Newbie Mega Tree dual power supply question

[Homer911]

Hey all,

First post, so be gentle... Great, content available here, thanks all for the input.

For my first project I decided to start small and build a 6m Mega tree.

I have 2200 pixels utilizing one Dig quad.

My main concern is the use of a second power supply. I realise that I need a second PS but I need a little guidance on how to wire it. I have read on multiple occasions that both PS -ve need to be connected but I have also read that they don't need to be if you have a power injection at the end of each pixel strip. Can anyone confirm this?

Should I just power two strips with the dig quad and the other two with the additional power supply? If that is the case, I presume they would require a fuse each?

Thanks in advance.

 

[Skymaster]

If you're running two independent power supplies, then you will need to separate the positives, but keep the negatives connected.
Without the negatives connected, the second PSU wont do anything as there would be no return path for its current.

Your power injection wires should be run with both positive and negative from the chosen source, not just positive as you've shown in the diagram. This is because additional current flows through both wires - in one and out the other. Adding power on one side won't help the situation (much).

Your suggestion of two strips per PSU is probably the easiest way to do it. You don't need to break any positive lines. Only wire the data and ground from the dig-quad for the two "alternative" PSU powered strings.
Fuse them to match your wire gauge.

Given you have a 600W PSU there, I don't think you'd need to worry about a second power supply though. Do not run all that current via the Dig-quad though, it won't handle it.
Run a separate fuse block for each PI run. 5A or 7.5A fuses are probably the most appropriate for 0.75 / 1mm2 (16/18awg) wire.

 

[thewanderingpine]

Agree with @Skymaster that you probably only need one 600W PS.
What’s your intended layout of strings. I’m not sure that xLights will like 600/500/500/600.

 

[Homer911]

Good pointers mate, thanks.

I did realize about the -ve for the PI. I just didn't draw it in. I have some Injection Tee's that have set aside for that.

I was just estimating the power demand from this web calculator, maybe I entered the data wrong.

https://www.lightshowhub.com/tools/...5, 153, 0)&secl=rgb(255, 190, 0)&ant=ramp_red

I would love to operate just with one PS, which would make it a little less time-consuming to build and simple for a simple fella like myself....

I was wondering about the 30A Dig Quad rating with the 50A PS. The separate PI's from the "alternative" PS will solve this.


Would this Fuse block work ok?

 

[Homer911]

Agree with @Skymaster that you probably only need one 600W PS.
What’s your intended layout of strings. I’m not sure that xLights will like 600/500/500/600.

Thanks,

The plan for the layout is 22 strings with 100 pixels each.

XLights? One step at a time mate...

 

[Skymaster]

Thanks,

The plan for the layout is 22 strings with 100 pixels each.

XLights? One step at a time mate...

So this is where you need some forethought.

In xLights, a "string" is a controller connection, and a "Stand" is a physical item on a tree.

If you have 20 "strands" of 100 on the tree, and 4 strings(controller ports), it means that you are physically wiring it as
Controller Port 1 -> Strand 1 Up -> Strand 2 Down -> Strand 3 Up -> Strand 4 Down -> Strand 5 Up
Controller Port 2 -> Strand 6 Up -> Strand 7 Down -> Strand 8 Up -> Strand 9 Down -> Strand 10 Up

Each Controller port would therefore have 500 pixel strings attached, zig-zagged into 5 strands of 100 pixels a piece,

What @thewanderingpine is getting at, is that xLights requires you to specify the zig-zag number on the tree model, and it's a single number for all strings.
22 does not divide into 4 equally. So you'd need to do 600-500-500-600, for example, which does not work, because you can't specify 6 strands per string for port 1 and 4, and 5 strands per string on ports 2 & 3.

So whilst it may seem OK to begin with, you may end up snookering yourself for integration down the line.

 

[Skymaster]

Would this Fuse block work ok?

I use the 6 port version in my megatree, albeit from eBay or Aliexpress where it's half the price of Jaycar
See this post here for pictures.

Controller fans

I'm after some advice on how many fans to install on my main controller box. I have a falcon v3 and 2 power supplys. Being in Vic it will get fairly hot over December so do I need 1 fan or 2 ( 1 sucking 1 blowing to keep air curculating) thanks

auschristmaslighting.com

 

[Homer911]

So this is where you need some forethought.

In xLights, a "string" is a controller connection, and a "Stand" is a physical item on a tree.

If you have 20 "strands" of 100 on the tree, and 4 strings(controller ports), it means that you are physically wiring it as
Controller Port 1 -> Strand 1 Up -> Strand 2 Down -> Strand 3 Up -> Strand 4 Down -> Strand 5 Up
Controller Port 2 -> Strand 6 Up -> Strand 7 Down -> Strand 8 Up -> Strand 9 Down -> Strand 10 Up

Each Controller port would therefore have 500 pixel strings attached, zig-zagged into 5 strands of 100 pixels a piece,

What @thewanderingpine is getting at, is that xLights requires you to specify the zig-zag number on the tree model, and it's a single number for all strings.
22 does not divide into 4 equally. So you'd need to do 600-500-500-600, for example, which does not work, because you can't specify 6 strands per string for port 1 and 4, and 5 strands per string on ports 2 & 3.

So whilst it may seem OK to begin with, you may end up snookering yourself for integration down the line.

That makes perfect sense. Well explained. Never used Xlights, so that's good to know as it will save me a headache down the line.

I did want to add some more "strands" to it, but I couldn't find any W2811 100 pixels that were not out of stock. 20 it will be then....

 

[Homer911]

I use the 6 port version in my megatree, albeit from eBay or Aliexpress where it's half the price of Jaycar
See this post here for pictures.

Controller fans

I'm after some advice on how many fans to install on my main controller box. I have a falcon v3 and 2 power supplys. Being in Vic it will get fairly hot over December so do I need 1 fan or 2 ( 1 sucking 1 blowing to keep air curculating) thanks

auschristmaslighting.com

The usual, I can't wait for it to travel from China . Xmas is imminent!

 

[Skymaster]

That makes perfect sense. Well explained. Never used Xlights, so that's good to know as it will save me a headache down the line.

I did want to add some more "strands" to it, but I couldn't find any W2811 100 pixels that were not out of stock. 20 it will be then....

There is one way to get around it, especially if you want more.

Consider it as a 2400 pixel tree - with 24 strands of 100.
In xLights, model it as 6 strands per string, 4 strings.
Then just leave the last two disconnected, so its 600-600-600-400.
It means that anything that xLights renders on the last two verticals will be ignored by the lights, but that's often not a big deal. If there's something like a border effect, you can play with the rendering down the track.

Then next year you can add your two extra verticals and everything will be good and even.

 

[Homer911]

If you're running two independent power supplies, then you will need to separate the positives, but keep the negatives connected.
Without the negatives connected, the second PSU wont do anything as there would be no return path for its current.

Your power injection wires should be run with both positive and negative from the chosen source, not just positive as you've shown in the diagram. This is because additional current flows through both wires - in one and out the other. Adding power on one side won't help the situation (much).

Your suggestion of two strips per PSU is probably the easiest way to do it. You don't need to break any positive lines. Only wire the data and ground from the dig-quad for the two "alternative" PSU powered strings.
Fuse them to match your wire gauge.

Given you have a 600W PSU there, I don't think you'd need to worry about a second power supply though. Do not run all that current via the Dig-quad though, it won't handle it.
Run a separate fuse block for each PI run. 5A or 7.5A fuses are probably the most appropriate for 0.75 / 1mm2 (16/18awg) wire.

For the PI line coming from the PS to the strand, can I use a larger diameter dual cable (+ve & -ve) and then branch them off to their respective locations (just to reduce the quantity of cabling) or should I run a separate line for each injection? I may need to buy some 18 AWG cable.

 

[Homer911]

There is one way to get around it, especially if you want more.

Consider it as a 2400 pixel tree - with 24 strands of 100.
In xLights, model it as 6 strands per string, 4 strings.
Then just leave the last two disconnected, so its 600-600-600-400.
It means that anything that xLights renders on the last two verticals will be ignored by the lights, but that's often not a big deal. If there's something like a border effect, you can play with the rendering down the track.

Then next year you can add your two extra verticals and everything will be good and even.

If I can find some LED's, I think I will do that.

 

[thewanderingpine]

If I can find some LED's, I think I will do that.

Even if you can’t this year - the 600/600/600/400 approach that sky suggested is a better one for the long term.

 

[Homer911]

Even if you can’t this year - the 600/600/600/400 approach that sky suggested is a better one for the long term.

Agreed