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Subject: 
RE: Eclipse ideas
Newsgroups: 
lugnet.robotics
Date: 
Thu, 12 Aug 1999 21:24:43 GMT
Original-From: 
Hall, Duncan <duncan.hall@exnz01.exch.eds.=spamcake=com>
Reply-To: 
duncan.hall@ieee.org/AntiSpam/
Viewed: 
598 times
  
While this suggestion will track the sun in right ascension (more or less),
a further challenge is to craft the tracking mechanism to follow the sun's
apparent annual figure '8' motion in declination as it travels along the
analemma (see http://www.uwm.edu/~kahl/Images/Weather/Other/analemma.html
for more details) ...

Duncan Hall
duncan.hall@ieee.org


-----Original Message-----
From: Dallas C. Hockley [SMTP:hockleyd@cybersurf.net]
Sent: Friday, 13 August 1999 05:01
To: lego-robotics@crynwr.com
Subject: Re: Eclipse ideas

Laurentino Martins wrote:

Any ideas how to track the sun trajectory using some gears and one RCX?


The trick would be getting the gear ratio and timing right.  You need to
step the rotation speed down to 1 rotation every 24 hours, to equate to
the sidereal motion.  If you've seen an equatorial mount for a
telescope, that's what you're looking for.

Basically, you elevate a platform to the angle of your latitude, and
point the axis at the north star.  The motor turns that axis once every
24 hours.  If the "telescope" is pointed at the north star, it just
rotates in place still looking in the same direction but rolling over.

Then you add a turntable to the platform.  As you turn the scope on this
platform, you increase the 'declination' of the telescope.  Now when the
motor turns, it points the telescope around in a circle around the north
(or south) guide star.  (Note that this is tricky in the southern
hemisphere as the guide star is not as obvious as the north star, nor is
it near the north pole. But I digress)

Celestron has a basic site with some pictures of telescopes on mounts at
http://www.celestron.com/tb-mtrms.htm

The motor I would expect will need to be pulsed after it's beed
reduced.  I hope you have a *lot* of gears to go from 300-1200 rpm to 1
revolution per day.

Good Luck!  I Hope this info helps!

Dallas Hockley
hockleyd@cybersurf.net

Watching the eclipse I had this wild idea of creating a permanent • projection of the sun in a wall in my room. B-)
Using some gears, a lens or binoculars, a sun filter and a mirror this • might be possible.

Laurentino Martins

[ mailto:lau@mail.telepac.pt ]
[ http://www.terravista.pt/Enseada/2808/ ]

--
Did you check the web site first?: http://www.crynwr.com/lego-robotics
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Did you check the web site first?: http://www.crynwr.com/lego-robotics
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Did you check the web site first?: http://www.crynwr.com/lego-robotics



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