[time-nuts] temperature sensor

Bernd Neubig BNeubig at t-online.de
Mon Jul 21 13:59:44 EDT 2014


regarding the commercial availability of temperature sensor crystals, I
already had pointed to the tuning fork type RKTV206, which is on the AXTAL
website together with an application note.
Other temperature sensing crystals are using thickness shear mode, and are
basically rotated Y- cuts
The most prominent cut is the Y-cut or the same with a few degrees (about 5)
rotation from Y-axis. This cut exhibits a tempco of about -90 ppm/K, but is
not very linear. There are a few on the market in HC-52/U size.
The most temperature-linear cut was the LC-cut invented by olde
Hewlett-Packard, which had a complete temperature test system offered around
this sensor crystal. It is an doubly-rotated cut with some -40 ppm/K
sensitivity. Sorry I am in a hurry, so I have not the time to dig the
literature for you at the moment.


Bernd  DK1AG

-----Ursprüngliche Nachricht-----
Von: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] Im
Auftrag von Attila Kinali
Gesendet: Sonntag, 20. Juli 2014 18:11
An: Tom Van Baak; Discussion of precise time and frequency measurement
Betreff: Re: [time-nuts] temperature sensor


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

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

			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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