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Is there a specific way to figure out the gear ratio I would need for a wind up mechanism that could last around one year? Would I start out with a really high tooth and step down too a small enough ratio for a complete cycle to last a year?

Do I need to devise a polynomial function, then use calculus to solve for the gear ratios, number of teeth, and time?

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    $\begingroup$ One approach would be to copy (or scale) existing practice, search "400 day clock" for a starting point. $\endgroup$ Oct 5 '16 at 10:55
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Starting with the gear ratio is the wrong way to look at this problem. Start by determining the total energy you need for one year. No amount of gearing can fix it if the fully wound coil doesn't hold the energy you need.

Once you know the energy you need, you look for a spring coil that can store at least a little more than that. Only then are you ready to consider gear ratio. The spring spec will give you the number of turns over the coil's useful discharge life. Only you can tell how many turns of some shaft you need to run your device for one year. The overall gear ratio is then the latter divided by the former.

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  • $\begingroup$ So your saying in a perfect world, I can make any amount of energy last for an entire year? I would just need to know the given amount of energy, longevity, and other factors involved in the spring I am using? $\endgroup$ Jun 22 '17 at 9:11
  • $\begingroup$ @Chris: No, that's not what I said. $\endgroup$ Jun 22 '17 at 12:15

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