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my controller box

Discussion in 'How is my display put together...' started by heathwithnoteeth, Nov 4, 2015.

  1. heathwithnoteeth

    heathwithnoteeth Full Time Elf Generous Elf

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    im posting this here to see what opinions people have (I am open to anything --- well not anything ;) )


    [​IMG]


    Parts Used


    Pixlite 16


    This power supply
    http://www.aliexpress.com/item/12V-350W-switch-mode-power-supply-LED-power-driver-AC90-260V-input-DC12V-350W-output-constant/1948832565.html

    This fuse box
    http://www.narva.com.au/pressreleases/press-releases/new-12-way-fuse-box-eliminates-messy-wiring

    mains has inline 10 Amp glass fuse to supply




    any pointer, opinions, flame sessions etc would be appreciated.
     
  2. AAH

    AAH I love blinky lights :) Community Project Designer

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    Other than the wire size as I mentioned in chat I have also developed a liking for mounting the controller and wires to the lid. It makes it easier to get the wires out of the enclosure and fitting off of the connectors is easier as it's not deep inside the box. The only issue is the lack of hinging. All you need from the back of the enclosure to the front is the power wiring and potentially the cat5 wiring. You can get away with mounting the power supply in the back of the box and the controller to the door.
     
  3. OP
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    heathwithnoteeth

    heathwithnoteeth Full Time Elf Generous Elf

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    thanks for the input AAH. would 12 awg wire be better? the awg to mm2 chart tells me that should be 2mm2
    i think i have bootlace ferrules that would fit.


    cheers
     
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    heathwithnoteeth

    heathwithnoteeth Full Time Elf Generous Elf

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    i am having trouble working out which cable is 14awg in the metric sizing...


    for reference which one would i get from jaycar/bunnings/masters/autobarn ?


    cheers
     
  5. SmartAlecLights

    SmartAlecLights Im a SmartAlec what can i say! Community Project Designer

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    i use 6mm automotive cable as its rated at 50amps at 12v

    also how did you make such a perfect base plate..
     
  6. OP
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    heathwithnoteeth

    heathwithnoteeth Full Time Elf Generous Elf

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    ok cool.


    i laser cut the base plate (a perk of having two of them next to me all day) :D
     
  7. i13

    i13 Senior Elf

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    Keep in mind that we're typically trying to avoid voltage drop when choosing a wire thickness. The maximum current rating shouldn't really matter because it is usually higher than the currents at which voltage drop becomes a problem. The length of the wire is equally important. The 101 manual has quite a good section on wires and the resistance values are given so you can calculate the voltage drop with Ohm's law.
     
  8. AAH

    AAH I love blinky lights :) Community Project Designer

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    The cable voltage drop calculator that David put up on http://www.da-share.com/calculators/ is a handy calculator is you don't want to resort to finding data and punching it into ohms law. A 5% voltage loss total down both + and - is probably the maximum you should allow yourself at full load.
    For example if you had a 12V 30A power supply with only 1 pair of wires coming from it to a fuse board 50cm away you'd have an allowable voltage drop per wire of 0.3V. Punching in some numbers you could get the required drop by using 1mm2 (17AWG) wire. This however is in contravention to the maximum rated current for 1mm2 cable which is about 10A.
    It's always good to start with a minimum sizing of 1mm2 per 10A and then check to see if you need heavier cable.
     
  9. OP
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    heathwithnoteeth

    heathwithnoteeth Full Time Elf Generous Elf

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    so i calculated using the da thingo.


    i got some 2.5mm2 single core power cable from masters, if i have about 450-500mm of wire from output on supply to input on controller (including distance through fuse block).


    this gives me a result of 0.08 voltage drop each wire. this is using the method of 10a per 1mm2
    (i assume this equates to 25A for 2.5mm2 cable)


    is it correct i have 10 Amp fuses? or shall i use bigger/smaller value ones?


    sorry in advance, but my math skills are crap.


    cheers
     
  10. i13

    i13 Senior Elf

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    What current are you planning on having? That's not an easy question to answer because the AliExpress listings generally have higher current values than the lights actually draw.
     
  11. AAH

    AAH I love blinky lights :) Community Project Designer

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    The fuses are primarily designed for protecting the wire. As long as the fuse rating isn't heavier than the wire you are using then you should be right. For instance the 2.5mm 25A wire you are using shouldn't be protected with a 30A fuse.

    By the way Aliexpress numbers always have to be taken with a grain of salt. They are often cut and pasted from other sources and the specifications that they provide don't always match up with what you are looking at. That's kinda what happens when a sales person with no technical knowledge converts from Chinese to Chinglish.
     
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    heathwithnoteeth

    heathwithnoteeth Full Time Elf Generous Elf

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  13. i13

    i13 Senior Elf

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    Hopefully those pixel nodes are only 10mA per colour which is 30mA per IC. Sometimes the 12V ones are 18.5mA per colour which causes voltage drop problems the same as 5V plus you then have a higher power consumption. If they're 30mA per IC then your strings will draw 6 amps (ignoring the 8 pixels removed).

    I don't know what current the stars draw but due to the two series branches (I expect) they're probably the same as a 6 LED section of your strip. Still it appears you only have 4 mini trees so the current drawn by 4 stars is insignificant. Ignoring these makes up for me ignoring the 8 pixels removed.

    The strips probably run at 30mA per IC as well although I haven't measured them. I just suspect they do because I'd think they'd suffer from voltage drop along their length otherwise. You have 10 metres of the strip at 20 ICs per metre which is 6 amps as well.

    Your show should therefore draw about 12 amps but it could be as high as 17.1 amps if your strings draw 18.5mA per colour. As you can see I'm really only estimating current draw here so it is always best to measure it for yourself and leave room in your design to allow for extra current draw such as the 17.1 amps.

    Also a warning about those stars; they are not very good at passing on the 2811 signal over long distances so you might need a null pixel immediately after them if you plan on doing this.
     
  14. OP
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    heathwithnoteeth

    heathwithnoteeth Full Time Elf Generous Elf

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    i have 5 null pixels, was thinking about putting one after two trees, then after the next two trees and then one in between the arches.
    and i as also thinking of injecting power at the same places.


    cheers
     
  15. OP
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    heathwithnoteeth

    heathwithnoteeth Full Time Elf Generous Elf

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    here is my second attempt at wiring. opinions appreciated thanks.

    [​IMG]
     

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