Review: Bedtime Bulb E27 LED (2200K, CRI95)

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puglife2
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yeutterg wrote:
Thanks for your support, and I’d love to hear your honest feedback. Cheers.

Greg

Hey! I tested them last night and I like them very much, the tint is very nice and cozy, they replaced my 2200K edison led bulbs in my bedroom Thumbs Up

There was no visible fluctuation but my house is not that old (1881) so.. I can’t speak for the others.. Big Smile overall i’m happy with my purchase and I hope they last for years BUT I would love to have a 60w equivalent version or even 80-100 for my living room Cool

yeutterg
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Cool, thanks again! Enjoy, and let me know if you have any more feedback after continued use.

Bedtime Bulb: The Light Bulb for Healthy Sleep

Joshk
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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.

https://www.nema.org/Standards/ComplimentaryDocuments/C78-376-2014-Conte...

yeutterg
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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.

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Joshk
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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.

jon_slider
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puglife2 wrote:
Hey! I tested them last night and I like them very much

since we have read that the bulbs have a flicker problem in USA, and maukka reports they also have a flicker problem in Finland

where in the world are you located?

you did what kind of test?
did you look through a camera, was there any banding?
did you test for flicker, some other way?

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puglife2
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jon_slider wrote:

since we have read that the bulbs have a flicker problem in USA, and maukka reports they also have a flicker problem in Finland

where in the world are you located?

you did what kind of test?
did you look through a camera, was there any banding?
did you test for flicker, some other way?

Im from canada, I just leave the light on for an hour or two at night before I sleep, no camera just my eyes

yeutterg
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jon_slider wrote:
since we have read that the bulbs have a flicker problem in USA, and maukka reports they also have a flicker problem in Finland

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.

Bedtime Bulb: The Light Bulb for Healthy Sleep

yeutterg
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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.”

Bedtime Bulb: The Light Bulb for Healthy Sleep

SammysHP
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Here are some numbers from the original footage of my video.

First I exported one frame every second:

ffmpeg -i 00000.MTS -vf fps=1,scale=640:480 frames/%05d.png

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. Big Smile
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.

yeutterg
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SammysHP wrote:
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.

Thanks for that test. It’s very helpful.

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?

Bedtime Bulb: The Light Bulb for Healthy Sleep

SammysHP
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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.

yeutterg
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OK, thanks for the clarification. And it may well be a “badtime” bulb in this instance!

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yeutterg wrote:
And it may well be a “badtime” bulb in this instance!

Oops. Facepalm Big Smile

JamesB
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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.

Lightbringer
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Big AC, fridge, anything with a big honkin’ motor that draws a lot of current on startup (compressor motor kicks in, etc.).

Circular saws and other power-tools are good for that, too.

09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0

Watermanchris
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Lightbringer wrote:
Big AC, fridge, anything with a big honkin’ motor that draws a lot of current on startup (compressor motor kicks in, etc.).

Circular saws and other power-tools are good for that, too.


And vacuum cleaners. They will pull some juice!
SammysHP
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For the last days I have used the Bedtime Bulb in my bedroom as the only light and have observed visible output fluctuations several times.

hank
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Thanks for the pointer to https://www.ies.org/fires/melanopic-green-the-other-side-of-blue/

This is why we use amber LEDs as household lighting in the evening. The amber floodlights available appear to mostly use Luxeon Rebel emitters:
https://www.luxeonstar.com/lxml-pl01-0040-amber-luxeon-rebel-led-77lm

And at critical locations around the house, we have this sort of thing for don’t-step-on-the-pets perambulation at night:
https://www.mrbeams.com/amber-stand-anywhere-light

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SammysHP wrote:
For the last days I have used the Bedtime Bulb in my bedroom as the only light and have observed visible output fluctuations several times.

Thank you for confirming the Bedtime Bulb has the fluctuations that maukka reported.

His review of the Remez SunLike E14 LED bulb reports:

maukka wrote:
There’s no visible flicker to the eye

I would buy the Remez, not the Bedtime

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JamesB
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SammysHP wrote:
For the last days I have used the Bedtime Bulb in my bedroom as the only light and have observed visible output fluctuations several times.

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

SammysHP
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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.

JamesB
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I suspect when this happened in our little extreme electrical load experiment that the voltage change might have been much greater than 1v since i’ve been told even the plasma TV went dark for moment when i was looking at the bedroom bulb.

yeutterg
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Thanks for the feedback so far. We have two people who have noticed any kind of brightness change during normal operation. Six people have not noticed any change. We are still continuing the investigation.

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jon_slider
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statistically
50% of people dont notice flicker
25% dont care if there is flicker
25% wont buy a product that has been tested by reputable people, who know what they are talking about, and have both calibrated instruments and trained eyes

out of every 8 people, only 2 care enough to find a light that does not flicker

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yeutterg
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jon_slider wrote:
statistically
50% of people dont notice flicker
25% dont care if there is flicker
25% wont buy a product that has been tested by reputable people, who know what they are talking about, and have both calibrated instruments and trained eyes

out of every 8 people, only 2 care enough to find a light that does not flicker

I appreciate that you care a lot about the flicker issue. Trust me, I do as well (both visible and invisible flicker). That’s why we’re running this investigation and have delayed the launch of the product until we have more info.

However, that conclusion is not correct. I specifically asked all the testers to look for the issue. No instrumentation is required to do a check for the visible flicker we are talking about—you either notice it or you don’t. Seeing if it correlates to voltage changes is nice to know and helpful for when we do a redesign, but not necessary to verify the behavior.

Please take this in the kindest way that I would appreciate more patience as we carry out this test. You wouldn’t get this kind of attention and openness from pretty much any other manufacturer.

Bedtime Bulb: The Light Bulb for Healthy Sleep

JamesB
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For the purpose of adding context, the local final transformer of my electricity provider is 20 meters from my house and my household is the only permanently living in the little hamlet, i wish i had the equipment to log my AC voltage fluctuations, i suspect it’s very clean.

yeutterg
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Thanks a lot!

Bedtime Bulb: The Light Bulb for Healthy Sleep

Bardo219
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Sorry if I’ve overlooked something but what are you all referring to as a flicker? As in the light dims and then gets brighter? Or as equivalent to visible PWM in a flashlight? I feel I am picky about PWM.

I’ve been using the bulb the past 4 nights and not noticed any dimming by eye. Looked through iPhone camera and could not detect anything either. I don’t have any scientific way of testing but in real use I am pleased and would recommend. I am in the US.

yeutterg
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Hey Bardo219, thanks for giving BB a try. In this case, we are looking for visible brightness changes every few seconds or minutes for the European bulbs. The “invisible” flicker is very low at around 3% modulation (120 Hz in the US and 100 Hz in Europe).

The US bulbs don’t have the problem, except in rare instances. So thanks for adding another data point on that front.

Let me know if you do ever notice anything. Otherwise, enjoy!

Bedtime Bulb: The Light Bulb for Healthy Sleep

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