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Author Topic: How do kinetic watches work?  (Read 4686 times)

Offline thedoc

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How do kinetic watches work?
« on: 01/05/2012 17:04:01 »
Hi Chris

Just listened to your podcast on Circadian Rhythms - excellent as always - which led me to wonder about the kinetic watch on my wrist.

I don't need to wind it nor replace batteries. I understand that this is because my wrist moves about so much during the day that that is enough energy to keep the watch going, but how exactly does that work?

Thanks as always.

Regards
Neil
Asked by Neil S. Briscoe


                                        Visit the webpage for the podcast in which this question is answered.

 

« Last Edit: 01/05/2012 17:04:01 by _system »


 

Offline syhprum

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Re: How do kinetic watches work?
« Reply #1 on: 30/04/2012 22:39:02 »
Some watches are able to communicate with frequency standard radio transmitters to get the correct time but I have never heard of this function being built into a self winding watch.
 

Offline RD

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Offline graham.d

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Re: How do kinetic watches work?
« Reply #3 on: 30/04/2012 23:17:33 »
Hmm, I can only assume that the "self-winding" mechanism does not wind up a spring but is used to produce a current to charge a battery or, maybe as the watch seems to stop relatively quickly if not kept active, just a large capacitor. If it regains the correct time I guess it must have a receiver to pick up some time signal (Various Long Wave time signals or, maybe, GPS). Perhaps Neil could say the make and type of watch because I think there must be some advertising blurb that says what it does.

The mechanism to do this is simply an eccentric weight on a central shaft which will respond to your wrist movements (because of its inertia) by pivoting around its central shaft. There may be a mechanical system for creating from this, a rotation in one direction or, if it is to drive a small generator, this could be done electrically by rectifying the voltage output. However, there may be a cleverer way of doing this given the introduction of electronics. If it is mechanical you can usually sense the eccentric weight by feel when you move the watch about.

 

Offline Geezer

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Re: How do kinetic watches work?
« Reply #4 on: 01/05/2012 02:10:40 »
I believe in the new-fangled ones, the eccentric weight drives a generator that charges a supercap. The old-fangled ones were entirely mechanical. The eccentric weight wound a spring through a ratchet mechanism.
 
Of course, assuming you have too much disposable income, and you have several of these things, you have to buy at least one of these -
 
http://www.youtube.com/watch?feature=fvwp&NR=1&v=BzJAI4MPdUg
 
 

Offline RD

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Re: How do kinetic watches work?
« Reply #5 on: 01/05/2012 02:42:39 »
Of course, assuming you have too much disposable income, and you have several of these things, you have to buy at least one of these -
 
http://www.youtube.com/watch?feature=fvwp&NR=1&v=BzJAI4MPdUg

cheaper solution: get one with a wrist strap big enough to use as a cat collar. :)
 

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Re: How do kinetic watches work?
« Reply #5 on: 01/05/2012 02:42:39 »

 

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