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Thread: Planning first prop; need review

  1. #1
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    Default Planning first prop; need review

    OK, I'm planning my first prop and would like a quick review of my concept.

    I'm more of a halloween person, so that is where I am starting. I saw the spider on Nick A's youtube channel (https://m.youtube.com/watch?v=zSO9DRM1eSY), and want to take it to the next level. Basically, I am planning to use RGB bullet pixels inserted into PVC pipe, and control it as though it were a 360 degree, 8 strand "mega tree".

    I'm planning to get 5V "promotional" pixels from Ray Wu (https://www.aliexpress.com/store/pro...2d9f956dRCQSZE). These are 50/string, and I'd get 8 strings, one for each leg. These will be daisy chained together, and power inserted using 3-2-3 T cables. So there will be 1 "universe", or string of 400 lights (plus an extra 32 for the eyes). If all the lights were on at the same time at full power, I'd need about 30A, which at 5V is 150W power supply.

    I believe the high level approach I need to follow is:
    1) Create a sequence in lights on my desktop computer
    2) Sneakernet the sequence to an RPi running Falcon Pi Player
    3) The RPi is hooked to a Falcon PiCap (can control 2 universes at 800 pixels, I'm only using 1 with 432)
    4) Lights on first leg are hooked to PiCap

    I know there are many possible workflows, but is what I have outlined above complete and correct? Have I missed any links? Is there a "better" or more "recommended" way?

    I'm also planning to "interlace" the pixels in the PVC by inserting a pixel into every other hole on the way down, then filling in the gaps on the way up. This allows me not to have to create a return signal all the way back up the leg. With 5" spacing between the pixels, this should easily allow for 2.25" effective spacing, of >9' of effective length, which should be good for each leg. I may go with tighter spacing later to increase the density at the expense of overall height. I assume that xlights has an option to control lights wired in this manner.

    I'm planning to have this as a standalone prop. The brains would be in an enclosure on the back. Inside the enclosure would be a power supply, the RPi, and the PiCap. The only inputs to the enclosure would be a power cord. There would be 8 outputs from the enclosure. (1x) 3-wire output to the first leg, and (7x) 2 wire power outputs that would connect into the 3-2-3 T cables.

  2. #2
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    Default Re: Planning first prop; need review

    Quote Originally Posted by Dougw View Post
    So there will be 1 "universe", or string of 400 lights (plus an extra 32 for the eyes).
    Just to not send you down the wrong terminology path. You will have 2.5 universes.

    Quote Originally Posted by Dougw View Post
    2) Sneakernet the sequence to an RPi running Falcon Pi Player
    No need for sneakernet if you put WiFi on the pi and can hit your home network. I would strongly suggest you have some way to get to the pi while it is installed in your prop.

    Quote Originally Posted by Dougw View Post
    (can control 2 universes at 800 pixels, I'm only using 1 with 432)
    Just that terminology thing again. Two outputs at 800 pixels.

    Quote Originally Posted by Dougw View Post
    I assume that xlights has an option to control lights wired in this manner.
    It is oh so close to a 8 string, 50 pixel, 2 strand per string mega tree. But you might want to create a custom model with sub models so you can more easily run down the leg and back up, run down the leg and back up in "natural order", alternate between the first half and second half of the leg, light the the ends of the legs, light the tops of the legs, etc. It will be a little work to setup but will make the effects more effective.

  3. #3
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    Default Re: Planning first prop; need review

    Many thanks.

    Note taken -- universe = 512 channels, which for pixels at 3 channels/pixel is 170pixels/universe. For my outlined design with 432 pixels that is the 2.5 universes you mentioned.

    I will also make sure to put the pi on my network. That is at the "next" level of detail, but will be important when I go to figure out which Pi to purchase.

    I'll play around with XLights soon, but I believe I understand what you are outlining. The model with submodels will act just like a tree model and can accept the same effects. Each submodel would be created like "n1s1 n50s1 n2s1 n49s1 ...", ""n1s2 n50s2 n2s2 n49s2 ..." ... I could then also create the eyes as circles based on "n1s9 n2s9...n16s9" and "n17s9 n18s9 ... n32s9".

    The other option would be to change my planned layout to more closely match a typical "mega tree". This would simply involve a direct stringing of pixels, but add in a long return extension line from the bottom to the top. Not really that much more work, since I could run this cord inside the PVC.

    Thanks again.

  4. #4
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    Default Re: Planning first prop; need review

    You do not want to interleave your pixels. You are not going such a large distance. Just run the return wire inside the pvc. While you can do such a thing, the patching you will have to do to make it work properly will leave your fingers (not to mention your mind) numb.


    2018 - Moving and going to visit my Daughter in New Zealand. Most likely I will be dark or nearly dark, Some static stuff that is simple to put up.

  5. #5
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    Default Re: Planning first prop; need review

    FYI I bought some of these pixels and they use smaller gauge wire then 18awg. I think someone asked and they are 22awg. Powered from one end I get some pink at the end of the string with 100% white. May not be a problem since you will probably never go 100% white. If that might be an issue you can get pixels from Ray that use 18awg for $3.50 more.https://www.aliexpress.com/store/pro...14936dc5pOrZCH

  6. #6
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    Default Re: Planning first prop; need review

    That is when you power inject every 25 pixels or from both ends.


    2018 - Moving and going to visit my Daughter in New Zealand. Most likely I will be dark or nearly dark, Some static stuff that is simple to put up.

  7. #7
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    Default Re: Planning first prop; need review

    Martin,
    What exactly do you mean by "patching"? I think I can drill the holes in the PVC and insert the lights from the back. I can understand the tedium/finger strain from this, but I don't think I need to cut the strand and patch it back together. I will have to wire the 8 legs together no matter how I wire up the legs.

    I also found a better search term for this. What I am doing is more like a spinner than a mega tree. Seaching for spinner pulled up this video, which describes the custom model with submodels: https://www.youtube.com/watch?v=-24vw9UGcwE
    Coaster,
    The wire guage may very well be why these are "promotion". I don't think I will be running all white, and as Martin suggested, I was probably planning to inject on every string. The nice thing about the lights I selected was they were the only ones I saw at 5" spacing, which makes the final length about right if I choose to go with interleaving.

    Lots of interrelated tradeoffs to estimate before I make my order.

    Thanks again everyone.
    Last edited by Dougw; 06-07-2018 at 12:27 AM.

  8. #8
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    Default Re: Planning first prop; need review

    I have a better idea of how to do a custom model with submodels. The trick for me was to search for spinners, not mega-trees. Here is a video that I think describes what was suggested above: https://www.youtube.com/watch?v=-24vw9UGcwE

    Yeah, I suspect that the reason these lights are "promotion" are at least partially due to the smaller gauge wire. However, these lights were the only ones I saw with 5" spacing, which is what allowed me to think about running in an interleaved manner and still have enough total length for a respectable spider (at least in my current thoughts). I believe people have asked Ray for custom spacing, but it would probably end up at the cost like you pointed out. Is the savings worth it? W/ 5V/18gauge pixels, I need to inject every 50, so I believe I need at least 4 injection locations. With the lights I was looking at, I probably need to 8 injections (at the start/end of each leg), which means 8 injections. I think I would go with a power distribution board in either case. So the cost differential is going to be in the extra 3-2-3 T's and the 2 core power wires. Another full cost trade would be to just go with 12V pixels, and I may not need a power board at all.

    Martin,
    What exactly to you mean by "patching"? I know that I have to join each leg together, but I don't see any difference in cutting/joining between running the pixels straight down the leg, and interleaving. Can you please elaborate?

  9. #9
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    Default Re: Planning first prop; need review

    Quote Originally Posted by MartinMueller2003 View Post
    the patching you will have to do to make it work properly will leave your fingers (not to mention your mind) numb.
    Martin,
    What exactly do you mean by "patching"? I have read about the monotony of inserting pixels into PVC, but that will be the same amount of work interleaved or straight. I don't see why interleaving would cause me to cut the string and patch it together any more often that running it straight either. Please elaborate when you get a chance.

  10. #10
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    Default Re: Planning first prop; need review

    patching is what you do to tell your sequencing software about the silly things you did with the hardware. To make an effect, the sequencing software needs to think about those pixels as being sequential (for a chase etc) yet you have wired them in a way that is not sequential at all. lets use a 20 pixel string wired the way you are proposing. you will somehow need to tell the software that the pixels next to each other are arranged like this:

    1,20,2,19,3,18,4,17,5,16,6,15,7,14,8,13,9,12,10,11 .

    To do this you need to create a map on the sequencing software between how things look and how you wired it. In Vixen three you would handle this by manually mappping 'patching' each pixel. If you did not do the interleave, then you can map the entire string in a single operation.


    2018 - Moving and going to visit my Daughter in New Zealand. Most likely I will be dark or nearly dark, Some static stuff that is simple to put up.

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