I’m relatively new to FastLED but I absolutely love how easy it is to work with. So I started my project on a smaller 5m 50pixel 150 LED WS2812B strip with success. Now when everything is tested and working I’m ready to go bigger. So I ordered three 5m 300pixel 300 LED strips using same 5V WS2812B but am experiencing problems. Even using single strip I cannot go higher than brightness 60 when weird flickering from the other end of the strip occurs. It is very visible in pure white but it is noticeable in other colors as well. With increasing brightness the end of the strip start loosing green and blue leaving red only. I would normally think it is caused by weak power supply but I use 300W 5V 60A switching power supply outputting verified steady 5V. I try testing this eliminating all me known variables ending with single FastLED.Show() with brightness above 60 to see same result. No loops, no variable pots, just single push to lid up 300 white LEDs. I’m baffled at this point with no more ideas. I found this great live forum with hope finishing my DIY project with the new LED strips. Thank you!
Still seems to me like a power issue ! When you say single strip, do you mean a 5m strip ? with 300 pixels ?
You should probably inject power at least from both ends of a 5m strip probably even somewhere in the middle specially if the voltage drops too much along the strip.
Did you actually measure the voltage at various points along the 5m strip ?
Operational specifications for the WS2812b are given for Vdd between 4.5~5.5Vdc. Voltage anywhere along your strips should never be below 4.5V. I actually prefer to never let that voltage drop below 4.9V anywhere. 0.5V drop on 5V is 10% loss of voltage and surely an influence on brightness consistency between pixels.
Hey Roy. Thanks for the suggestion. Yes, it is the low voltage on the other end. It dropped to 2.2V! I thought the LEDs are powered in parallel so with 60 amp supply I will be good. I calculated each strip could take up to 19 amps. I’m surprised there is such drop on the end. So the only option is to resuply power in between each strip? That will negatively affect my plan to have a single power/data entry line to the interconnected strips around the ceiling.
Welcome to some of the laws around electronics. There’s always volatge drop along a wire. This drop can be exacerbated by things like the wire being thin (thicker gauges can help with this), draw on the line by other things (in this case, the leds), etc… etc… etc… The rough rule of thumb that I tell people is inject power every 100-200 leds.
Hi @Lumir_Karas , As you correctly assumed, the power supply is very good for this job but…the problem is in the strips themselves. They use a very thin trace of copper to conduct the current and with that much current, thin tracks will drop the voltage. Copper is expensive and manufacturers do not want the strips to be too stiff also.
When you say each strip, do you mean each 5m strip ?? or do you actually have 5 strip of 1 meter each ??
Thanks Daniel! So I suppose I have several options. 1. resupply power from different power supplies, 2. resupply using thicker wires lined alone the strip and powered by the original 60A power supply, 3. maybe reducing brightness, using the library power consumption functionality?
If you have a single power supply that can push enough amps, then you can go with just one power supply - and you can just break out multiple lines if you’re using a thick enough gauge of wires. Unfortunately 3 won’t help you too much - because there will be a point where the voltage drop will still be too high, even if all the leds are dark (though it can help in a pinch - you can also use FastLED’s power management code to max out the power draw that you use)
Hey Roy. I meant three 5 meter strips to place around the ceiling perimeter. So I was hoping to have a single entry with power and Arduino uC. I should do my homework before getting all the parts :o)
@Lumir_Karas In that case, you probably just have an easy access to supply power at both ends of the 5m strip. Try that first and go test the voltage at the strip mid-point (at the 150th pixel) when all pixels are set to the brightest setting you intend to use. Use the lowest gauge wire that is practical for you (the lower gauge means a thicker wire and less voltage drop with same current). This site may be of some help here…
If you do not get at least 4.5V, I would suggest 2 options:
I would find a way to inject 5V power somehow in the middle of that strip
2 I would reduce the overall brightness to an acceptable level using the power management code (or any other brightness control) until that mid-point voltage is OK.
Thanks for the info Roy. I think I’ll do it using the 12V version. I tested one and even with 3V drop on the other end all LEDs still work fine with much smaller power supply in full brightness.