[time-nuts] Casio Watches 13 Year Drift in Seattle

Bob Camp kb8tq at n1k.org
Mon Jun 29 16:53:30 EDT 2015


Hi

Well there are a few possibilities: 

1) The person wears their watch 24 hours a day
2) They take it off for random periods of time
3) The person swims marathons weekly in cold water with their watch on
4) The watch sites in a cabinet for 10 years

The further down that list the colder the watch runs. 

Cassio and pretty much everybody else *do* temperature compensate their watches for the nominal temperature characteristic of the crystal they use. It is easy to do digitally and thus costs nothing (either in silicon area or power). They also adjust the watch on frequency digitally rather than mechanically. Compared to the way we used to do it (40 years ago), it’s a lot cheaper to do it the “new way”. It is interesting that
the nominal set point is still “fast” though. 

Bob

> On Jun 29, 2015, at 2:42 AM, Bryan _ <bpl521 at outlook.com> wrote:
> 
> But wouldn't normal watch wear just balance itself over time, one wears their watch for say 12 hours and the rest it sits on a counter at a much colder temperature. So wonder if Casio would actually go to such lengths to compensate. Maybe, interesting though.
> 
> -=Bryan=-
> 
>> From: kb8tq at n1k.org
>> Date: Sun, 28 Jun 2015 20:41:15 -0400
>> To: time-nuts at febo.com
>> Subject: Re: [time-nuts] Casio Watches 13 Year Drift in Seattle
>> 
>> Hi
>> 
>> Just to clarify:
>> 
>> In the “art” the watches all ran fast rather than slow. They *would* have run slow if the
>> room temperature / skin temperature delta was an issue. Since they did not, one assumes 
>> that Casio digitally compensates this model (and probably all their watches).  The typical 
>> watch tuning fork will shift more than the observed delta when run in a cold court house if 
>> un-compensated.
>> 
>> By far the best explanation is the “set to deliberately run fast” one.
>> 
>> Bob
>> 
>>> On Jun 27, 2015, at 8:19 PM, Jim Palfreyman <jim77742 at gmail.com> wrote:
>>> 
>>> My Casio g shock keeps extraordinary time. I did open it up and tune it,
>>> but still I'd expect it to drift.
>>> 
>>> After 6 months untouched I still can't separate by eye the second from UTC.
>>> 
>>> Also, with regard to the video's query about all the clocks running slow -
>>> they have been tuned to run at the temperature of a person's wrist.
>>> 
>>> On Sunday, 28 June 2015, John Stuart <j.w.stuart at comcast.net> wrote:
>>> 
>>>> I think there may be a new Time-Nut in the Seattle area, , ,
>>>> 
>>>> Art, Engineering and Justice - how accurate is a Casio watch?
>>>> <https://www.youtube.com/watch?v=hwOMUhS8gV0>
>>>> 
>>>> 
>>>> 
>>>> John, KM6QX
>>>> 
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