[time-nuts] quartz clock/watch question

David McGaw n1hac at dartmouth.edu
Sat Apr 19 04:00:22 UTC 2014


I have done that as well.  The G-Shocks have a trimmer cap (I have a 
DW-6900/module 3230).  I don't remember the frequency at the adjustment 
test point but it is something like 100 Hz.

David


On 4/18/14 7:40 PM, Jim Palfreyman wrote:
> 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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