led stripvoltage
I need to put an LED strip (ws2812) which uses 18watt per meters at 5V.
I intend to use 1 meter but the power supply is 10 meters away.
I can't use bigger wire than awg20 which I know will cause big voltage drop.
I thought about mounting multiple leds in parallel but it would need a tone of wires which is quite expensive.
Could I use something like a supercapacitor to help with the voltage drop?
I'm going to be wiring the rows up snake style and dual feeding to keep brightness consistent across the array.
If Dual Feeding is what I think it means, you already know what to do.
Feed the 5v to each 106cm section individually or in pairs. Don't chain the power through the entire 17m length. Sure, this means 8 or 16 sets of 5v and Gnd cables, but with each only carrying 2A or 4A over a small length, heat/current/resistance issues go away. Same reason you only see 18 AWG wire in ATX Power Supplies. Instead of a single 10AWG 12v Cable, it uses 8 or 12 18AWG wires to carry the same current.
You would keep the data cable the same. Just make sure to tie the grounds together.
Actually, pretty much how the datasheet for the Sparkfun item you linked to already has it, for a snake layout.
For 1M strips (106cm = 1.06M) the voltage drop would be insignificant.
You can't avoid some current passing thru the ground in the strip connections but, if the resistance of the busbar cable is significantly smaller then it shouldn't be an issue; most of it will flow in the busbar and do the job as you intend.
Best Answer
Ok so you need a stable voltage without an overly thick wire. You also don't want to put bulky components near the load.
So what are our options.
I wouldn't nessacerally rule out a regulator chip near the load. There are some impressively tiny switched mode converters available nowadays though heatsinking can be an issue.
Another option is "remote sensing". A pair of thin wires is brough back from the load to the power supply. This lets the power supply measure the voltage at the load and compensate.
If we know the resitance of the wires we can just build a power supply that compensates based on he known cable resistance but that risks overvolting the load if the cable is shortened.
Linear techonlogy has a clever soloution to this which they call virtual remote sensing. They use the decoupling capacitors in the load to measure the cable resistance and compensate for it without the need for physical sense wires or known cable lengths. The downside seems to be that it's measurements will cause some output voltage ripple.
http://www.linear.com/docs/30159