Show HN: I built a JavaScript-powered flipdisc display
flipdisc.io
flipdisc.io
The lifespan is probably not as limitless as you might have imagined, the discs tend to fall off or get stuck. But they are really neat while they are working, especially how they sounds.
I was at an office with these flip dot displays, and eventually we dismantled the display. I took some picture of the pieces and you can see how stuck discs look like:
How do you remove dust from them? I imagine that's when they break.
But some differences are that flip-discs rotate 180° whereas DLP pixels only tilt a little bit to redirect the light to a heatsink, flip-discs have different colors on each side whereas DLP has mirror pixels, flip-discs probably have finite lifespan whereas DLP is good for trillions of cycles, and DLP responds so quickly (in microseconds) that grayscale is accomplished by duty cycle modulation (PWM).
How did they buy them, and for how much?
I feel like that's a key data point that would help people decide if they want to explore this further.
edit: someone further down the thread discusses pricing: https://news.ycombinator.com/item?id=40791049
They build and ship from Poland. They don't have a publicly available price list but they cost approx 220 EUR per 7x28 panel. Expensive, but few places still manufacture them.
If you continue reading the post, they also link out to other manufacturers including ones on AliExpress that seem to be cheaper.
I love to see Javascript used for stuff like this. It blew my mind that the James Webb Telescope uses a custom Javascript runtime for a lot of the onboard functions.
https://news.ycombinator.com/item?id=19739454
Still not sure why they chose JavaScript.
According to their paper it's a commercial JavaScript engine however:
https://ui.adsabs.harvard.edu/abs/2006SPIE.6274E..0AB/abstra...
It would be like being excited at seeing someone using aluminum to build something over steel/wood/etc.
I think Javascript is a really fun language. I've done a lot of embedded C and it can be... exhausting? I would love to try Javascript on an embedded system, IoT device, etc. I'll bet a lot of the most annoying stuff can be abstracted away pretty easily on modern hardware.
I found this comment: https://news.ycombinator.com/item?id=19739454
" The language itself wasn’t so important as having adequate performance, robustness, memory use, reproducibility and extreme QC"
but I still don't understand. Interesting they went with a language that doesn't even have integers.
At least the comments on this reddit thread have some hilarious jokes:
https://old.reddit.com/r/javascript/comments/wrtny3/the_jame...
Looks like they released a paper, the abstract of which, indicates it's not a fully custom runtime, which would make more sense:
https://ui.adsabs.harvard.edu/abs/2006SPIE.6274E..0AB/abstra...
Unfortunately they want money to read the rest of it and I'm curious but not that curious, and I probably wouldn't understand it anyway.
For the unawares, the original video: https://www.youtube.com/watch?v=FtutLA63Cp8
My favorite version, also using real-life objects: https://www.youtube.com/watch?v=lT-fdnIK0k0 (HN discussion: https://news.ycombinator.com/item?id=39527559)
For that I used a Python module (https://github.com/tuna-f1sh/flipdot) and Python Flask/React based manager, with sequence info in a SQLlite db. Same outcome as your App with pre-loaded transitions and of course, Game of Life: https://engineer.john-whittington.co.uk/2020/04/game-of-life...
It's my project TODO list to make a FPGA based direct HDMI controller for the Alfa-Zeta modules since refresh rate of the on-board firmware leaves a little to be desired.
https://www.smoothware.com/danny/woodenmirror.html
or more recently
https://tisch.nyu.edu/itp/news/spring-2024/daniel-rozin--itp...
Ingenious!
"niche technology" is probably the better term - that niche being readability in sunlight. A few years ago, flipdisc displays used to be very common in buses, trains etc. Then LEDs got better and the niche vanished...
His code can be found at https://github.com/owenmcateer/FlipDots.
So how much do one of those cost? The website (https://flipdots.com/en/products-services/flip-dot-boards-xy...) notably has no prices listed.
I love the idea but that's WAY to expensive for me.
[1] https://hackaday.io/project/159415-flip-dot-display-diy-cont...
Thank you for sharing
Or traveling. I imagine if you wanted to you could position the disc at any point between “on” and “off” by constantly flipping it back and forth.
The clicking, its sooooo satisfying.
Reminds me of the “flip flap” boards in old train stations. Like https://www.vestaboard.com/
Now it’s all LED, which is way more practical and so much less magical.
Assuming (literally just a guess) that the tiles "operate" at a rate of 3 times per second playing back a video or something:
(150 million operation) / (3 operations/ second) = 50 million seconds = 578 days
It's likely much slower than 3 operations per second too - so probably 6-10x that in reality, which would be on the order of a decade of continuous runtime before they reach expected EOL.
From Alfazeta's page (including the typos). 15 frames per second feels pretty wild, but would also, unfortunately, change this math pretty considerably if you ran it full tilt.
It does leave you exposed to the risk of a video where one of these does flip like 12 times in a second for like 20 seconds or something.
You could probably analyze whatever video is being played to calculate some kind of like "risk" value or "expected-lifetime-decrease" value to at least better understand what the impact is of the video being played. All that goes out the window when you do the sort of real-time mirroring shown in the article.
>AlfaZeta makes brand new displays, with a controller board. Their XY5 displays (14x28) sells around 500€ (VAT and shipping included).
https://hackaday.io/project/159415-flip-dot-display-diy-cont...
The result is really nice, and makes the conclusion make a lot of sense.
> I do hope that flipdiscs become more accessible for hobbyists. If anyone wants to collaborate on new affordable flipdisc hardware, let me know!
€4500 is quite the pill to swallow (unless prices have gotten cheaper since that 2018 Hackaday project)
You might as well say a motor has no moving parts, because it's done with electromagnetic impulses. But that would be absurd.
Obviously the hinge of each disc will wear and tear and eventually fail. Buildups of dust and oil will affect them too and prevent them from flipping. Flipdiscs are as mechanical as mechanical parts get.
You writing in the intro: "...have no moving parts, near limitless lifespan..." is just not credible.
And if I'm being entirely honest, that's where I stopped reading your post, because you simply didn't seem trustworthy. You might want to focus more an accuracy rather than hyperbole if you want to maintain readers.
I really did think about whether or not to write that last paragraph. But the thing is, it's the truth. And I think it's going to be more helpful in the long run for authors to know these things.
Believe me, I've been on the receiving end many times and it's made me a vastly better writer and communicator. When somebody stops reading your article because of a howler, it's much better for you to hear why so you can learn from it.
(And you don't need to be an expert in the field to realize that discs that flip are mechanical, or that they don't have a "near limitless lifespan". These aren't exactly subtle mistakes, and it's one of the main justifications presented in the introduction itself.)
Though I do wish for more accuracy. These things are totally moving parts, and there is no way they have even a long lifespan, let alone a "near limitless" one. Though to be precise, "near limitless" is meaningless.
What is the movement of a stone standing still?
What is the rolling rock that goes nowhere?<link rel="canonical" href="http://localhost:4321/">
HN extracts these.
I've fixed it now.
What? The display is made almost entirely of moving discs.