How a NPN Transistor can be used for amplification?

[amun]

Transistor

Hi,
I want some information about how a NPN Transistor can be used for amplification?
What is the working principle?

Can somebody tell me?

 

[IanP]

Re: Transistor

Try this site:
**broken link removed**
It is a nice tutorial on transistors ..

 

[cedance]

Re: Transistor

actually, the one u have asked is more general... too difficult or rather looooong to give an answer.. only references could suit better for ur question.. reg. that.. tehre are many good books available.. which according to me i have ordered...

1) Microelectronic circuits by sedra and smith
2) grey and meyer book.. u would know it i suppose
3) art of electronics - horowitz and hill
4) microelectronics - Donald A neaman
...
..
goes on...

better get one sedra smith! the best one i would suggest..

/cedance

 

[dkace]

Re: Transistor

Well a quick answer should be:

Ic=βxIb

So it is that simple. Now, if you want to know why, better check all the above links. Oh, and don't go to transistor at once. Start from diode in order to better understand how a pn junction operates with voltage difference.
D.

 

[samcheetah]

Re: Transistor

a great explanantion of transistor amplification

http://amasci.com/amateur/transis.html

 

[truebs]

Re: Transistor

This is one the mysteries for the beginner that how can any device so simple in working and looking can actually amplifu a signal !

And most of the textbooks offer slightly complicated explaination as per the beginners.
Let me give it a try to make you unsetstand the basic principle involved :

"TRANSfer resISTOR , is transistor i.e it transfer resistor !'
Consider a transistor as two diodes connected back to back.
Any diode reverse biased offers a very high rsistance and that with forward biased offers very low resistance.
In use an amplifier NPN transistor works in active region where Base Emiter junction is forward biased whereas base collector reverse biased.
In our two diode analogy ,one diode is forward and other reverse biased.
Now current flows through forward biased region,ie.B to E but ,
this current has no other way out but to go at collector.
Hence this tiny little current reaches the collector and flows, but this is a very high R region and HIGH R X low current ,is much greater than low R X low current (Ohms law ), This results in amplification.

Note : This is a very basic explaination for unserstanding ,please refer indtrocutory electronics books for more details.
One good book i can suggest available on our forum is :
"Teach yourself electronics and electrical"

 

[NTFS]

Re: Transistor

hi
a very simple answer is:

imagine a pipe that have a hydrolic tap. the tap needs a little force to open and when it opened, a lot of water can running through the pipe.
Base of transistor is like a tap and the heads of pipe is Collector and Emitter.

NTFS

 

[brahma]

Re: Transistor

basically transistor acts a switch.its name is derived frm transfer resisitor. when the input exceeds the threshold level [ Vbe=0.7(silicon) and 0.4(germanium) ]. u can find more information on

1.integrated circuits- millman and halkias
2.solid state devices- david A bell
3.solid state devices and circuits - streetman and banergee

u can find basics of transistor in

1. electronics principle - malvino
2.electronics circuits and devices - boylested