[HN Gopher] Show HN: Belshazzar's Clock, luminous paint night clock
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Show HN: Belshazzar's Clock, luminous paint night clock
Author : mkarliner
Score : 71 points
Date : 2025-01-08 11:14 UTC (1 days ago)
(HTM) web link (blog.karliner.net)
(TXT) w3m dump (blog.karliner.net)
| Cerium wrote:
| Sweet hack, thanks for sharing. I remember playing in the dark
| with luminous paper as a kid - If I remember correctly, I would
| take a hacked up disposable camera and put various objects in
| front of the paper before triggering the flash.
|
| I imagine that you could improve the consistency and readability
| some by modeling the state of each pixel of paper. That way when
| the drum comes around you can compensate the exposure per pixel
| based on the current state to achieve better uniformity of
| display. In this way you could do exposure compensation on each
| row of output to make the display equally bright top to bottom.
| This would be similar to how a "no-refresh" epaper display works.
| mkarliner wrote:
| Interesting, I'll have to think about that. Actually, with rare
| earth paints, the big issue is persistence, which is rather too
| long. In the current script, I only turn the drum 1/4 turn, so
| it takes roughly 4 minutes to illuminate the same patch again.
| Otherwise the lowest digit tends to be blurred because it is a
| combination of the last two values.
| thanatos519 wrote:
| Have you tried 360nm LED? The higher orbitals drop faster or
| so I've been told.
| mkarliner wrote:
| Another interesting suggestion to think about. Thanks.
| avidiax wrote:
| Maybe you could make a clock based on a cylinder of sealed
| powder. You draw the time on it, and when it's time to
| update, you rotate the cylinder enough to mix the exposed
| powder and draw the next time.
|
| Maybe the same thing could be done with beads and something
| similar to the marble machines to replenish a screen of
| beads, then dump it when the time is invalid.
| xattt wrote:
| > I would take a hacked up disposable camera
|
| Memories unlocked of extracting the flash unit from disposable
| cameras to flash on demand.
| rob74 wrote:
| Looks cool, but if the "writing on the wall" is only supposed to
| be the current time, there are enough (much more mundane-looking
| of course) alternatives, e.g. https://www.walmart.com/ip/Emlimny-
| Digital-LED-Projection-Al...
| Terretta wrote:
| Indeed. And the red most use (a) doesn't blow your night
| vision, (b) isn't visible through your eyelids. (I recommend
| one where, if it also displays the time itself, shows the time
| in red too, at least when the room's dark.)
|
| Once you've had this on the ceiling for a while, it's annoying
| to have to look for time on a nightstand or your wrist.
| gigaflop wrote:
| Not sure if you can get this where you are, but I've personally
| used some of these glow powders, and they get _very_ bright:
| https://unitednuclear.com/glowinthedark-items-c-101_45/
|
| I've had Aqua and Green, and they look gorgeous.
| mkarliner wrote:
| Thanks, I'm in the UK, and US-UK shipping is horrendous, but I
| may give them a try.
|
| Right now I'm try to find a longer persistence photochromic for
| the daylight version.
| bigiain wrote:
| Have you come across Stuart Semple/ Culture Hustle?
|
| He makes a lot of interesting paints and pigments, and is UK
| based.
|
| https://culturehustle.com/collections/powder
|
| I've bought a couple of versions of his blackest black paint,
| and one of his whitest white, and they've all be
| extraordinarily good.
|
| I have some of his "LIT - THE WORLD'S GLOWIEST GLOW PIGMENT",
| but I haven't used it yet. I have no doubt it'll be great as
| well.
|
| (I have a vague plan to paint a motorcycle in Black4.0 to see
| if it's unreflective enough to evade the IR laser speed
| detectors cops use here...)
| djsavvy wrote:
| That's a great idea. I'd love to see if it works.
|
| I've wondered whether it would be possible to design a
| motorcycle with a surface that's non-reflective to radar
| because of it's shape or texture, like how stealth planes
| work.
|
| EDIT: I realized the super black paint is probably the
| worst thing you could do for your own safety on a
| motorcycle, but that's besides the point...
| bigiain wrote:
| I've been riding motorcycles for about 30 years now, I
| started back when Neal Stephenson's Zodiac was still new,
| and this part was still ringing in my head:
|
| "I had to ride slow because I was taking my guerrilla
| route, the one I follow when I assume that everyone in a
| car is out to get me. My nighttime attitude is, anyone
| can run you down and get away with it. Why give some
| drunk the chance to plaster me against a car? That's why
| I don't even own a bike light, or one of those godawful
| reflective suits. Because if you've put yourself in a
| position where someone has to see you in order for you to
| be safe--to see you, and to give a fuck--you've already
| blown it... We had a nice ride through the darkness. On
| those bikes we were weak and vulnerable, but invisible,
| elusive, aware of everything within a two-block radius."
| -- Neal Stephenson, Zodiac
| exmadscientist wrote:
| My brief experience with Black 4.0 was not particularly
| impressive. This video pretty much hits it dead on:
| https://www.youtube.com/watch?v=oKOC3Z9tDiI
|
| I didn't compare with the other paints (I only found that
| video after ordering the paint...) or with the difficulty
| of painting (I got the intern to do it!) but in terms of
| the final result, that's exactly the same result I got.
|
| I also have some of their glow pigment and it's a lot
| more impressive. This particular color doesn't glow very
| brightly or for terribly long, but the hue... glow
| pigment isn't supposed to be _this_ color!
| froh wrote:
| fun :-)
|
| say, why don't you move mirrors but the whole laser?
| jareklupinski wrote:
| i want to mix this with https://github.com/LingDong-/shan-shui-
| inf to make a real-life infinitely scrolling procedural animation
| mkarliner wrote:
| Very interesting challenge. May need a slightly different tech.
| Stay tuned :-)
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