4 ms·

Show HN: Belshazzar's Clock, luminous paint night clock

73 points by mkarliner 2y ago

jareklupinski 2y ago
i want to mix this with https://github.com/LingDong-/shan-shui-inf https://github.com/LingDong-/shan-shui-inf to make a real-life infinitely scrolling procedural animation
- deleted 2y ago
  [deleted]
- mkarliner 2y ago
  Very interesting challenge. May need a slightly different tech. Stay tuned :-)
Cerium 2y ago
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 2y ago
  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.
  - avidiax 2y ago
    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.
  - thanatos519 2y ago
    Have you tried 360nm LED? The higher orbitals drop faster or so I've been told.
    - mkarliner 2y ago
      Another interesting suggestion to think about. Thanks.
- xattt 2y ago
  > I would take a hacked up disposable camera Memories unlocked of extracting the flash unit from disposable cameras to flash on demand.
rob74 2y ago
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-Alarm-Clock-Table-Bedroom-Bedside-Sleep-Timer-Large-Ceiling-Temperature-Time-Date-Display-Adults-Kids/3943469983?classType=REGULAR&adsRedirect=true https://www.walmart.com/ip/Emlimny-Digital-LED-Projection-Al...
- Terretta 2y ago
  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 2y ago
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/ https://unitednuclear.com/glowinthedark-items-c-101_45/ I've had Aqua and Green, and they look gorgeous.
- mkarliner 2y ago
  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 2y ago
    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 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 2y ago
      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 2y ago
        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
deleted 2y ago
[deleted]
froh 2y ago
fun :-) say, why don't you move mirrors but the whole laser?

73 points by mkarliner 2y ago

i want to mix this with https://github.com/LingDong-/shan-shui-inf https://github.com/LingDong-/shan-shui-inf to make a real-life infinitely scrolling procedural animation

deleted 2y ago
[deleted]
mkarliner 2y ago
Very interesting challenge. May need a slightly different tech. Stay tuned :-)

Cerium 2y ago

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 2y ago
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.
- avidiax 2y ago
  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.
- thanatos519 2y ago
  Have you tried 360nm LED? The higher orbitals drop faster or so I've been told.
  - mkarliner 2y ago
    Another interesting suggestion to think about. Thanks.
xattt 2y ago
> I would take a hacked up disposable camera Memories unlocked of extracting the flash unit from disposable cameras to flash on demand.

rob74 2y ago

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-Alarm-Clock-Table-Bedroom-Bedside-Sleep-Timer-Large-Ceiling-Temperature-Time-Date-Display-Adults-Kids/3943469983?classType=REGULAR&adsRedirect=true https://www.walmart.com/ip/Emlimny-Digital-LED-Projection-Al...

Terretta 2y ago
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 2y ago

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/ https://unitednuclear.com/glowinthedark-items-c-101_45/ I've had Aqua and Green, and they look gorgeous.

mkarliner 2y ago
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 2y ago
  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 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 2y ago
    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 2y ago
      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

deleted 2y ago

[deleted]

froh 2y ago

fun :-) say, why don't you move mirrors but the whole laser?