Off grid LED display using FPP.

[BlueSkies27]

I'm developing a small project that I plan to run off the grid in the evenings for a week. This is NOT a Christmas light display, more of a decoration of a temporary outdoor space that needs to run entirely off-grid without a PC always-on.

I'll be using 12 strings of 50 LED ws2812b 5v pixels (they're a different type from the pixels and strips that many use today, link below) to create a matrix that is 10x50m. I'm planning to use Xlights to sequence it, but I'll leave the computer off for the majority of the week, unless I have issues or need to tweak a sequence. FPP will be running on a Raspberry Pi 3B. I'll have a very small TP-Link usb-powered router (with no internet connection) that all devices will connect to. If I can find one, I might set up a Pi Zero W to fill this function instead. All controllers can be located within 2-3 meters of the router, probably closer, so I don't expect range issues. I'll be using 2x Wemos D1 Mini V4 or Pro V2 (probably the latter, as the JST power supply option will be useful on other projects in the future) as LED controllers. There will also be two more ws2812b strips (5m 30 led/m) with separate controllers. One major limitation: my display needs to run entirely on 5V, and do so as efficiently as possible, as I have somewhere between 50-100AH at 5V to work with per day, and I'd like it to run for 6-8 hours per day. I'm OK being selective in my brightness and color settings (no white, patterns where all LEDs and pixels aren't always on, etc) to accommodate for power limitations. I'm also expecting to need to inject power every 100 pixels in the matrix, which will probably have 600 pixels total. Not planning on injecting power in the 5M strips.

The majority of the LEDs I'm using (the transparent wire option)

WS2812B RGBIC Christmas Lights LED String 5 m 50 leds WS2812 Birthday Party Room Decoration Light Addressable Individually 5V 12 - AliExpress 39

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

I'm using these because my matrix needs to be flexible, lightweight, and fairly weatherproof, and the omnidirectional light is nice also. Regular strips are fragile, and the pixel strings everyone has been using to date are a bit heavy for my project. I'm somewhat new to this particular WS2812B pixel string type, so if anyone has experience or knowledge of how they differ from the typical WS2812b pixel strings that everyone loves, I'm interested to hear your thoughts.

Does my design seem sound? Will the hardware I've chosen work well together? Is there something I've gotten wrong?

Disclaimer: this is my first project of this scale, and my first time using Xlights. I've played around with WLED a bunch and FastLED with demo code a bit for very small & portable LED projects (ones that run on small USB power supplies), and I've never built an addressable LED Christmas light display (yet!).

 

[Mark_M]

Welcome along to the hobby, I see this is your first post here on ACL.

FPP will be running on a Raspberry Pi 3B. I'll have a very small TP-Link usb-powered router (with no internet connection) that all devices will connect to.

FPP uses internet time or you manually set it. If the device is being turned on/off, the time is not saved and will need to be manually set on start.
Or, set FPP to start a playlist as soon as it boots.

If you want it to keep the time, you could use a Real Time Clock (RTC). This is basically a little board that plugs into the Pi and it keeps accurate time.

However, I think that setting FPP to play as soon as it is powered on would be fine for your task.

---

Those 'soft wire' seed pixels seem to be rigid enough for outdoors. I have been working on a large prop with 2,400 of these.
Current of my version (from GFLAI lighting) is about 34mA per node at 100% white.

In this graph I measured the current draw of a string of 50, 10 and 1 node, then divided to work out the current per node.
Obviously the longer string of 50 used less current per node because of the wire resistance.
*Test string was powered from one end (no power injection).

From my testing, I found power injecting every 50 nodes should be fine.
Without power injection, node ~70 onwards goes noticeably off-white.

Seed pixels.

• Mark_M
• May 25, 2022
• 5v pebble pixels seed pixels ws2811

Softwire seed pixels from @gflai .
Mattos Design's also sell these under the 'Pebble'...

Personal opinion:
I do not like the wire insulation quality. I found when soldering onto the bare wire that the insulation nearby would quickly melt. This results in the bare wire being longer than you anticipated.
A simple fix is using a longer piece of heat shrink.




There is some talk about this type of pixel string in this thread: https://auschristmaslighting.com/th...oft-mini-string-lights-mass-production.14370/

 

[BlueSkies27]

Welcome along to the hobby, I see this is your first post here on ACL.


FPP uses internet time or you manually set it. If the device is being turned on/off, the time is not saved and will need to be manually set on start.
Or, set FPP to start a playlist as soon as it boots.

If you want it to keep the time, you could use a Real Time Clock (RTC). This is basically a little board that plugs into the Pi and it keeps accurate time.

However, I think that setting FPP to play as soon as it is powered on would be fine for your task.

---

Those 'soft wire' seed pixels seem to be rigid enough for outdoors. I have been working on a large prop with 2,400 of these.
Current of my version (from GFLAI lighting) is about 34mA per node at 100% white.

In this graph I measured the current draw of a string of 50, 10 and 1 node, then divided to work out the current per node.
Obviously the longer string of 50 used less current per node because of the wire resistance.
*Test string was powered from one end (no power injection).
View attachment 20527
From my testing, I found power injecting every 50 nodes should be fine.
Without power injection, node ~70 onwards goes noticeably off-white.

Seed pixels.

• Mark_M
• May 25, 2022
• 5v pebble pixels seed pixels ws2811

Softwire seed pixels from @gflai .
Mattos Design's also sell these under the 'Pebble'...

Personal opinion:
I do not like the wire insulation quality. I found when soldering onto the bare wire that the insulation nearby would quickly melt. This results in the bare wire being longer than you anticipated.
A simple fix is using a longer piece of heat shrink.




There is some talk about this type of pixel string in this thread: https://auschristmaslighting.com/th...oft-mini-string-lights-mass-production.14370/

Yup, first post!

Thanks, didn't anticipate a scheduled power-on being an issue. I figured that the FPP device or the individual controllers would store time based on the last time they were connected to the internet, even if that time is wrong (I'd do some math to work with whatever time the FPP thought it was). I was planning on having it scheduled to turn on at a specific time and then run for a specific amount of time, but I'm ok manually turning it on, as I'm assuming I can set it to go off after a playlist completes, and the system time isn't needed for that step. I'll typically be there to turn it on, but I'll be leaving it unattended for the majority of the time.

I'm happy to know these seed pixels draw less power. I had noticed they seemed to be less bright than other options, relieved to know they're probably not less efficient, just less powerful (individually). That'll help me with power consumption. Might even be able to add a few more pixels.

I hadn't tried to solder them yet, but I'm considering doing so to change the aspect ratio of my matrix. Happy to know it's possible (its one of the reasons I chose the soft wire over the bare wire option), and thanks for the heads up regarding the super melty insulation! I'll be ready with extra shrink tubing.

 

[Mark_M]

I hadn't tried to solder them yet, but I'm considering doing so to change the aspect ratio of my matrix. Happy to know it's possible (its one of the reasons I chose the soft wire over the bare wire option), and thanks for the heads up regarding the super melty insulation! I'll be ready with extra shrink tubing.

I certainly reckon the 'soft wire' variant is better.
I used the solid enamel copper wire version last year, and some of the coating flaked off and corroded.

Do be aware that current consumption is likely vary between manufactures.
I stated my tested consumption, but the other manufactures might use another WS2812B LED chip.

 

[BlueSkies27]

I certainly reckon the 'soft wire' variant is better.
I used the solid enamel copper wire version last year, and some of the coating flaked off and corroded.

Do be aware that current consumption is likely vary between manufactures.
I stated my tested consumption, but the other manufactures might use another WS2812B LED chip.

Thanks for all of the info and suggestions, I'll keep it all in mind!

I'll report my progress once I start to build it, I'm awaiting delivery of pixels and controllers from AliExpress, so it'll probably be a few weeks.

 

[thewanderingpine]

From my testing, I found power injecting every 50 nodes should be fine.
Without power injection, node ~70 onwards goes noticeably off-white.

*injecting* every 50? Or injecting every 100 so that no node is more than 50 from a power source?

 

[Mark_M]

*injecting* every 50? Or injecting every 100 so that no node is more than 50 from a power source?

ah, right.
50 would be powered from one end.
Theoretically you could do every 100 then.

Now to add confusion lol, my current project with these pixels is a string of 80 and powered from both ends. The middle nodes look slightly yellow when set to 100% white.
Weird huh? That's 40 pixels from each power source, yet 50th node powered from one end at 100% white looks fine??
My best guess is the connector I soldered on has significant voltage drop given it's small wire gauge (oops).