What is h21e? Is it gain? (RE: Transistors)

[chromesphere]

Hi everyone,
Been seeing parameters in datasheets for transistors "h21E" and "h21E Range".  The ranges given look like HFE ranges.  50-150 for example.  Just wondering, is h21E the same as HFE?
Thanks for any help!
Paul

[drolo]

Hi Paul,

Not too many useful info when googling. I found some german technical document documenting h21e as "differentieller Stromverstärkungsfaktor" (something like differential current amplification factor) so i think it might well be hfe. Probably a term that is not used much any more. Someone with more experience, who has been around when transistors were new might have better info though ...

[chromesphere]

Thanks for the info Drolo! Yep, i cant find an explanation for what i means yet either.  No answer on google...which is...impossible isnt it?  

Edit: Correction, google does come up with a result.  This thread   Wow, google works fast these days!

So far ive seen it with some Russian germaniums but also the AC125 datasheet, which is written in English obviously, which makes it more of a mystery...i thought that h21E might be a Russian way of saying Hfe but obviously not!

That said, it probably just another way of saying Hfe though..

Paul

[Kesh]

Yeah it's same as Hfe. The 2 and the 1 stand for terminal 2 and terminal 1 of a transistor in the Hybrid Pi model (where the H comes from in Hfe). That's collector and base. So it's the current multiple between them, which is what Hfe is.

[chromesphere]

Nice one Kesh, thanks for the confirmation!
Paul

[jozef]

Was looking for the same and found this German document explaining transistors http://www.et-inf.fho-emden.de/~elmalab/bauelement/download/BdE_7.pdf

From mentioned document:

h11e = r_BE = ΔU_BE/ΔI_BE assuming constant U_CE
h12e = D = ΔU_BE/ΔU_CE assuming constant I_B
h21e = beta = ΔI_C/ΔI_B assuming constant U_CE
h22e = 1/r_CE = ΔI_C/ΔU_CE assuming constant I_B