[sdiy] Discrete Op Amps

[Roman Sowa]

That's the point, make thousands of transisotrs, measure their 
characteristics to select into 2-3 different types and toss the rest.
What else could you do back in the 60's when epitaxial technology was 
not so widely available.
BTW, symetry was asured by the round hole in germanium holder.

Roman


W dniu 2017-04-11 o 10:19, John P Shea pisze:
> Manually checking that the dopant is 1 part per 10 million of germanium,
> and I presume you need a steady hand to get good symmetry so that vf for
> the depletion zone is the same each side?
>
> On Tue, 11 Apr 2017 at 5:22 pm, Roman Sowa <modular at go2.pl
> <mailto:modular at go2.pl>> wrote:
>
>     A little thin plate of germanium is enclsed in metal envelope with round
>     holes on each sides. Then you put (manually with a tweezers of course)
>     little ball of dopant and bake it so it melts. Then do the same to the
>     other side.
>     Dopant is migrating into germanium during melting creating 2 p-n
>     junctions.
>     Then connect wires to the little balls, those are collector and emiter,
>     while the base is this envelope holding germanium plate.
>
>     Roman
>
>     W dniu 2017-04-10 o 21:49, Ingo Debus pisze:
>     >
>     > Have there ever been transistors that were not on chips? How were
>     they made then?
>     >
>     > Ingo
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