Author Topic: Power injection requirements/hardware  (Read 769 times)

Offline rickswa

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Power injection requirements/hardware
« on: August 11, 2017, 05:20:02 PM »
Hello,

I'm making four pixel arches to span my driveway this year.  I'm to the point now of trying to figure out the power injection requirements and best way to do this.  The arches are 34' long cut into 3 sections each.  There are two sections each of Ray Wu 100 pixel 12v ws2811 and one section of the same pixels but only 59 of them.  I just got the falcon f16v3 with integrated power supply and now am trying to figure out how big of power supply I need for the injection part.  I understand that i need to T the ground in with my current power supply, but does this have to happen inside my current f16 enclosure or is there a way to do it externally?  I've also seen the power injection T' fittings but wonder if this is best for my application.  I have the 3 core RayWu pigtails on my strings and the arches are made out of pex pipe so I don't have a ton of room to work with on the back side of the arches since I've drilled holes every 1 1/2" to insert the pixels in.  Just curious on opinions as to whats would be the best way to go about this and also what fittings should I use since I plan to break these back down into 3 pieces each for storage so I was hoping to find something that is both weatherproof and also has a way to undo it so I can take the arches apart without cutting the wire every year.  My last questions are will I need an inline fuse for the power source and also any good recommended power source/enclosures to use?  I had planned to use a weather proof power source but still put it in an enclosure. I have access to both sides of the yard so I can put the other PS on either side.  Thanks for any help.

Offline pixelpuppy

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Re: Power injection requirements/hardware
« Reply #1 on: August 11, 2017, 05:39:34 PM »
I'm a little confused about where you intend to put the "T" fittings.  If I read you correctly there are 4 arches and they are 259 pixels each.  Why not just inject power at both ends of each arch (at the start and end of each 259 pixel string).  No "T" needed.


EDIT:  after posting I realize that you might be wanting to use just one or two ports on the controller. (Keep in mind there is a limit of 1024 pixels max per port)  I was thinking you were feeding each arch with a separate port on the controller. 
Vixen and xLights for sequencing / FPP for scheduling and playing / Falcon controllers for pixels / DIY controllers for everything else

Offline rickswa

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Re: Power injection requirements/hardware
« Reply #2 on: August 11, 2017, 09:05:20 PM »
Actually you are right the first time. I may be making this harder than I need to. The plan is to use one port on the f16 for each arch.  So total of 4 ports.  I had thought since I had one string per section that I would inject power before each string. But if I understand better now,  I can just get a separate PS and run it to the "far" end of each arch, tie into the falcon PS ground and all should be ok? That sounds much better than what I thought needed to be done. Any idea what size the PS should be for injection? Also, as far as weatherproof connections, could I just solder a pigtail I have to the 12V from the PS and another to the end of my pixel string and just use that for my connection? Thanks again for your help. This issue has been one that it seems I'm making it harder than it has to be.

Offline jeff

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Re: Power injection requirements/hardware
« Reply #3 on: August 11, 2017, 11:03:47 PM »
If I read correctly, no you don't just want to hang a different power supply on the end. That would tie the positives of two power supplies together which you want to avoid. If you cut the positive halfway through each arch, then a power supply on each end is fine. That would mean powering ~130 pixels from each side which is doable, but approaching the limit. You may need to turn the brightness down a little if they look strange near the center of the arches.

As for size, 130 x 0.06 = 7.8 amps for 100% white x 4 = 31.2 amps. If you reduce brightness, you lower the power needed. If you never run all white, even less.

I did a YouTube video on Injecting power at https://www.youtube.com/watch?v=bvN91XDH2V0&feature=share that hopefully explains it a little better.

Jeff

Offline rickswa

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Re: Power injection requirements/hardware
« Reply #4 on: August 12, 2017, 03:16:24 PM »
Thanks for the video link. So if it's the same power source, you can inject without cutting the 12v+, but if different power source, you must cut the 12v+ so they don't "oppose" each other, right?  I've attached a very crude diagram of my idea now. If I only use one extra PS, the closest arches will be about 5' away from it and the two furthest about 10' and then I would have another 24' up to the injection point.  So now I'm thinking of using two extra PS and cutting the 12v+ between each  strand so the F16 would power the first 100 nodes, the first power injection point from the other PS would power the next 100 nodes and the last injection point would do the final 59 nodes. Will this injection allow the data to travel the 34' (plus the 10' extension from controller to arch) without problems?  Also can I just hook the ground of the extra ps to the 12v - wire at the end of each arch or do I need to run it over into the f16 ps box? Two more things that are giving me a headache are do i need an inline fuse, and if so, what size? Also, since I'm cutting the 12v+, can I run spt2 for the injection (longest run would be about 35' or so) and can I just T off it for the second power injection or would I need one wire for each? Should I use Ray Wu pigtails and just attach the 12v+ connection or is there a smaller weatherproof connector that allows connecting and disconnecting easily? Sorry for all the questions, but just when I think I get it, I end up feeling like I really don't get it.

Offline pixelpuppy

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Re: Power injection requirements/hardware
« Reply #5 on: August 12, 2017, 08:09:05 PM »
In this case, the strings are long enough that you could inject power at each end using two different power supplies without needing to cut the positive in the middle.  The voltage drop along that length and the load of the pixels is more than enough to keep the PSUs from opposing each other.   

While this is true in this case, its not always true.  If you don't understand why the voltage drop allows this to be true then just break the positive line in the middle of the string and it will be fine too  Feeding 130 pixels with 12v is not a problem - especially if they are the newer pixels with voltage regulators instead of the old voltage dropping resistor designs.

Also, in this case you should not need to run a separate ground between the PSU's. If you're powering one end of the string from the Falcon then the ground conductor of the string will provide the common ground reference (assuming you don't cut the ground in the middle of the string.

But if I understand better now,  I can just get a separate PS and run it to the "far" end of each arch
In this case, yes.   No need to make it more complicated.

That would tie the positives of two power supplies together which you want to avoid.
Connecting two power supplies together at the same end of the string should be avoided.  But connecting them at opposite ends of long strings can be done if you understand the limitations.  In this case its not a problem.
« Last Edit: August 12, 2017, 08:36:08 PM by pixelpuppy »

Offline rickswa

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Re: Power injection requirements/hardware
« Reply #6 on: August 15, 2017, 02:36:04 PM »
SO it really is as easy as I've drawn in this photo?  Would there be any problem using one PSU like this with the distance from the arches shown or should I just use one extra PSU per two arches?

Also, I'm still a little confused on the inline fuse size.  Should I

a. put the inline fuse between the PSU output and power block so that one fuse handles the entire output

or

b.  put inline fuses in each 12v+ output to each arch

Also, given whatever is the better option, how would I calculate what size fuse(s) I would need?

Offline JonB256

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Re: Power injection requirements/hardware
« Reply #7 on: August 15, 2017, 09:18:15 PM »
I don't bother cutting the 12v line.

but, I do run a separate wire between the power supply negatives. It makes the Data signal more stable.

Offline rickswa

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Re: Power injection requirements/hardware
« Reply #8 on: August 15, 2017, 10:16:31 PM »
Thank you. If I were to run a ground across the arch to connect both PSU's can I leave out the ground to each arch from the 2nd PSU or is it still a good idea to run it to each arch as well?


And ideas on the fuse issue?

Offline JonB256

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Re: Power injection requirements/hardware
« Reply #9 on: August 16, 2017, 07:16:40 AM »
No, leave all your other ground wires as they are.

Since I use power distribution boards (various sources, including the Falcon board), I have a lot of small fuses (5 amp).

https://www.pixelcontroller.com/store/index.php?id_product=46&controller=product


Offline Yamr6rider

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Re: Power injection requirements/hardware
« Reply #10 on: August 16, 2017, 07:33:28 AM »
And ideas on the fuse issue?

Based on the common calculation of 0.06 amps per Pixel, as Jeff stated previously "130 x 0.06 = 7.8 amps for 100% white" I would get a small fuse block or inline automotive fuse and run an 8 amp fuse to each side of each arch.
Jon

Working on my first year display:
 1 - Raspberry Pi3,  1 - Falcon F16V3,  3 - 30A 360W PSU's, 1200
12v Pixels - Mounted in 3/4" SCH40 PVC (3-1/4" spacing), and 3 pixel strip arches.

Offline rickswa

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Re: Power injection requirements/hardware
« Reply #11 on: August 16, 2017, 09:45:39 AM »
THANK YOU. 

But now I realize I have another issue to deal with.  I bought the ready to run version of the f16v3 with PSU.  The fuses on the board are 5A.  So this basically tells me I have to limit my pixels on the f16 side and am back to having to inject in multiple points.  Am I correct in this thinking or is there some way that the 5A fuse on the f16 board will be able to handle 130 pixels all white at 100% brightness?  Every time I think I have it down....nope.. :o

So I'm going to run the 12v+ and 12v- to each end of the string from different power sources.  Then as was mentioned above, I'll run a line between the psu's to connect the 12v-.  But just so I'm clear, we are talking about connecting the 12v- between psu's and not the ground connection, right?  So it would be 12v- to each end of the arch and then 12v- connection directly between psu's? Is it also acceptable to just connect these right to the terminals of both PSU's instead of trying to T into each wire?  Thanks for all the help.  Noob trying to switch from LOR over to xlights and get into the pixel world and just want to make sure I get this right before I ruin any components or lights.


Can I ask one last question? Do you use SPT wire from the distribution boards/PSU to the pigtails or is there a better or more appropriate wire I should use? I thought of either SPT2 or just taking an outdoor extension cord and cutting it to length and connecting only two of the wires in it. Thanks again for the great replies. It helps a ton.
« Last Edit: August 16, 2017, 10:45:56 AM by rickswa »

Offline lwillisjr

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Re: Power injection requirements/hardware
« Reply #12 on: August 16, 2017, 04:41:19 PM »
I haven't read this whole thread so a bit hesitant to weigh in......  but yes you will need to connect the 12v-  between the PSUs.


Offline rickswa

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Re: Power injection requirements/hardware
« Reply #13 on: October 03, 2017, 01:39:47 PM »
sorry to keep beating this to a pulp but I just want to make sure that I'm going to do this right.  I have 3 power supplies, all Meanwell 350W.  I was going to carry the V- from the first power supply, over to a terminal block in PSU #2 that has the v- hooked to it, then carry another wire from that terminal block over to the v- terminal on PSU #3.  Will this be ok in this "daisy chain" style run?  Also, the one thing I want to make sure, I have both a V- and GND output on the PSU's.  Do I use the V- connection for this and not the ground?  I had thought the V- but then read in other posts to use the GND so that's where I'm getting a little concerned about using the wrong terminal.

Online Emuney18

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Re: Power injection requirements/hardware
« Reply #14 on: October 04, 2017, 05:58:51 AM »
sorry to keep beating this to a pulp but I just want to make sure that I'm going to do this right.  I have 3 power supplies, all Meanwell 350W.  I was going to carry the V- from the first power supply, over to a terminal block in PSU #2 that has the v- hooked to it, then carry another wire from that terminal block over to the v- terminal on PSU #3.  Will this be ok in this "daisy chain" style run?  Also, the one thing I want to make sure, I have both a V- and GND output on the PSU's.  Do I use the V- connection for this and not the ground?  I had thought the V- but then read in other posts to use the GND so that's where I'm getting a little concerned about using the wrong terminal.
The negative D.C. outputs are what you connect together.  They are usually labeled V-  a lot of people like myself will just call it ground.  Never hook a D.C. Ground to an AC ground.


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