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I am using a 2 meter strip with 144 led/m on a WS2812B led strip. By doing the maths on how much current would be required to power this we get

60mA * 288 = 17.28 amps.

However, I am not planning on having the LED's at full brightness and I do not plan on having any white LED that will draw more current. I will have the LED's at 40% brightness so I would need ~7a. But once again this would be if the LED was white.

So with these numbers, I bought a 5v 10a power supply. The schematic that I am using is attached to this post. It is from the NeoPixels uberguide, in the section "Powering NeoPixels". I have also attached a picture of the connections that were already wired up on the LED's.

I am completely new to any sort of circuitry especially at these high currents and to be honest it scares the crap out of me worrying that I will completely burn down my house!

So here are my questions:

  1. I am currently using the Arduino Uno starter kit along with the included jumper wires. From looking up online I can see that the gauge of these wires is 22 AWG which I believe is not suitable for the ~7a that I need (Please correct me if I am wrong). So I know I would need to get better wires, however I am not sure what gauge wires I would need?

  2. If I was to get different wires, for example 16 or 14 AWG, are they available as jumper cables and will they fit into the Arduino pins?

  3. My LED strips have 5 wires coming off of them already, two red, two white, and a data cable. One of each of the white and red cables a long with the data cable, go to a female connector that I plug the jumper cables into. Would I be able to plug the bigger cables into this connector and are these wires suitable to handle the current or do I need to unsolder them and re solder new wires?

  4. I also bought a barrel jack adapter that splits the power supply into the + and - connections. I believe it is called a 5.5mm x 2.1mm adapter. The brand is EFISH and once again I am wondering if this can handle the current?

  5. As you can see from the schematic, there is a 1000uF capacitor on the + and - from the power supply, I then connect the wires to the LED as well as the ground to the Arduino. What is the best and safest way to cover all of this once I am done testing and ready to install?

  6. Finally, I know that it is suggested to power both ends of a strip to ensure equal brightness and colour accuracy especially across 2m of LEDs. The end of my strip has the same wires already connected however, instead of the female connector, it has a male connector. How do I power this end of the strip? Do I simply wire the white and red cables into the same power supply as I did with the other end?

I know there are a lot of questions here but I am very excited to get this working but mainly I am very nervous about all of it! So any help or input would be greatly appreciated!

  • owjo

Circuit schematic

Pre-wired strip

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  • \$\begingroup\$ I am using 96 LEDs strip with max brightness 32 of 256x3. Measured current is 200 mA. Powered from one side, measured drop voltage over 1 m string is approximately 200 mV. Whose LEDs is bright enough. So consider what brightness you need. \$\endgroup\$
    – user263983
    Dec 16, 2020 at 20:26
  • \$\begingroup\$ I don't need any crazy brightness as honestly a brightness of 80 out of 255 is bright enough. As it's a 2m strip do you think that powering from either end will be enough to have a consistent brightness? \$\endgroup\$
    – owjo
    Dec 16, 2020 at 21:56
  • \$\begingroup\$ I don't know the condition in which you gonna use it so can not define the consistent. Just star from small numbers and increase it slightly. Then measure the consumption. I gave the example for inside house use with not very bright environment. In total darkness it even too mach. \$\endgroup\$
    – user263983
    Dec 16, 2020 at 22:44
  • \$\begingroup\$ This will be used inside in my bedroom as just a splash of colour above my monitors when my room is dark. I have the LEDs at brightness of 50 beside me now in the dark and they are V bright so it looks like I won't be needing much! \$\endgroup\$
    – owjo
    Dec 16, 2020 at 23:09
  • \$\begingroup\$ Even when LEDs not glow one WS2812 chip consume little bit under 1 mA, so you will have ~250 mA. And if you want mix the colors in different proportion some number should be set. Depends what combinations you want. My guess for dark room 1A in total will be bright enough. \$\endgroup\$
    – user263983
    Dec 16, 2020 at 23:31

2 Answers 2

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Do not route the LED power through the MCU, connect it per the diagram you posted.

The strip LEDs use constant current drivers in PWM mode. Therefore, the brightness will not decrease until the voltage is below the point at which it can no longer maintain the constant current. On my strips this occurs when the LED voltage is roughly 4V. I haven't performed precise measurements, but it is somewhere in that range. I don't see a noticeable brightness drop-off until my power supply voltage is below 4.3V. And I know that there is some drop in the wires and PWB traces to the LEDs.

I have 120 LEDs in a strip that is powered on only one end. It works fine at moderate brightness. Since you have about twice as many LEDs, you should power from both ends.

If you will eventually have a stand-alone setup where one power source powers the LEDs and the MCU, there is another issue that can occur. My setup is powered by batteries and if the LEDs are ever set to a high brightness, the voltage is pulled down to the point where the MCU won't function, but the LED chips still maintain their settings. I need to power cycle to recover.

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  • \$\begingroup\$ Yep, I am going to disconnect the 5V power from the MCU but keep the GND connected from the strip to the MCU, then power with a separate power supply. I will definitely power from both ends then. So does that just require me to put the white and red wire on the other end of the strip into the same power adapter? My plan is to power the MCU with my PC and power the LED's with the external power supply. \$\endgroup\$
    – owjo
    Dec 16, 2020 at 22:38
  • \$\begingroup\$ Yes, just connect the 5V and GND on the other end. \$\endgroup\$
    – Mattman944
    Dec 16, 2020 at 22:47
  • \$\begingroup\$ Since you have 10A power supply it can keep 5V under load. Just run pair of wire from PS to Arduino separately. Brightness of WS2812 not depended on voltage, but by specification it should be from 4 to 6V \$\endgroup\$
    – user263983
    Dec 16, 2020 at 23:02
  • \$\begingroup\$ Could you clarify this a bit more? I'm not really sure how I would do this? Edit: Oh sorry do you mean to power the Arduino? \$\endgroup\$
    – owjo
    Dec 16, 2020 at 23:10
  • \$\begingroup\$ Yes , two wires from power supply to Arduino board only. \$\endgroup\$
    – user263983
    Dec 16, 2020 at 23:16
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  1. Thin wire you can not solder to PCB strip. If you planning high brightness, few wires should be used in parallel. AWG22 is big enough. If max current 7A, power wires should be connected both side and in middle.
  2. Power wires going from supply, from MCU board only data, you may not connect power. But make sure grounds of board and strip connected.
  3. One side of strip connector is signal input plus power, second to connect next strip input usually female, but check the strip side where wires soldered, should be marked IN.
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  • \$\begingroup\$ Could you clarify what you mean by "ribbon", I'm unfamiliar with this term. For your second point, currently I am powering a few LED's of the strip from just the arduino. So I plan to remove the power cable (5V) from the arduino but keep the GND that goes from board to strip to power supply, once I get my power supply tomorrow. \$\endgroup\$
    – owjo
    Dec 16, 2020 at 22:01
  • \$\begingroup\$ By ribbon I meant flexible printed sircuit board with WS2811 integrated circuits and another electronic elements soldered to it. Also if you Arduino board can be powered +5V, you can use same power supply for both devices. \$\endgroup\$
    – user263983
    Dec 16, 2020 at 22:37
  • \$\begingroup\$ Oh okay, thanks for the clarification. I was originally planning on powering the Arduino with my PC through USB and using the 5v power supply to power the LEDs \$\endgroup\$
    – owjo
    Dec 16, 2020 at 22:41
  • \$\begingroup\$ Not necessarily. Connection from PC to Arduino board need only for loading program to MCU. \$\endgroup\$
    – user263983
    Dec 16, 2020 at 22:50
  • \$\begingroup\$ Yeah I think I'm going to have to look into this. However, I like the idea of being able to change the lighting on the fly by having it connected to my PC. \$\endgroup\$
    – owjo
    Dec 16, 2020 at 23:11

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