Different way to do detection....

crusader27529 Mar 10, 2016

  1. Sumner

    Sumner TrainBoard Member

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    Quite impressive.

    Sumner
     
  2. crusader27529

    crusader27529 TrainBoard Member

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    Thanks......I should have it installed in my new club layout in some months, but that's out of my hands as far as timing is concerned, as we're constructing a new building and a new layout. I have no idea when it'll be ready to actually lay track and do wiring. Currently, the roof isn't even finished.
     
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  3. olequa

    olequa TrainBoard Member

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    I use simple SMD phototransistors as detectors. Yes they are sensitive to ambient radiation. But they are naturally shaded by a car body when that would be an issue. They are triggered by darkness. The only radiation that they receive at the critical time is from the single illuminator on the other side of the rail. I don't see how ambient can be an unresolvable issue. It has not been in tests so far.

    The detectors I have used so far have been 0603 size but I will have to switch to 1206 since that is what JLCPCB has for assembly off the shelf. Should still work.

    George
     
  4. olequa

    olequa TrainBoard Member

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  5. crusader27529

    crusader27529 TrainBoard Member

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    I had decided that saving the granularity ot the state level wouldn't be an issue in the real world, because if one of the state machine status was lost, the Force Block Clear (FBC) is available if needed. The frequency of needing the FBC is minimal in my experience.

    The primary reason for saving the state (actually just the count of things/wheels/cars in a block, so that if the layout was shut down at the end of use, the rolling stock would specifically NOT be required to be cleared. Maybe on very large, strictly operating layouts that's what's done, but the vast majority of layouts would most likely not be run that way.
     
  6. olequa

    olequa TrainBoard Member

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    Here is a photo of the PCB that contains detectors and emitters as obtained from JLCPCB.com. Five of these boards for $2 with excellent quality. Unfortunately I have to cut these out somehow because they can't panelize to these small dimensions. I have done a few by hand and one is shown in the foreground. It is about 4x25 mm and that's too big in the 4mm dimension. Of course these are unpopulated with components so it may be more of a struggle to cut them with the components mounted as they would be close to the edge. I submitted another order today with several different configurations that may be easier to deal with. One of the new configurations uses side looker sensors which will allow the board to be mounted flat rather than on edge. That may be a more flexible way to go as it allows the board dimensions to be larger.

    George

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