Transistor Explicado - Cómo Funcionan los Transistores

Summary

Este video ofrece una visión detallada del transistor, uno de los dispositivos electrónicos más importantes jamás inventados. Se explica que los transistores, disponibles en formas y tamaños variados y principalmente de dos tipos (bipolares y de efecto de campo), actúan como interruptores y amplificadores de señales en circuitos electrónicos. Los transistores de bajo poder están protegidos en una carcasa de resina, mientras que los de alta potencia requieren de una carcasa parcialmente metálica para disipar el calor generado. Seguidamente, se describe la estructura de un transistor, con sus tres pines principales: emisor, base y colector. A través de ejemplos prácticos, se demuestra cómo un transistor puede controlar una luz con una pequeña señal en la base, amplificando así una señal más grande en el circuito principal. Además, se explora la diferencia entre los transistores NPN y PNP, y cómo funcionan internamente, utilizando la analogía del flujo de agua y la explicación de los electrones y la dopación en semiconductores. Finalmente, se ofrecen recursos para continuar el aprendizaje en ingeniería electrónica y se invita a seguir las redes sociales de la plataforma.

Takeaways

• 📡 Los transistores son dispositivos electrónicos cruciales, venidos en muchas formas y tamaños, y se dividen principalmente en dos tipos: bipolares y de efecto de campo.
• 🔩 Los transistores tienen dos funciones principales: actuar como interruptor para controlar circuitos y amplificar señales.
• 🌡 Para disipar el calor generado en transistores de alta potencia, se utilizan carcasa parcialmente metálica y se suelen adjuntar a disipadores de calor.
• 🔍 Los transistores tienen tres pines etiquetados E (emisor), B (base) y C (colector), cuya configuración puede variar según el modelo.
• 🤖 Los transistores se pueden controlar con una pequeña señal en la base para permitir el flujo de corrientes más grandes en el circuito principal.
• 📶 Un pequeño cambio en la tensión en la base del transistor puede causar un gran cambio en el circuito principal, actuando como amplificador.
• 📈 El ganancia de corriente, representada por el símbolo beta, es la relación entre la corriente del colector y la de la base, y se encuentra en la hoja de datos del fabricante.
• 🔋 Existen dos tipos principales de transistores bipolares: NPN y PNP, que difieren en la dirección del flujo de corrientes y la conexión a la batería.
• 🔵🔴 Los diagramas eléctricos representan transistores con símbolos donde la flecha señala en la dirección del corriente convencional, indicando cómo conectarlos en los circuitos.
• ⚙️ La función de un transistor se puede entender comparándola con el flujo de agua a través de una tubería controlado por una compuerta.
• ⚛️ Los electrones son los portadores de la electricidad en los conductores, y su flujo se designa como corriente convencional desde el polo positivo hacia el negativo.
• 💠 Los semiconductores, como el silicio, se pueden doplar para cambiar sus propiedades eléctricas y formar la unión PN para crear transistores.

Q & A

¿Qué es un transistor y cuáles son sus dos principales funciones?

Un transistor es un componente electrónico pequeño que puede actuar como un interruptor para controlar circuitos y también amplificar señales.

¿Cuáles son los dos tipos principales de transistores?

Los dos tipos principales de transistores son el bipolar y el de efecto de campo (field effect).

¿Por qué se utilizan disipadores de calor en los transistores de alta potencia?

Los disipadores de calor se utilizan para ayudar a eliminar el calor generado por los transistores de alta potencia, lo que previene el daño a los componentes a lo largo del tiempo.

¿Cómo se identifican las pines de un transistor?

Las tres pines de un transistor están etiquetados como E (emisor), B (base) y C (colector). En los tipos de transistor con cuerpo de resina, el borde plano indica el emisor a la izquierda, la base en el medio y el colector a la derecha.

¿Cómo funciona un transistor como interruptor?

Un transistor bloquea el flujo de corriente cuando no se proporciona voltaje a la base. Al proporcionar una pequeña cantidad de voltaje a la base, el transistor comienza a permitir que el flujo de corriente pase por el circuito principal, encendiendo así una luz o activando un dispositivo.

¿Cuál es la relación entre la corriente en la base y la corriente en el colector, y cómo se conoce?

La relación entre la corriente en la base y la corriente en el colector se conoce como la ganancia de corriente y se representa con el símbolo beta. Esta relación se puede encontrar en la hoja de datos del fabricante.

¿Cuáles son las dos variedades principales de transistores bipolares y cómo se diferencian?

Las dos variedades principales de transistores bipolares son el NPN y el PNP. A pesar de que visualmente pueden ser muy similares, se diferencian verificando el número de parte para determinar su configuración y polaridad.

¿Cómo se representan los transistores en los diagramas eléctricos?

Los transistores se representan en los diagramas eléctricos con símbolos que tienen una flecha que apunta hacia el emisor, lo que indica la dirección de la corriente convencional para saber cómo conectarlos en los circuitos.

¿Cómo funciona un transistor NPN y cómo se diferencia de un transistor PNP?

Un transistor NPN permite que la corriente fluya cuando se aplica voltaje a la base, mientras que en un transistor PNP, la corriente fluye hacia afuera de la base y regresa a la batería. La corriente en un transistor NPN se combina, mientras que en un transistor PNP, la corriente se divide.

¿Cómo se forma la unión PN (yacente a positivo) en un transistor y qué ocurre en esta?

La unión PN se forma al combinar materiales de semiconductores de tipo N (con exceso de electrones) y tipo P (con falta de electrones). En la región de la unión PN, se crea una zona de despoblación donde se forma una barrera debido a la migración de electrones y huecos, creando un campo eléctrico que impide que más electrones se muevan a través.

¿Cómo afecta la dopación en el funcionamiento de un transistor y cuáles son los tipos de dopación?

La dopación afecta el funcionamiento de un transistor al cambiar las propiedades eléctricas del silicono. Existen dos tipos de dopación: P tipo, donde se agrega un material como el aluminio que tiene electrones insuficientes, creando huecos, y N tipo, donde se agrega un material como el fósforo que tiene electrones adicionales, lo que permite que los electrones sean libres de moverse.

¿Por qué se dice que los electrones fluyen de manera opuesta a la corriente convencional y quién lo demostró?

Se dice que los electrones fluyen de manera opuesta a la corriente convencional porque, a pesar de que en el diseño de circuitos se asume que la corriente fluye desde el polo positivo, en realidad los electrones fluyen desde el polo negativo. Esto fue demostrado por Joseph Thomson, quien realizó experimentos para descubrir el electrón y también probar que fluían en la dirección opuesta.

Outlines

00:00

📡 Introducción a los transistores

Este párrafo introduce los transistores como dispositivos cruciales en la electrónica, distinguiendo entre los tipos bipolares y de efecto de campo, y enfocada en el bipolar. Los transistores son componentes electrónicos que sirven como interruptores y amplificadores de señales. Se describen las características de los transistores de bajo y alto poder, así como su protección contra el calor. Se menciona la importancia de la hoja de datos del fabricante para conocer las especificaciones de voltaje y corriente de cada transistor. Finalmente, se explica la función de los pines emisores, base y colector, y cómo el transistor puede ser utilizado para automatizar el control de circuitos.

05:02

🔌 Funcionamiento y tipos de transistores

Se profundiza en el funcionamiento de los transistores como interruptores y amplificadores. Se describe cómo un transistor controlado por una pequeña señal de voltaje en la base puede regular una corriente más grande en el circuito principal. Se exploran los tipos de transistores NPN y PNP, comparando cómo fluye la corriente en ambos y cómo se representan en diagramas eléctricos. Se utiliza una analogía del flujo de agua para explicar cómo un transistor puede controlar la cantidad de corriente que fluye a través de él. Además, se discute la corriente convencional versus el flujo de electrones en los circuitos electrónicos.

10:06

⚛️ Electrones y semiconductores en transistores

Este párrafo examina la conductividad de los materiales desde el punto de vista del flujo de electrones. Se describe la estructura atómica de un conductor y cómo los electrones se comportan en los diferentes shell orbitales. Se compara a los conductores con los aislantes y se introduce el concepto de semiconductor, como el silicio, que puede actuar tanto como conductor como aislante. Se explica el proceso de doping para crear materiales P y N, y cómo estas sustancias se combinan para formar un transistor. Se discute cómo la unión de estos materiales crea una región de despoblación en la junción PN, que actúa como una barrera para el flujo de electrones.

15:07

🔄 Biasing y operación del transistor

Se explica cómo el biasing, es decir, la aplicación de voltaje en un transistor, afecta su funcionamiento. Se describe el efecto de conectar una fuente de voltaje en un transistor NPN y cómo esto puede causar un sesgo hacia adelante o hacia atrás, permitiendo o impidiendo el flujo de corriente. Se discute cómo el transistor puede ser completamente abierto con una alta voltaje en la base, lo que permite un mayor flujo de corriente y electrones. Finalmente, se invita al espectador a continuar aprendiendo sobre ingeniería electrónica a través de otros videos y se promueven las redes sociales y el sitio web del canal.

Keywords

💡Transistor

Un transistor es un componente electrónico pequeño pero crucial, que puede funcionar como un interruptor para controlar circuitos y también amplificar señales. En el vídeo, se explica cómo un transistor puede controlar la iluminación de una bombilla con una corriente de 1.2A y cómo su funcionamiento es fundamental en la automatización de controles eléctricos.

💡Bipolar y Field Effect

Existen dos tipos principales de transistores: bipolar y efecto de campo (field effect). El vídeo se enfoca principalmente en el transistor bipolar, que es el que permite el control y la amplificación de señales en los circuitos electrónicos.

💡Interruptor

Un interruptor es un dispositivo que permite o interrumpe el flujo de corriente en un circuito. En el contexto del vídeo, se utiliza un transistor como un interruptor para controlar la luz de una bombilla, mostrando cómo se puede automatizar el proceso.

💡Amplificador

Un amplificador es un dispositivo que aumenta la amplitud de una señal, lo que permite controlar una corriente o voltaje más grande con una señal o corriente más pequeña. El vídeo demuestra cómo un transistor puede actuar como un amplificador al controlar la brillantez de un LED con una señal de voltaje en su pin base.

💡Disipación de calor

La disipación de calor es esencial en los transistores de alta potencia para evitar que los componentes se dañen debido al exceso de temperatura. El vídeo menciona el uso de carcasa de metal y disipadores de calor para ayudar a eliminar el calor no deseado generado por los transistores.

💡Datasheet

Un datasheet es un documento que proporciona información técnica detallada sobre un componente electrónico, incluida su capacidad para manejar voltaje y corriente. En el vídeo, se resalta la importancia de consultar el datasheet del fabricante para entender las especificaciones y límites de un transistor.

💡Pines E, B y C

Los pines E, B y C en un transistor representan al emisor, la base y el colector, respectivamente. Estos pines son cruciales para la conexión y el funcionamiento del transistor en un circuito, como se describe en el vídeo al explicar cómo se conectan estos pines en un transistor de cuerpo de resina.

💡NPN y PNP

Los transistores bipolares vienen en dos configuraciones principales: NPN y PNP. Aunque visualmente son similares, funcionan de manera diferente y requieren de distinta conexión en un circuito. El vídeo ofrece una comparación detallada de cómo fluye la corriente en cada tipo de transistor.

💡Gana de corriente

El gana de corriente, representado por el símbolo beta, es la relación entre la corriente en el colector y la corriente en la base de un transistor. El vídeo utiliza un ejemplo para ilustrar cómo se calcula el gana y su importancia en la amplificación de señales.

💡Dopado

El dopado es el proceso de añadir un material a un semiconductor para cambiar sus propiedades eléctricas, creando así material P tipo (con exceso de electrones) o N tipo (con huecos o falta de electrones). Este concepto es fundamental para el funcionamiento de los transistores, como se explica en el vídeo al describir la creación de la unión PN.

💡Unión PN

Una unión PN es una juntura entre un material de semiconductor P tipo y otro de N tipo. Esta juntura crea una barrera que impide el flujo de electrones, pero puede ser controlada con una señal adecuada, lo que es esencial para el funcionamiento del transistor como interruptor o amplificador, como se describe en el vídeo.

Highlights

Transistors are one of the most important devices ever invented, crucial for modern electronics.

Transistors come in two main types: bipolar and field effect, with a focus on bipolar in this video.

They serve as switches to control circuits and can also amplify signals.

Transistors have three pins labeled E (emitter), B (base), and C (collector).

Resin body transistors for low power applications do not require a heat sink.

Metal body transistors for higher power applications are attached to heat sinks to dissipate heat.

Each transistor has a part number for referencing the manufacturer's datasheet.

Transistors are rated for specific voltage and current, essential to check before use.

A small voltage applied to the base pin can control a larger current in the main circuit.

Transistors can act as amplifiers by amplifying signals input to the base pin.

The current gain, symbolized by beta, is the ratio of collector current to base current.

NPN and PNP transistors have different configurations and current flow directions.

Transistors are represented with symbols on electrical diagrams, with the arrow on the emitter indicating conventional current direction.

The working principle of a transistor is analogous to controlling water flow with a gate.

Conventional current flow is used for circuit design, despite electrons actually flowing in the opposite direction.

Electrons flow easily in conductive materials due to the overlap of valence and conduction bands.

Semiconductors like silicon can act as both insulators and conductors based on doping and energy provided.

Doping silicon with specific materials forms P type and N type layers, essential for transistor operation.

PN junctions create a depletion region that acts as a barrier to electron flow without sufficient voltage.

Forward and reverse biases affect how electrons and holes move at the junction, controlling the transistor's state.

The operation of a transistor involves the movement of electrons and the application of external voltages to control current flow.

Transcripts

This is a transistor

It is one of the most important devices ever

to be invented.

So, we're going to learn how they work in detail in this video.

What is a transistor?

Transistors come in many shapes and sizes.

There are two main types, the bipolar and the field effect.

We're going to mostly focus on the bipolar version in this video.

Transistors are small electronic components with two main functions.

It can act as a switch to control circuits

and they can also amplify signals.

Small low power transistors are enclosed

in a racing case to help protect the internal parts.

But higher power transistors will have a partly metal case, which is used to help

remove the heat which is generated as this will damage the components over time.

We usually find these metal body transistors

attached to a heat sink, which helps remove the unwanted heat.

For example, inside this DC Bench power supply

We have some mosfet transistors which are attached to very large heat sinks.

Without the heat sink

the components quickly reach 45 degrees Celsius or 113 degrees Fahrenheit.

With a current of just 1.2A.

They will become much hotter as the current increases.

But for electronic circuits with small currents, we can just use these resin body transistors

which do not require a heat sink.

On the body of the transistor.

We find some text.

This will tell us the part number which we

can use to find the manufacturers datasheet.

Each transistor is rated to handle

a certain voltage and current, so it is important to check these sheets.

Now with the transistor we have three pins labelled E, B and C.

This stands for the emitter, the base and the collector.

Typically with these resin body type TRANSISTORS

with a flat edge,

the left pane is the emitter,

the middle is the base, and the right side is the collector.

However, not all transistors use this configuration.

So do check the manufacturers datasheet.

We know that if we connect a light bulb to a battery, it will illuminate.

We can install a switch into the circuit

and control the light by interrupting the power supply.

But this requires a human to manually control the switch.

So how can we automate this?

For that, we use a transistor.

This transistor is blocking the flow of current.

So the light is off.

But if we provide a small voltage to the base pane in the middle,

it causes the transistor to start allowing current to flow in the main circuit.

So the light turns on.

We can then place a switch on the controlling pin to operate it remotely

or we can place a sensor on this to automate the control.

Typically, we need to apply at least 0.6V

to 0.7 volts to the base pin for the transistor to turn on.

For example, this simple transistor circuit

has a red LED and a nine volt power supply across the main circuit.

The base pin is connected to the DC Bench power supply

The circuit diagram looks like this.

When the supply voltage to the base pin is

0.5V the transistor is off.

So the LED is also off

at 0.6V the transistor is on, but not fully.

The LED is dim because the transistor is not yet letting the full current flow

through the main circuit.

Then at 0.7V the lead is brighter because the transistor is letting almost the full current through.

At 0.8V, the LED is at full brightness.

The transistor is fully open.

So what's happening is we're using a small

voltage and current to control a larger voltage and current.

We saw that a small change to the voltage on the base pin

causes a large change on the main circuit.

Therefore, if we input a signal to the base pin,

the transistor acts as an amplifier.

We could connect a microphone which varies

the voltage signal on the base pin, and this will amplify a speaker in the main circuit

to form a very basic amplifier.

Typically, there is a very small current on the base pin,

perhaps just 1mA or even less.

The collector has a much higher current, for example, 100mA.

The ratio between these two is known as the current gain and uses the symbol beta

We can find the ratio in the manufacturers datasheet.

In this example, the collector current is 100mA

and the base current is 1mA.

So the ratio is 100mA divided by 1mA, which gives us 100.

We can also rearranges formula to find the currents also.

NPN and PNP transistors

We have two main types of bipolar transistors,

the NPN and the PNP type, the two transistors look nearly identical.

So we need to check the part number to tell which is which.

With an NPN transistor.

We have the main circuit and the control circuit.

Both are connected to the positive of the battery.

The main circuit is off until we press the switch on the control circuit.

We can see the current is flowing through both wires to the transistor.

We can remove the main circuit and the control circuit lED

will still turn on when the switch is pressed

as the current is returning to the battery through the transistor.

In this simplified example,

when this switch is pressed, there are 5mA flowing into the base pin.

There are 20mA flowing into the collector pin

and 25mA flowing out of the emitter.

The current therefore combines in this transistor

With a PNP transistor.

We again have the main circuit and the control circuit,

but now the emitter is connected to the positive of the battery.

The main circuit is off until we press the switch on the control circuit.

We can see with this type that some of the current flows out of the base pin and returns to the battery.

The rest of the current flows through

the transistor and through the main led and then back to the battery.

If we remove the main circuit, the control circuit, LED will still turn on.

In this example, when the switch is pressed,

there are 25mA flowing into the emitter,

20mA flowing out of the collector and 5mA flowing out of the base.

The current, therefore, divides in this transistor

I'll place these side by side so you can see how they compare.

Transistors are shown on electrical drawings

with symbols like these, the arrow is placed on the emitter.

The arrow points in the direction

of conventional current so that we know how to connect them into our circuits.

How does a transistor work

To understand how a transistor works,

I want you to first imagine water flowing through a pipe.

It flows freely through the pipe until we block it with a disc.

Now, if we connect a smaller pipe into the main one and place a swing gate

within this small pipe, we can move the disc using a pulley.

The further the swing gate opens,

the more water is allowed to flow in the main pipe.

The swing gate is a little heavy,

so a small amount of water won't be enough to open it.

A certain amount of water is required to force the gate to open.

The more water we have flowing in this small pipe,

the further the valve opens and allows

more and more water to flow in the main pipe.

This is essentially how an NPN transistor works.

You might already know that when we design electronic circuits,

we use conventional current.

So in this NPN transistor circuit,

we assume that the current is flowing from the batteries positive

into both the collector and the base pin and then out of the emitter pin.

We always use this direction to design our circuits.

However, that's not what's actually occurring.

In reality, the electrons are flowing

from the negative to the positive of the battery.

This was proved by Joseph Thompson, who carried out some experiments

to discover the electron and also prove they flowed in the opposite direction.

So in reality,

electrons flow from the negative into the emitter and then out

of the collector and the base pin. We call this electron flow.

I'll place the side by side so you can see the difference in the two theories.

Remember, we always design circuits using the conventional current method.

But scientists and engineers know that electron flow is how it actually works

by the way, we have also covered how

a battery works in detail in our previous video.

Do you check that out

links can be found in the video description down below.

OK, so we know that electricity is the flow of electrons through a wire.

The copper wire is the conductor and the rubber is the insulator.

Electrons can flow easily through

the copper, but they can't flow through the rubber insulator.

If we look at this basic model of an atom

of a metal conductor, we have the nucleus at the centre and this

is surrounded by a number of orbital shells which hold the electrons.

Each shell holds a maximum number

of electrons, and an electron needs to have a certain

amount of energy to be accepted into each shell.

The electrons located furthest away from the nucleus hold the most energy.

The outermost shell is known as the valence shell.

A conductor has between one and three electrons in its valence shell.

The electrons are held in place by the nucleus,

but there is another shell known as the conduction band.

If an electron can reach this, then it can break free from the atom

and move to other atoms. With a metal atom such as copper.

The valence shell and the conduction band overlap,

so it's very easy for the electrons to move

with an insulator the outermost shell is packed.

There's very little to no room for an electron to join.

The nucleus has a tight grip

on the electrons and the conduction band is far away.

So the electrons can't reach this to escape.

Therefore, electricity cannot flow through this material.

However, there's another material known as a semiconductor.

Silicon is an example of a semiconductor.

With this material,

there's one too many electrons in the valence shell for it to be a conductor.

So it acts as an insulator.

But as the conduction band is quite close,

if we provide some external energy, some electrons will gain enough energy

to make the jump into the conduction band and become free.

Therefore, this material can act as both an insulator and a conductor.

Pure silicon has almost no free electrons.

So what engineers do is dope the silicon

with a small amount of another material which changes its electrical properties.

We call this P type and N type doping.

We combine these materials to form the PN junction.

We can sandwich these together to form an NPN or PNP transistor.

Inside the transistor we have

the collector pin and the emitter pin

between these in an NPN transistor,

we have two layers of N type material and one layer of P type.

The base wire is connected to the P type layer

in a PNP transistor this is just configured the opposite way.

The entire thing is enclosed in a resin to protect the internal materials.

Let's imagine the silicon hasn't been doped yet,

so it's just pure silicon inside.

Each silicon atom is surrounded by four other silicon atoms.

Each atom wants eight electrons in its valence shell

but the silicon atoms only have four electrons in their valence shell,

so they sneakily share an electron

with their neighbouring atom to get the 8 desire.

This is known as covalent bonding.

When we add the N type material such as phosphorus,

it will take the position of some of the silicon atoms.

The phosphorus atoms have five electrons in their valence shell.

So as the silicon atoms are sharing electrons to get their desired eight,

they don't need this extra one, which means there's now extra electrons

in the material and these are free to move around

with P type doping we add in a material such as aluminium.

This atom has only three electrons in this valence shell.

It therefore can't provide its four neighbours with an electron to share.

So one of them will have to go without.

This means a hole has been created where an electron can sit and occupy.

We now have two doped pieces of silicon,

one with too many electrons and one we not enough electrons.

The two materials join to form a PN junction.

At this junction we get what's known as a depletion region

in this region some of the excess electrons

from the N side will move over to occupy the holes in the P side.

This migration will form a barrier

with a build up of electrons and holes on opposite sides.

The electrons are negatively charged and the holes are therefore considered positively charged,

so this Build-Up causes a slightly negatively charged region

and a slightly positively charged region.

This creates an electric field

and prevents more electrons from moving across.

The potential difference across this region is typically around 0.7V

when we connect a voltage source across the two ends

with the positive connected to the P type material.

This will create a forward bias and the electrons will begin to flow.

The voltage source has to be greater than the 0.7V barrier.

Otherwise, electrons cannot make the jump

when we reverse the power supply so that the positive is connected to the N type material.

The electrons held in the barrier will be pulled back towards the positive terminal

and the holes will be pulled back towards the negative terminal.

This has caused a reverse bias

in a NPN transistor.

We have two layers of N type material, so we have two junctions and therefore two barriers,

so no current can flow through it ordinarily.

The emitter N type material is heavily doped,

so there are a lot of excess electrons here.

The base P type is lightly doped, so there are a few holes here.

The collector N type is moderately doped,

so there are a few excess electrons here.

If we connect a battery across the base and the emitter with the positive

connected to the P type layer,

this will create a forward bias.

The forward bias causes the barrier to collapse

as long as the voltage is at least 0.7V.

So the barrier diminishes

and the electrons rush across to fill the space within the P type material.

Some of these electrons will occupy a hole

and they will be pulled towards the positive terminal of the battery.

The P type layer is thin

and was lightly doped on purpose so that there is a low chance of electrons falling into a hole.

The rest will remain free to move around the material.

Therefore, only a small current will flow

out of the base pin, leaving an excess of electrons in the pitot material

if we then connect another battery between the emitter and the collector

with the positive connected to the collector,

the negatively charged electrons within the collector

will be drawn to the positive terminal, which causes a reverse bias.

If you remember, with the reverse bias, the electrons and holes of the barrier are

pulled back across, so the electrons on the P type side

of the barrier are pulled across to the N type side

and the holes on the N type side are pulled back to the P type side.

They are already an excess number of electrons in the P type material.

So they will move to occupy these holes and some of them will be pulled across

because the voltage of this battery is greater.

So the attraction is much higher.

As these electrons are pulled across, they flow into the battery.

So a current develops across the reverse bias junction.

A higher voltage on the base pin fully opens the transistor,

which means more current and more electrons moving into the P type layer.

Therefore, more electrons are pulled across the reverse bias.

We also see more electrons flowing

in the emitter side of the transistor compared to the collector side.

OK, that's it for this video,

but to continue learning about electronics engineering, click on one of the videos

on screen now and I'll catch you there for the next lesson.

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