I made a small LED panel | Hacker News Reader

I made a small LED panel

stavros.io

154 pointsBrajeshwar81 comments

I was about to comment that I also made a small LED panel, but then realized it was me.

Here's the latest LED thing I'm working on (the design isn't mine): https://immich.home.stavros.io/share/oXerU8gnLn-dNHunPOg8lM8...

Do you know if the panels can be bodged to be non square? There shouldn't be a lot of fancy wiring to screw up if it's all WS2812. Can you (delicately) chop a few LEDs out and bridge the connections?

(hoping I have seeded this idea, so I'm not the first one to attempt this)

I think you'd be far better off to make a custom PCB in whatever shape you like from the like of JLCPCB, PCBWay, or others.

The WS2812s here all connect to each other in series, so if you cut the board down, you'll have to replace the cut connections with bodge wires. To my mind, that plus the cutting is way more work than just making a PCB in exactly the shape you want.

You can get cheap PCBs for $5-$6 for qty 5 100mm x 100mm boards delivered to your door in the US. Add on LEDs at $0.03 to $0.05 each and I'd way rather make than modify here.

Perhaps a stupid question but why not just not use those LEDs? Shut down in the software..

Because you want the panel to fit a non-square shape, with no room for "leftovers" - think making it round to fit in a doorknob hole or oval to go in place of a car brand badge, etc.

In that case, it would definitely be much cheaper to design a custom PCB and get it assembled. It would probably take you much less time than all the cutting and soldering.

Sure, you can connect the LEDs together however you like (am I misunderstanding the question?).

Theoretically you can. It's whether it all goes pear shaped when you take a Dremel to the board to make it

    OO    OOOO   OO
    OO    OOOO   OO
    OO    OOOO   OO
    O    OOOOOO   O
    O    OOOOOO   O
    O    OOOOOO   O
        OOOOOOOO
        OOOOOOOO

And how fiddly it is to stitch up the edges. I shall find out in a couple of days when the panels arrive.

Oh that's what you mean! Yes, you can, but you'd have to bridge all the data connections by hand. Much easier to just leave those LEDs off in software.

I mean... as a lay-person, you've got point-lights and his isolation/diffusion layers in between. If you're 3d-printing your diffusion-thingy, then you've got tons of room to play games with the shape of the final glow. Even moving light via '265μm with 64 Fiber, Optical Grade Plastic Light Guide' if you're not hitting the corners well enough.

That... is a really good idea. I was thinking of cutting a flat piece of diffusing material to shape.

My intuition is that there would be pain in 3d printing a diffusion structure because slicers etc. would not be optimised for producing a homogenous solid. I would guess that 100% infill is actually something like 99.98% with tiny voids that stick out like a sore thumb when you shine a light through. I might be wrong about that, I'm not a 3d printing expert.

The principle of reshaping I think is awesome though. It might just be an issue of modulating brightness to counter any uneven distribution. It's got me thinking about a Faceted approach. 3d Print a faceted basin and then print a thin edge divider to sit in it. Fill it with something that sets solidly enough and makes a good diffuser (this too sounds like a war with bubbles). Take it out of the basin when set and you potentially have a nice faceted surface with each facet individually colourable.

you're right at re-inventing "prismatic acrylic flat sheet replacement light cover" stuff.

https://www.fluorolite.com/buy-now/f12-100-2347flatsheet/

for a cheap test, put wax paper between two grids/grilles and see how it looks (ie: double-diffusion). ie: [ LED | <grid> | <wax paper> | <grid> | <wax paper> ]

...the first grid isolates the color, the first wax paper diffuses the LED, the second grid "receives" the isolated color (diffused, not spot/point) which then gets finally diffused for viewing.

Surely you can look up how to avoid bubbles on a semi-transparent resin pour.

>Surely you can look up how to avoid bubbles on a semi-transparent resin pour.

I know how that's done (usually a combination of careful stirring and a vacuum chamber). The principle is easier than the practice. I am dispraxic and generally shouldn't be allowed near physical objects, but I like them so.

Poke at blender / sketchup!

https://blenderartists.org/t/how-do-i-put-a-soft-glowing-led...

...all the joy of creation with none of the cost or danger of losing fingertips! :-P

spidermanspointing.jpg

Jokes aside this is super cool. I always find LED panels really interesting to look at under the hood. I’m so picky about the ones I like to use almost purely based on vibes when filming. They’re just one of those things that you immediately know you’re going to love or hate in post the moment they hit your subject

What can I say, I'm addicted to LEDs. I tried so hard to not make that cube above, but I failed.

Did you ever try to use LED's as an input device?

My next LED cube project will be oriented towards trying to do that.

How do you mean? Like the magnetometer above? LEDs are outputs, no?

Not always, they can be configured to behave as photodiodes, too:

https://www.codrey.com/electronics/the-led-photodiode-trick/

This is also in my "TODO" list, maybe with the next magicShifter revision, or possible once I get the current new design booted and refactored, a bit ..

https://www.instructables.com/LEDs-as-light-sensors/

Ahh ok, you don't mean WS2812s then, just plain LEDs. I don't really have any ideas for what to do with a photodiode, but I have some of those straight LEDs and I really want to make something with those.

What kind of thing would you want to make with LEDs as inputs?

MIDI things. :)

Pretty cool way to fail

All credit goes to https://www.printables.com/model/337027-cubled-led-cube-8x8-...

How did you connect the individual smaller LED panels together? I guess the cool color patterns and the individual addressing comes from WLED then?

There's a photo of the panels connected to each other, each panel has three input and three output pads, and you solder those together. The software just sees one long strip, and you configure the shape of it so it corresponds to what you have in reality.

Nice work! I've done a few LED thingies too ..

https://magicshifter.net/

.. and, I recycled some old scoreboard display panels to make something similar to your latest project, also:

About the panels: https://metalab.at/wiki/Blinkofant/LED-Display_History

The Blinkophant: https://i.imgur.com/3aPytEp.jpeg

I made something close to MagicShifter a while ago, I didn't add an accelerometer, though:

https://www.stavros.io/posts/behold-ledonardo/

I would really like to make it work with an accelerometer, as right now it's a bit fiddly to get the right speed for images, but I don't know if I can make it work.

Not just accelerometer, but magnetometer too. :)

This means you can basically use the magicshifter3000 as a knob. Or, a slider.

Its very fun with MIDI.

Oooh fantastic! That's the kind of thing I really like to see.

Perhaps you will understand what this is, then:

https://www.youtube.com/watch?v=syP8_lccIQA

Haha, amazing! Is it based on the accelerometer, or do you have a microphone connected somehow? I can't tell whether you're tapping the desk they're on.

Then again, the right ones light up more than the left ones, so I think you're tapping on the right edge of the desk. Very cool!

The accelerometer and the desk, being tapped by me offscreen just to be sure things were responding .. alas, they are kind of hard to keep in one big pile, but yes very fun to play with en masse! :)

(This was some years back, note.)

Where did you get the scoreboards? eBay?

Donated to metalab through a member connection. Austria/Vienna has a bit of a 'recycle/re-use/repurpose' scene, and this was an early example of a metalab win:

https://metalab.at/

We devoured the panels and did all kinds of funky things with them.

https://metalab.at/wiki/Blinkofant/LED-Display_History

This is great! Your TLS cert is invalid, though, so the site doesn't load properly, I think.

Yeah, expired a while ago, its a pretty old site and we have to get the old gang back together to fix it.

Thanks for checking out the magicShifter3000!

I've got a new one designed, currently in prototyping stages .. a bit more powerful and a lot more oriented towards audio/synthesis. Same form-factor, and probably MS3000 and midiShifter will have an ecosystem ..

If you have the site on GitHub, you can deploy it to Cloudflare Pages with a few clicks, and it will take care of all of that stuff for you.

Also, a few friends and I have a maker Discord server and you'd fit right in, I can send an invitation if you like! My email is in my profile.

Server: not my department. :)

But yeah, we'll probably reboot magicShifter soon ..

On the topic of small LED panels, Jason of Evil Genius Labs has been making some really small LED panels [0] with addressable 1mm x 1mm LEDs (yes, individually addressable AND only 1mm on each side!). Fitting 128 onto a 1" circle is pretty sweet.

I keep meaning to design some PCBs with them [1] but it's too far down my ever-growing list of projects to see the light of day...

[0] https://www.evilgeniuslabs.org/one-inch-fibonacci128

[1] https://www.lcsc.com/product-detail/C5349953.html

Kingbright recently released 01005 (0.45mm x 0.25mm x 0.2mm) sized LEDs, which afaik are one of the smallest ones easily available. One neat idea would be to pack those on DIP14 sized pcb, making tiny neat character display. I guess something like 5x7 or 6x8 matrix could be doable with small mcu to drive them.

For those 1mm addressable RGB LEDs I've been thinking how you could do cool cyberpunk looks by stringing them on some hairthin magnet wire and sticking them on your body/face/hair/etc. Blend them in with some latex or something if needed. Just need to hide the controller/battery somewhere.

Ah, the joy of being a Brit. That first link is just full of purple rectangles containing the text "content not viewable in your region" (Imgur).

I'm feeling safer already. sigh.

Looks like a fun site though, I'll take a look when I'm not on my work computer.

Those are just really small WS2812, I get those at 160 led per meter on a strip of 5 bucks per meter. I just mean to say they are cheaply available in many form factors. I use them a lot in cosplay clothing.

https://spotpear.com/shop/ESP32-S3FH4R2-Matrix-8x8-RGB-LED-W...

Those look like normal 2.5-3mm LEDs, that is big difference to 1mm² LEDs. The circle disc from OPs link has 2.5x higher LED density, and they could be probably packed even more densely in a grid.

Looks like they're WS2812B-2020, like on this PCB:

https://www.wemos.cc/en/latest/d1_mini_shield/8x8_rgb.html

BTW: The 2020 are super bright, but the 1010 not so much.

Why are you doing this to me

Speaking about small led panels, I also recommend the "Fluid Simulation Pendant" from mitxela: https://mitxela.com/projects/fluid-pendant

Mitxela is on another level though, it's not fair.

Life ain’t fair. Take it as a compliment and a challenge! <3

I will make another small LED panel with ONE MORE LED!

That's the spirit!

For a second I thought this was about custom LED construction.

But apparently, LEDs require advanced processes unlikely to be available for makers, anytime in the near future.

However, Zinc sulfide phosphor mixed into epoxy can be used to make voltage activated luminescence. For some interesting guidance on "doping" for color, I present a 1953 patent:

> zinc" sulphide' activated by both copper ad manganese in accordance, with the present invention is strongly electroluminescent, the addition of. manganese to the copper-activated material resulting in a shift in the color of luminescence toward the red end of the spectrum. Thus, the materials of the invention, when excited by a fluctuating electric field, show colors of luminescence ranging from bluish-green through shades of bluish-white, pinkish-white and yellow to orange. [0]

Looks like some level of RGB was possible from the get go.

[0] https://patents.google.com/patent/US2743238A/en

A more modern approach of doing the same to use polymerized quantum dots (I believe it emits wide spectrum white when a voltage is applied), and passing that through a quantum dot film to get any specific wavelength.

Cool! What kind of voltage ranges are we talking, and how toxic is Zinc sulfide phosphor?

Not that toxic, unless inhaled (take precautions) or ingested, or heated to high temperature, which produces a toxic gas.

Doping of course can change that.

May require 100+ V AC at 500-2000 Hz. So probably not the right element to implement 4k in! Or for an early education science experiment, unfortunately.

I don't know what the currents would be, proportions or dimensions of epoxy, or much else. Some more research would be required. But in terms of resistive heating creating gas: measure and be careful!

Seems within reach of a hobbyist maker, at least the slightly unhinged kind (in the best meaning). Since considerable energy is needed but also avoiding excessive heating, integrating temperature measurement into the bulb might be prudent. Or at the very least having regulation on current+voltage. There might be risk of thermal runaway, if conductivity goes up when voltage is applied to the epoxy mixture.

The diffuser really makes this. The resulting effect looks great.

It really did! It looked much better than I hoped, I really liked the result.

I dont understand it. The resolution is only 8x8. How does the animation at the end looks so smooth and way higher resolution?

The diffuser fakes the resolution, basically, by blending the colors together physically.

I believe you, my brain doesn't. Those movements are so smooth. The line where two different colours merge have no sharp edges and look perfectly curved. Only thing edgy was the very last blinking animation where there weren't any colours.

Thinking more, if there were only 4 LEDs I can imagine how they would look like diffused.

Initially I was thinking if 8x8 can show all those smooth details and motions, can it be used to show any other higher resolution imagery instead of just moving colours.

I think the thing that fools us here is the fact that we're used to pixels being discrete, so it doesn't "look" low-res because the colors blend into each other. If you imagine that each LED produces a small circle onto the diffuser, and that this circle overlaps the ones around it a bit, it gets easier to see through the illusion.

It's much easier to understand when you can change the distance of the diffuser to the panel (which I did when testing), because then you can see the lights go from little squares with lots of dark space around them, to this, to big blobs of one color.

A diffuser is basically applying a convolution to the underlying pixel array (moving the diffuser away from the LED increases the convolution width, but unfortunately also reduces the intensity).

I don't think you can exploit that to show something higher resolution than the original pixel array,

For the diffuser, there's a nice one or two in all LED/OLED monitors. More stuff in there too, acrylic/polycarbonate glass and a Fresnel lens. Worth scavenging if you come across a broken one.

I think you mean "LCD/LED" monitors (where "LED" is commonly used to mean an LCD panel with an LED backlight, and "LCD" is used to differentiate old CCFL-backlit LCD panels).

OLED screens do not have a backlight and thus don't have a diffuser.

Whoops, guilty as charged. Thanks.

Oh that's a great idea! This also reminds me of the video where the guy took out the LED panel and used just the light and the Fresnel lens to make a window with very natural-looking light.

Tried my hand at this too. Except more janky and was aiming at lots of output.

LED get freaking hot fast at higher wattages and quickly found myself dealing with heat sinks etc.

Do you need to run them at max brightness? I run them at 10% or so, they're really bright.

Don't recall percentage but was pushing a lot of power into it around 8W. That heat obviously needs to go somewhere.

Think the LEDs I had were pretty crappy though, so they probably produced more heat per unit of light than they should

i.e. was more brute force than colour & control

Hm that's about 256 LEDs, must have been a 16x16 board. Sounds about right, good point.

LED matrix panels are tons of fun! I strung a bunch of them together to make a marquee across my basement soffit: https://youtu.be/W0_3rzvq9Ks?si=aTT_uOZfOYh9NLUi

I have to resist the urge to tile every surface with blinky lights. I think part of the appeal goes back to why I enjoyed writing programs on my C64 to bounce my name around the screen. It’s a limited playground, and limitations inspire creativity.

This looks fantastic. Your basement really has a nice aesthetic to it, and that marquee looks great in it!

I have a bunch of these 8x8 panels on their way from AliExpress right now for an art project that a part will look remarkably like the video. V1 will probably be a 32x32 just like it.

I still haven't decided if I want to have a partition grid between the panel and the diffuser to make square edge pixels. It's definitely going to have a rp2350 inside. PIO is the best thing ever.

https://kno.wled.ge/

This is neat! Any notes on the algo for controlling the output of the ws2812s?

Maybe WLED plasma effect (number 97)?

https://kno.wled.ge/features/effects/

https://github.com/wled

Yes, it's probably something like that. WLED has a ton of patterns, it's really nice.

I wonder what material is diffuser made of

It's just this:

> a two-layer white square out of PLA

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