Power injection best method. And Fuses

Discussion in 'Power Supplies' started by cdjazman, Oct 7, 2016.

  1. cdjazman

    cdjazman Full Time Elf

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    Afternoon all,

    I was wanting to get opinions on best method for power injection.

    See option A and B attached.

    Secondary is that I have seen mentioned the use of fuses with direct power injection from power supply to led strip. Can someone please expand on this. Is it a necessity?
     

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  2. OzAz

    OzAz Full Time Elf

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  3. djgra79

    djgra79 Senior Elf

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  4. OP
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    cdjazman

    cdjazman Full Time Elf

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    curious - so the pcb is that 1 in 3 out?
     
  5. battle79

    battle79 Full Time Elf

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    Each of the three bottom connectors goes through 2 fuses to two of the connectors on the top row. I just run three 12V red 2.5mmsq cables from the power supply to each of the terminals. Then run 12V from each prop into one of the outputs. For the ground/negatives I run black cable from PSU to a terminal block and also bring all props grounds back to this terminal block.

    I also run the ground from each controllers output to the terminal block. That way all the grounds are commoned. This is important to ensure data signal is read properly by pixels, if powering pixels from different PSU to the controller.

    Hope I didn't confuse you more,
    Rowan
     
  6. multicast

    multicast Senior Elf Generous Elf

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    Its your choice.


    Fuses, or burn your house down.
     
  7. OP
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    cdjazman

    cdjazman Full Time Elf

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    Hehe. Maybe just a little. I am much better with flow style diagrams.......

    So run +/- from prop/strip to "Hexfuse" and then run "Hexfuse" +/- to power supply?

    Quick diagram........ :) :) :)
     

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  8. OP
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    cdjazman

    cdjazman Full Time Elf

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    Well this is the dilemma.

    Two years ago i purchased a mega tree from another forum user. He made it with power injection that runs straight from the power supply along the 20 strands.

    No fuse in use.

    Looking to do the same this year for other props I have seen a couple of posts that have mentioned fuses.

    Therein lies the confusion in having computer and not electronic background.

    It has run for two Xmas seasons without issue.
     
  9. battle79

    battle79 Full Time Elf

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    Not quite with the diagram.

    You only run the + to the fuse board. The - goes straight to the PSU, or to a common terminal block that runs back to the PSU -.

    As far as your existing mega tree, buy enough of the fuse boards and take the + from each strand to the fuse board outputs and run + from PSU to the inputs on the Fuse board. You might have to check if each section of the + is isolated from the next and if not I would recommend separating so that each fuse does its own section of lights.
    Usually just before the injection point I cut the + cable so that the injection point only feeds forwards along the strand of pixels.

    Cheers,
    Rowan

    The - and data lines can be left exactly as is. Depending on how many pixels in each strand will decide how many strands can go onto each output. If you had
     
  10. djgra79

    djgra79 Senior Elf

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    Here's a pic of one of mine in use. All the blue neg wires go direct from PSU to pigtail. Only the red Pos wire has the hex fuse in line.
     

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  11. ԆцряєсϮ

    ԆцряєсϮ Senior Elf

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    I always like reading these posts when they pop up..... :D
    A fuse is not there to protect your mega tree or blinky star or mega spiral twisty arch.......
    A fuses sole purpose is to protect the cable that connects your electrickery to your props.
    Your prop may run for years and never blow a fuse..(thats what its supposed to do)..... Its that one time when a fault occurs that all of a sudden a cable that normally carries about 3 amps is trying to carry 80 or 100 amps, if theres no weak point (fuse) to pop then that cable just turns into magic smoke and burny melty plastic. Thats when the leader of the opposition.... or minister of finance (depending on your political persuasion) gets very upset and starts to work out how to seperate you from your man bits........
    Thats why I use fuses :D
     
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  12. scamper

    scamper Senior Elf

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    And now we all have the fuses situation down pat...
    The power injection drawings you have are basically a parallel or series cct.
    If you are running say 8 x 5v pixel strings on props that are 50 pixels and are all running next to each other, then you could run them in series if you were to use say 5mm 2 core wire with a flylead off to each strip.


    If however, you had smaller wire, or the props were further apart (voltage drop applies) or there were more pixels per string so the current draw was higher, then you would use the parallel cct. ie. a power lead to each prop.


    It is all about calculating the current draw and voltage drop on the given cable/cct.


    Oh, and yes, use fuses! (or keep a fire extinguisher handy)
     
  13. ShellNZ

    ShellNZ Senior Elf

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    I do not use fuses, well I do for my matrix I do but thats it :)
     
  14. OP
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    cdjazman

    cdjazman Full Time Elf

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    Thanks all.

    Scamper. So I have the power injection cable for the mega tree already made when I purchased it. It runs series.

    Does logic come into play and I could run the negative from the series cable to a fuse and positive to power supply. Would that work?

    Sent from my HTC_PN071 using Tapatalk
     
  15. scamper

    scamper Senior Elf

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    It is a better idea to fuse the positive side just in case of a short to earth, having said that, a fuse in line whether positive or return is still going to be better than none.
     

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