BN Ottumwa Subdivision

John Raid Dec 31, 2020

  1. John Raid

    John Raid TrainBoard Member

    I moved a little east of the Mississippi bridge and decided to replace the cardboard HWY 34 overpass with styrene. I scratch built the bridge from some 0.040" sheet and 5/32" I-beams. I put BLMA k-rails down the middle. You can't tell it from this angle but the road is curved, super elevated, and arched. I still need to make the support piers.

    I masked for the stripes an used reefer white and UP Armor Yellow. I've finally decided I'm sick of trying to spray acrylics and bought some Tru-Color. This seemed like a good project on which to try it out. I like it. It took a little futzing with but once I thinned it enough I was pretty pleased. It doesn't cover quite as good as Floquil used to but it dries quick, doesn't stink too bad, and most of all doesn't clog my airbrush and splatter. I also still need some gravel shoulders and guard rails. And I really really need to do my photo backdrop.


    I also built a signal for the other end of the Connett control point. It's a Showcase Minutures kit. I'm not sure I did it justice. They are nice kits. Of course I tested the lights at each step and once I installed it the bottom red doesn't work. Arg. I'm hopping it's a cold solder joint? I'm not real excited about replacing the LED.

    Now I have to do the one for main track 2. All told the signal took me about 15 hours, 3 of those were trying to shove 7 40AWG wires through a 0.035" OD brass tube, 3 for each light and 1 for my IR emitter on the mast for the detector. The mast is +3.3V supplying the anode of the LEDs. I'm not sure it's actually possible to get 7 wires through the tube, but the next one I'm going to start with the wires at the bottom and feed them out through the side hole and then solder them to the LEDs.


  2. HemiAdda2d

    HemiAdda2d Staff Member TrainBoard Supporter

    Superb signal work.
    John Raid, BNSF FAN and badlandnp like this.

    BNSF FAN TrainBoard Supporter

    Signals look great and so does that highway!(y)(y)(y)
    John Raid likes this.
  4. John Raid

    John Raid TrainBoard Member

    Thanks! So there's at least as much under the layout as there is on top. The signal LEDs are driven from an i2c I/O expander based on an SX1509 breakout board. There's room for the other signal on the near connector. I have one of these for each end of the control point.
    i2c signal head driver.jpg

    The I/O board is driven by a Teensy 3.1/3.2 from PRJC. I mostly just solder on connectors to interface to detectors, signals, and panels. I wrote a fairly simple Arduino program to read and write bits based on Michael Adams's excellent ArduinoCMRI library. Note: the code is pretty specific for my layout in the event the JMRI isn't running so the signals use local panels and detectors. Regardless when it's talking JMRI it's just a bunch of inputs and outputs.
    Teensy Pinout.png

    I designed and built my own IR detector boards. They filter out 60Hz and provide gain with a threshold adjustment so the detectors work the same with layout room lights off or on. Each board can interface 3 detectors to a Teensy data concentrator. I also use them for turnout position.
    IR detector.jpg

    The C/MRI bus is on the back is RS485 and interfaces with a breakout board. I modified them to allow me to connect ethernet cables from one to the next around the layout. They are also powered from a 12V accessory bus with some small regulators I found on Ebay.
    Teensy data concentrator.jpg

    Finally JMRI running on an old laptop provides the logic reading all the panel positions, turnout positions, IR detectors, and other signals to generate the correct logic for each signal.
    JMRI signal config.jpg

    Now to figure out why my red LED doesn't work. It wasn't a cold solder joint Ugh.
    Last edited: Apr 2, 2021
  5. mtntrainman

    mtntrainman TrainBoard Supporter

    You guys that do all this fancy electronics stuff are just amazing ! (y)
    It's all 96% Greek to me...although its still somewhat easy to understand. :)...:coffee:
    Like I's amazing what you guys accomplish electronically (y)(y)
    badlandnp, BNSF FAN and John Raid like this.
  6. Shortround

    Shortround TrainBoard Member

    I agree.(y)
    Back in the late '80s and '90s I help wire the big layout and some computers. But, there wasn't any of this DCC stuff.:confused: But now that's what I have for power.
    John Raid likes this.
  7. John Raid

    John Raid TrainBoard Member

    Over the weekend I got the other signal built. It went much better than the first one. I had to pull the first one off the layout and found out I had one broken wire and one shorted. After repairing it I decided to protect the bottom where the wires came out of the mast with a dab of crystal clear. I was able to get all 7 wires to fit in the second one and had no issues.

    As far as JMRI they work great with detectors and following the next signal but I can't figure out how to get them to show diverging routes. Well I got is set up using Logix and it works once and the goes batty. I think there are bugs in Logix (as noted in the release notes). I don't really want to become a JMRI developer.

    I think 3139 passing the signals makes for a nice scene. I modified that Kato GP50 from a phase I to a phase II back in 1994 including building an angled blower housing out of brass. If only it ran as well as it looks.

    BN3139 Eastbound at Connett.jpg

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