MODELING It's Monday, September 14th 2020: Weekend Modeling Accomplishments

Jim Wiggin Sep 14, 2020

  1. Bookbear1

    Bookbear1 TrainBoard Supporter

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    I got a solid five hours on the smaller layout Sunday. Some time ago I removed a small fruit and vegetable stand from the larger layout and saved it for use on the smaller one, which has a couple of vacant areas. The first job was to clear the trees and undergrowth in an open area next to the motel

    The Salmonella Bros. building was placed
    Produce stocked and customers added

    And finally a tree replanted

    Still to come is a freight loading dock for the rear of the building and wooden fence close to the tree, both kits on order.
     
  2. BoxcabE50

    BoxcabE50 Staff Member TrainBoard Supporter

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    "Salmonella Brothers". Love it! (y)(y)(y)(y):ROFLMAO:
     
    Kurt Moose likes this.
  3. rray

    rray Staff Member

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    Yay! I figured out what my grief with the Tortoise / Hare combos are... My Hare's seem to be failing. So I measured the tortoise outputs on the failed ones and get almost 0V unloaded. I tested the good ones and I get 10.5V unloaded. When I toggle the Hare, the voltage goes to -10.5V on a good Hare.

    Next I measured every pin on the PIC16F636 chip with pin 1 on J5 (the tortoise motor connector) and could not find either + or -10.5V, then I measured the LM358 dual op amp, and found -10.5V on pin 7. Looking up the dual op amp, it gets inputs from the pic and outputs on pins 1 and 7. Measuring the voltage at pins 2 and 3, the voltage goes from -2.5 to +2.5 when toggling the Hare, and the voltage on pins 5 and 6 (the other op amp in the package) goes from +2.5 to -2.5. So the working Hare toggles op amp outputs from -10.5 to +10.5, and the bad Hare's measure 0V output. I just need to replace the LM358 op amps to repair the Hare's.

    I got 50 pieces ordered of SOP-8 packaged LM358's for $8 from Amazon to repair my bad Hare's, which I have 3 of so far. A replacement Hare costs about $30, so I can repair all of them for 1/3 the cost of one replacement. :D
     
  4. Bookbear1

    Bookbear1 TrainBoard Supporter

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    RRAY, I am in awe of your troubleshooting abilities!
     

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