Subject:
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slightly off topic: two questions (one of them for EE types)
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Newsgroups:
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lugnet.robotics
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Date:
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Mon, 25 Jan 1999 05:03:00 GMT
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Reply-To:
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berwin@ANTISPAMtufts.edu
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Viewed:
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1035 times
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I hate batteries. I have a lego bubble-blower in my office that I use
as a demo when people tour our center, and it is really annoying to have
the battery-pack batteries die at inopportune moments. It seems silly
to have the $250 serial interface box hooked up to it just for a measley
9 volts. (Of course, hooking it up to the interface box for only those
moments when I need to turn it on is a possibility, but that would be
too easy. Besides, what I want would also be useful for the middle
school that I teach at, and the interface box 'on' port doesn't allow
you to vary speed.)
Having said that, I wanted a cheap AC-adapter-to-lego thing that would
allow me to change polarity and voltage (direction and speed), kind of
like the functionality of the controller to the lego train. So my first
question is this:
1) Does lego sell the train controller separately, and for how much?
Next...
I drilled two holes in the battery pack and added a 100K pot and coaxial
DC power jack. It works pretty well, but I noticed something. The lego
motor goes from full power to totally stopped in only 30 or 40 degrees
of rotation of the pot (out of 300 degrees).
So...
2) Is something wrong? When I look at the voltage it looks like a
pretty linear decrease for the full rotation, and I was under the
impression that the standard lego speeds (1-8) corresponded to equal
decrements of voltage out of 9 volts. I guess not(?)
That's all...
Thanks for help in advance.
-Ben
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