Random Flickering

Now that I have resolved my ground issue, the light effect modes appear to be working as expected. However I am noticing that certain modes, there are random flickering of the lights. Here is an example of Merry Christmas.

Merry Christmas Effect

Here is the hardware I have that I am using. I have two WS2811 12V LED strings to start off with.

  1. Meanwell LRS-350-12 Power supply
  2. ESP8266 NodeMCU
  3. BINZET DC Converter Step Down Regulator 5V

All cables are 18-22 gauge for the exception of the jumper wires.

Here is the updated wiring diagram

Any suggestions in which direction I should begin to troubleshoot?

The app settings are the default. I updated the LED count to 100 and tried to update the amps to 2amps with no change.

Did you look here? https://github.com/Aircoookie/WLED/wiki/FAQ#led-issues

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Hi @tonyno, thanks for the quick reply. That made me realize I forgot to add some details to my inquiry.

My original issue was due to #1 and is reflected in my diagram above.

I am not sure about #2 because it mentions using 5V lights and I have 12V. Not sure if the matters or the concept is the same.

I did fix #3 earlier. I saw this in another post. I originally had a 6ft cable and shortened it to about 2ft. The present decoration in the video has my power supply and controller and hooks up to the closest PVC right next to it

#4 doesn’t apply because the LED works but just get random flickering.

I just noticed your buck converter is one that has shown to be problematic, if yours looks like the pic.

The one in the pic is the exact model and grabbed off of my order off of Amazon. Can you provide details on what the potential issue is? Do you have a suggestion on replacement/work around for this? I would like to understand the issue so that I am aware. Next year I will most likely go with another controller.

Just lots of strange issues. I use these. https://www.amazon.com/gp/product/B0758ZTS61

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@icordova I don’t have a fix for you, but I just wanted to say that you and I have almost the exact same setup, even down to the wiring. My only have a couple differences:

  • I have a 3.3->5v level converter hooked up before the first LED. The 5v and ground for my level converter are hooked up to the 5v terminal of the dc-dc 12-5v converter. I have 3.3v and ground from the esp to the low side of the level converter
  • I have a 470Ohm resistor on the signal wire after the level converter.
    *I had to put a capacitor from the “en” pin to ground because of a boot issue with my ESP32

Oh, and I have an ESP32 not an ESP2866. Otherwise I’m doing the same power supply and I have the exact same 12-5 converter and almost the same wiring.

I’m having the exact same problem as you and have not been able to figure out a cause. If it’s the case that the voltage converter is a problem, I’d love to know too.

If you have access to an oscilloscope (and these days, a smartphone can do it for low voltages with the right app), you might want to look at the signal coming out of the converter, or, to fix it, add a couple 1000µF capacitors across the 5V and 12V lines to smooth out the noise a bit.

I’m kinda new to all this, but you mean put a cap between the 5v and ground and another cap between 12v and ground, right? Can you ELI5? :slight_smile: @huggy-d1

Yes, 2x1000µF capacitors, rated at least 16V so it won’t matter which capacitor you put where.
If you find things improve but still have problems, add another 1000µF across the 5V / 0V(GND or COMMON) wires.
If that does not help, move the cap to the 12V/0V wires and check.
At some point, you will see some improvement and be able to figure out where the noise is.
If you happen to have an old capacitor for a car amplifier (that goes right across the battery and weighs ~1kg…), you can use that for testing. It will smooth out any power fluctuations right away.

If you reduce the number of configured LEDs (not actual) in WLED, does the problem get better? Like for example, you have 500 but configure it for 100. Do those first 100 suddenly behave better?

I haven’t seen reducing the number of controlled LEDs make a difference, but if I turn the global brightness down it does make it behave better. I’ll try putting some capacitors in to see if that makes a difference.

Sorry for the delay on my part. I haven’t had a chance to try the suggestions yet but I would still need to purchase the parts to test it out. But I had tried reducing the number of LED’s without any changes.

Now I do notice that the more lights/colors that are on such as Merry Christmas, Rainbow, or Pride, the flickering will happen more but if I do something small such as Bouncing Ball, Android, Chasing and make the light span small, it does not happen as often.

Question, I do have a small /cheap multimeter. Is there anything I can test out now to validate noise in the lines?

Voltage measurements across the power / common lines for the LED strip at several places along the strip. It should be pretty high close to every power injection point, and slowly drop off further from the nearest injection point.

If you do not have any power injection points, add one to the middle and far end.

I’ve got a couple of lines, not sure which ones to add a capacitor to:

  • 12v and ground going into buck converter from power supply
  • 5v and ground coming out of buck converter to high side of level converter
  • 5v and ground coming out of buck converter to VIN on the ESP32
  • 3.3v and ground coming out of ESP32 going in to low side of level converter

I’m really not sure where a capacitor would be useful here…all the places?

I would start with 12V - GND and 5 - GND on VIN of ESP.
The level shifter should NOT have capacitor.

Ok, here’s where I’m at today:
I have 3.3v signal coming from the ESP feeding into the low side of a level shifter. The high side of the level shifter gets its reference from a buck converter set to about 5.2v (which is fed from the 12v power supply).

I wrote small sketch for the ESP to pull the pin high every 3 seconds followed by 3 seconds of low. I’ve confirmed the 3.3v high from the ESP, and also confirmed a high of 5.2v from the high side of the level shifter (followed by 0v for 3 seconds).

When I hook this up to my LEDs after a 10 foot run, the first few flicker randomly and the rest don’t light up. If I hook up the pixels with only a few inches of wire between the shifter and the first pixel, they work relatively fine.

Any thoughts?

Which shifter? There are some that don’t work for what we’re doing.

I’m using those ones.

Yep, I think those are too slow. Use one mentioned in the wiki.

I have tried those logic level converters as well. The KeeYee ones…they really don’t work. They do behave properly for very slow signals to boost to HV or reduce to LV but when a highspeed signal is applied to the LV side I find that the HV side output results in reduced peak to peak voltage instead of higher. I scoped both sides of the device and this is pretty consistent. They are incredibly sensitive to increased capacitance even from a oscilloscope probe…better off using a true level shifter like a SN74AHCT125N. I find the output from my Wemos D1 Mini Pro on D4 is about 3.83V and powers the strips fine even over 20 to 30 feet of cable.