Hi, I need to power my LEDs (WS2811) from several feet away.

Hi,
I need to power my LEDs (WS2811) from several feet away. There are four sections of 240 LEDs 2.5ft away from the 20A power supply. The LED sections are 4ft long. I will put two 1000uF capacitors at the start of each section. I know that I will never need to carry 5A, but I’d like to have that wire capacity in place in case that I add LEDs (also, I would never run this power supply at full 20A for a prolonged period). I have plenty of Cat5e on hand, but I don’t think that that will handle the power (voltage drop).

I am thinking about picking up some wire by the foot from Home Depot. I calculated that I need 10 AWG to be safe. Should I get three conductor wire (3 + bare ground), two conductor wire (2 + bare ground) or separate wires? The three and two conductor wires are solid core, while the single wires are stranded. Will the power interfere with the data when run directly in parallel? Do I need to run a power line to the ends of the strips as well to prevent fading/discoloration (if so, should I move the capacitors)? I know that the data line doesn’t need to be extremely low gauge, but it would be convenient to run only one wire.

Three conductor: http://www.homedepot.com/p/Southwire-By-the-Foot-10-3-Gray-Solid-CU-UF-B-W-G-Wire-13059199/204632775
Two conductor: http://www.homedepot.com/p/Southwire-By-the-Foot-10-2-Solid-Romex-SIMpull-CU-NM-B-W-G-Wire-28829099/204724934
Individual wire: http://www.homedepot.com/p/Southwire-By-the-Foot-10-Black-Stranded-CU-THHN-Wire-22973299/204631945

Hi @Perry_N_DaAwesomeP ​ i run several hundred leds over the front of my house at Christmas.
The psu and driving hardware is in the garage, meaning i have to get power and signal along a 50’ run to get to the first led.

I use 3x1mm (i think thats 17 gauge in murica) stranded conductor flex cable, the kind thats typically used on electrical appliances (toaster ovens, coffee makers etc) and use the eath wire as the signal/data.
I run power into the start and end of the strip, and i have large-ish (47,000uf) capacitors near the start and end of the strip to account for instantaneous demands (from a white strobe effect).

I use cat5e for some other effects, but they only carry signal/data and ground. I supply power close by.

Most cable manufacturers have spec sheets available with the DC losses per length.

@Stuart_Taylor 3mm is around 9 or 10 AWG. So you’re saying that I should just cut up extension cords/power cords? I’m sure that the 220v/16A cords (I assume since you’re not in America and don’t use AWG) are probably a bit thicker than we have here for 120v/15A, but I’m also not going 50 feet—I’m going 2 or 3 feet. I have plenty of extra IEC power cords, so I’ll be sure to cut some up and try it! I’ll also put a large cap at each end of each strip.

Thank you for answering my questions!

Hi @Perry_N_DaAwesomeP

I’m using 1mm conductor, there are 3 of them in the jacket. Hot, neutral and ground/earth. But yes, appliance cord.

You could work out your max current consumption. The rule of thumb is 60ma per led (20mA per R G B).

60mA X number of LEDs = current consumption.

But given it’s only a couple of feet, you probably could use cat5 cable if you double up the conductors.

I arrived at my solution through a few iterations.

I started by feeding from one end, and found that if I set the strip to 100% white (each led full on) then as the LEDs progressed further away from the power they picked ap a red hue, the LEDs at the end of the strip being quite red indeed (definitely not white).

I fixed that issue by feeding power to both ends.

The next problem manifested itself when I would briefly flash the whole strip a bit like a strobe. Some of the LEDs would do their own things and show random colour until they were refreshed. That turned out to be a localised brownout. The demand for instantaneou current consumption would produce a voltage drop.

I fixed that with the reservoir capacitors.

The Arduino (or whatever architecture you choose) only has to drive the first pixel chip in the strip.

Don’t forget to post back and #showOffYourWork

OK, here’s my master plan:

I’ve settled on this Mean Well power supply: http://www.mouser.com/search/ProductDetail.aspx?R=0virtualkey0virtualkeyLRS-100-5

I will have a total of 240 LEDs x 60mA = 14.4A. I could get a 15A supply, but I want room to add more LEDs. I will use 48LED/m strips: https://www.amazon.com/Mokungit-Digital-Addressable-Flexible-Waterproof/dp/B019H9BBCA

I will have power via cut up appliance cord/extension cord go to either end of each of the four strips. I will put a capacitor at both ends of the strips: http://www.mouser.com/search/ProductDetail.aspx?R=0virtualkey0virtualkeyUVR0J472MHD

I will connect the data input end of the strips through the third conductor of the appliance cord to a Teensy 3.2. I should be able to run them in parallel.

Thank you @Stuart_Taylor for all of your help!

I’m bumping an old post here… What I’ve been doing is running power to my strips at 12v or 24v and then stepping down to 5v right at the strip using a high amp DC-DC buck converter like the one I’ve linked to. Doing this lets me use smaller gauge wire. Depending on the project, it also lets me use fairly inexpensive “24v laptop power supplies” that aren’t all big in size like a high-amp 5VDC supply would be.

Just remember that Power = Current * Voltage, so if your leds are 0.3 watts / LED and you have 100 of them, you’ll need at minimum a 30 watt power supply and your DC/DC converter will need to be rated 30W / 5V = 6 amps. Since you should always give yourself some margin of safety, you’ll probably want at least a 60W PSU and a 10 amp DC converter…