[volt-nuts] How to keep voltage stable in the sub-100nV range?

[Orin Eman]

The Russian K72P teflon capacitors on ebay are really good and not
expensive.  They are however, huge!

I was investigating replacing the integration capacitor in an HP 3455A (it
is responsible for the +/- 2 digit jitter in auto-cal mode).  I have now
replaced the original polypro 82nF with two K72P 39nF in parallel and the
reduce the jitter to less than one digit.  Unfortunately, physically, the
K72Ps don't fit and dangle over the edge of the AtoD board.  The 82nF K72P
I tried was worse!

I built Bob Pease's dielectric absorption circuit and tested several
capacitors.  More details here:

http://www.eevblog.com/forum/testgear/hp-3455a-last-digit-jitter-in-hi-res-auto-cal-mode/

There are a couple of oscilloscope screenshots of the absorption of the
original capacitor and the K72P.  I've not found anything better than the
original capacitor other than the K72Ps and I've tried polypro,
polystyrene, C0G etc..


On Wed, Nov 2, 2016 at 7:18 AM, Poul-Henning Kamp <phk at phk.freebsd.dk>
wrote:

> --------
> In message <f3847ee8-a5ec-099c-91b1-d7c0b17599d4 at mounty.de>, Andreas
> Bergmann writes:
> >On 02.11.2016 14:44, David wrote:
> >> Teflon is the best but is also expensive and has poor
> >> availablity.
> >
> >Quick check on ebay:
> >http://www.ebay.com/bhp/teflon-capacitor
> >
> >One pair for $150.-? wohooo ....
> >Is this a part of the audiophoolery community?
>
> Yes, they are very much in demand for audiohomoepathy, up to the
> point where people actually roll their own.
>
> --
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk at FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
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