23-04-2012, 02:33 PM
(23-04-2012, 01:38 PM)Joe Wrote: I was thinking about changing T2 as the data says T2 and T3 and T4 and T5 are matching pairs.
Don't worry about that - it makes no difference here. It's nice if the outputs are reasonably matched, but even that isn't especially critical. Certainly, T3 does a very simple job, as does T2 - but these jobs are very different to each other, and matching them won't bring any benefits whatsoever. Honest
Also, what precisely does "matched" mean? Almost certainly the current gain - beta, or hfe if you prefer. But as you might already know, hfe is a decidedly "shifty" parameter, so no-one designs circuits around hfe. Really, don't sweat it...
Quote:Interestingly it also says that the EARLY version has OC81s
Yes, that's just what Mullard supplied when you ordered the "LFK4 package". Again, no biggy...
Basically, although there are millions of different transistors out there, they are all much the same. There are a handful of basic parameters to consider, but most circuits are very tolerant of the transistor type - especially in circuits like this. As you learn more, you'll appreciate what all the differences and subtleties are, but for now, that's "too much information"
Regarding power supplies, I'll send you a PM in a while...
