Transistor! (1 Viewer)

[KingofthieF]

omg can someone explain how transistor works to me?
especially on how it actually amplify singals...farout all the textbook stuff is confusing me! THANKS~~

 

[Dumbarse]

a transformer changes voltage i think, (step up/step down)
you would have used em at skool, its the silver box with ac /dc
hope that helps

 

[smithy]

transistors

The way i see it (but don't quote me on this)- is that basically it acts as a switch to amplify the signal.
If a signal is applied at the base lead of a transistor(the one that controls the p-n junction)- then the transistor will allow current to flow according to the amount of current at the base lead.

If we then apply a larger current to one of the other leads- the signal applied at the base controls the flow of the other current- thus the larger current flows in the same pattern as the signal does.

If you're more confused now don't worry- i'm not a very good teacher- i know what's going on myself but don't seem to be able to put it into words.

 

[KingofthieF]

thanks smithy~
i'm just really confused over these points:

1. The Emitter/Collector voltage does not affect the emitter/collector. It is a violation of ohm's law and an example of "constant current power supply".

2. What does it mean by current amplifier? Is it the emitter/base current or the emitter/collector current amplified? But isn't the current in series circuit constant through out??

ps all the textbook sort of skip the detail and just talk about the result.. which is really werid... all textbook...

 

[smithy]

Originally posted by KingofthieF
thanks smithy~
i'm just really confused over these points:

1. The Emitter/Collector voltage does not affect the emitter/collector. It is a violation of ohm's law and an example of "constant current power supply".

2. What does it mean by current amplifier? Is it the emitter/base current or the emitter/collector current amplified? But isn't the current in series circuit constant through out??

ps all the textbook sort of skip the detail and just talk about the result.. which is really werid... all textbook...

Ok, ok- i'm not sure whether you were quoting me, but i'll try again.

There are 3 leads on a transistor. The middle one is usually the base- this is the lead that applies a current to the n or p type silicon in the middle of the sandwich of silicon. (which is the same as the "Grid" in a thermionic device.

If a small varying signal is connected to the base lead, it causes the n or p type silicon in the middle of the sandwich to "switch" according to the amount of current supplied at the base.

Now, if a larger current is placed at either the collector of a transistor, waiting to flow through the transistor. The switching which is done by the base allows this larger current "waiting" at the emmitter, and as the middle part of the silicon wafer is switched by the base, it allows current to flow in accordance with how much current is at the base.

Because of this, the larger current applied is made to flow in the same way that the signal at the base is oscillating.

Quoting Oxford university press Physics in context- "Small currents applied at the base produce large variations in the current flowing between the emitter and collector."

So basically, it is not the same signal- it is simply a way of turning a larger current applied to one part of the transistor into the waveform or variance that is applied at the base.

I don't know how basic this is- our class didn't actually even learn the names of the different leads- i'm just a bit of an electronics buff.

 

[smithy]

Now, if a larger current is placed at either the collector of a transistor, waiting to flow through the transistor. The switching which is done by the base allows this larger current "waiting" at the emmitter, and as the middle part of the silicon wafer is switched by the base, it allows current to flow in accordance with how much current is at the base.

wait wait wait- hold the phone- let me rewrite the paragraph quoted above.

Now, if a larger current is placed collector of a transistor, waiting to flow through the transistor. The switching which is done by the base allows this larger current "waiting" at the collector, and as the middle part of the silicon wafer is switched by the base, it allows current to flow in accordance with how much current is at the base.

 

[KingofthieF]

oh ic ic
thanks a lot smithy~
what a legend