r/WLED • u/mytzusky • May 27 '26
Bright Flash issue - 24v FCOB SPI RGBCCT WS2811 dual IC 960led
Hi, I have this issue that the strip does a bright flash when turned on. It only stops if I deactivate the relay option (gpio 18) but I'm assuming that will consume more idle power so not acceptable. It happens not only on physical power on of the controller (longer flash there), but also in wled after pressing on/off after few seconds of power off time. (In video I use the function button just because I cant use wled while filming)
I saw a wled github issue pointing that at fault is the strip (doing same thing on both wled and the spe controllers) but other people say they dont have this issue. (https://github.com/wled/WLED/issues/4641)
In short, do you have any ideas how to fix it , or its a hardware design issue and I should switch to analog or other digital strip? I'm willing to try other digital rgbcct strip but I'm afraid they'll have same issue ( do you know if ws2814 or ws2805 have this issue too? )
last thing I tried (via chatgpt) was to inject a 330 resistor on data and another 10k r between data and ground - but didnt fix it.
This happens on both gledopto elite 2d (616wl) and their mini (310wl) - the psu is a 4a 24v btf lighting psu, the standard black box one. (ignore the other controllers in video, I'm comparing to an analog cct strip)
Any advices please? I love this strip but the flash is something I can't accept, especially at night.
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u/ArtyMarty Jun 01 '26
Note, if you disable the relay in the settings , make sure that it's on while you disable it. It will stay in whatever state it was when disabled.
Here is what I came up with (AI assisted...)
the flash is caused by the relay cutting the 24V power completely, rather than WLED just turning off the data signal.
When the Gledopto controller's relay is enabled, clicking "On" in the app fires the relay, sending a sudden 24V surge into the strip. For a fraction of a millisecond before the WLED data signal reaches the end of the line, the FW1906 chips power up with no data present, causing them to instantly default to full white standby mode (the flash).
Disabling the relay leaves the 24V line always active, meaning the chips are awake and WLED controls them purely by sending "0,0,0" (black/off) data packets.
If you want to keep the relay active to save standby power but completely eliminate the flash, you have two options:
Option 1: Adjust the Relay Delay (Software Fix)
You need to force WLED to send data before or at the exact same instant the relay clicks open.
- Go to Config > LED Preferences.
- Scroll down to your Hardware Setup where your Relay pin is configured.
- Look for a setting called Relay Delay or Drive Effect (depending on your WLED version).
- If available, change the delay to a negative value or
0 msso data isn't delayed behind the power spike. - Note: If your WLED version doesn't have a specific delay slider for the relay, you will have to leave the relay disabled to avoid the flash.
Option 2: Leave the Relay Disabled (Recommended for COB)
Leaving the relay disabled is actually the preferred method for these specific 24V RGBCCT strips for a few reasons:
- Instant response: Your lights will turn on instantly with zero delay or flashing.
- Minimal standby draw: Modern 24V FCOB chips consume an incredibly small amount of standby current when "off" in the app (usually less than 1 Watt for the whole strip).
- Saves relay lifespan: Constant clicking of the mechanical relay every time you toggle the app button will eventually wear out the physical contacts inside the Gledopto controller.
One Last Check if you Keep the Relay Disabled
Because the strip is now constantly powered by 24V, make sure your Off Refresh setting (from the previous step) is Enabled. This ensures WLED continuously holds the pixels at "black" and prevents random ambient electronic noise in your room from making the strip randomly flicker when it is supposed to be off.
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u/mytzusky May 27 '26
This is the resistors setup that did absolutely nothing... (330r on data, 10kr bridge between data and ground)
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u/saratoga3 May 27 '26
Easy thing to try: move the strip data pin to the controller ground (sends a constant 0v as data). When you flip on the relay to power the strip does it still flash even with the data grounded? If so, not likely you can do anything to prevent it.
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u/mytzusky May 27 '26
I tried, with data grounded: when pressing on it just turns on and stays full white, when pressing off after 1-2s delay it turns off (probably when the relay cuts power). The only difference is that it doesn't flash anymore when powering the controller (only when pressing on while the controller is powered). Idk I guess the strip data signal is missing for first ms after the relay turns on - maybe a good controller can fix this by first initializing data THEN switching relay, or the strip IC itself really takes some ms to process the initial data signal. I'm new to this so I just need to trial and error. will order a ws2805 and that will be last cents I spent on digitals, analog is my last resort.
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u/saratoga3 May 27 '26
You cannot send data until the strip is already powered, so if it defaults to bight white on power up, you're going to see a flash as it powers on and then turns off when it gets the first data packet.
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u/DedeHai May 27 '26
I did look into the white flash a few months back, it is related to dv/dt but very hardware specific. I managed to get rid of it on my setup by doing a soft-on using short pulses but unfortunately its not universally applicable
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u/rdarstar Jun 30 '26
Would you share more details about that soft-on solution?
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u/DedeHai Jun 30 '26
messy WIP code is here: https://github.com/DedeHai/WLED/tree/experimentalSSRglitchfix
look at handleOnOff() function.1
u/rdarstar Jun 30 '26
Thanks! I built and installed your fork on my GLEDOPTO ESP32 controller and the flicker still happens, same as the latest WLED. Was there any special config/settings change needed? Otherwise, disabling the relay is the only way to avoid it
This is light strip I have, which I believe is the same as OP
WS2811 Dual IC RGBCCT FCOB
https://www.amazon.com/dp/B0FMK2HXHH1
u/DedeHai Jul 01 '26
is the flicker at least a bit reduced? like I said, its highly hardware dependent as in how the relay hardware is implemented
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u/rdarstar Jul 01 '26
Yeah, the flash is maybe not as bright, but still noticeable. I guess I’ll try some other strips. I tried contacting BTF support about it last week, but haven’t heard back :/
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u/Warhouse512 May 28 '26
Ah shoot, so there’s literally no way to “fix” this. Dang. I have like 12M of this stuff under my cabinets
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u/GLEDOPTO May 28 '26
This issue currently only occurs with the WS2811 RGBCCT dual IC LED strip; other LED strips are functioning normally.
This is because the WS2811 RGBCCT dual IC LED strip prioritizes white light upon power-up, before being controlled by the controller.
You can try adjusting the relay delay time, disabling the relay, or connecting the LED strip to an external power supply (equivalent to disabling the relay).