The store today will thus discussed transistor Uh and how they work.
An inside look.
Then we'll talk about basic types and beyond and B and B then we will see basic transistors circuits
switch and amplifier.
This is the transistor symbol as you can see here.
And this is the internal structure of the transistor consists of collector base emitter collector based
emitter to diodes throw you cannot make a transistor simply by putting two days together back to back.
It is useful to look at the transistor as made up of diodes to better understand what is happening inside.
Now let's see this symbol transistor illustration.
Take a look at this representation of the inner workings of IBM and be transistor Close inspection reveals
that there are two diodes with their B balls CONNECTED TOGETHER.
THIS TO BE BORN THE beyond junction is represented by the Nano but black line in an actual transistor.
The B material would really be just a very narrow strip of material not as represented in this graphic
but this is for making things easier to understand and this circuit of all sorts is applied between
the base and diameter.
As you can see here this is the base and this is diameter.
The Positive voltage the base is negative to the emitter an additional bar source is applied between
the collector and the base.
Then you get the Volt the base.
That was the Volt the collector the base emitter although it is followed by us which remember of course
that they ought to conduct electrons allowing the electrons to move left to right and the holes right
to left
now.
Uh as you can see
something interesting happens in this case through the transistor effect as the electrons from the base
emit of diode go across the B and junction the B layer is so thin and there are so few holes to accept
the electrons that allow the electrons continue to flow.
I and call the base could lift although to start conducting and allowing the current to pass through
the transistors of the collector in effect a small followed by us on the base emitter diode causes the
transistor to turn on and bass can throw that emit up to collect all junction so basically you have
you you can either forward or reverse bias.
A transistor by controlling its base voltage uh you need to follow by us one of the junction to allow
it to flow.
We will see this in more detail once we go next uh in the switch and amplifier circuits.
This is the same circuit but another verse by a small manner.
This space is connected to the negative bone as you can see here.
So I am positive the negative will increase these two areas by selecting areas so no conducting is here
while the previous example
while in the previous example as you can see here uh positive and uh positive is connected to this positive
uh terminal.
So it's followed by us and positive uh halls.
We'll go there and they're uh connected uh with electrons so this area will be reduced.
This answer insulating area and it will conduct RL In the second case the negative and positive born
negative will attract the positive halls which will make this area wider and will allow electrons to
pass.
Now we looked uh that one's a store.
There are two basic types of funds a solid bending of the arrangement of the material B and B and and
B and as you can see here as easy phrase to help remember the appropriate symbol is to look at the arrow
B and B pointing and proudly and B and not pointing in and not be pointing and in B and B pointing and
proudly so this will help you remember the arrow direction and uh identify the transistor depending
on that arrow.
The only operational difference is the source polarity and B I'm not pointing in B and B pointing and
proudly now if we looked here uh the transistor switch during the next two activities you will build
a transistor switch and a transistor amplifier.
They've been out of the 2 and 3 3 9 0 4 transistor as indicated here.
As you can see uh you must purchase it or you can simulate it using brought us the transistors as a
switch with the circuit.
Uh as you can see the circuit uses hook up wire to serve as switches to connect the current to the transistor
based here.
What happens when you first apply bar when the base is left floating not connected.
Now as you can see here we have allowed 300 armed with this total on to the store in the collector to
limit the current flowing through the lid.
Remember when the transistor begins to conduct the bathroom the another sort of very raw resistance
without the current limiting the store too much can will damage the component addition of the 1000 to
the store and the base Circuit also limits.
In this case.
Well the best image updated conducts there is a low resistance path without current limiting the funds
for can be damaged when the circuit is completed.
Nothing should happen because the base emits update of the transistor is not biased.
So the transistor does not conduct.
Now when we call when the base is connected the nine volt the best metal diode is followed by us and
conduct.
This in turn turns on the transistor and current flows through the lid to turn it on.
You should know that that it goes off when the base voltage is removed.
Now a full lock.
Uh.
And replace the hook up wire connection with connection to our one point five volt battery as.
What happens when blast one point five volts is applied to the base.
What happens when the battery is reversed and one point five volt is applied to the base.
Examine this on your brought aboard or test bench.
Then get back to this video to see that is on when the voltage is positive on the base.
The transistor conducts and the lead is the um they are controlling a much larger voltage with a small
voltage.
This is the base.
Uh this is the goal form this circuit to show you that we can control it using a transistor you can
control a high voltage thing outboard using a small Volt in both and the transistor base.
Uh this will become more important in the following circuit.
Uh when a transistor amplifier is explored.
But for now you cannot.
You need to understand that we can use small Volt on the base to control high voltage output
okay.
Now uh let's see if this circuit the voltage across the variable to stop is the battery voltage at the
white part of the variable resistor taps of that is stored at different places depending on how the
screw control on the variable does is to set the battery but this could become a voltage divider sort
of the voltage on the base can range from ground low voltage to 9 volt and all Volt in between when
the circuit as well uh you can adjust the range until that it is fully lit using the Volt o meter armies
of low voltage of the base of the transistor and recall the value on the test pit the voltage was boiling.
Seven eight Volt.
So this is the amount of all that is required.
So the valid can fully it.
Uh.
Next you can this crease uh or decrease the voltage by adjusting the variable to the store until that
it is just barely visible.
And again measure of the base voltage on that is below the voltage was buoyant.
Six eight volts.
Finally move the variable as the store until the lid is fully off.
And recall the voltage on that is bad.
The voltage was born six evolve.
As you can see depending depending on different value of the base voltage uh we can differ on.
Uh we can examine different behavior of the valid.