[sdiy] Cannot find % of precision of 2N2223 matched pair ..

Timothy Daugard daugard at cox.net
Tue Jan 14 16:50:52 CET 2014


On 1/14/2014 8:48 AM, Tom Wiltshire wrote:
> Hohoho. Does hfe within 20% even count as matched? I could probably do better pulling random trannies out of a box.
>
> The other figure it gives is Vbe to within 15mV. How does that rate? Sounds pretty poor to me - it's the biggest number on the list. The better ones manage <5mV.
>

But in the '60s this was pretty good. I replaced some of these in failed 
military equipment. The circuit would probably use an opamp now, but 
back then 2223s where used as dif amps. But since I was replacing them, 
I'm not sure how reliable they were either. I suspect now two random 
3904s (from the same batch) with a piece of aluminum wrapped around them 
is just as good.

Tim Daugard





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