[time-nuts] "The Penultimate HP5065 A15"

[Poul-Henning Kamp]

--------
Bob kb8tq writes:

> > I have not given much thought to A11 yet, and I do find a certain
> > elegance in the wien-bridge approach.  It is worth noting that the
> > actual heaters run of the unregulated supply, when I stabilized
> > that, A11 worked less hard.
>
> The AC bridge approach certainly worked well 'back in the day'.

Actually, what I like is that it makes it possible to decide the
frequency spectrum of the inevitable noise, and in this case put
it up around a kilohertz where it is a lot less likely to cause
trouble.

The "modern" approach to that is to modulate or dither with a
good long PRNG to whiten the noise, and while good in theory,
it is not _that_ easy to get right in practice.


-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
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