[time-nuts] Stable Watch Clocks

M. Simon msimon6808 at yahoo.com
Wed Dec 12 05:01:06 UTC 2012


This quotes .038 ppm/C^2 delta T from the turn over point:

The fly in the ointment is the aging rate of 5 ppm the first year (13ppb/day) and 3 ppm (8ppb/day) after. 

I'm sure holding 1 degC is easy.  .1 C with some care and .01 C - my measuring eqpt ain't that good. So temperature ceases to be a problem. Is the other stuff workable?

I would go with a 32KHz crystal for a "production" version to make it easy to multiply up to 10MHz. 


Engineering is the art of making what you want from what you can get at a profit.

> From: Tom Van Baak <tvb at LeapSecond.com>
>To: Discussion of precise time and frequency measurement <time-nuts at febo.com> 
>Sent: Wednesday, December 12, 2012 3:55 AM
>Subject: Re: [time-nuts] Stable Watch Clocks
>> Typical 32KHz clock crystals are very stable in frequency if you can keep them 
>> close to the turnover temp. If you can hold 1 degC it is .04 ppm. 
>That's far better than I thought. Do you have a reference for this spec?
>I agree you might be able to make one accurate to 0.04 ppm, however briefly, but I've never seen one stable to 0.04 ppm. I mean, that's like 1 second a year.
>> I currently have no method for testing such a rig for stability. 
>Oh, the slipperly slope you are on. I have just the solution for you ...
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