I’m using WS2812 LEDS, the 144 LEDs per meter version. This is 25 lengths of 17 LEDs all soldered together into a single zig-zag strand. But, its not lighting up. I used a multi-meter on the positive and negative connections and they all come through. So I’m assuming its the data connections which is faulty somewhere or its drawing too much power. I have the program set to 30% brightness which is typical of what I use.
I added an external power source to the strip, nada. So I unsoldered the ground wire between strip 12 and 13 and removed the external power supply. Now the 1st strip lights. I’m basically going solder joint by solder joint and I’m up to 4 strips lighting. But is there an easier way that I’m missing? There’s no way to test the connectivity of the data connections, is there? And why would I get a positive reading on the +/- connections? A bit frustrated here…
Something might be shorted down in the chain. You could do a binary search tree…cut the array in half, if there’s still a problem then it’s in the first half of the array. Cut that array in half and test again. You’ll narrow it down to the exact strip very quickly.
Garrett’s method has served me well over the years in different fields. This is also why I slowly build up and test as I go, as opposed to building the whole thing and then tear my hair out.
Thanks for your help guys, I was able to get it all fixed last night. The half/half concept worked well but in the future I do think I’m going to test as I go. I did learn a couple of things - those tiny copper solder pads are a real challenge, and more solder isn’t a good idea. Some of the pads had too much solder and was contacting other pads or the legs of the LEDs themselves. I had to replace a strip because something was wrong with the last 2 pixels. In any case, its up and running.
In regards to power, this is the first project I’ve ever done using this many pixels. This is for a wearable project so portability is important. I plan on powering it with Lipoly batteries but I’m open to other ideas. I have never powered a strand of LEDs with more than one battery and I’m not sure what the rules are in regards to this when using Lipoly batteries. Last thing I need is to have one of those heat up and catch fire! Any guidance would be appreciated!
First. You need to calculate (or measure) your instantaneous power requirements. Then how long you want that power for. Your amp hours.
LiPo batteries can be daunting.
Golden rule. Dont let a cell drop too low.
There are loads of alarms available from the RC world, and they are real cheap too. These will alert you once the battery or a single cell hits a limit you set.
LiPos are a bit funny. Fully charged a single cell present 4.2v and fully discharged is 3.8v
So batteries are often advertised as 3S (this is the number of cells in series).
Choose a pack (weight vs size vs amount of power) and couple it with a DC to DC converter. E.g 11v in 5v out.
for ease of you, find yourself a nice USB charger. I use 20k mah Anker ones with 2x 2.4amp output (up to 4.8 total). I use fastled to limit the draw to about 3.5 and its still goes plenty bright. Its kinda a big pack but works super easy. If you go lipo, please track your build as Id like to look into some smaller compact power supply for wearables too!
@Randal_B I try to use LiPoly due to the size constraints. I put these LED’s on Top Hats for music festivals and the less wires outside of the hat, the better. You Anker battery idea is a good one, and I even have one of those batteries, would have to run wires from the hat into a pouch or something.
I’ve used these LiPoly batteries before and they work great, lasted all 8 hours even.
