G+_Newton Robinson Posted March 25, 2018 Share Posted March 25, 2018 I want to create a LED sign about 3' by 2'. I want to use WS2812 LED string with 60 LEDs per meter (300 LEDs in a 5M string). These are 5V and18 Watts per meeter. So 90 watts per real. I will cut each real into six 50 LED segments. I will use 6 reals, which will give me a sign resolution of 50 LEDs by 36 LEDs. I plan to connect 6 50 LED segments together for power. I plan to use two 5V, 300Watt, 60A power supplies. So three reals will be connected to each power supply. Each power supply has three connectors for power. I assume the power bus in the power supply are all connected internally. So 90Wats times 3 Reals is 270Watts, So I assume that is feasible. I have a wire layout that will only have a few inches between 50LED segments. I also plan to have a 4 foot connecter between the power supply and the LED String. Questions: -Is the above feasible? -What gauge wire should I use? -Do I need resisters? -Is there anything I'm missing? To start with I will use a ARDUINO MEGA 2560 R3. I'm told that it will not be sufficient to run at video speeds. But I hope it is enough to get started. I have also looked at software like Jinx! Any idea on an LED driver that can support it (and does not cost too much)? I would rally like to get some feedback before I start. Has anyone done something like this already? Do you have a Wiki? Thank you Link to comment Share on other sites More sharing options...
G+_Jim Hofmann Posted March 25, 2018 Share Posted March 25, 2018 Ah ... no. 12ga I think is good for 20A, 60A would require 3 X 12ga or a car jumper cable. It is the amps that limit the cable size and the voltage is the insulation rating. No, maybe a little harsh. This can be done, there are smaller examples out there. But anything over 5A requires caution. However, electrical code limits you to 100VA, 5V @ 15A. First thing would be to look at 12V, I'm sure I've seen them. This gets you to 12V @ 8A but still 24A for 300W. I've seem people use a chunk of 8ga with the insulation striped, some standoffs, as a buss bar, then solder a bunch of fused pigtails off that. FUSE everything. At least above 5A. Fuse the transformer(s) or buy with a resetable fuse. Each 5M length draws 18W, 5V @ 3.6A. 2 strips ~8A plus safety margin = 10A which 18Ga might handle (I need to check). 4 lenghts and now you need a 12 or 14Ga buss to distribute to each strip. You'll want to parallel power, If you series the strips the tracings must carry the power for everything downstream. Bottom line, you are doing the right thing by asking. Draw up a power distribution scheme. I'm sure there are KITAs here ready to help. Good Luck. Link to comment Share on other sites More sharing options...
G+_Newton Robinson Posted March 25, 2018 Author Share Posted March 25, 2018 If I understand you correctly; I power each string of 50 separately from a shared power bus, this will solve my problem. Basically each power supply would power 18 strings of 50. But each length would be short only 3 feet long. A shared power cable to the bus. This also solves my cable size issue. Not at 3% loss, 5VDC 1.2A per string of 50 LEDs, and 8 foot length, should allow me to use 12AWG wire. Where do I need to put the fuses? Would one per power supply be ok, or do I need on each string? Or does the lower draw eliminate the need for fuses? I will try to draw something. I know a picture is worth a 1000 words. Link to comment Share on other sites More sharing options...
G+_Newton Robinson Posted March 25, 2018 Author Share Posted March 25, 2018 Very simple diagram. Kind of like Back to the Future. Not to scale and crude. I'm not sure on the marking of the LED's, but consider the top as ground, bottom as power, and middle as data. This is not the Arduino I will be using, just wanted something small for the diagram. As you can see each strip is powered fro a common connection. Grand is common as well. Blue is data and strings them together to form the matrix. This is my diagram after the discussion above. Link to comment Share on other sites More sharing options...
G+_Newton Robinson Posted March 25, 2018 Author Share Posted March 25, 2018 Seems like 12 Gauge is overkill. I don't even think I could solder it to the strip. Recalculating not counting the power cord to the bus (that one will be 12 or better). But from the bus to the led strips plus the length of the LED strip: 3% loss, 5VDC, 1.2A, 1 Meter length calculates to 22 AWG. Does this calculation make since? Link to comment Share on other sites More sharing options...
G+_Paul Hutchinson Posted March 25, 2018 Share Posted March 25, 2018 Yes, 1.2A through a 1 meter loop (2 meters total length) of 22AWG wire will drop less than 0.15V (3% of 5V). Link to comment Share on other sites More sharing options...
G+_Newton Robinson Posted March 27, 2018 Author Share Posted March 27, 2018 I went with 20AWG. I think that will cover it. Now I need to figure out how to control them. Link to comment Share on other sites More sharing options...
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