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I've tested a bunch of bulbs for flicker with a handheld flicker meter and with a photodiode connected to an oscilloscope. It's funny that some of the bulbs out

I've tested a bunch of bulbs for flicker with a handheld flicker meter and with a photodiode connected to an oscilloscope. It's funny that some of the bulbs out there claiming to be "healthy" have terrible flicker. One product from Soraa was flickering at over 50%, almost as bad as the cheapest/worst LED bulbs you can buy. I don't have a database, but I can say that most (but not all) filament designs are terrible for flicker--ours is an exception. Philips products seem to have gotten worse in quality over time, probably to remain competitive, but they are better than the worst. Ikea's stuff is pretty good overall. I don't have a consistent recommendation for low-flicker general lighting right now, as every brand has good and bad products.

pistachiopro 8y ago
Thanks to GP for the links, I completely missed that previous thread! And, yeah, I tried that Soraa healthy bulb, and it was shockingly bad, given how it was advertised. Even the regular Soraa bulbs were disappointingly flickery, though less so. Also, just looking at the pattern it makes on my phone's rolling shutter, the wave is quite saw-toothed, and I wonder if that makes it worse? I have some Ikea candelabra bulbs which were always pleasant, and I was surprised to see they also left quite a visible flicker pattern on my phone, though much more sinusoidal/smoother. It's a shame about the flicker in the Soraa bulbs, since the colors really did seem nice.
- yeutterg 8y ago
  The Soraa bulb looked pretty sinusoidal on my scope when I tested it briefly. But it's a lot of flicker regardless. What's interesting is that the bulb seems to have a nice build quality (from the outside, I didn't open it) and is quite heavy. I suspect they are putting a BIG heatsink in there, as violet pump phosphors tend to degrade quickly. The other thing that irks me about this product is the "zero blue" messaging. Yes, I can confirm the spectrum looks like what they are advertising, with a peak around 415nm, almost nothing between 440-490nm, and then all the rest of the colors from green to red. But, green light is just as bad as blue for sleep! The ipRGCs are sensitive to both blue and green (up to around 600nm) This bulb has a lot of green, more than a lot of other light sources. It also has a very unpleasant greenish color (IMO) and low-ish CRI, around 78 on the bulb I tested. Is it better than a normal 600lm bulb for sleep? Yes. Is it novel? Yes. Is it good in practice? I don't think so.
  - pistachiopro 8y ago
    That's right, the Soraa Healthy was very green! So, even without the flicker, the fact that it makes everybody look like undead zombies would be reason enough to disqualify it as a bedroom night light.
    - yeutterg 8y ago
      Haha, totally agree! If you are still in the market for a low-blue, low-flicker solution, may I humbly suggest a look at my product, Bedtime Bulb [0]? I know I basically bashed the Soraa product here, but not without technical justification. [0] https://bedtimebulb.com/ https://bedtimebulb.com/
retSava 8y ago
> flickering at over 50% what does that mean? Duty cycle is 50%, frequency at something Hz? Not being snarky - curious whether there is some kind of standard that your tool compares against. A duty cycle 50% (or any percent really) isn't bad in itself, it's the frequency that is the culprit. Too low PWM freq and you'll notice it.
- yeutterg 8y ago
  When I refer to % flicker, I am talking about the modulation % as defined by IEEE 1789-2015 and some documentation from the Illuminating Engineering Society [0][1]. More correctly, invisible flashing is known as the stroboscopic effect or phantom array effect. Two factors are often used to describe flicker for lighting: - Modulation %, a.k.a. % Flicker [The height or modulation of the waveform, formula is 100% * (A - B) / (A + B)] - Frequency [self-explanatory] Flicker Index is also used (refer to [1] page 7 for more info) but rarely. Duty cycle is not considered relevant, as you mentioned. Some tools designed to measure lighting, such as my UPRtek CV600 [2], spit out % flicker, frequency, and flicker index, in addition to a bunch of spectrophotometry metrics. It's also pretty easy to calculate the modulation % with an oscilloscope and photodiode, it's just Vp-p / Vmax. IEEE 1789 [0][1] roughly says that the higher the flicker frequency, the more acceptable it is to have a high modulation %. If you look at the graphic on [1] page 18, you can see this relationship. The white area is considered unsafe, the yellow area is "low-risk", and the green area is "safe." I don't 100% agree with this personally, as most incandescent lighting, with around 6-11% flicker at 100-120 Hz, would fall into the unsafe or low-risk category. But the Soraa product is definitely in the unsafe category. For reference, I plotted my product (Bedtime Bulb) against an incandescent A19, Lighting Science's Goodnight A19, and Soraa's Healthy A19 on an IEEE 1789 graphic [3] with a Python tool I'm developing, Beautiful Flicker [4]. You can see that this incandescent, measured around 10%, is on the border between unsafe and low-risk by this standard. Hope this helps! [0] IEEE 1789: A new standard for evaluating flickering LEDs?: https://www.dial.de/en/blog/article/ieee-1789-a-new-standard-for-evaluating-flickering-leds/ https://www.dial.de/en/blog/article/ieee-1789-a-new-standard... [1] Flicker: Understanding the New Recommended Practice (PDF) https://www.energy.gov/sites/prod/files/2015/05/f22/miller%2Blehman_flicker_lightfair2015.pdf https://www.energy.gov/sites/prod/files/2015/05/f22/miller%2... [2] UPRtek CV600 https://www.uprtek.com/en/product/SPECTRAL-COLOR-METER/CV600-Spectral-Color-Meter.html https://www.uprtek.com/en/product/SPECTRAL-COLOR-METER/CV600... [3] IEEE 1789 Graphic Comparing 4 Light Sources https://github.com/yeutterg/beautiful-flicker/blob/master/out/Low%20Blue%20Flicker%20Comparison.png https://github.com/yeutterg/beautiful-flicker/blob/master/ou... [4] Beautiful Flicker https://github.com/yeutterg/beautiful-flicker https://github.com/yeutterg/beautiful-flicker

pistachiopro 8y ago

Thanks to GP for the links, I completely missed that previous thread! And, yeah, I tried that Soraa healthy bulb, and it was shockingly bad, given how it was advertised. Even the regular Soraa bulbs were disappointingly flickery, though less so. Also, just looking at the pattern it makes on my phone's rolling shutter, the wave is quite saw-toothed, and I wonder if that makes it worse? I have some Ikea candelabra bulbs which were always pleasant, and I was surprised to see they also left quite a visible flicker pattern on my phone, though much more sinusoidal/smoother. It's a shame about the flicker in the Soraa bulbs, since the colors really did seem nice.

yeutterg 8y ago
The Soraa bulb looked pretty sinusoidal on my scope when I tested it briefly. But it's a lot of flicker regardless. What's interesting is that the bulb seems to have a nice build quality (from the outside, I didn't open it) and is quite heavy. I suspect they are putting a BIG heatsink in there, as violet pump phosphors tend to degrade quickly. The other thing that irks me about this product is the "zero blue" messaging. Yes, I can confirm the spectrum looks like what they are advertising, with a peak around 415nm, almost nothing between 440-490nm, and then all the rest of the colors from green to red. But, green light is just as bad as blue for sleep! The ipRGCs are sensitive to both blue and green (up to around 600nm) This bulb has a lot of green, more than a lot of other light sources. It also has a very unpleasant greenish color (IMO) and low-ish CRI, around 78 on the bulb I tested. Is it better than a normal 600lm bulb for sleep? Yes. Is it novel? Yes. Is it good in practice? I don't think so.
- pistachiopro 8y ago
  That's right, the Soraa Healthy was very green! So, even without the flicker, the fact that it makes everybody look like undead zombies would be reason enough to disqualify it as a bedroom night light.
  - yeutterg 8y ago
    Haha, totally agree! If you are still in the market for a low-blue, low-flicker solution, may I humbly suggest a look at my product, Bedtime Bulb [0]? I know I basically bashed the Soraa product here, but not without technical justification. [0] https://bedtimebulb.com/ https://bedtimebulb.com/

retSava 8y ago

> flickering at over 50% what does that mean? Duty cycle is 50%, frequency at something Hz? Not being snarky - curious whether there is some kind of standard that your tool compares against. A duty cycle 50% (or any percent really) isn't bad in itself, it's the frequency that is the culprit. Too low PWM freq and you'll notice it.

yeutterg 8y ago
When I refer to % flicker, I am talking about the modulation % as defined by IEEE 1789-2015 and some documentation from the Illuminating Engineering Society [0][1]. More correctly, invisible flashing is known as the stroboscopic effect or phantom array effect. Two factors are often used to describe flicker for lighting: - Modulation %, a.k.a. % Flicker [The height or modulation of the waveform, formula is 100% * (A - B) / (A + B)] - Frequency [self-explanatory] Flicker Index is also used (refer to [1] page 7 for more info) but rarely. Duty cycle is not considered relevant, as you mentioned. Some tools designed to measure lighting, such as my UPRtek CV600 [2], spit out % flicker, frequency, and flicker index, in addition to a bunch of spectrophotometry metrics. It's also pretty easy to calculate the modulation % with an oscilloscope and photodiode, it's just Vp-p / Vmax. IEEE 1789 [0][1] roughly says that the higher the flicker frequency, the more acceptable it is to have a high modulation %. If you look at the graphic on [1] page 18, you can see this relationship. The white area is considered unsafe, the yellow area is "low-risk", and the green area is "safe." I don't 100% agree with this personally, as most incandescent lighting, with around 6-11% flicker at 100-120 Hz, would fall into the unsafe or low-risk category. But the Soraa product is definitely in the unsafe category. For reference, I plotted my product (Bedtime Bulb) against an incandescent A19, Lighting Science's Goodnight A19, and Soraa's Healthy A19 on an IEEE 1789 graphic [3] with a Python tool I'm developing, Beautiful Flicker [4]. You can see that this incandescent, measured around 10%, is on the border between unsafe and low-risk by this standard. Hope this helps! [0] IEEE 1789: A new standard for evaluating flickering LEDs?: https://www.dial.de/en/blog/article/ieee-1789-a-new-standard-for-evaluating-flickering-leds/ https://www.dial.de/en/blog/article/ieee-1789-a-new-standard... [1] Flicker: Understanding the New Recommended Practice (PDF) https://www.energy.gov/sites/prod/files/2015/05/f22/miller%2Blehman_flicker_lightfair2015.pdf https://www.energy.gov/sites/prod/files/2015/05/f22/miller%2... [2] UPRtek CV600 https://www.uprtek.com/en/product/SPECTRAL-COLOR-METER/CV600-Spectral-Color-Meter.html https://www.uprtek.com/en/product/SPECTRAL-COLOR-METER/CV600... [3] IEEE 1789 Graphic Comparing 4 Light Sources https://github.com/yeutterg/beautiful-flicker/blob/master/out/Low%20Blue%20Flicker%20Comparison.png https://github.com/yeutterg/beautiful-flicker/blob/master/ou... [4] Beautiful Flicker https://github.com/yeutterg/beautiful-flicker https://github.com/yeutterg/beautiful-flicker