Subject:
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Re: 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 11:45:35 GMT
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Viewed:
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1121 times
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On Mon, 25 Jan 1999 05:03:00 GMT, Ben Erwin <berwin@tufts.edu> wrote:
>
> 1) Does lego sell the train controller separately, and for how much?
Yep. Some sets (like 4558 - I got mine from a second hand 4558 I
bought with the controller, and traded for a Mindstorms without :) )
come without the controller, and you have to buy it separately. I
believe MSRP is arounf $50 or $40, but you can often find them for $20
or less in clearance season, i'm told.
> 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(?)
This is a pretty standard behavior for motors: they need a certain
voltage to work at all. I justr read 5 messages ago, that the RCX uses
Pulse Width Modulation for their motors (PWM), so that for speed 7,
it'll be on for 7 ms, off for 1, etc. If you use the train controller
to drive a Technic Motor (i have a really large helicopter as display
model, the rotor-blades alone are 70 studs long), it scales pretty
well from 0 to completely running, in an easy to adjust box. One
caveat: I've opened up the train controller, it decreases the speed in
steps, not stepless like with a pot. (It has the knob and the surface
under it basically like most cheap multimeters, if you've ever opened
one of those) --- Well, i have to go, so I can't finish this right
now. Reply if you have any questions :)
Jasper
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