Silly me, I just realized you need to compensate for the change in length with temperature.
This sounds like a great project! On Wed, Jul 21, 2010 at 10:26 PM, Bob Bownes <bow...@gmail.com> wrote: > 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 > <rich...@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 >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.