[time-nuts] A different timenuts interest

Bob Bownes bownes at gmail.com
Wed Jul 21 22:26:44 EDT 2010


There is at least one in DC, at the Smithsonian iirc.

RPI, where I went to college, had one in the 3 story stairwell in the
library. Don't know if it is still there.

I remember one someplace in London too.

Someone mentioned temperature compensation. What would you need to
compensate for? Temp change in the wire wouldn't effect the rotation
as far as I can tell. Swing length might be different based on temp of
the wire I guess, but with a long pendulum, I think the magnet is
going to way overcome that issue.

The one @ RPI had issues due to air movement in the shaft, but that's
a different problem.

I suppose the right method is to use a GPS disciplined oscillator and
the appropriate divider to drive the magnet under the floor. :) To cut
down in draft induced drift and jitter, you'd have to put the whole
thing in a vacuum though!



On Wed, Jul 21, 2010 at 10:13 PM, Richard (Rick) Karlquist
<richard at karlquist.com> wrote:
>
>
> Hal Murray wrote:
>
>> Several years ago, I found a web site for a commercial place that made
>> them for museums.  (I forget why I was looking for that sort of stuff.)  You
>> might find interesting stuff/ideas via google but I didn't find a similar
>> site with a bit of searching.
>>
>
> The Museum of Science and Industry in Chicago had one when I lived
> there in the 1960's.
>
> Rick N6RK
>
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