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Subject: 
Re: Automated shunter/switcher
Newsgroups: 
lugnet.trains
Date: 
Wed, 21 Mar 2007 14:17:39 GMT
Viewed: 
4228 times
  
In lugnet.trains, Matija Puzar wrote:
   So, I got this idea of making an automated shunter for our group’s exhibition layout, it would be a nice eye catcher and a great oportunity for the big trains’ motors to rest and cool off. In the simplest version, it would just come to a bunch of parked cars, take them to another location, park them there and then go away somewhere and give place to the big trains.

This is most probably not a new idea, but I haven’t seen any solutions so far (if I missed them, I apologise).

So, a few problems arise:
  • Detaching the cars from the locomotive - anyone with some clever and proven ideas? :) A mechanical arm coming in between and separating the magnets might be a solution, but it would be hard to make it unnoticable. It would also be a problem with regards to the number of motors needed if I’d want to be able to shuffle the cars automatically, i.e. sometimes take 1, sometimes 3, etc. An electromagnet would be also an idea, but hard to implement for more than just the locomotive (also, it might prove to be a heavy burden for the DCC decoder and funny things might happen if the engine loses power in the middle of the loop :)).

I built a powered decoupler from somebody else’s instructions quite awhile ago. A quick search brings up this LUGNET thread that might help you...

http://news.lugnet.com/trains/?n=19117

  
  • A lot of reed switches will be needed and multiplexing becomes a necessity. Has anyone been able to make a stable multiplexer for more than 3-4 sensors? If 3 is recommended, would you recommend the parallel or the serial version, or does it boil down to the same? I tried making one for 4 sensors, but soon found out how problematic it gets if the resistors are not extremely precise.

I have multiplexed up to 4 reed switches using four different resistance values in series with each switch, but it is tricky. (I used something like ~1K, ~2K, ~4K, and ~8K with 5% and stock resistance values, IIRC.) You usually have to calibrate the code to match the actual sensor value ranges that are returned from your particular setup. But you should be able to make this work using a single reed switch located right at the decoupler. Just use low speeds to count passing couplers, and be prepared to make some slight forward-backward micro-adjustments at a crawl. I think some of the GBC train modules use this technique.



Message has 2 Replies:
  Re: Automated shunter/switcher
 
(...) The one I always liked the best (can't find it right now... ah, here it is I think) was Gronk: (URL) not built it yet because I don't use LDCC or have an RCX on-board a train, but the idea is nice. And with those IR-controled Power Function (...) (18 years ago, 21-Mar-07, to lugnet.trains)
  Re: Automated shunter/switcher
 
(...) why not just keep it simple? build the decoupler into the switcher, put a touch sensor on the side or bottom and use it to trigger a program that is something like this: forward untill touch sensor depressed "ie attaches to train cars" stop (...) (18 years ago, 21-Mar-07, to lugnet.trains)

Message is in Reply To:
  Automated shunter/switcher
 
So, I got this idea of making an automated shunter for our group's exhibition layout, it would be a nice eye catcher and a great oportunity for the big trains' motors to rest and cool off. In the simplest version, it would just come to a bunch of (...) (18 years ago, 21-Mar-07, to lugnet.trains, FTX)

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