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Comment by rococode | Hacker News Reader

In a sci-fi future where people are making long journeys on spaceships I can imagine rooms decked out with these to mimic a natural day/night cycle and outdoor spaces.

I remember first seeing lights like these a couple years back before from CoeLux (https://www.coelux.com), iirc theirs are very expensive though. Awesome that this guy managed to DIY one!

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Spaceships? I can imagine these things in Alaska:

https://en.wikipedia.org/wiki/Whittier,_Alaska

> Whittier is a city at the head of the Passage Canal in the U.S. state of Alaska, about 58 miles (93 km) southeast of Anchorage.[6] The city is within the Chugach Census Area, one of the two entities established in 2019 when the former Valdez–Cordova Census Area was dissolved.[7] At the 2010 census the population was 220, up from 182 in 2000. The 2018 estimate was 205 people, almost all of whom live in a single building, the Begich Towers.

https://en.wikipedia.org/wiki/Begich_Towers

> The Begich Towers Condominium is a building in the small city of Whittier, Alaska. The structure is notable for operating like a small-scale arcology, being the residence for nearly the entire population of the city, as well as containing many of its public facilities. This has earned Whittier the nickname of a "town under one roof".

Riding the coattails of your comment to ask the hive mind: any reason I shouldn't try to build the simpler version from the tutorial using a more powerful (100W) LED from Amazon?

https://www.amazon.com/dp/B07T8RDF8F

Might not be as awesome as a $60k CoeLux, but for 1000x less cost, maybe it's worth a shot?

(Edit: come to think of it, with an 8x10 fresnel lens, it might be way too bright for the size.)

Don't forget that the volume of the device has a cost too. The video shows the construction of a really really nice, but takes up the whole hallway outside that room. Most of the time you'd probably prefer to use your hallway for walking in. On the other hand, maybe your house has an attic above one of your rooms that; there will be a lot less opportunity cost to using up that volume.

Use Fresnel lenses with a shorter focal length and reduce the depth.

It would be useful to start with a standard home-type window from, say, Home Depot, and build a unit about 120mm deep using multiple shorter focal length Fresnel lenses.[1] Then, in a basement or windowless room, mount some of these into a wall. Add curtains. Nice if your home office or workshop is in a basement.

This has commercial applications. Houses have few windowless rooms, but commercial structures have many.

[1] https://www.alibaba.com/product-detail/Fresnel-lens-plastic-...

DIY Perks has previously shown how to do that, and it looked pretty good.

Turning Smashed TVs into realistic daylight panels: https://www.youtube.com/watch?v=8JrqH2oOTK4

Keep watching the video - he builds Fresnel lens versions at the end of the video.

The satellite dish is more dramatic so I don't blame him for leading with it :)

The idea is to build this as a light box behind a standard windowpane frame. Like this one.[1] With a 120mm short focal length, the unit only needs to be about 150 - 200mm deep, if you angled the optics so you get light at a 30 degree angle or so. (Horizontal sun rays would look wrong.) That's a convenient size; you could hang it on a wall, like a rather bulky picture.

[1] https://www.walmart.com/ip/Darice-Wooden-Window-Pane-w-6-Pan...

lenses cause chromatic abberations though, the red/yellow halo around the beam you see in his cheaper version at the end.

I have a chromatic film on my actual windows because I like the effect so there's technically a market for it , especially if it makes it cheaper and smaller

I am really curious about this -- do you have it just for the effect? What does it look like?

It is much easier to take broken lcd screen and remove diffuser.

https://m.youtube.com/watch?v=8JrqH2oOTK4

That’s the same guy as this article link. This one is supposed to be an improvement over that.

the point of the parabolic reflector/fresnel versions are the parallel rays

maybe I should look at things first before commenting ..

I would advise to use some brass chassis for hot elements as fire accident may be more costly.

You'd still have to deal with the glare and chromatic aberration from the mirror sheets. Also the area covered would still be confined to the size of one sheet and you'd have to make a "bank" of them to cover any reasonably large area.

Especially if they emit the UVB light we need for Vit D production

I thought the official advice was to get supplemental vitamin d through oral supplements, rather than through artificial UV lamps?

https://www.nhs.uk/live-well/healthy-body/how-to-get-vitamin...

>Using sunbeds isn't a recommended way of making vitamin D.

There's at least some evidence that LEDs can be more effective than sunlight at synthesizing D. There's a specific wavelength of light that triggers it and I'm not sure if a standard tanning bed emits it.

https://www.nature.com/articles/s41598-017-11362-2

FWIW there's not evidence vitamin D supplements have any health impact (asides from crickets).

I’m confused by this comment. There is evidence that Vit D deficiencies have all sorts of health impacts, and that supplements raise in-blood levels. What other evidence is needed?

https://www.bulletproof.com/supplements/vitamins-minerals/vi... (11 scientific references linked at the bottom)

Most things related to vitamin D are just correlation. If you are weak and frail you may not get out much and won’t have so much vitamin D. That doesn’t mean giving you vitamin D will make you strong. I heard that most studies don’t show benefits from vitamin D a supplements but maybe I’m wrong.

Sounds to me like what you heard could be easily proven/disproven by reading some studies.

I searched google scholar for “vitamin d meta analysis”. I skimmed the abstracts. These are some of the earlier results.

It seems supplements help but randomised controlled trials are needed: https://jamanetwork.com/journals/jamainternalmedicine/fullar...

“Vitamin D supplementation appears to reduce the risk of falls among ambulatory or institutionalized older individuals with stable health by more than 20%” http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.578...

Oral vitamin D supplementation between 700 to 800 IU/d appears to reduce the risk of hip and any nonvertebral fractures in ambulatory or institutionalized elderly persons. An oral vitamin D dose of 400 IU/d is not sufficient for fracture prevention. https://jamanetwork.com/journals/jama/article-abstract/20087...

High levels of vitamin D among middle-age and elderly populations are associated with a substantial decrease in cardiovascular disease, type 2 diabetes and metabolic syndrome. If the relationship proves to be causal, interventions targeting vitamin D deficiency in adult populations could potentially slow the current epidemics of cardiometabolic disorders. https://www.sciencedirect.com/science/article/abs/pii/S03785...

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At this point I got bored of looking at results (I omitted a few which only looked for correlations).

So while there is some evidence of some benefits for some people, I didn’t find evidence of vitamin d being the magic panacea that it sometimes feels it is claimed to be by people on the internet.

Well, if it may have benefits and costs pretty much nothing, it would make sense to take it...

I think you need to add "among people with sufficient levels of vitamin D" to that statement.

It follows almost from definition that if you are deficient in something, supplementing that something is beneficial. There might be some exceptions, but then we've really just got deficient defined poorly or no effective method of supplementation.

Aside from _in_ crickets experimentally, or aside from crickets as in you hear nothing?

rickets, not crickets

Ohhhhhhh, that makes total sense.

I looked into it for a client's commercial building. $40k each for parts only.

I had a room in an apartment that had no sunlight, and was lusting after CoeLux after it launched. Almost goes without saying, but the first to manufacture an affordable solution at scale would make a ludicrous amount of money, especially with much of the world in lockdown.

Low dose UV light would also be a good addition.

Low dose UV light would also be a good addition.

I'd also like a bit of optional IR so you get a tiny bit of that toasty sun feeling if you want it.

If you use a parabolic reflector and can prescatter the light it's as easy as adding another light source.

A computer chip costs $1 billion to make.

A billion of them cost $1.1 billion to make.

Too right!

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