Transistor selection guide

Thread Starter

kammenos

Joined Aug 3, 2008
127
I was struggling to purify an undervoltaged 3wire PC fan rpm signal (yellow wire). I tried several methods but under 600rpm, i always had problems. I tried 2n222 alone and darlington. I also tried some other transistors. And then, out of the sudden, i tried a transistor that just worked!

What i want to result is, what criteria are there to choose a transistor?
Is there a site and/or a book (that i would rather prefer) for transistor selection?

Thanks again
 

Thread Starter

kammenos

Joined Aug 3, 2008
127
PERFECT!!!!! THANX

But i would like to know basically the way to choose. Some theory you know... How to choose hfe, what type of transistor, PNP or NPN? You know....
 

bertus

Joined Apr 5, 2008
22,270
Hello,

The transistor specification is dependent on the way you want to use it.
There are a couple of questions you can ask for selecting a transistor.
1) how many power has it to dissipate?
2) how many current will the transistor have to handle?
3) what is the working voltage?
4) is the transistor used as amplifier or as a switch?
5) what gain will be required?

Greetings,
Bertus
 
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