This is interesting guys. It seems ANSI has a C78.376-2014 standard that accepts 3500K as the neutral. I always thought it was odd to call 4000k neutral, as it looks cool to me. It seems this standard lines up with our opinions.
It’s interesting for sure, but many (most?) manufacturers still define their spec sheets based on a 3000 K nominal. Despite this, a lot of lighting designers like 3500 or 4000 K.
I think our natural tendency toward round numbers is to blame. I believe if 3500 were a round number, and the next increments were 2500 or 4500 there would never have been any doubt.
Visible brightness fluctuations are rarely an issue in the US. Trust me, we would know about it if it was a widespread issue (we’ve sold tens of thousands of bulbs).
We are testing with ~15 people now across Europe to see if it is repeatable. We are only asking them to observe if there is a visible change.
By the way, the camera banding test is not a very good indication of flicker. My phone camera (Google Pixel 3) will pick up even 2% flicker and make it look like we’re at a disco. Other flagship phones appear to have the same “issue.”
Then I took the average brightness of each exported frame:
for x in frames/*.png; do convert $x -colorspace gray -format "%[fx:100*mean]\n" info: >> log.csv; done
This is the result:
There are some fluctuations. Not sure if they correlate with the mains voltage, too lazy to OCR the text from the multimeter.
Oh, this doesn’t tell us if there’s a flaw in my setup. But random noise looks different.
edit: I manually compared the brightness and the mains voltage and both correlate with each other more or less. I think this is very similar to the result from maukka.
If I’m understanding the graph, the camera is picking up minor brightness fluctuations of around 1% (from a trough of ~52.7% to a peak of ~53.7%). You also notice some slight visual changes in the output just by observing. Is that correct?
I don’t think the absolute values of the scale mean anything (although it is in percent, but percent of what?). The changes are very hard to notice and I think it depends on the situation and the observer if it is noticed at all.
IMHO the point is that the Badtime Bedtime Bulb has a behavior that is not found in other bulbs.
So today i received a bulb from Yeutterg, there were 4 people at home, we all tried to see visible flicker in different scenario (direct vs indirect, dark room vs a little bit of light) all of us failed to see any fluctuation in intensity or flicker, i’ll do some further testing tomorrow.
Is there any kind of typical household load i can put on my electrical system that is susceptible to induce voltage fluctuation ?
I also must say that the light produced is superb for a bedside table or such in my opinion, very soothing and high CRI compared to my 3000k osram led bulbs.
What sort of fluctuations ? Is it a rare short dip and back to stable or is it lasting alternating changes ?
The only detectable fluctuation we manage to see is a short dip in intensity when our AC compressor turned on when a lot of other appliances where on also
Yes, it appears as a dip whenever there is a jump in the mains voltage. A sudden jump of 1 V is enough to be noticeable. In both directions. The brightness an the mains voltage seem to be proportional.