to go to this side.

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This will make that area that depletion area as small as possible which will allow current to flow.

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Now if we look at this circuit setup the circuit illustrated on the Pluto brick ball as a store diode

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and a battery and sure to note the cathode banded end of the diode the cathode is connected that it

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is to use a 330 armed to the store that is the store and the circuit is our current limiting resistor.

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So we are using it to limit current so that it won't blow the diode now set up the circuit illustrated

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and the prototype.

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And sure to know the cathode the Comfort is now connected the battery negative terminal and unless connected

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there is a store and examined the difference between these two circuits um billed as there is a circuit

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much of the voltage drop across the day that is forewarned by us it will equal Boyne 7 which is the

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amount of all that is required to build uh a fourth wall by US situation for the diode.

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This is the simplest model to say this.

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Now if AC is applied to a diode during one half of the cycle that is followed by us and current flows

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during the other half of the cycle that diode is reversed by us and stops come.

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This is the process of rectification allowing current to flow and only one direction.

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It's commonly used in changing AC into DC.

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As you can see here this is the AC signal and this is the output that I wrote.

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It only allows um AC to flow as you can see the positive portion of the signal on the floor.

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The negative is zero since it's reversed biased for the diode.

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Uh this is commonly used in the rectification circuit for turning AC signals to DC signals.

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Now let's look at the light emitting diode in normal diodes when electrons combines with holes heat

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is produced while some material when electrons combine with holes photons of light are emitted LEDs

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are generally used and as indicators throw they have the same realities as a regular diode but instead

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state of dissipating here they are submitting light.

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This is a simple circuit that can light lightly build at a certain circuit on the brutal board the longer

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let lead is the anode and the diode you will see two leads a long one and a short one long is the positive

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and the short is the negative the reverse the lid and observe what other now you need to reverse that

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led and observe what will happen.

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You'll note that 20 alone the current limiting it is a storm not only limits the current but also controls

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lid brightness.

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So if we place the 7000 on uh resistor the light will be damned if we placed 100 under this too.

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The light will be uh that it would be brighter.

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Next we will look at Xena of the old okay.

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This is the symbol of the Xena of the eurozone diode is designed through appropriate the dubbing so

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that it can conduct an ability to mind the reverse voltage so the difference between it and normal doubt

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is that it does operate in the reverse direction that it begins to conduct and then maintains that the

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to mind voltage that over voltage and associated current must be dissipated by the diode as heat.

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As you know that is constructed so that it will conduct one reversed by us above certain voltage.

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The Axis voltage and current dean is conducted to ground and the energy is dissipated as heat as you

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know acts as a symbol voltage regulator.

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In the case involved source as you can see here is bus throw count limiting resistance to drop the voltage

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somewhat.

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To take the brush out of the scene.

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If the xenon was not in place the amount of voltage drop across that of the store would depend on the

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amount of carbon being down from the circuit.

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With this as it was you know in place the four point seven Volt would be maintained by the xenon acting

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as a bath for the excess.

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Come on that is not being drawn off of this excess current has to be dissipated as here.

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Therefore there are current limits on the and others that the designer need to consider.

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That's it for uh diodes.

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Next we will uh discuss transistors and more details.

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Thanks for watching.

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This is education engineering team.