Working Diorama

Discussion in 'Tech Talk' started by Hermit, Aug 29, 2017.

  1. Hermit

    Hermit Member

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    Christian:
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    This thread is about reinstating old technology to operate a scratch-built model of a lift-span bridge. The old technology part is the operating console of an actual lift-span bridge in our Shire. This console was the original console installed in 1962, and replaced in 1995.

    Besides the console being antiquated, so am I. The last time I dabbled with electronics was thirty years ago. Because of this, I will be introducing old technology again to the console, but one that is to operate a small DC motors instead of industrial AC motors, servos and solenoids.

    This project was initiated by our local maritime museum. It acquisitioned the console and wanted it to operate a scale model of the bridge it came from. Word go around town that I was the antiquated person to assess the antiquated technology. I sure got sucked into that one.

    I said it was possible for the console to operate a model bridge. However, they had no model bridge or anybody to build one. I am not a model builder, let alone being up to scratch with electronics, but somehow I let myself to volunteer to see the project through to its completion. This is when I said a prayer, "God, please favour the bold and foolish".

    Here are photos of the actual bridge and its old console.

    Sorry about that but I cannot upload any .jpg photos no matter how small I make them.
     
    Last edited: Aug 30, 2017
  2. reba

    reba Staff Member Administrator

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    Christian:
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    can you take your photos to some place and load them from there

    Papa Zoom Nathan Nick i dont have the correct words to help Hermit .. you guys do :)
     
  3. Papa Zoom

    Papa Zoom Staff Member Moderator

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    Yes. Imgur.com. I have an account there and can post any image. I need to be at my pic and I can post instructions.
     
  4. Hermit

    Hermit Member

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    Thank you reba and Papa Zoom, I've got it now. I am using Flickr.

    Okay, here are the two images I promised.
    The lift-span bridge:
    [​IMG]

    and the old console:
    [​IMG]
     
    Last edited: Aug 30, 2017
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  5. Hermit

    Hermit Member

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    Christian:
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    I had trouble understanding some of the switch labels on the control panel. After speaking to the current bridge operator, he was able to enlighten me, as well as the procedures for operating the bridge. It's quite involved. It is not just a matter of flicking a switch to raise and lower the lift-span. Pedestrians, river and road traffic, have to be controlled before considering to unlock and raise the bridge. But I won't go into that unless you really want to know.

    The plans for the bridge are not available to the public, so I had to calculate the size of the bridge using two reference measurements. I measured the width of the road and the length of the span. From these two diagonal measures I was able to get a rough idea of the other measurements from photographs.

    The console schematic drawings are no longer available. Reverse engineering was required to understand the contact arrangements of the switches. Plans had to be drawn for both the bridge and console before I cold even get an idea what parts and materials I would need for the project. This part of the project took about a month.
    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    Below is a collage of some of my drawings for the model bridge.
    [​IMG]
     
    Last edited: Aug 30, 2017
  6. JohnDB

    JohnDB Staff Member Moderator

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    Christian:
    Yes
    Ok...
    You don't have to use electronics. "Ice cube relay" switches have "normally open" and "normally closed" positions you can wire them up with. These little jewels can even have a timer relay and a "latching" function if power goes out. (So it will remember where it was at when the power comes back on)

    And truthfully...it's what all electronics are based upon. And where I can make a 555 circuit out of a chip and resister (turn signal flasher)...I like the ice cube relays better.
    After all...they wanted "old school"...:thumbsup

    And I can't see any of the pics because I don't have Yahoo.

    Oh well.
     
    Last edited: Aug 30, 2017
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  7. Edward

    Edward Member

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    Christian:
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    I can't see them either.
     
  8. wondering

    wondering Member

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    I could see them.
    The colors are very pretty.

    (sorry to interrupt. I'm following along and am interested.
    Don't understand why the old system might be better...)
     
  9. Hermit

    Hermit Member

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    Can you see them now? I just replaced them with images from Imgur.com as recommended from Papa Zoom.
     
  10. Hermit

    Hermit Member

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    I am using 'ice cube relays' but not basing the electronics on them. I spent a long time trying to get the relays to follow the complicated sequencing of operating the bridge, and at the same time being child-proof (out of sequence switching). But it proved impossible without having to use enormous amount of relays. So now I am going to use logic circuits for gating and latching. Using minimal amount of relays and mainly for the end stages where more amps get switched around.

    I decided to use a simple two transistor flip-flop circuit for the flashing amber traffic lights as well as a 15 second delay on the switching from amber light to red stop lights. I like the 555 timers, but not in this case.

    Actually the museum president want me to use microprocessor modules such as the Raspberry Pi. But it is me who wanted to use the old technology (not valves, but logic ccts and transistors) so I don't have to spend too much time learning the to program them. I promised myself to play around with them after this project.

    Thanks for your input.:thumbsup
     
  11. Edward

    Edward Member

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    Christian:
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    I can see them now. :)
     
  12. Hermit

    Hermit Member

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    Christian:
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    It is not an interruption to ask a question (not with me anyway).
    The old system might be better for me, because I am an old system.

    The console, externally, with be preserved with the antiquated look (rusty but cleaned up). This means that all the switches and panel lamps, on the control panel, will be used in operating the model bridge. The electronics, the electrical circuitry, will be not so old, but understandable for me. The important thing is that the system has to run on low voltage direct current (DC) as opposed to, how it used to run on, lethal high voltage alternating current (AC). This is for safety reasons.

    Hope that has answered your question, wondering. ... No pun intended.
     
  13. Hermit

    Hermit Member

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    Great!
     
  14. JohnDB

    JohnDB Staff Member Moderator

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    Christian:
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    This sounds like a great project.
    Ice cube relays can operate on low voltage (12v ac or dc) and switch low voltage or high voltage. All in what you ask for. And pretty much anything is possible with a small transformer bought to specifications and a bridge rectifyer so you can actually plug in your model to the wall and not use batteries.

    And as far as computerized/electronic control....
    They sell all kinds of systems these days with up to 24 input/output terminals which will program with nothing more than a mouse from your computer.

    The days of XIC and XIO are almost gone anymore.

    (I kinda specialize in motor controls as an industrial/commercial Electrician. I end up doing a ton of special lighting controls these days as so few understand how to make them work)
     
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  15. Hermit

    Hermit Member

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    Thanks John. I have already designed and built the DC Power Supply Unit. It has three outputs, with an option of an extra one in case I need it. They are +24v@2A, +12v@2A, and +5v@2A. The 24v is for panel lamps and at least one relay so far. The 12v is mainly for relays and tow DC motors. And the 5v is for the logic circuits and servo motors. You will see these shortly.
     
  16. Papa Zoom

    Papa Zoom Staff Member Moderator

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    Nice! I like imgur but can't figure out how to use it on my ipad. The app isn't very good. But I love the site because otherwise it's easy to use.
     
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  17. Nathan

    Nathan Staff Member Tech Support

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    Looks like Papa got you hooked up with the images. :)

    On the side note, if it were me, I would introduce a small(but very large improvement) change into the system. I would use a PLC to operate all the controls, but have the 'old school' switches/lights to be the inputs/outputs. The PLC would be hidden, so it would look like and operate just like it had relays. It would make things very simple and you would have a fraction of the wiring to do. With todays technology, you might even be able to save money on the PLC vs relays and such.
     
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  18. JohnDB

    JohnDB Staff Member Moderator

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    Christian:
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    I believe that is what he is doing.
     
  19. Papa Zoom

    Papa Zoom Staff Member Moderator

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    Just like the bridge, this tech talk is over my head. :lol
     
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  20. Knotical

    Knotical Staff Member Moderator

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    Christian:
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    I know a quick way to fix that problem. Lay your ipad on a sturdy table. Go find the largest hammer you can find. Vigorously smite said ipad until thoroughly transformed into the sum of all its parts.
     
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