[sdiy] SSM2220 dual PNP clones?

[René Schmitz]

Hi David,

David G. Dixon schrieb:
> And another, closely related question:  If I were to try to match PNP
> transistors by hand, what would I actually be matching?  Beta?  If it's
> beta, then that's easy, because my multimeter has a beta-reading doohickey.

You would need to match Vbe for a given collector current. Beta itself 
is relatively unimportant, which you can see from the fact that it 
doesn't show up in the equations describing the exponential convertor.

If you want to short cut it using a DVM, then use the diode tester. 
(Effectively matching Vbe at Ic = 0)

Cheers,
  René

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uzs159 at uni-bonn.de
http://www.uni-bonn.de/~uzs159