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Subject: 
Re: Grade Crossing Signal Thingy...
Newsgroups: 
lugnet.trains
Date: 
Thu, 16 Dec 2004 21:27:19 GMT
Viewed: 
4233 times
  
> 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)

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.

> 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!)

Right, I'd think you'd need a lead time of around two baseplates or more, lest
those poor minifigs wander across the tracks...  :^)

> Xposted to lugnet.robotics as there are a lot of resources there as well.
> 
> Hope that helps.

Thanks again!

-Stefan-



Message has 2 Replies:
  Re: Grade Crossing Signal Thingy...
 
(...) In fact for realistic operation (if you really want that!) you'd need 4 sensors, because the "exit" sensor is much closer to the crossing than the "entry" sensor in real life. But who wants realistic? This is LEGO! ROSCO (22 years ago, 16-Dec-04, to lugnet.trains)
  Re: Grade Crossing Signal Thingy...
 
(...) Yeah, I am not too crazy about modding LEGO either, but there are some mods that are fine by me. Chris's read switches are just such a mod. His crossing gates are awesome, and the read switches that control them work very well. I just I (...) (22 years ago, 28-Dec-04, to lugnet.trains)

Message is in Reply To:
  Re: Grade Crossing Signal Thingy...
 
(...) 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 (...) (22 years ago, 16-Dec-04, to lugnet.trains, lugnet.robotics)

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