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Clock Project

Discussion in 'Electronic Basics' started by [email protected], Mar 6, 2007.

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  1. Guest

    Would like to build a digital clock with a long-duration mechanical
    escapement ("artistic" part).

    I found Bill Bowen's site

    http://ourworld.compuserve.com/homepages/Bill_Bowden/

    and could probably decipher something here, but thought I'd try for
    some advice/ shortcut.

    I envision empirically determining the periodicity of my "escapement
    mechanism" and inputting that time period into my clock via dip
    switches. This number (not much resolution needed due to mechanical
    vagaries of long-period escapement) would then be latched into the
    clock electronics to provide the clock increment.

    One could call this a "variable increment clock", I guess.

    Could someone point me to a circuit that comes close to this?

    Marc on the North Coast
     
  2. I had to read this a couple of times before I got it (I think). If I
    understand you, you want to use a pendulum of arbitrary length (and
    arbitrary period) and then have this advance the clock mechanism the correct
    amount for each swing. For example, say you used a 1 meter long pendulum
    with a period of 2 seconds. You would want to advance the the clock 2
    seconds each cycle. Correct?
    Not sure what you mean here, there is nothing vague about the motion of a
    pendulum.
    Bryan Mumford has something like this going, but he uses a pendulum to
    generate the pulses to an electrical drive system for the hands. He keeps
    the pendulum going with magnetic impulses. The impulses are triggered by
    the pendulum itself, so that the pendulum is the thing actually keeping
    time.
    http://www.bmumford.com/clocks/em2/index.html
     
  3.  
  4. Thanks for the reply, Anthony.

    You understood okay, but I was thinking of a complex escapement
    mechanism that is amusing (?) to watch and has a period of many
    seconds. Accuracy is not a goal here; the goal is more: "you can keep
    time with THAT ?"

    The latched increment input into a clock driver is the part for which
    I'm seeking help.

    Thanks again.

    Marc
     
  5. ehsjr

    ehsjr Guest

    I'm lost on your description, too.
    Do you want to _add_ the incremental value
    to the previously stored value each interval?

    Ed
     
  6. Right, Ed. Time value is incremented by the escapement period time
    value. (This is true of every mechanical clock, when you think about
    it.)

    I didn't provide detail on the "escapement mechanism" b/c it's not
    important regarding the portion I need help with. The Increment will
    be many seconds and you understood perfectly. The "ecapement
    mechanism" operates over a repeatable-enough period of time and THAT
    time period will be the "increment".

    My own thought since I described the problem is that instead of
    counters, gates and DIP switches, a small microprocessor chip would be
    the easy way to program the increment function (especially regarding
    re-programmability). --probably cheaper, too.

    Thanks for responding.

    North Coast Igor - Marc
     
  7. ehsjr

    ehsjr Guest

    So conceptually:
    impulse from escapment-> add N to totalizer
    is all we have so far. First, flesh out the
    impulse generator: microswitch, opto, what?
    Debounce it as needed. You can google "debounce circuit"

    Apparently you've already figured out how to
    come up with N - but why on earth do it that way
    when you've already decided to use a micro?
    It can count the time between impulses probably
    better than you, and with better resolution and
    no need to gate the value stored in a bunch of
    dip switches. Just count directly using the
    micro. That also takes into account any physical
    abberation in the escapement.

    But after impulse from escapment-> add N to totalizer
    what happens next? Does the value in the totalizer
    cause something to happen? Seems to me it should,
    and logically it is something like "is value in
    totalizer >= X" if yes do something, if no do
    nothing. Do you want the value to cause the hands to
    move some particular distance?

    You need to do a complete set of specs for what you
    want to happen. It _has_ to be more than just
    adding a number to a total or else there is no
    purpose to doing the addition. I don't mean this
    as criticsm, but I don't think anyone here wants
    to drag the specs out of you one at a time. I think
    that's what I'm doing, and it's not fair of me to
    waste your time because I just plain don't get it.

    Ed
     
  8. Rich Grise

    Rich Grise Guest

    First, you're supposed to bottom-post, to follow the natural flow of the
    thread.

    Given that, google "compound pendulum" - you'll find some really
    impressive-looking designs for pendulums (pendula?) of practically
    unlimited period, probably even adjustable ones.

    Good Luck!
    Rich
     
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