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  1. #46
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    Default Re: 1 second Regulator – state of play (By: Phil Burman)

    It may be harmonic resonance. In the past I've mentioned that
    things like where the crutch attaches to the pendulum can create
    resonances in the rod. These can cause the pendulum to pull slightly
    off frequency if they were close to harmonics of the pendulum.
    If the harmonics were high enough, you could have a step like action
    as the pendulum changes frequency.
    Tinker Dwight

  2. #47
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    Default Re: 1 second Regulator – state of play

    I'm still struggling with the temperature compensation. Contrary to my previous proclamation the pendulum didn't have zero change without any temperature compensation. It now seems that my invar rod has a coefficient of expansion 0.0000021 mm/mm/deg C which is about right for annealed invar. It seems that cold drawn gives the normally quote value of 0.0000011 m/mm/deg C. I'm about to try a 170mm aluminium compensation tube and hopefully that will nail it.

    In the meantime I've be working on the barometric compensation. I was lucky to obtain 2 of the correct type of aneroid capsules (self sprung) off ebay. I built a low cost vacuum chamber in order to calibrate them, see photo. The system uses a dial indicator for deflection measurement, the Microset atmospheric sensor for pressure and a low cost brake bleeding vacuum pump. In hindsight a good pair of lungs would probably have been sufficient.

    I have included a graph of the result for one of the capsules, the other gave almost the same result.

    Click image for larger version. 

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  3. #48
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    Default Re: 1 second Regulator – state of play (By: Phil Burman)


    Tinker Dwight

  4. #49

    Default Re: 1 second Regulator – state of play (By: Tinker Dwight)

    Hi Phil,

    Thank you so much for keeping us informed of your progress with your clock and experiments/developments.

    Your thread is a keeper for sure!

    "To invent you need a good imagination and a pile of junk." - Thomas Edison
    Best wishes to Ya'll. Sincerely, Jim

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