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Transistor Gain

MAHABA

Apr 13, 2012
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Apr 13, 2012
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Hi guys,,

How to know the transistor gain when designing for npn transistor??

I dont know the collector current, I only know base current !!!

In the data sheet there is no specific number for the gain!!

thx
 

john monks

Mar 9, 2012
693
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Mar 9, 2012
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Datasheets typically use a term call "beta" or "HFe" to describe gain".
And this is current gain. The number represents the collector current divided by the base current. Typically this number will be around 10 to 300.
The gain of a transistor with a beta of 100 with a base current of 1mA will have a collector current of 100mA.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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Of course the hfe only describes the maximum gain.

Depending on your circuit, you may get a lower gain (in fact most often in linear applications you will want to control the gain).
 

KrisBlueNZ

Sadly passed away in 2015
Nov 28, 2011
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If you want any really useful answers, you need to explain a lot more about what you're doing.

Can you post a schematic? Can you tell us why you need to know the number? Do you have a particular transistor in mind? Are you designing a circuit to work to a particular specification? We're playing tennis in the dark with you unless you give a lot of background information.
 
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