DCC Track Sensor Positioning Advice

TrickyZXR Apr 18, 2021

  1. TrickyZXR

    TrickyZXR New Member

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    Hi, New to DCC and have built the layout below. I have placed some sensors on the layout but not on actual board yet in entries of sidings and at the end as a stop sensor.

    My goal is to be able to send a loco from one location to another or just run around for a few circuits and at a later date be able to monitor which loco is exactly where on my layout at any given time. I am using an Arduino Mega so have quite a few digital and analogue inputs as well as outputs for turnouts.

    I was wondering if anyone can advise me if these are correct positions and also where else I should place them please?

    Thanks in advance for any suggestions.


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    Shortround likes this.
  2. Shortround

    Shortround TrainBoard Member

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    Interesting. I think I'll be following along. Back in the '80s and '90s I was into basic electronics, mostly computers. But not much since '04 but wanting back into it, if possible.
    Though your layout could make me dizzy! :eek::LOL::LOL:
     
  3. sidney

    sidney TrainBoard Member

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    i got dizzy looking at that one too. hahah
     
    BigJake likes this.
  4. TrickyZXR

    TrickyZXR New Member

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    Massive help NOT!!!
     
  5. BigJake

    BigJake TrainBoard Member

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    You haven't said what kinds of sensors you have, and what you want to be able to do automatically. That has a lot to do with how many sensors you need, and where they need to be placed.

    What are your eventual goals? Do you want to be able to run the layout and trains completely automatically, or is some manual intervention OK?

    Without such information, nobody can give you useful suggestions for where sensors need to go, and probably why nobody has responded with the information you sought.

    Most people start out with sensors to control track signals, which can begin to support some automation. Some want to go full automation which requires smarter signals (tell you what is there, rather than "something" is there) and/or much smarter computing.

    Your Mega can probably handle polling sensors and reporting to another computer running JMRI. You might also try looking into commercial systems that are similar to what you want, and reading their documentation to get ideas.

    I would start with a MUCH less ambitious track plan (say a simple oval with a couple of spurs), and try making that work like you want, before adding and handling a passing siding, etc., then adding more complexity.
     
  6. TrickyZXR

    TrickyZXR New Member

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    Hi Thanks @BigJake for feedback and comments. I thought by using the word sensor it doesn't really matter if they are iR or current sensors but guess it does.

    1. Sensors are TCRT5000 Infrared Reflective Sensor Module with DO & AO outputs
    2. All trains, points to be run automatic
    3. Would like to be able to identify where each train is and what it is but don't want to go down the route of RFID. If not possible then will leave for later
     
  7. Chris Hall

    Chris Hall TrainBoard Member

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    Hey mate,

    I had similarly ambitious plans like yours to have a fully automated layout using a combination of IR, Reed and CT sensors for complete "hands off" operation and realised it is currently beyond my capability, so I've decided to tone it down a little.

    Unfortunately with the search function down your best bet is to google the crap out of it and read as much information as you can find. Each sensor has its own good/bad points and everyone has a varied opinion on which is best. The majority of my sensors are reed as I can fit them in-between the rails on my N scale layout, versus the IR sensors which were just a little too big. Down side is I have to fit a magnet to the underside of each loco.

    From what I could gather, for automated scripts it is best to group sensors in to three's, so the system can determine direction of travel, especially if it is on a loop. When I build my next layout I will do exactly as @BigJake suggested and start with a simple loop and build from there, learn about how the sensors interact with JMRI and how to design scripts to run the automation.

    As for identifying trains and locations RFID seems to be the best option for this, especially with the microdot's you can buy now. In theory you could dot every wagon and loco you have and know where it is. Not sure how you could use an IR sensor to uniquely identify a specific vehicle, I guess you would need some way of barcoding the information from the sensor.
     
  8. BigJake

    BigJake TrainBoard Member

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    In theory, if properly initialized with the trains, their sizes and locations on the layout, SW which is controlling the trains and layout could (given adequate sensors) "keep track" of the trains as they move around the layout, past various sensors, and therefore know which train is where at all subsequent times. The more complex the layout (in terms of different routes through it), the more difficult it becomes to keep track of everything.

    In practice...?

    If you're into AI, perhaps all you need is an overhead video camera watching the whole layout... Until the train enters a tunnel.
     
  9. Sumner

    Sumner TrainBoard Member

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    Never really looked into RFID before so thanks for bringing it up. Looks really fascinating. I found the following nice write up of using it on a HO setup but looks like you could make it work for N also....

    http://www.pcrnmra.org/pcr/clinics/RFID-in-Model-Railroading-20130123.pdf

    I'm not interested myself in automatic running but can see I might want some sensors for other situations and will keep it in mind,

    Sumner
     
    Chris Hall likes this.
  10. Chris Hall

    Chris Hall TrainBoard Member

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    My arduino kit came with an RFID sensor and a couple of keys so I looked into whether it was feasible to use on the layout. I remember spending a lot of time googling it and found both the PDF you posted and another club site that used RFID to ID all the Loco's and wagons to track club ones and private ones. The concept is great and I like the idea of tracking the location of a specific wagon but it was not suitable for my layout. At the moment the RFID sensors are quite large for N scale. I found that if you have two main lines running together it would pick up traffic on the other rail. I'm sure there are smaller sensors out there but I decided not to go that route so didn't bother to explore it further.
     

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