[time-nuts] quartz clock/watch question

Jim Palfreyman jim77742 at gmail.com
Fri Apr 18 19:40:42 EDT 2014


I've opened up my Casio G-Shock watch, found an electrical point, put an
oscilloscope on it and successfully adjusted it. From memory the frequency
was something weird, but I still tuned it successfully to within about a
second a month. I even think I posted to time-nuts on this...

Jim Palfreyman



On 19 April 2014 09:25, Bob Albert <bob91343 at yahoo.com> wrote:

> I have tried to pick up the oscillator from my wristwatch and have been
> unsuccessful.
>
>
> I tried both magnetic and electric probes.  Nothing.
>
> Bob
>
> On Friday, April 18, 2014 4:12 PM, Tom Van Baak <tvb at LeapSecond.com>
> wrote:
>
> > When a quartz watch or clock is assembled, what method is used to get it
> as accurate as possible?
>
> Bob,
>
> First generation quartz watches had a tiny F/S (fast/slow) trimmer
> capacitor. These days it's done with skip cycles and one-time factory
> calibration. Think leap days or leap seconds -- it's easier and more
> reliable than changing the frequency of the oscillator itself. It's also
> one less part, easier to calibrate, and unlike active and passive
> components, math has no environmental sensitivity.
>
> Have a quick read of 32 kHz watch IC's like:
> http://www.nxp.com/documents/data_sheet/PCA2000_2001.pdf
>
> /tvb
>
>
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