Author Topic: Wiring Layout - Assistance  (Read 2345 times)

Offline JonB256

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Re: Wiring Layout - Assistance
« Reply #45 on: February 08, 2017, 08:51:59 AM »
Ok perfect.

I was thinking about it.. it's essentially power supplies wired in parallel right?


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Yes, and it works because there is a pixel "load" between power supplies. That means no worries about power supplies oscillating their voltages competing with each other.

Offline b0nafide

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Re: Wiring Layout - Assistance
« Reply #46 on: February 08, 2017, 09:50:50 AM »
I assume Jon is talking about a power injection T. 

I assumed wrong so removed so I do not confuse people.

Actually State you got me thinking.. I think you had a point there.

The true diagram for DIYLEDEXPRESS Ts are  below:

http://www.doityourselfchristmas.com/wiki/images/0/05/Wiring_Diagrams_3_pin.jpg

So given that.. I guess it's up to the individual whether they connect the V+ (green) to the second PSU or not.




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Offline Wolfie

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Re: Wiring Layout - Assistance
« Reply #47 on: February 08, 2017, 02:18:25 PM »
Hello Everyone,


I'm looking for feedback and general assistance concerning my proposed wiring diagram. I am not quite sure that I'm understanding the concepts correctly, so please fill me in if this looks completely mixed up. Please keep in my this is my first year working with pixels...


- I plan I running 12V WS2811 bullet pixels purchased from DIYLEDEXPRESS.
- The pixels will likely be run at 50% output (based on what I've read 100% is not necessary) which I understand will suck about 1A per strand on full white.
- 4" spacing
- I may be able to combine Output 3 & 4 based on location but I'm just going to keep them separate for now
- I can combine Output 17 & 18 but they are going to be on a fence line and I'd like to accommodate the fence gate by keeping them separate.




Questions:


1. On Output 17 & 18, can I power inject at the end of the run (at pixel 150) or must I do it in the 100 pixel mark (as shown)?


2. At the Differential Receiver board when I plug in power from the PSU, is the board capable of sending 12V power to the pixels or do I need to inject power at pixel 1?


3. Where does the Raspberry Pi3 receive its power from? (I hadn't ever considered this question until I made this diagram)


4. My Wi-Fi router is maybe 15 feet away from my proposed mounting location of the Controller & Pi. Can I just use my current WiFi router to talk to the Raspberry Pi3 (via WiFi), or does it need it's own? Does it need a switch to itself?


5. Did I label output 17 & 18 correctly? Is that right? Is output the right word?


6. Will I need to run the Controller at 32 string mode because I have an expansion?


7. The PSU at the Controller... Can I attach a Power Distro board there and use that location to inject power too or does it need to be dedicated to the controller? (This would make it easier to combine output 3 & 4)




.... I have a whole wack of questions but these are the biggies for now.


Thanks!

TLDR whole thread.

However, instead of answering your questions directly, maybe I could link a post I just put up on my site (I am rebuilding my site so new content is getting put on it now).  I think perhaps the info in the post is more valuable than answering the specific power questions of "should I'.  Read this post:
http://www.wolfiesden.com/diylighting/power-injection-101/
Read through it and absorb the concepts there.  I think that understanding "why something is", is better than someone just saying "it is".  Because later, you will have to ask again because nobody explained why.  Hopefully that post will help you with the why part.

I could read through the thread here and give you a direct answer, say to your question 1, but you wouldn't know why.  I feel its more important to understand why.  Then you will have your answer.  And then you will be able to divine similar answers yourself on future projects without having to ask "should I" about them too.

After you read through it, if you still have questions, I will try to help out best I can.

Offline Bwinter

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Re: Wiring Layout - Assistance
« Reply #48 on: February 08, 2017, 02:29:12 PM »
Thanks Wolfie,

However, the biggest source of confusion (here) is how to PI from multiple PSU.

Offline b0nafide

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Re: Wiring Layout - Assistance
« Reply #49 on: February 08, 2017, 02:31:02 PM »
So based on your blog post Wolfie, you would recommend not supplying any power from the controller end and just supplying power through the injections (down the line) in both directions?

Makes a lot of sense and your illustrations help hammer the point home.

What seems to be the discussion piece right now at the last few pages of this thread is when powering from the controller end using PSU1 and later injecting power with PSU2 at a separate location. Do you sever the V+ from PSU1 and now Power the pixels from PSU2 or can PSU1 & 2 have their V+ connected?

If I am to use your water analogy... at the end of a strand (say Pixel 120 ish on a 12v) the water is not filling up the hose anymore (maybe a trickle).. if I was to add a power injection at pixel 240 (according to your post) then I would be filling up that hose with another trickle of water (this full)?

I dunno..

Thank you for posting and taking the time to chime in.



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Offline Wolfie

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Re: Wiring Layout - Assistance
« Reply #50 on: February 08, 2017, 02:35:16 PM »
So based on your blog post Wolfie, you would recommend not supplying any power from the controller end and just supplying power through the injections (down the line) in both directions?

Makes a lot of sense and your illustrations help hammer the point home.

What seems to be the discussion piece right now at the last few pages of this thread is when powering from the controller end using PSU1 and later injecting power with PSU2 at a separate location. Do you sever the V+ from PSU1 and now Power the pixels from PSU2 or can PSU1 & 2 have their V+ connected?

If I am to use your water analogy... at the end of a strand (say Pixel 120 ish on a 12v) the water is not filling up the hose anymore (maybe a trickle).. if I was to add a power injection at pixel 240 (according to your post) then I would be filling up that hose with another trickle of water (this full)?

I dunno..

Thank you for posting and taking the time to chime in.



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Yes. You sever the connections.

So for the megatree diagram:


See the connection between S4 and S5?  Its carrying V+, Data and Ground.  Thats because that whole section is powered from one PSU.  Ok, say you can't do that because the strands are too long and you need 2 PSUs per section?  Simply break the V+ line there between S4 and S5.  Make sure to carry ground and data only.  Then PI point 1 is from PSU #1 and PI point 2 is from PSU #2.  V+ lines never connect.  Grounds DO.

Offline Wolfie

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Re: Wiring Layout - Assistance
« Reply #51 on: February 08, 2017, 02:39:53 PM »
The reason you sever them is that most of the PSU that we use are not designed to paralleled.  Can you?  Maybe.  Totally depends on how well the PSU takes to having alien voltage pumped back into it from an outside source.

You are better off making sure the streams never cross (Ghostbusters reference).  So you divide and conquer.  Separate the V+ lines and apply the water analogy to each section as though it were the only section there.

Each of my sections apply this logic.  My tree is powered from 3 separate PSUs.  Each section of 8 strands from a single PSU.  The end of the section (as shown above) dead ends at the right.  Nothing is carried to the next section, not even data.  However, if the F16 could drive that many pixels, I would carry data and ground from section to section and each would still be distinctly powered from a single PSU using multiple PI points.

Offline b0nafide

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Re: Wiring Layout - Assistance
« Reply #52 on: February 08, 2017, 02:41:20 PM »
See above post 43 from Jon...  he makes an argument for not severing the V+


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Offline Wolfie

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Re: Wiring Layout - Assistance
« Reply #53 on: February 08, 2017, 02:52:24 PM »
See above post 43 from Jon...  he makes an argument for not severing the V+


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Can it work?  Yea, again, as I said, it totally depends on the PSU that you use.  Most of these are not designed specifically for being wired in parallel.  The problem arises in the output circuitry.  How well will it feel about having voltage not its own fed back into it.

Real world you will never get two PSUs to have the exact precise same output voltage will you?  No.  One could be a microvolt or a volt off from the other.  If there is ANY difference, then current can and does flow back into the output circuitry of the one with the lower voltage.  How will it handle that?  Will it confuse its regulators?  Will it confuse its filtering?  Just depends on the PSU design and how well (or cheap) its made.

There ARE PSUs out there that are designed to be paralleled.  They have protection circuitry designed to handle the situation of voltage differences.

Then there is the question of what happens to one PSU should the other fail?  Does it become a short or load?  Does it take out the other PSU as well?

For these reasons, I choose to separate my V+ lines.  If one PSU fails, it won't take any others with it.  I don't have to worry if they are designed to handle the backfeed of power into them from another PSU.  I don't have to worry that their voltages are set precisely.  Breaking the V+ lines solves, or at least circumvents, more problems than any benefits of keeping them tied together provide.  At least in my world.

Offline JonB256

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Re: Wiring Layout - Assistance
« Reply #54 on: February 09, 2017, 06:44:31 AM »
The drawing in Post #50 (2 PSUs, each driving half of the pixels) is a very good solution, especially if your pixel lengths are that symmetrical. (though I still don't understand the aversion to powering pixels from the controller end)

In that case, using just 2 power supplies and not powering from the controller, I would consider severing the +V between the halves. Not because of "paralleling" of the supplies but in case one PSU dies. That would put such a amperage load on the remaining supply that it might also die or blow a fuse.

Even cheap power supplies (and I use the very cheap Ray Wu clone supplies) do not exhibit voltage swings due to paralleling when there is a sufficient load between them (and that suggested drawing in #50 has a sufficient number of pixels between them to act as a load).

The "parallel" voltage swing issue exists when you try using Redundant supplies connecting at the same point. So in Post #50, that would mean 4 PSUs, using 2 at each injection point. THEN I'd worry about voltage swings. The easy fix there is to adjust the voltages to be 0.5vdc different so that one is the Lead and one is the Standby supply. But I'd still never bother doing that on a home, hobby display. Perhaps on a Commercial display where someone else is paying for that kind of reliability.

Offline Wolfie

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Re: Wiring Layout - Assistance
« Reply #55 on: February 09, 2017, 08:53:33 AM »
Its not an aversion.  In my circumstance at least, my controller is powered by a different PSU than  my props.  The PSU in the housing with the F16 supplies V+ for the F16 and for my FM box (a separate cg1000) which contains my show Pi, my 8p switch and my FM transmitter.  I use it during testing but generally do not supply pixels from it.  Its on a dedicated AC line and remains powered at all times.  The AC lines going to all other PSUs is on a timer and shuts off late at night and comes back on in the afternoon the following day.  This allows the PI, switch and F16 to remain powered during off times so I can perform any needed uploads/maintenance as needed while allowing for the pixel power to be shut off.

One of the reasons I choose not to feed from the controller is the typical limit of 5a per output.  This is commonly insufficient when long chains of props are connected to a single output as is my personal case.  I do not feed a single prop on a single output and even if I did, 5a would only be a very small prop.  In every case, I have hundreds (very much plural) of pixels on each output usually in many different props.  5a is about 100 12v and only 80 5v pixels.  Thats it. 

Just one singing bulb takes 143 pixels and is about 7.5a alone.  I have two on a single output.  Then it goes up to a 100px (roughly) node window frame made from 30/10 strip.  5a simply doesn't cut it.  I have 2 more bulbs on the other side and another window frame.  And 10x 10w floods and an eve line made from huge 40mm round nodes each with 6 5050 LEDs.  My spiderweb is 200px alone (nearly 10a right there) and after that it goes to a string of spooky eyes each with 3 LED pixel modules, and then 4 arches.

So, you can see, unless you are running SMALL props, 5a from the controller is all but useless.  So I completely discount it except for small props and intermetant testing.  Its simply not worth the effort and wiring to use in my layout.  I prefer to use cat5 for data lines, its only 24ga.  Some things I do carry power via cat5 (tie all solids to gnd, all but o/w stripes to V+ yielding 3x24ga for V+ and 4x24ga for gnd and 1x24ga for data).  But its not conducive to large numbers of pixels.  The current capability simply is not there.

Even on very small controllers like the J1Sys P12's that I used last year that only support 170px (one universe) per output, thats 9a for 12v pixels per universe yet its fused for 5a.

So, for me, its not aversion to running V+ out of the controller, its practicality and convenience not to.

For the props that are further out or, in the example of the megatree, consume sufficient power that they need more than one PSU, I don't deliver DC to them through long cables, I deliver AC to PSUs closer to the load.  There is far less loss that way because you reduce the length of low voltage high current cable while increasing the length of high voltage low current cable.

Like many aspects of this hobby, there are many ways to skin each cat here.  Mine is but one of them.  Each has merits and drawbacks.  Each of us must weigh the options and choose the one that best fits our situation.

Offline JonB256

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Re: Wiring Layout - Assistance
« Reply #56 on: February 09, 2017, 12:39:02 PM »
On my roof's snowflake display, the main reason I used a Falcon F16v2 instead of something RasPi or BBB based was that I can just "pull the plug" on it and it will reliably boot back up when power is reapplied. I do this when it is raining a lot since having 12vdc applied 24/7 to the pixels and to the "waterproof" connectors will lead to unnecessary galvanic corrosion.

Wolfie, your use of a smaller supply for just the controller and RasPi and Data makes sense for that case. The 12vdc for the pixels could be switched off when not needed (I've got some RasPi USB Relay boards that would be perfect for controlling the AC to my power supplies. I may rethink my roof strategy for 2018. Not a major change. Will still need to tie my DC grounds together, though.

A few years ago, I had massive failures of the square, metal pixels (had 4 5050 LEDs that were not well sealed in epoxy). From both rain and morning dew, over 25% of them failed or showed gross corrosion through the thin areas of epoxy. It was having power applied 24/7 that made it worse.

That said, I still won't cut my V+ between Power supplies. :)

Offline b0nafide

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Re: Wiring Layout - Assistance
« Reply #57 on: November 12, 2017, 10:10:10 PM »
Just wanted to show you all the final product. Thank you for all of your assistance and advice. Here is my lights for 2017!




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Offline Bwinter

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Re: Wiring Layout - Assistance
« Reply #58 on: November 12, 2017, 11:21:00 PM »
Looks very nice!


How did you finally end on your wiring schematic?

Offline b0nafide

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Re: Wiring Layout - Assistance
« Reply #59 on: November 13, 2017, 07:46:00 AM »
Looks very nice!


How did you finally end on your wiring schematic?


Ill post a layout soon to help others but basically:

Output 1 - Lower Roof outline - Data and V- from controller. PSU2 injects at pixel 100 and 180. 303 total pixels.

Output 2 - Upper roof outline - Data and V- from controller. PSU2 injects at pixel 100ish and 230 ish. 350 ish total pixels.

Output 3 - Wreaths. Data and V- from controller. A uAmp before the data hits the first pixel. PSU2 injects in between wreath 1 & 2 (100 pixels in each wreath).

Output 4 - Front door outline. Data, Power and V- from Controller. 60 ish total pixels.

Output 5 & 6 - Pillars. Data, Power and V- from controller. 160 pixels each pillar, 320 total pixels.

Output 17 & 18 - Backyard. Differential Expansion and Receiver. 80 FEET CAT5 cable to backyard. 150 pixels on each output. PSU3 provides power. 300 total pixels.


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