Subject:
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Re: Grade Crossing Signal Thingy...
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Newsgroups:
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lugnet.trains
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Date:
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Sat, 18 Dec 2004 02:17:51 GMT
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Viewed:
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1360 times
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> First, how do you protect the motor? In this particular design it looks like
> you could actually rotate the arm past vertical, which I guess isn't a problem
> until you hit the ground on the other side. Or, if you were to go the other
> way, you could lower the arm instead of raising it, again smashing into the
> ground. At that point, if you don't let up quick, aren't you going to strip the
> motor?
The way that my design ended up, that isn't an issue. The arm just goes up and
down as the wheel/motor rotates. It doesn't go past horizontal or vertical
positions (by luck, not design :^) )
> This might not be a problem for AFOLs, but I'd like to have some things like
> this on a layout that would be played with by my 4-year-old, so it needs to be
> robust to abuse. Should I always go though a clutch gear? Or is there some
> other clever trick to cut the power to the motor when it goes too far?
>
> A similar question applies to those nifty motorized track switches I see used at
> shows. There, even with an adult operator, it looks like it'd be easy to hold
> the button down too long and end up frying the motor. Why isn't this a problem?
There's a weak spot in my signals above the lights, but other than that, they're
rugged enough to endure the motor going crazy on 'em. I can't speak for the
switches, I've never made any.
> Next: when controlling a crossing like this from an RCX, is cumulated error a
> problem? I'm talking about imprecision in the position of the arm after many
> up/down cycles. I don't see a rotation sensor on this unit, so how does the RCX
> know exactly where the arm is? Or is the RCX/motor combo so precise that this
> isn't a problem?
The RCX is fairly accurate it seems, but the motor drive shafts have a tendency
to spin down after power is cut. I'm still trying to figure out how to get
around the cumulative error problem, as mine doesn't have a stop built into the
motor disc like Ross suggested.
> (Told you they were newbie questions!)
I'm a relative newbie myself, it's all good.
Hope that helps!
-Stefan-
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Message has 1 Reply:
 | | Re: Grade Crossing Signal Thingy...
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| (...) Try braking. This is from memory so might be all wet... If you just turn power off, the motor coasts to a stop. But supposedly you can send the motor a speed 0 command, I think, and the motor stops right then, frozen in place. It takes more (...) (20 years ago, 18-Dec-04, to lugnet.trains)
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Message is in Reply To:
| | Re: Grade Crossing Signal Thingy...
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| I have a couple of newbie questions about things like this. First, how do you protect the motor? In this particular design it looks like you could actually rotate the arm past vertical, which I guess isn't a problem until you hit the ground on the (...) (20 years ago, 17-Dec-04, to lugnet.trains)
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