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Thread: Individually addressable led strips, over a larger distance? (for use on stage)

  1. #1
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    Individually addressable led strips, over a larger distance? (for use on stage)

    Bear with me as I'm a complete programming/arduino/teensy noob, And even though I have done quite some research I'm totally inexperienced...
    I do hope you could help me with our project though!

    The idea
    We want to make multiple fixtures with the 'Infinity mirror' effect that we can mount/put up on stage and have addressable RGB leds.
    (probably starting with two... or multiple smaller ones)
    Something like this:
    Click image for larger version. 

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    Controlling them

    I would like to control them with a program like Glediator, Jinx or Pixelcontroller or another pixel mapping application from a laptop.
    I'd like to control them from the side backstage, or from the sound/light booth, since I wont be the performing myself.

    Also, as opposed to most projects I've come across with the Teensy and Octows2811 library/adapter, there would be quite some distance between the different led strips/fixtures...
    This is a really quick mockup of a possible shape/setup:
    Click image for larger version. 

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    This guy has a pretty cool setup:


    Artnet right?
    I'm pretty sure working over Artnet/Ethernet is preferrable over USB, considering the longer distance and I might want to expand the amount of leds or add other dmx/artnet fixtures in the future...
    So I've taken a good look at this thread: https://forum.pjrc.com/threads/24688...-to-OctoWS2811
    Unless there's something I'm overlooking and theres a better option all together...

    Questions
    - How would I best go about connecting the fixtures with the controller and eachother?
    (I believe the guy in the video said in the description he used xlr cables to connect the leds... how would that work?)

    - Would it be feasible to work with standard led strip connectors/extension cables like these?
    Click image for larger version. 

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    - Also, does the length of wire that does not have leds impact the sort of power supply I should use much?

    - When everything is this far apart... does the Teensy need it's own power supply? Should I be using multiple power supplies for every fixture? (is that even a thing?)

    What I think I'm going to need
    Because our budget is kind of tight, I haven't ordered anything yet, even though I would like to experiment a little. But that's why I'm making this thread here, to try and find how to best tackle this project
    So far I believe I'm going to need the following:

    • A Teensy 3.x
    • An Octows2811 adapter
    • Wiz820io adapter
    • Wiz820io ethernet module
    • WS2811 or WS2812b led strips
    • A beefy power supply
    • Loooong cat5 cables


    I hope I'm not too off the mark or missed some extremely obvious tutorials or anything... but anyway, thanks for reading!
    Last edited by Yabbus; 11-09-2017 at 02:35 PM.

  2. #2
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    Probably first step is thinking LED numbers. OctoWS2811 is all about blasting lots and lots of pixels out (and keeping perfect sync_, and from your description you are talking 100s not 100ks of LEDs and are after effects, not actual images so quite possible fastled/or Pauls new single channel Octo variant may be the right hammer for this, so each prop has it's own controller, power supply and wiring harness and your interconnectivity turns into whatever lighting control system makes sense.

    It would be possible to have a single Octo board feeding two strips to each prop, but the signal length here would be marginal and you would only find out that it didn't work when it was finished. So suggestion would be to look at what you need for a single prop, and think about how this will tie to the rest of the stage. Artnet, MIDI and DMX are all fairly well supported systems that could be used to get data between the units so choice pretty much comes down to what you already have (so you can raid existing spare cables) and are comfortable working with.

    All the interface specs will constrain how many effects you can get into the infinity mirrors in some way so need some thought there.

    The number of LEDs will directly impact the power supply and wiring size so some careful thought there to limit how much current you need and save you a bunch of drama later with thumb size cables running around the place.

    Edit: Those cables will work for short lengths within the prop but would only be powering one to two meters of strip. With long leads you get noise, which impacts the signals but also voltage drop
    https://en.wikipedia.org/wiki/Voltage_drop
    in the cable. So you can have a short length of 1mm cable powering a strip, but roll of 30 meters of it leaves things running on 4 volts and colours all strange. Better idea is to have say 24 volt cabling and a DC/DC converter in each prop with some good sized filter caps to get a stable 5V supply. The 24 volt supply is both to give lots of headroom and because the DC/DC conversion steps voltage down and current up, so 10 amps at 5V draws just over 2 amps at 24 volts which cuts the cable loses.
    Last edited by GremlinWrangler; 11-10-2017 at 08:54 AM.

  3. #3
    Senior Member PaulStoffregen's Avatar
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    Running LED data signals over long distance is asking for trouble. It can work. I recently did a project with ~20 feet cables. But those signals aren't really meant to go a great distance. They're pretty susceptible to interference, ground voltage shift and other signal quality problems. This sort of gamble is better to make for an art installation where you can carefully control everything and test extensively on location. For a show where it'll be on stage with other gear you don't control, much riskier...

  4. #4
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    Thanks for the clear answers! Sorry I couldn't get back to y'all a bit sooner.

    So if I understand correctly, it would be better to make them independent objects.

    Each of them would contain:
    ---
    LEDs
    Controller (single channel Octo variant)
    power supply
    Wiring
    ---

    Would it then be possible to use an ethernet switch to connect both (or multiple) of them to my desired control device (which would be a laptop running an artnet compatible control program)?
    Like with DMX would I then have to set up the controllers/objects to have their on addresses?

    And then all the longer distance cabling would be ethernet cables, which handle artnet signals, and the LED data signals would only be inside the objects right?

    Thanks again

  5. #5
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    Keeping the LED signals shorter will make things easier certainly. One thing you will need to check is connecting artnet on ethernet to a Teensy which doesn't have built in ethernet support. There is an example in the OCTOWS examples, and there is also
    https://github.com/natcl/Artnet/issues/12 and many others firing the logical internet search.

    Both use https://www.pjrc.com/teensy/td_libs_Ethernet.html or the variants found around the internet at various prices and qualities as the physical hardware.
    The above will probably do what you want out of the box so make sure you budget some time for getting your Artnet config driving your LED config. The end result will be much more flexible than some of the more basic options though, especially if you are already used to working with artnet.

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