From: nospam@de-ster.demon.nl   
      
   Eric Flesch  wrote:   
      
   > I looked for a time or clock group to post this to, without success.   
   > This topic isn't exactly physics, but time-keeping and clock faces are   
   > of interest to physicists, so here goes:   
   >   
   > To make analog clocks more dramatic, what's needed is for the three   
   > hands, hour-minute-second hands, to converge on the hour mark all at   
   > once.  So at the stroke of 9 o'clock, the minute and second hands   
   > should cross over the hour hand at the 9 o'clock mark right on the   
   > stroke.   
   >   
   > This is actually an impossible design if you want to keep the standard   
   > duration of the hours, minutes, and seconds.  I thought it essential   
   > to keep the standard duration of the hour and second, so by relaxing   
   > the length of the minute (to equal 72 seconds) I was able to design   
   > such a 24-hour analog clock.   
   >   
   > The movement of the 3 hands is as follows:   
   >   
   > Hour hand: 1x sweep per day (a sweep being once around the clock   
   > face).   
   >   
   > Minute hand: 25x sweeps per day.   
   >   
   > Second hand: 1225x sweeps per day.   
      
   There is a much simpler method to achieve the effect you want   
   without 'sacrificing' minutes or seconds.   
   This is to use a revolving dial clock or watch.   
   It has a single fixed pointer etched into the glass of the watch,   
   set at a convenient angle for viewing, for example at two o'clock.   
   The 'dial' consists of three concentric rings   
   that rotate at the appropriate rate for hours, minutes and seconds.   
   At the whole hour the three rings all pass under the pointer   
   at 09/00/00 for example.   
   The things are avilable commercially in many variantions.   
   [snip]   
      
   > Such a movement is impossible to design for a 12-hour clock if keeping   
   > the standard second -- the clock-face can't display an integer number   
   > of time-ticks.  So this works for the 24-hour clock only.   
   >   
   > I've looked in vain for an on-line clock with programmable hand   
   > sweeps.   Cheers.   
      
   Such a thing should be easy to make using stepper motors   
   and digital frequency dividers,   
      
   Jan   
      
   --- SoupGate-Win32 v1.05   
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