Naked Science Forum
Non Life Sciences => Technology => Topic started by: neilep on 29/10/2011 13:16:08
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Dearest Watchologists,
As a sheepy I of course collect watches . Yep, it’s all I think about really. Collecting watches is my all time favourite way to accumulate wrist enabled time pieces !
However, As accurate as digital watches are I wonder as to how accurate they really are !
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Because Digital watches are full of electronic stuff ewe’d think that they are very accurate but do they lose their precision ?..can they slow down as well as speed up ?...Are the most expensive watches far more precise than el-cheapo watches ? How do they maintain their time keeping?..It’s all to do with a quartz crystal yes ?..where is it in my watch ?..do I need a microscope to see it ?
Hope ewe find the time to help me here !! *le groan*
huggy kuggy
mwah mwh
neil
Watching this space is time consuming
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The timekeeping is done with a quartz crystal, generally in a small 2mm by 10mm long can ( approx) inside the watch. If you have ever changed the battery you will see it there. Generally these are cut and ground from an artificial quartz, as natural quartz is too expensive and rare to find in the right purity ( colours mean impure, you need a clear white quartz with large crystals) cut along specific axes and ground to size. These are than aged to release any strain from the cutting then trimmed to the correct dimensions before being packaged.
You will find there is both a tolerance on the absolute frequency it generates, as well as a dependence on temperature, so most are cut for the correct frequency to be achieved at around 35C, your skin temperature under the watch. You will find your watch will either lose or gain a few seconds a month if you wear it all the time, and slightly more if you do not.
A more expensive watch will have a higher price crystal, that has been cut to be more accurate ( and has been aged for 3 years or more before final trim, to get the best initial accuracy) as well as being calibrated and adjusted inside the watch after assembly to get the best results for the particular unit, and these are checked for long term stability for a few days after manufacture. Adds to the cost, and there are some that are able to compensate for the inaccuracy through software inside the watch itself.
Cheap watches just put the parts together and rely on the initial accuracy to do everything, only checking if it is actually working before shipping.
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I'm also using the camera smart watch. You can