transistors

[Gamal]

  How does a p.n.p works when current flows from negative.

[APS]

Can you explain your question. What do you mean "current flows from negative".

[desolatordan]

  How does a p.n.p works when current flows from negative.

You won't have current flow from a negative to positive node unless it's an active component with some chemical or magnetic emf.

Are you referring to the orientation of the collector/emitter of a pnp versus npn?

[Gamal]

 
  Correct, I expect emmiter to collector current flow (negative to positive) n to p through a n.p.n. transistor. Would I get

the same emmiter to collector current flow through a p.n.p. transistor with changed polority? Dont make sense to me that`s

positive to negative current flow (p to n). I am still confused.

                                                                                       Gamal

[desolatordan]

http://en.wikipedia.org/wiki/Bjt

[APS]

http://www.mayothi.com/transistors.html

[icemagic]

Reading the above two links won't help you understand *how* it works unfortunately. If you want to know *what* it does though, the above two links will be just fine. However, you won't be able to make sense of why it does the things it does until you learn about the model. There is a book, Physics of Semiconductor Devices (3rd edition), which might help you begin to understand it.

Unfortunately, BJTs are a lot more difficult to understand than MOSFETs or diodes. Hope this helped.

[yoshiki]

I seriously recommend you get Microelectronics Circuit Analysis & Design by Donald A. Neamen (excellent book) as I am not really understanding your question (sorry). That book will tell you all you would want to know about a transistor either that or try to re-structure your question