Hi all,
I am controlling a 20x20 (400) ws2812b LED Matrix with an Arduino and the help of Glediator. My LED Matrix is directly plugged into my arduino, with the 3 wires 5v, Gnd, and Data.
My question is simple: do I need an extra power source for this kind of setup? The the light from the LEDs does seem to be a bit shaky when the matrix is running.
Thanks in advance for your help,
Bybye.
My answer is simple yes of course you do. One that can delever over 24 Amps.
I don't actually believe you can get much from the half amp limit on a USB power supply, you must be screwing it something shocking.
Really? I just tried with 60 LEDs with the arduino plugged into my macbook and it's working fine.
mooop:
Really? I just tried with 60 LEDs with the arduino plugged into my macbook and it's working fine.
Quite simply you are either mistaken or lying.
See Powering NeoPixels | Adafruit NeoPixel Überguide | Adafruit Learning System
It says:-
Each individual NeoPixel draws up to 60 milliamps at maximum brightness white (red + green + blue).
So for 60 LEDs all showing white then that will be 3.6 Amps. If something hasn't broken it soon will.
Measure the voltage on the 5V rail when these LEDs are on. I think you will be in for a surprise.
Which power supply do you recommend for my type of matrix please?
It depends on where you live and what you can get. I would search eBay for a power supply that can delver at least 30A at 5V.
for my type of matrix
The kind of matrix has no baring on what power supply you use, only that it can supply the appropiate amount of current.
I think once you have proper power you will be amazed at how bright it all is.
I see. Thank you for your help.
Ok so 60mA x 400 LEDs = 24 amps needed.
I want them at about 60% brightness, so 15 amps will do. This one is my guy right:
?
Thanks for your help Grumpy_Mike it is much appreciated.
I would not balance on the edge. Leave headroom, even if you are 100% sure you only drive them at 60%. So I would not get anything less then 20A if you want to go up to 60% brightness. Ad be 100% sure you don't accidentally write all white because that can damage the supply. Aka, add a fuse 
And use biggggg cables. 4mm2 at least I would say or multiple thinner (like 2,5mm2) would even be better, all connected at the supply. And don't try to connect it just in one place on the strip. 24A will give a significant voltage drop, even over a 4mm2 cable of moderate length.
Hey septillion, thanks for your help.
How do I go down to 60% brightness wutg a 20A power source?
Also, what do you mean by big cables? In between the LEDs or just from the power source to the first LED of the strip?
Here is how far i am in the project. If I made mistakes let me know, this took me a long time to put together, i have 2 months left for this project before I have to present it to a jury. I am an art student not electronics, I am trying to put this LED panel together for a performance/presentation. I guess you learn for your mistakes, so if I have time to redo it all within 2 months, let me know.
This is the front of the panel which took me a lot of time to glue:
And this is the back; which took me a lot of time to solder:
As you can see I am using really thin wires, 0.5mm.
As for the power output, for now I just have the 3 wires 5V, Gnd and Data connected to the arduino with 0.5mm wire, and my arduino is hooked up to my macbook pro via usb. I haven't tried lighting up all the LEDs at the same time yet, but I have already gone up to 160, and noticed the LEDs light starts to be shaky and unstable.
My questions are:
I need 24A in total, but if it can help my wires to only use 10A, I will happily do so, I don't really have time to start everything over. Is it also maybe possible to split the LED panel in 2 sections, with 2 different 10A power outputs like this one?
I started this project because I needed to, I need to experiment, and you learn from your mistakes, so let me know what I can do to make this project work.
Thanks in advance for your help.
Let's start with, I don't see pictures.... To fast 
Keep in mind I started writing without pictures.
mooop:
How do I go down to 60% brightness wutg a 20A power source?
What we normally refer to when talking about power supplies is a voltage source. And that's indeed what you need, you need a fixed 5V source. The amperage rating is only what YOU can max pull out of it.
The leds just want 5V and will draw what YOU control them to draw (max 60mA per led) with the data you send to them. You DON'T limit the brightness by just grabbing a 15A supply. Because even though it's just a 15A supply, the leds will happily try to draw the full 24A if you tell them to.
mooop:
Also, what do you mean by big cables? In between the LEDs or just from the power source to the first LED of the strip?
24A is massive! In a normal Dutch house we have groups of 16A and in a lot of countries that's even just 10A. And heat and voltage loss don't depend on the voltage, just on the current (and of course material and surface area). So in order to keep that in check (aka, don't burn wires and supply 5V to each led and not just 3V because you dropped 2V) you need to use (multiple) thick wires. Only connecting it to each start will just not work and will probably burn the strip [edit]I assumed pre-fab strips[/edit]. But am I correct you use sections of 20 leds? That's 1,2A per section. So even for just a section a 0,5mm wire (which is just 0,2mm2) is pretty thin... But maybe if you supply it at both ends with power (which effectively increases the area / 600mA for both ends) you can make it. But you need to supply each section with a much thicker wire!
But it's a grid, that makes it a bit easier. I would grab 4mm2 (11AWG) and run power (so GND and 5V) on both sides of the grid creating a power bus on both sides. And connect both sides of the power buses to the supply again. That will thus give you 4 times a GND wire and 4 times a 5V for the supply. Don't forget a fuse!
mooop:
As for the power output, for now I just have the 3 wires 5V, Gnd and Data connected to the arduino with 0.5mm wire, and my arduino is hooked up to my macbook pro via usb.
I haven't tried lighting up all the LEDs at the same time yet, but I have already gone up to 160, and noticed the LEDs light starts to be shaky and unstable.
Then you are very very very lucky you didn't blow anything and it even kind of worked... 160 leds already need 10A and a computer port can only do 500mA... But probably the thin wires saved you from blowing things up / limiting the current severe. But that would be wayyyyyyyyyyyyy out of spec for the leds.
mooop:
- What would be a proper setup to light up the LED panel the right way?
- Do I have to start everything over, and is it doable in less than 2 months?
- Is there a compromise between what I have done and what should be done? Can I keep some things from what I have done and restart from that?
So in a nutshel:
mooop:
Is it also maybe possible to split the LED panel in 2 sections, with 2 different 10A power outputs like this one?
2 times 10A still isn't 24A... And it's not a power supply problem (just get one big enough and you're fine) but a wire problem. 0,5mm wire will just light up on it's own with 24A...
Don't forget that when you first power on the LEDs they can come on in any state. Sometimes they come up all off but other times with me that come up full brightness cyan, so that would be 40mA per LED.
Most power supplies have a current limit in them, that is if it is a 10A power supply and your load wants to draw 15A then the power is shut off or limited to 10A. The only way the current can be limited is if the voltage drops so you will then be feeding a 5V signal into a chip being powered by less than 5V. That can damage the first LED, which is why it is vital to have that resistor in series with the data line.
As to the wires they look fine to me. Remember these things are normally sold in strips and those wires will carry a lot more current than the PCB foil in a strip. What I would do however is to connect all the ends of the strips together, that is both the 5V and the ground. Do this on both sides of the rows and that way you will minimise any voltage drop, which is what generates heat and is the factor limiting the current capability of a wire. I don't think the comparison with domestic wiring is relevant here because 10A at mains voltage is one thing but it is not 10A at 5V.
Do I have to start everything over,
I wouldn't.
However the photos are too small to see if you have decoupling capacitors on those LEDs.
Grumpy_Mike:
I don't think the comparison with domestic wiring is relevant here because 10A at mains voltage is one thing but it is not 10A at 5V.
Why not? 10A is 10A. Will generate the same heat and voltage drop no matter if it's 5V DC or 230V AC. Only because here you only start with 5V the voltage drop is wayyyyyy more important. But yeah, 10A or 24A will probably just melt the 0,5mm wires...
PS The photo's are not that tiny but the forum likes to make them tiny inline... 
Why not? 10A is 10A. Will generate the same heat and voltage drop no matter if it's 5V DC or 230V AC.
Yes but the rating on domestic wiring allows for only a very small increase in temperature. This is a much much smaller rise than is acceptable in a project like this, and it comes no where even remotely close to melting a wire.
But here, although you can get away with the rise in voltage, you can't get away with the increase of voltage loss...
Look at the LED strips on flexible PCBs. What do you imagine the current carrying capability of those are? It is way lower than those wires he is using.
you can't get away with the increase of voltage loss
Yes you can.
Thank you guys so much for your help.
Here are the 2 links to the bigger pictures I sent before.
So based on the advice I got, here is what I'm going to do.
Buy a 5V 20A power source, I really don't need full brightness, and if the LEDs ask for the 4 remaining amps when on full white, is it that of a big deal? Here is the power source I'm thinking of buying, is this ok? https://www.amazon.com/dp/B01JA3T8MI/ref=twister_B01JA3T7W4?th=1
Have big cables (4 to 5mm) from the power source to the first LED strip, but keep my small wires for the rest.
Do my wiring differently. Here is how my LED panel is wired up right now:
I don't know if i'm understanding your suggestion correctly. Connecting both ends of the strips together would make something like this:
Add a resistor in series before the first strip on the data line.
Here is a picture of the setup I have to achieve, tell me if i'm mistaken:
Thanks a lot for your help, am I forgetting anything based on what you told me?
