[time-nuts] Microphonic Inductor?

Neil Gruending neil at gruending.net
Tue Apr 13 18:19:55 UTC 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.


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
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