[time-nuts] Microphonic Inductor?

Neil Gruending neil at gruending.net
Tue Apr 13 14:19:55 EDT 2010


True enough, but don't forget that a shaker table is a big moving
electromagnet right next to the device under test. I would think that
the shaker's field would dominate any such errors, especially for
larger tables running in random vibration or pulse modes.

Cheers,
Neil
www.gruending.net

On Tue, Apr 13, 2010 at 10:57 AM, Poul-Henning Kamp <phk at phk.freebsd.dk> wrote:
> In message <OF2E427F16.3B191983-ON85257704.0060021C-85257704.00603EAF at mck.us.ra
> y.com>, Joseph M Gwinn writes:
>
>>> If anyone knows a good inductor-series (leaded or smt) that is
>>> known-insensitive to vibration please let us know!
>>
>>Air wound coil potted in wax.  Or soft epoxy.  You can make your own, if
>>it comes to that.
>
> Be aware that all non-closed coils are microfonic relative to the
> earths magnetic field, and there is nothing you you can do about
> it, but a closed design (toroid) or a mu-metal shield.
>
> This is more pronounced for cored coils than air-coils, because all
> core materials has magnetic hysteresis.
>
> The effect is usually ignored, but I wouldn't be surprised if it
> showed up for time-nuts...
>
> Poul-Henning
>
> --
> 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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