long time watcher, first time attempting... and im lost!!!

Harlo

New elf
Joined
Jan 12, 2021
Messages
4
Gday,

I recently bought 32 strings of 50 node WS2811 (5v) from Ray Wu (Made the mistake of buying 24AWG) with 5 inch spacing... My intention was to construct 2 Mega Pixel trees (16 strings of 50 nodes each tree) for Christmas this year to start my display, with an intention of looking at adding in the future (not sure what yet).

I am hoping for some advise on controllers (was thinking one per tree) and power injection locations and number/types/specs for power supplies.

If anyone is willing to give me some of your advise and guidance, it would be greatly appreciated.
 

i13

Dedicated elf
Joined
Jul 5, 2013
Messages
1,172
16 strings of 50 nodes each is 800 nodes in total. This means that you can run them on a single controller output from many (but not all) controllers. 40 frames per second might not be possible unless you use two or more controller outputs. Extra capacity might be sensible because a future expansion possibility is to add a star or something similar onto the top of each tree and that'll need controller capacity too. There are many controller options with Falcon, Kulp and Advatek's being popular. If the trees are near each other then you could use pretty much any option. If the trees are further apart and sharing a controller board then the signal will struggle to go the distance from the controller to the first pixel. Ways to overcome this include differential controllers with receivers (a main controller sending a long-distance signal to small receiver boards that connect to the lights), coaxial cable between the controller and first pixel (doesn't work for all controller types), pixel extenders or null pixels.

24 AWG is not great, especially when combined with 5V and a wider spacing. I see that you realise this already. I estimate that you'll need to power these strings at both ends. If I assume that the pixels run at 55 mA at full brightness white, 800 pixels is 220 watts (0.055A multiplied by 5V and 800 pixels) so I'd suggest one power supply per tree. Considering all of this, I'd suggest running a pair of very thick injection cables to the top of the tree and back to the same power supply that powers the strings at the base of the tree. Ray's T-connectors might come in handy. A different option to overcome voltage drop is to run the pixels at a lower brightness. Despite the voltage drop, I do think that 5V is a sensible choice. You'll have a large number of pixels in a small area. The small area makes power injection practical and the power consumption compared to 12V will be much better due to the number of pixels.

If you want to start building and testing before choosing a controller, a pixel tester can be used to make sure your wiring is correct. I'd recommend getting one anyway. They're available on Ebay or from Ray Wu. https://www.aliexpress.com/item/32261108366.html
 

AAH

I love blinky lights :)
Community project designer
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Dec 27, 2010
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The spacing of your pixels is probably not ideal for a megatree. It's quite common to run with pixels at either 2" or 3" spacing. There's nothing wrong with using 5" spacing pixels at 2 or 3" spacing except you have a lot more wire (pronounced voltage drop) than you need. I have a 5V megatree with strands of 75 up and 75 down and I connect some medium duty figure 8 cable from the base to the 2 joins in the strings of 50 pixels and I also do a short connection about a foot long between the start and the ends of the strings. Power injecting at each of the starts of the strings of 150 gives me no problems when running at 100%. The use of a T connector is an easy way to power inject. Personally I have additional 2 core pigtails at the start of my strings of 150.
I have most of what you need on my site. I have the rpi-28D+ which along with a Pi will control up to 2 outputs of 1600 pixels (800 at 40fps) or the HE123Mk2 which will control 16 outputs of 1600 (800) or up to 48 outputs with the addition of 2 daughterboards. I also have a bunch of different power distribution boards, power supplies, pixel testers and lots of other stuff. I'm based in Central Vic which means overnight delivery (pre covid) is common.
 

Old Salt

Apprentice elf
Joined
Dec 8, 2020
Messages
80
If cost becomes a concern, you might want to look into a controller (Falcon F16, Kulp K16 A-B) that supports receiver boards. Locate the controller at one tree, and the receiver at the other. Both would require power supplies. Another option would be a smaller controllers (Falcon F4, Kulp K4 PB) for each tree. The Falcons are expandable, but require either an SBC (Pi) or running network cables to the controllers. The Kulp is not expandble, and comes with an SBC (Pocket Beagle) requiring no network cables. The Kulp K4 PBs with the Nano 1200 WiFi will cost less than the Falcon F4 (without an SBC).
 

Harlo

New elf
Joined
Jan 12, 2021
Messages
4
You people are all too kind with your assistance. It is greatly appreciated. I now have a better understanding of what I have got myself into lol.

Bring on the good times :D
 
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