Date: 26 Sep 2003 12:06:10 -0400

Author: William Beaty

Subject: Re: Awesome EM induction demo!

Post:

I've made one using a variable speed motor attached to a gear with every
other tooth milled off. The marbles are stored in a helical plastic
tube with approx the same i.d. as the marbles. A slit is cut into the
end of the tube and the gear slides in. As the gear turns it releases
one marble for each tooth. It runs for about a minute or so and is
visible by everyone in our large lecture hall.

Mike Timmins


On Thu, 2003-09-25 at 16:04, Gary Steinberg wrote:
> I'm trying to recreate an old demo that was used in the 60's that
> is similar to Meiners 7-1.15 (page 115). Basically its an apparatus that
> drops balls at a set rate in synchronization with a strobe. The main
> difficulty is the dispenser--does anyone know of any industrial or
> consumer products that can dispense regular objects at a set rate? Or
> will this have to be custom made...
>
> Gary Steinberg
From billb@eskimo.com Fri Sep 26 09:28:39 2003
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Date: Fri, 26 Sep 2003 09:11:57 -0700 (PDT)
From: William Beaty
To: tap-l
Subject: Re: Awesome EM induction demo!
In-Reply-To: <3F738C03.1BC3B262@pitt.edu>
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On Thu, 25 Sep 2003, David Willey wrote:

> I only got a 7 inch drop, any more and the magnet hit the copper.

Maybe it's not cooled all the way. Did the nitrogen poured on top of the
copper still boil?



> It's just commercial copper block, cost me $100.


Everyone: does a 2" slab work better than a 1/2" slab? Or a 1/4" slab?
NOT IN THEORY, since we're after visible differences rather than numerical
differences. I.e. what happens when you actually try each one?




Alaskan Copper quote for single items up to 6", not including shipping:
$30 for a half-inch bar, 6" x 6"
$50 for a one-inch bar, 6" x 6"
More expensive if wider than "bar" type (if wider than 6")
WAY cheaper for larger quantities. $50 min order
http://www.alaskancopper.com


(((((((((((((((((( ( ( ( ( (O) ) ) ) ) )))))))))))))))))))
William J. Beaty SCIENCE HOBBYIST website
billb@eskimo.com http://amasci.com
EE/programmer/sci-exhibits amateur science, hobby projects, sci fair
Seattle, WA 206-789-0775 unusual phenomena, tesla coils, weird sci

From reberg@physics.umd.edu Fri Sep 26 09:30:20 2003
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Date: Fri, 26 Sep 2003 12:13:42 -0400 (EDT)
From: Richard Berg
To: tap-l@listproc.appstate.edu
Subject: Re: Van de Graaff
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Jerry,

Sewing black spandex seems simpler than glueing strips of latex. Any
particular brand or composition of the spandex - or is this Spandex (a
"brand" name)? And if so do they have different types? Do you have a
"formula" for how short you cut it to allow for stretching when it is
installed?

Dick Berg

On Fri, 26 Sep 2003, Jerry DiMarco wrote:

> I made a belt for our old Winsco N100V VDG out of a strip of black spandex back in the previous century (Oct of '97).
> Last spring it had to be retired, it just wanted to curl in from the edges and run off the end of the roller. So that's 5
> 1/2 years, compared to ~1 yr for the replacement belts. It requires a little sewing skill. If you're interested in details,
> let me know...
>
> Jerry
>
> P.S. The belt made from surgical tubing sounds interesting (howstuffworks.com). Surgical tubing lasts awhile. Has anybody
> tried this?
>
>
> At 12:22 PM 9/25/2003, you wrote:
>
> Hello tappers,
>
> Does anyone have ideas about replacement belts for the Winsco Van de Graaff generator? The belts can be
> purchased from Sargent Welch for about $10. The problem is these rubber belts only last from 3 to 6 months in our
> science building's (we share with chemistry) caustic environment. Our budget (none for the moment) does not
> permit us to stock up and these replacement belts go bad on the shelf as well. Any ideas for homemade belts?
>
> Thanks,
>
> Brian Magness
>
>
>
> <><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
>
> Jerry DiMarco
> Manager of Lecture Demonstrations and Instructional Labs
> Montana State Univ., Physics Dept.
> Bozeman, MT
>
> Our Motto: "There's a demo in there somewhere."
>

***********************************************************************
Dr. Richard E. Berg, Professor of the Practice
Director, Physics Lecture-Demonstration Facility
U.S. mail address:
Department of Physics
University of Maryland
College Park, MD 20742-4111
Phone: (301) 405-5994
FAX: (301) 314-9525
e-mail reberg@physics.umd.edu
www.physics.umd.edu/lecdem
***********************************************************************
From stephen@concord.org Fri Sep 26 09:37:34 2003
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