Hello everyone,
I'm building a led panel with 6 led strips for a party. The panel will be placed 2.5 m high on the wall. I'm using ws2812b led strips(5v) where each led takes 0.3W and 0.06A. I have around 250 led in total so I bought a 5v 20 A power supply to have a good margin. Each strip will show different letters and has up to 55 leds (so 3.5A to have a good margin). The panel will also have a breadboard with an Arduino nano to send data to the strips, so I will also need to supply power to it and connect Arduino ground to strips ground. I need help to wire this, I'm new to electronic world. I will post a simple diagram to help you understand.
My questions are: what kind of wire do I need? I have 25 m of 7A wire
Is it better to attach each strip directly to the power supply?(so I'll have 14 wire, 2 for each letter and 2 for arduino) because I don't think a single wire can handle 15A peak.
Do you think there will be voltage drops?
Each strip needs its own power supply; those strips can't handle all. The data line of course has to be connected strip to strip in series.
A strip can be powered from either end, the data connection is directional, so keep that in mind when you hang them up.
I'd place the power supply as close to the strips as practical, to minimise the length of high current wires, as that's where most losses are. 55 LEDs draw no more than 3A, so one of your 7A wires would comfortably feed two of such strips. Then you have three pairs of wire from your power supply (you can of course have two or three together on the same screw terminal) to the strips, each to two strips.
By the way, 250/6 = 41.7. So it seems you're seriously short on LEDs - 250 of them doesn't even make five strips of 55. You actually need 330 of them for this project, drawing up to 20A when all set to white at maximum brightness, so a 25-30A power supply would be more like it. Or two or three smaller ones, of course.
Thanks for the fast reply, I'll follow your advices. So a single data line from the nano can handle all the leds? It's like 10 m strip in total
That's the thing with these LEDs... if not for them they simply pass on the data to the next in line! One Arduno pin can control hundreds if not thousands of those LEDs - it's just that you'll run out of RAM well before you reach that number, and the refresh rate becomes pretty poor.
330 LEDs x 3 bytes/LED = 990 bytes. 2048 in a Nano could be plenty, depending on what else your code is doing.
Is each strip just making the one letter? P, A, R, T, Y, and x ? And all you are doing is changing their color, making them flash, etc. using FastLED.h library or similar?
Might be easier to use 'dumb' RGB strips then, any only have to control 3 transistors per strip, 18 total.
wvmarle:
A strip can be powered from either end, the data connection is directional, so keep that in mind when you hang them up.
Actually, it is more to the point that a strip should be powered from both ends. The foil in these strips is pretty thin so you lose some voltage and the colours far away from the power supply will tend to have a "red shift".
Also remember that where the data travels from the "out" of one strip to the "in" of another, the ground must also travel together with it, with a cable adequately rated to carry some power if there is a disparity in the ground voltage between those two points.
In my experience no problem with strips of about 60 LEDs, double the length did show issues.
Powering from both ends would indeed be best, if possible.