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In lugnet.trains, Stefan Garcia wrote:
> Magnets, righto.
>
> How do I do that?
>
> I've spent most of today trying to put together a program for a pressure pad
> triggered setup, haven't had any sucess. Same with a light program. I don't
> have any idea how to use magnets. Do you have a program I could use for the
> magnets, or pics of their construction?
You'll need more than a program, you'll need to make sensors of some sort, as
sensors that detect magnets are not on offer from LEGO. Chris Phillips made some
(reedswitch based, I think) sensors, and documented what he did. it requires
some surgery.
Here's a post to get you started searching on how to construct magnetic sensors:
http://news.lugnet.com/org/ca/rtltoronto/?n=7337 (Chris's writeup)
Once you have the sensors though, the program that you would need to create is
similar to that used to detect touch sensors as I understand it. you probably
will need debounce logic for best results, although maybe not. What you really
want is for the gate to stay up some seconds after the last time you saw a touch
(or magnet reed switch closure), and then go down, till the next time you see a
touch sensor.
For bidirectional operation, you will need two sensors, one for each direction
of travel (so the gate has time to go down BEFORE the train hits the crossing!)
Xposted to lugnet.robotics as there are a lot of resources there as well.
Hope that helps.
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Message has 2 Replies:
 | | Re: Grade Crossing Signal Thingy...
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| (...) I know Lego doesn't make those sensors. The first post in that thread though is exactly what I was looking for! Thanks! I'm not too crazy about modding Lego so I'll go with the pure version. (...) Right, I'd think you'd need a lead time of (...) (20 years ago, 16-Dec-04, to lugnet.trains)
| | | Re: Grade Crossing Signal Thingy...
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| (...) Check the previous posts on (URL) the motorized cows. These use optical sensors to trigger cow head moooovement...I'm sure they could activate a level crossing using the same RCX optical detection scheme. -Rob A. (20 years ago, 17-Dec-04, to lugnet.trains, lugnet.robotics)
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Message is in Reply To:
| | Re: Grade Crossing Signal Thingy...
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| Magnets, righto. How do I do that? I've spent most of today trying to put together a program for a pressure pad triggered setup, haven't had any sucess. Same with a light program. I don't have any idea how to use magnets. Do you have a program I (...) (20 years ago, 16-Dec-04, to lugnet.trains)
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