i want to set up an LED strip(WS2812b), which is about 4 meters long. I control it with the NodeMCU ESP8266 with Blynk and Neopixel Library. Everything just works fine but when i want my strip to be white at an rgb value of 255,255,255 just the first 40 cm are white and the color becomes yellow and red at the end of the strip. I guess there is a current limitation. The Power Supply is connected with Jack ( Female DC Power adapter - 2.1mm jack to screw terminal block : ID 368 : $2.00 : Adafruit Industries, Unique & fun DIY electronics and kits ) and by jumper wires to a breadbord with resistor, capacitor and connections. Then i connected the breadbord with jumper wires to the LED-Strip. Is the current limited by one of these? If yes, how can i improve that?
I'm guessing you are feeding power to the strip at one end only. The resistance of the conductors in the strip is fairly high, certainly too high to feed 4m reliably from one end. Feed power to both ends and to the middle, possibly the 1/4 and 3/4 points too. Use thick wire.
The length of the strip is the main limitation. It is essential to connect power at both ends and maybe at intermediate points along the strip. The "wire" in the strip is very thin and can't carry that amount of power very far.
Ohmann:
What do you mean with "thick" wire? Could you leave a link or sth.?
Wire size is measured in "gauge" in America, specifically American Wire Gauge or AWG. Bigger numbers mean smaller wire. 24 gauge is small, suitable for signals, switches and that kind of stuff. 16 gauge is pretty thick, useful for currents of 10 Amps or more.
In other places, the wire is measured by its area in square millimeters. This can cause confusion when a multi-core cable is measured by the total area of all cores. For a single core 1mm2 is thick for an Arduino project.
(I have worked in places where wire sizes went up to 1m2 so the "thin" wires there were still too heavy to lift.)
Ohmann:
What do you mean with "thick" wire? Could you leave a link or sth.?
Maybe something like Red Black
Although if you have wire, any wire, and you connect from various points along the strip directly back to the power supply, so there are, perhaps, 3 or 5 connections from the strip for 5V and the same for 0V each going directly to the power supply then you are going to improve the situation a lot.
MorganS:
In other places, the wire is measured by its area in square millimeters. This can cause confusion when a multi-core cable is measured by the total area of all cores. For a single core 1mm2 is thick for an Arduino project.
There is no confusion with total square millimetres, you can directly calculate the resistance of the cable,
since copper has a resistivity of ~1.68 x 10^-8, only one number to memorize, and no need to use a lookup
table of gauges.
If a cable is N square mm, its resistance per metre is about 17 N milliohms. Unless its the dreaded CCA.
The whole wire guage system bewilders me, its a hangover from the industrial revolution as far as I can
tell and hinders rather than helps. For instance someone who does appreciate the system will automatically
assume larger number is better, which it isn't - they go to buy AWG16, but only 14 and 18 are available,
they might think 18 is a suitable safe alternative...
MarkT:
There is no confusion with total square millimetres, you can directly calculate the resistance of the cable,
since copper has a resistivity of ~1.68 x 10^-8, only one number to memorize, and no need to use a lookup
table of gauges.
It matters if you have a 3-wire mains cable that is only carrying current in 2 of the 3 wires.