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2014 BIGW only display

Discussion in 'How is your display put together...' started by franky_888, Oct 6, 2014.

  1. franky_888

    franky_888 Apprentice Elf

    Dec 31, 2013
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    Hey all,

    After discovering how close to Christmas we are it's time for me to start putting my display together. I put everything I've collected over the previous year on a new workbench and it appears I had more than I thought!

    I have a couple of queries so I'll list what I'm thinking of doing and then my questions.

    So I can test the water this year, I'm planning to integrate all of my BIGW strings only into a 2811 display. I have purchased a P2 from j1sys and a 2811C30 from Hanson Electronics. I've also bought bits and bobs from Ray Wu including some strip and string, but I don't plan on integrating that this season.

    I'll be using a Raspberry Pi running Falcon Pi Player to run the display. The Pi has a wireless usb device connected to allow me to manage the display without needing to run a data cable to where I'm mounting the enclosures.

    I'm using the $10 special from Masters as my enclosures as I'm lucky enough to have one just down the road. I've cutout a thinnish piece of poly carbonate and used that as a mounting board. I've secured the circuit boards to the poly using motherboard screws. I plan on drilling some additional holes in the poly so that I can use some cable ties for strain relief.

    My display will be split over 3 enclosures, all mounted on a piece of ply and screwed to the wall of my house.

    Here's where the enclosures are at so far:
    Enclosure 1: 30v Ray Wu power supply, supplying to 2811DC30 and P2
    Enclosure 2: Housing Pi, P2 and 5v power transformer
    Enclosure 3: Housing 2811DC30 / LED string connections.
    My questions should anyone be kind enough to answer:

    - I know this question gets raised a lot, but it all seems to surround pixel strings. Assuming that each string could contain 600 LEDS, and that each string draws about 0.01A (10mA), this works out to be 6amps / string (3A / channel at full load. Do these strings need to be fused individually (they don't appear to be fused out of the box)? I found this page http://www.powerstream.com/Wire_Size.htm which suggests that 3.5A is the max (24AWG chassis wiring).
    - If the answer to above is yes, what would be the best approach for doing this through a 2811Dc30 (using a central fuse block? separate to the DC30 (so no +V connected on the board itself?))
    - Should I be fusing between the 30V supply and the 2811DC30 / P2?

    - Having an abundance of PC power cables at my disposal, I've been using individual wires

    - The enclosures will be mounted on a western wall under a verandah, so by the time the display turns on they may have warmed up a little. That being said however should I be installing a cooling fan/s? If yes, I was planning on tapping into the 5V supply for the Pi and stringing it to the enclosures.


    - I really only want to mimic the out of the box controllers for these strings this year, is this simple enough to do? Most of the sequencing seems to be geared toward songs so I don't know if it's easy enough to configure a simple loop of basic on / off / fade / twinkle etc.

    Thanks for taking the time to read and thanks again if you reply. Sorry if my terminology is off; still trying to soak up some things. So far I've really been enjoying working with wiring again, it definitely makes me respect some of the larger displays noting how much effort is actually involved.
  2. AAH

    AAH I love blinky lights :) Community Project Designer

    Dec 27, 2010
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    A few random replies.
    Firstly. I've found it easier to mount boards on the lids of boxes with the Ray Wu plugs exiting immediately beside them. This makes it exceptionally easy to get the 2 or 4 pin plugs into the board and depending on the enclosure you may be able to put a power supply in the back half of the box. Because this half has the bitey bits in it it needs to be fixed better and you don't want it winging in the wind.

    Your calculation for the leds appears to be wrong. You've worked it out at 10mA per led times 600 leds to give 6 Amps per string. Depending on the construction of the led strings there's probably 6 to 8 leds per section to give 24-30V drop so it's probably 0.75A - 1A.

    The DC30 has a fuse as the 1st thing that the power meets. Any of these style of boards don't really need any additional fusing. Only boards that don't have fusing should have fusing added (something like a 2A fuse for a P2, 15A for a Ray Wu 27ch etc etc. Power injection for pixels needs fusing).

    Ventilation is something I go on a bit about in chat and in a heap of threads. If the power supply is running at anything even remotely above 30% or so full load then it's a must that there is forced ventilation. It doesn't need much but the plastic boxes are awesome thermal insulators and passive ventilation requires a temperature differential that means there is excess heat in the box. I personally now use the inbuilt fans in the power supplies to vent to the outside world.

    Sequencing a few dozen channels to music is quite simple especially if you don't plan of doing fancy things with colours. Sean gives great tutorial (like all of his) on how to do an "auto" sequence with xlights/nutcracker. It's fairly simple and you can do each song in a few minutes after you draw everything up.

    Side note. You have used some green cable ties. It is very very unlikely that anything other than black ones are UV stabilised which means you get the benefit of replacing them after a few months of exposure to the sun.
  3. David_AVD

    David_AVD Bite my shiny metal ass! Community Project Designer Generous Elf

    Jun 12, 2010
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    Victoria Point (Brisbane)
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    Big W 200 count LED strings draw approx 100mA (0.1A) per channel. That's 200mA for the whole string.
  4. OP

    franky_888 Apprentice Elf

    Dec 31, 2013
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    Thanks for the help thus far. I misread the wiki article about the calculations about the LED usage, so it's working in my favour.

    So far this week I've managed to get my PSU's mounted in the enclosure. I managed to get two PSU's mounted in a Masters enclosure. Both fans are positioned in the center, and I plan to install 2 x 90mm PC fans to get some flow through ventilation.

    pwroverview.jpg pwr1 wiring.jpg

    The PSU's were mounted with a 40mm piece of aluminum angle (40mm x 40mm) and secured to the PSU using 10mm M4 screws and 3 washers. Washers used to prevent the screw from penetrating into the PSU too far (thanks David_AVD for this pointer).

    Now, the PSU's only *just* squeeze into the enclosure in this orientation, so much that I would hazard a guess that enclosure wouldn't be water tight any more. Being out of the weather I'm concerned more with the security of them (preventing sticky fingers) rather than water resistance, so anyone reading this is planning to mount these out in the open I'd aim for 1 per box only.

    Today's set of questions:
    - Is there anything wrong with how I've mounted the loop in / out power in the PSU? Both connections are tight and passed the tugtest, but I'm not sure if I'm not supposed to mount two of these bootlace ferrules per terminal.

    I was just trying to be festive! :D On a more serious note, these ties won't normally see the light of day, but thanks for the advice, I'll make sure to get some black ones for external use

    Thanks to AAH for the suggestion of getting some bootlace ferrules. I think the pack of ferrules and crimping tool set me back about $30 from AliExpress, but the time it has saved has paid itself off already.

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