I think I know the answer to this, but I’m hoping I’m wrong. I hung a 300 LED strip on the eves of my place. It’s something I’ve been wanting to do to make not only Christmas a little bit more hi-tech and showy, but I could change the code to reflect whatever holiday I wanted.
So, they’re up there and I coded up a couple of patterns. In particular, I’m using the palette method to display red and white candy cane stripes. Trouble is, about halfway down the strip, my whites become oranges. I’m also doing the rainbow cycle and a red/green (holly_gp) pattern, which look great.
My fear is that this is a power issue. The arduino uno and the lights are powered by a 5v 2.5 amp wall wart separated on a break out board. Powering both sides of the strip aint happening, cuz I aint gonna rent a ladder again. I could probly get a better power supply, but before I go spending money, I thought I’d consult the boards.
Almost certainly a power issue. (I didn’t look at your code, sorry.) You can verify it by just writing all white to the whole strip… it’ll probably go yellow, orange, and then maybe even red as you go down the strip.
A bigger supply probably won’t help much, the voltage sags as more and more LEDs down the strip demand more energy. Strips are wire-limited more than they are supply-limited.
One thing you can do without a ladder, though, is lower the brightness. If it’s a power issue, you should see it stay white farther out.
When designing for WS2811 style RGB LEDs, I use 50 milliamps per pixel to select an adequate power supply. 300 LEDs X 50 ma is 15 Amps if you set all of them to full brightness white.
Your wall wart is definitely not up to the job. Change your PSU for a 15 or even 20 amps model, they are not that expensive. You do not describe how exactly you have your strips wired, you may still get some voltage drop along the strips if your wiring is too small and/or too long but the PSU update is a must in your case so start with that.
I’m about 75% done my exterior lighting project. I was/am paranoid about power so the longest strip I have with power at both ends is only about 2 meters (30 LEDs per meter). Any strips that are 3 meters (10 feet) or longer get power at both ends and in the middle.
On top of that, most strips have their own power line going to them. Many of those lines tap into the same source at the moment, but I now have the option of giving them their own separate sources if need be.
Right now I’m using a computer PSU running some of the strips off the 5-volt and others off the 12-volt using buck converters to step down the voltage first. I get super bright primary colors at half and three-quarter brightness, but haven’t tried full-white, full bright yet (my buck converters handle a max 3A each, and I don’t want to risk burning anything out until the off season).
Regarding the ladder… are you going to be more miserable acquiring and climbing one again… or more miserable looking at faded out patterns for the next few years?
Maybe instead of renting a ladder you can borrow one from family/friend/coworker – or even trade some of your LED skills.
Definitely try using the power management features of FastLED. I have found that the brightness curve on most LEDs means you can drop the max current in software down quite considerably before you notice much difference in effective brightness.
It’s an awful photo, but here they are. The strip is a 5m, 300 LED, 5v strip. I’m using ethernet cable that runs down the right side painted to look like the wall and into an outside storage closet where I’ve mounted the Uno and plugged the whole shebang in.
I’m not familiar with the power saving features, so that’s definitely something I’ll start looking into. I’m already using
FastLED.setBrightness( BRIGHTNESS );
to set everything at 128 (sketch says 200, but I’ve adjusted since then). I’ll try halving it again to see if it makes a difference, though the white stripes in the sketch are technically gray 128,128,128.
If anyone has PSU recommendations, I’m all ears. The best deal I found was on Amazon for a 5v 10a supply for 15. missing/deleted image from Google+
If you have thrift stores in your area, check out the power supplies they might have around. Sometimes the bricks from laptops or other electronics can deliver a lot of amps. Just double-check the voltage.
My best find so far is a computer PSU, still in the box, that pumps out 32A on the 5v, and another 32A on the 12v (that I can step down to 5). It’s the unit (once I have the time to hack it) that I’ll be using as the final power source for my house project .
I don’t know enough to give a solid recommendation or prediction, but I’ve been told the traces on the strips are quite thin… so even if you have enough amps, you might burn something out trying to move that much power all the way from one end of the strip to another. It’s another reason I fed my segments from both ends (and sometimes the middle). But I might have over-engineered mine.
The 10 amp brick sold by Adafruit has served me well. I have also bought a few from China that seem to be doing ok but since you can’t wait 3 weeks for delivery you may as well buy from Adafruit. Not sure where you live but Adafruit ships from New York so it is slow shipping to me in Colorado. http://Mouser.com is an Adafruit distributor based out of Texas that ships a lot faster and has the same exact pricing. You can also buy from Adafruit on Amazon but the prices are higher for some reason. As a side note, you may want to change the LINEARBLEND on line 88 to NOBLEND. I am testing your code and the green and red palette has some orange in it because of the blending.
Add this line in your setup function and see if it helps until you get a bigger power supply. Though you may want to lower the milliamps to prevent the supply from being maxed out.
I’m in CA, so yeah, New York is probly gonna be a few weeks out. There’s a chinese knock-off for 15 with the same specs and I can get it in two days with Prime. Thanks for the code too, I’m gonna give that a shot tonight.
I won’t lie, I’m just a little amazed even after reading the “voodoo” line on the FastLED wiki, but add that maxPowerIn bit seems to have done it. The lights look great now. I used 5, 1500 to be on the safe side and as this slightly less awful image shows, I believe I got it. I still intend to upgrade the PSU, but tonight’s results have most definitely put a small on my face. Thanks y’all!
