[time-nuts] quartz clock/watch question

Bob Camp lists at rtty.us
Fri Apr 18 19:41:02 EDT 2014


Hi

We used to do it with a microphone. Nothing fancy, just a simple little guy with the inductance resonated out at 32 KHz. The output feed a computing counter. It worked fine as long as the microphone was in contact with the watch or watch module. 

Bob

On Apr 18, 2014, at 7:25 PM, 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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