Re: Pinewod Derby Tracks
Gregory M Marr (gregm@WPI.WPI.EDU)
Tue, 24 Nov 1992 11:24:49 -0500
> I have no experience with these companies, but am very interested in your
> finish line circuit design. We must modify our finish line circuit as a
> result of last year's experience:
> Each lane has a wooden dowel leaver suspended over the finish line. Attached
> to this lever is a tube filled with mercury that, when tilted, completes the
> circuit of an electric switch that turns on a light for that lane. This finish
> line circuit worked fine for two years until ... (suspense building) ...
> a parent with a camcorder showed that his son's car had actually won when the
> light showed another lane. How? The car's sleek design was able to slip the
> nose under the lever without tripping the switch until the car had traveled
> further across the finish line! Now is that a photo finish, or what?!
> An obvious EC (engineering change) is to extend the length of the levers.
> However, I am interested in other successful finish line designs.
> Yours in Scouting,
> Mike Box, Cubmaster
When I was in Cub Scouts, our pack built a new track. The finish line
was a metal frame that fit around the end of the track. The frame had
electric eyes on it, one part on the top of the frame, and one part on
the bottom of the frame. There are holes drilled in the center of the
track to let the light through. On the top of the frame are three red
lights, one for each track. Only the light for the first lane to be
tripped would go on. This was a very sensitive device. It was almost
impossible to have a tie. Before we started using it, it was tested
with a bunch of threads, and it could detect those going through the
beam. There is also a 'control box' that has all the circuitry, as
well as three led's that correspond to the three lights on the frame,
and a reset button to clear the lights, and get it ready for the next
race. Since the beam goes from above the height of the cars to below
the track, and is right in the center of the lanes, there is no
problem with cars 'slipping under.' The circuit was designed by one of
the parents who was on the committee. He worked in the electronics
section of a major toy company. The frame was removable, and attached
to the track with a pair of allen screws.
Hope this helps.
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