Miniature 3456 LED Cube | Hacker News Reader

Miniature 3456 LED Cube

willempennings.nl

291 pointspicture55 comments

If you like that, make sure to also check out Greg Davill, the one whose LED cube inspired him to build one for himself. Greg built a twenty-sided LED dice from equilateral triangles for example [0]. Very recommended!

He's on Twitter and has a blog:

https://mobile.twitter.com/GregDavill

https://gregdavill.com/

He also enjoys photographing PCBs and the "media" tab on his Twitter feed has lots of great electronics pics for that reason.

[0] https://gregdavill.com/blog/d20

Related note: I spent a while trying hand soldering, hot plates, and hot air rework to solder SMT boards. I should've just gotten a cheap toaster oven like in the article. I guess I was scared off by all the people insulating them and installing PID controllers. Totally unnecessary for me. I just stick in a thermocouple and vaguely follow a reflow profile. I'm easily getting 100% successful boards down to 0402 and 0.4mm QFN.

When I was getting into the hobby I reflowed a number of boards by balancing them on a piece of tin flashing, holding it over a candle or alcohol burner, and trying to seat-of-my-pants my way through the temperature profiles from the back of the datasheet. Yield wasn't great, but I got there, and it was definitely cheap!

Doesn't a candle lead to soot deposit?

Yes, but on the tin rather than the board.

When you need to reflow a board while you're living in a box next to the van down by the river... nice!

Same experience here: this board[0] was hand-placed and soldered in a toaster oven by essentially opening the oven door when peak reflow temperature of the paste I was using was reached. Additional aside- I very much prefer Loctite GC paste: it has a non-refrigirated shelf life of 6 or 12 months (however, it seems fine to me even a year past expiration date)

0: https://linx.wot.lv/bvcoyurf.jpg

+1 for Loctite GC paste, used it professionally for prototyping and it has always worked well with crude toaster reflow. Still stuck on hot air and Mechanic paste at home.

Wouldn't it have been easier to just get them assembled? It costs less than $10 with JLCPCB and you avoid tons of hassle. I'm thinking of getting the assembled boards for this cube, if I can, as it looks amazing.

The JLCPCB assembly service has a really limited parts selection and in general all microcontrollers and interesting parts are in the extended parts list. So most of the time you are soldering in the critical parts yourself anyway.

I don't need them to solder the critical parts, I need them to solder the numerous parts. I don't mind soldering one MCU, but I do mind soldering twenty 0805 resistors (or 3456 LEDs).

Projects like these are not about the destination, man. They’re about the journey. My guess is that more than anything this was an exercise in learning the processes of soldering small, tightly packed smd components.

Eh sure, the journey is fun the first time, but I personally just get them assembled now because I'm tired of soldering a million small components for the Nth time.

Not wanting to do this, and the OP talking about eyeballing a reflow oven are kinda not the same thing. Not doing an ad-hom attack here, but you probably own a reflow oven.

Eye balling the reflow profile with a thermocouple you threw in there is brilliant! I have a thermocouple readout on my DMM. I could go do this today with parts I have right now. That is wonderful, thankyou!

> Not doing an ad-hom attack here, but you probably own a reflow oven.

I do not, I've never even done reflow. I briefly considered making the toaster, because it's a very fun project, but in the end I think I'm just going to get my PCBs assembled.

neat.

I am huge fan of automated assembly as well, I think it unlocks designs that no one would even start to think about, like laying out thousands of discrete components on a single board. Esp if applying an aspect to a circuit, like "apply esd protection" or "apply bypass caps" or "apply pull low / high".

There's a ton of journey left in the software side for those more interested in that.

I do get almost everything assembled, from JLC or MacroFab, but I've been tweaking precision analog stuff and I need a fast turnaround and JLC doesn't have the parts.

Leeds Hackspace built a 3 meter sized cube a few years ago for Leeds Light Night (which then made it to a few events around the country); though we stuck with 8x8x8 resolution. We had it playing some pre-made patterns as well as some interactive games (draw on the cube by drawing on a phone, play snake etc...)

It was a lot of fun, but even with the 8x resolution there were thousands of solder joints to deal with. We also had it wired in a daisy chain (power and data) which was easier to do, but makes it a bit christmas-lights when it comes to finding a problem.

As far as I know all the software and hardware was open sourced, and there's a pygame and an html based emulator too, for testing patterns.

https://github.com/pbrook/lightcube

https://www.youtube.com/watch?v=pj-1SvWIQTo (yup, that's disposable plastic cups acting as diffusers).

https://wiki.leedshackspace.org.uk/wiki/LED_Cubes

I have to say, after seeing the 3456 cube in the main article, I feel ours pales in comparison.

The video of Malt Whiskey's 16x16x16 LED cube is quite impressive: https://www.youtube.com/watch?v=ciaFar8nfHc

There was a huge version of this hanging on the ceiling of Zürich's main train station, a while back. The light display was a 3D plasma effect. Really cool!

The latest one is this: https://www.mk-illumination.com/reference/zurich-hb/

You could make a funky dice with this. For example the dice could do any number of 'sides'. When it lands, it detects the landing and then displays a random number from 1-N.

Shut up and take my money :)

And use an accelerometer as a source of randomness.

Reminds me of BigClive's super computers [0]: flashing or color changing LEDs, some resistors and that's it. Quite a nice effect!

[0]: https://youtu.be/7f8jgvvJe-Q

Hugged to death. https://archive.md/qKJ7I

That is really pretty and I'm happy you shared it with us.

I wonder how much compute would be required to have it map an image or short video clip to always be level, regardless of cube orientation or angle of the faces?

To determine orientation, not much compute at all, through a BNO in there for doing the 6DOF and a small SoC. To rotate the video clip or image, again, not much compute because there are not that many pixels to map.

Running a simple fluid simulation with the LEDs could be a really neat effect.

wish there was a video of the final result!

(and of the LEDs reflowing into place)

+1. Found some neat videos on the related project's site: https://gregdavill.com/blog/2020/6/13/miniature-3456x-led-cu...

This is awesome looking. It would be very cool to see various cellular automaton rules play out on it, treating each side of the cub as an extended screen. Both 2D automata like Game of Life and also 1D ones like Wolfram’s rule 30 would look awesome.

I love the aesthetics of this, I must have one. I didn't notice a link to the schematics in the post, is there one?

EDIT: Oh, apparently this author used the original panels and didn't make his own. Good enough for me!

With the high popularity of these and LEDs in general, I’m wondering why cubes like these are not yet a throwaway commodity on AliExpress. What’s preventing it? Or is it really much more niche than we think?

Mainly because they are still expensive, see https://news.ycombinator.com/item?id=29471706

It would probably be cheaper to put OLED screens on each face of the cube (MIT media lab did one a few years back). But anyone doing a successful crowdfunding one would be indeed cloned as a throwaway commodity on AliExpress in a few weeks, probably before they ship theirs.

another "screen saver" idea could be a self solving rubiks cube

A cube like this + Wifi or BLE (+ sane API for driving the LEDs) + wireless charging + at least some kind of an orientation sensor = Kickstarter time!

I could see that becoming big for RPG or board games!

How does one get those boards? Are there services that one can use to get them "printed"? What software does one use to create a plan?

This was very clearly mentioned in the article, the project was even sponsored by the board fab used (PCBWay). There are others, and prices for entry-level hobbyist-size boards are low.

Two freely available software options to Goog are KiCAD and EasyEDA.

You can sketch out your board in KiCad [0] and export it as a gerber that you can send to a printing service. CERN uses it now, so it's worth learning, as it'll only improve over time. As for PCB shops, I'd start with comparing [1] [2] and [3], and seeing which has the best price for your needs. Generally, just searching reddit for "PCB prototype manufacturer" will get you a couple decent options. It really depends on how complicated your design is and how big of a run you need.

[0] https://www.kicad.org/ [1] https://www.pcbway.com/ [2] https://jlcpcb.com/ [3] https://oshpark.com/

Warning: Learning how to design PCBs can be habit-forming (hehe)!

It is ridiculously cheap to get say, 5 boards made and fully assembled at a place like JLCPCB. However, due to the chip shortage a lot of components like microcontrollers have stock that comes and goes. I recommend checking the PCB manufacturer's inventory (e.g. https://jlcpcb.com/parts/) before designing anything because there's nothing more annoying than spending hours making a PCB and then finding out you can't get it assembled because some part you chose is out of stock.

You'll probably also want to regularly check the inventory of the parts you're using while you're in the design process (if it takes more than a few days) because it happens quite frequently that a part with say, 3000 in stock suddenly drops to under 1000 and then to 0 over the course of a few days.

I highly recommend getting into PCB design. It's super rewarding (and satisfying/zen connecting traces) and it's easier than you'd think. I say, "it's like the adult version of connect-the-dots."

Thanks. I'll give it a look!

I shared this blog post on Facebook, and FB repeatedly takes it down as spam. What gives?

Could be great to display the favicon of websites you are visiting

Okay, I'd buy that for $60 without asking questions!

Given the labor cost, it's more like $600!

Mass-produced ones would be nice.

I probably wouldn't mind that too. It looks awesome.

If you get the LEDs already placed, the labor cost should be much, much smaller.

$60 is enough to get you just the 3456 LEDs (They're €0.0152 each at qty 2000+). Another $30 for the 36 driver chips. You're probably looking at around $150 in parts alone.

Sorry, didn't mean to come off as dismissive. It's an impressive piece of craftsmanship and it deserves a fair price. I simply wasn't aware of the cost.

Ah, it didn't really come off as dismissive I just wanted to provide some insight as to what the raw pricing of something like this would be.

Ironically enough I didn't want to come off as dismissive either

Have you ever used JLCPCB for assembly? The price for parts here is okay (I MUST HAVE THIS CUBE) but I don't know how much it costs to assemble non-basic parts.

are you selling these??

Slightly off-topic, but can I say how great it is that there are still people doing things they like for fun, and sharing the experience with others on an advert-free platform without any particular expectations of profit? In my view that's what the hacker culture is about, and the sort of thing I come to HN for.

Reading all the incessant headlines on HN recently about web3 and the tokensisation and monetisation and hyper-financialisation of everything, it is easy to think that the end days of hacker culture are nigh, with every interaction driven by the expectation of personal profit, and no-one doing anything any more simply because they are fun, or because they are the right thing to do, or just because they can.

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