[time-nuts] Am I the only Time Nut who doesn't wear a watch?

[Hal Murray]

> This watch is not quartz, it is fully mechanical with a balance wheel. 

What is the temperature profile of a mechanical balance wheel?  That seems 
like something at least one time-nut would have good data on.

Graphs of offset vs temperature for crystals are readily available.  For the 
typical watch crystal, it's a parabola pointing down with the top at roughly 
body temperature.

For a typical (low cost) PC crystal, it's a squiggle: up, down, up.  The 
slope of the down part depends on the angle of the crystal cut.  The specs 
say (roughly) within X PPM for voltage within V and temperature with T.  The 
V and T form a box.  Some engineer gets to figure out the tradeoff between 
angle, accuracy, testing, mumble, ....  whatever works to get it within the 
box.

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> I wonder how well the human oven works in maintaining the environment of a
> watch xtal or balance wheel, assuming the watch is worn 24x7. 

I don't have any good sociological data, but I've seen reports that watches 
work much better if worn 24x7 rather than placed on a night stand while 
sleeping.


-- 
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