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I'm making high power LED-based home lighting. I was inspired by this post: https://news.ycombinator.com/item?id=21660718 https://news.ycombinator.com/item?id=2

I'm making high power LED-based home lighting. I was inspired by this post: https://news.ycombinator.com/item?id=21660718 https://news.ycombinator.com/item?id=21660718 Basically our hourses are 1-3 orders of magnitude dimmer than the outside; this is not good. Ben Kuhn's approach was to buy a big 30k lumen LED bulb for $100. I am doing a more DIY approach with a number of small LED COBs. Each finished module will output 13.5k lumens for a bit less than $100 (so multiple will be needed per room), but it comes with a number of benefits: - The light is extremely high quality, almost the exact same as sunlight. Fluorescent bulbs and normal LEDs do not give off the full spectrum of visible light we get from the sun and incandescent bulbs. In fact I tried growing some plants indoors a while ago, and even though they were seemingly well-lit they ended up dying due to a lack of light. - The light can be dimmed to warm. Each module has four LED COBs. Three are bright white and put out 13.5k total lumens. The other one is a warmer white which should be useful at night - like IRL flux/redshift. And these can all be dimmed smoothly from 100% to 1% brightness. - The modules are controlled with an ESP8266, so they have WiFi. Aside from controlling them via a phone/computer, I am going to set up a Raspberry Pi running some timed scripts to automatically adjust them. For example they can all turn on in the morning as a natural wake up alarm (I have a separate alarm clock project I'm working on to give this a normal physical alarm clock interface). And I'm going to investigate using PIR sensors to make them automatically respond to human presence. In the end this method is a bit more expensive than just buying high power bulbs (and more expensive than buying normal bulbs, but you would need like 70 of them in a room to match the total light output), but it has a number of seemingly useful advantages. Right now I'm working on the second (and hopefully final) prototype; the first was electrically OK but had thermal issues (LEDs still get very hot!). It's an interesting break from normal software engineering. There's a huge emphasis on getting it right, and on getting it right the first time. Since there are a couple of amps of power running through the system, it needs to be well designed and safe from the very beginning. And $6 shipping every time you order from DigiKey punishes iteration heavily, since if you're making small iterations then your shipping will be much more expensive than the parts. I spent probably around 60 hours researching before making the first order. After finding out that the thermal solution was inadequate I spent a bunch of time theoretically fixing that and finishing up every single loose end (up to well over 100 hours total now). So now my second order will very likely result in a 100% complete, functional, and safe (I think!) product. The only thing left is to design a lamp-style enclosure. The module is small enough to replace a lightbulb in an overhead socket, but the wiring would need to be changed slightly and working through a small hole in the ceiling is not really practical.

fasteo 6y ago
>>> The light is extremely high quality Which parameters are you using to measure quality ? To me, it basically boils down to >95 CRI, but I know next to nothing about lighting.
- the_pwner224 6y ago
  Most LEDs will quote a CRI value. There are 15 buckets of color which can be tested, but generally CRI will just be the average of the performance on the first 8 buckets only. You can see the colors of the buckets at [1] or [2]. Higher quality LEDs will quote their R9 performance. LEDs are most efficient at creating bluish light, and use a phosphor to even out the light. Many LEDs lack red light output, which is what the R9 bucket is for. However ideally you want great performance across the full spectrum. The LEDs I'm using are the Bridgelux Thrive. If you look at page 7/9 (page numbers / actual PDF page) on their datasheet [3], they have actual graphs of the light spectrums. Two pages above that they have a table with R1-R15 measurements. On the lower graph of page 7/9, the dotted line is a black body radiator at 4000 degrees kelvin. Basically hot stuff glows and the spectrum shifts depending on the temperature. Incandescent bulbs are around 2700 K and make a shitton of infrared plus a bit of red/yellow. The sun is at 6000-6500 K; while it still makes a lot of infrared the spectrum now covers the entire visible range and also some UV and shorter wavelengths. They plot against that spectrums from what would qualify as 80/90/98 CRI. You can see the 80 CRI has a large falloff on the red (right) side of the spectrum. Bridgelux invents a new number Average Spectral Deviation which just computes how different the light is from the black body radiator; as you can see the Thrive is almost the exact same except for the very deep reds and a small blue bump / green dip (which is a characteristic of most LEDs, you can see the others have a much bigger deviation). I was a bit surprised to see that the 98 CRI had such a huge deviation in the blue (seems it trades a bigger blue bump for a smaller green dip). I don't know how trustworthy the comparisons are, but at least the Thrive is damn near perfect. However it's not very efficient, outputting 100-120 lumens per watt. Less-accurate emitters can get close to 200 lm/W. Also there's not a very big difference between the prices of different LEDs, and a different module would likely be a drop-in replacement. So you could nearly double the output of the system I designed if you didn't care too much about color rendering, which would make it somewhat competitive with the market in terms of $ per lumen. There's still a bit of soldering and assembly involved though. [1]: https://en.wikipedia.org/wiki/Color_rendering_index#Test_color_samples https://en.wikipedia.org/wiki/Color_rendering_index#Test_col... (only has 14...) [2]: https://www.waveformlighting.com/high-cri-led https://www.waveformlighting.com/high-cri-led [3]: https://www.bridgelux.com/sites/default/files/resource_media/Bridgelux%20DS321%20Gen%207%20V13C%20Thrive%20Array%20Datasheet%2020191112%20Rev%20A.pdf https://www.bridgelux.com/sites/default/files/resource_media...

fasteo 6y ago

>>> The light is extremely high quality Which parameters are you using to measure quality ? To me, it basically boils down to >95 CRI, but I know next to nothing about lighting.

the_pwner224 6y ago
Most LEDs will quote a CRI value. There are 15 buckets of color which can be tested, but generally CRI will just be the average of the performance on the first 8 buckets only. You can see the colors of the buckets at [1] or [2]. Higher quality LEDs will quote their R9 performance. LEDs are most efficient at creating bluish light, and use a phosphor to even out the light. Many LEDs lack red light output, which is what the R9 bucket is for. However ideally you want great performance across the full spectrum. The LEDs I'm using are the Bridgelux Thrive. If you look at page 7/9 (page numbers / actual PDF page) on their datasheet [3], they have actual graphs of the light spectrums. Two pages above that they have a table with R1-R15 measurements. On the lower graph of page 7/9, the dotted line is a black body radiator at 4000 degrees kelvin. Basically hot stuff glows and the spectrum shifts depending on the temperature. Incandescent bulbs are around 2700 K and make a shitton of infrared plus a bit of red/yellow. The sun is at 6000-6500 K; while it still makes a lot of infrared the spectrum now covers the entire visible range and also some UV and shorter wavelengths. They plot against that spectrums from what would qualify as 80/90/98 CRI. You can see the 80 CRI has a large falloff on the red (right) side of the spectrum. Bridgelux invents a new number Average Spectral Deviation which just computes how different the light is from the black body radiator; as you can see the Thrive is almost the exact same except for the very deep reds and a small blue bump / green dip (which is a characteristic of most LEDs, you can see the others have a much bigger deviation). I was a bit surprised to see that the 98 CRI had such a huge deviation in the blue (seems it trades a bigger blue bump for a smaller green dip). I don't know how trustworthy the comparisons are, but at least the Thrive is damn near perfect. However it's not very efficient, outputting 100-120 lumens per watt. Less-accurate emitters can get close to 200 lm/W. Also there's not a very big difference between the prices of different LEDs, and a different module would likely be a drop-in replacement. So you could nearly double the output of the system I designed if you didn't care too much about color rendering, which would make it somewhat competitive with the market in terms of $ per lumen. There's still a bit of soldering and assembly involved though. [1]: https://en.wikipedia.org/wiki/Color_rendering_index#Test_color_samples https://en.wikipedia.org/wiki/Color_rendering_index#Test_col... (only has 14...) [2]: https://www.waveformlighting.com/high-cri-led https://www.waveformlighting.com/high-cri-led [3]: https://www.bridgelux.com/sites/default/files/resource_media/Bridgelux%20DS321%20Gen%207%20V13C%20Thrive%20Array%20Datasheet%2020191112%20Rev%20A.pdf https://www.bridgelux.com/sites/default/files/resource_media...