[time-nuts] temperature sensor

Attila Kinali attila at kinali.ch
Sun Jul 20 12:10:50 EDT 2014


On Sun, 20 Jul 2014 07:55:23 -0700
"Tom Van Baak" <tvb at LeapSecond.com> wrote:

> Thanks for this level of detail. Fascinating. Is the fundamental physics
> behind the quartz angle-of-cut well understood, or does this fall into
> advanced alchemy and industrial magic?

>From what i gathered from my excursion into solid state phyiscs, the
properties of crystals can be calculated "easily". If i'm not mistaken
the SC cut was calculated before it was experimentally proven (sorry,
cannot find the reference for that).

There are also several software packages to simulate quartz crystals.
(e.g. CS-01 from maxis-01)

> I understand about the time constant now. Yes, on the order of a
> few seconds makes sense. Would it be possible to have other mounting
> techniques that improve environmental contact with the crystal?

The problem here is, that any closer contact will lead to damping
of the crystal. Probably the best solution is, as Bob Camp said,
to use SAW instead of BAW.

> Do you know of any commercial quartz crystals (say, in the $1 to $10 range)
> that have been optimized for large tempco at room temperature? Or optimized
> for linearity over a large range (e.g., -40 to +40 C)?

As Bernd Neubig mentioned, Axtal has some:

As none of the usual distributors carries them, i have no idea what
the price is. Maybe Bernd can answer that question.

I'm pretty sure other quartz manufacturers have some as well.

> I was able to test
> one once, a 5x7mm XO, but I don't know any more about it other than it came
> from Switzerland.

Hmm... The only quartz manufacturer in Switzerland that is still producing
anything, is AFAIK Microcrystal. I'm not aware of any other (after 
Oscilloquartz got bought and their quartz business integrated into Microcrystal).

Unless you got it over Quarz AG (www.quarz.ch) which is merly a distributor.
(Yes, they sell beauty products too... )

BTW: for some reason, i did not get the two mails from Andras Pummer
which you quoted at the end of your mail. They don't seem to be in
the archives either.

			Attila Kinali

I pity people who can't find laughter or at least some bit of amusement in
the little doings of the day. I believe I could find something ridiculous
even in the saddest moment, if necessary. It has nothing to do with being
superficial. It's a matter of joy in life.
			-- Sophie Scholl

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