[HN Gopher] Ultrathin business card runs a fluid simulation
___________________________________________________________________
Ultrathin business card runs a fluid simulation
Author : wompapumpum
Score : 1070 points
Date : 2025-08-08 11:41 UTC (1 days ago)
(HTM) web link (github.com)
(TXT) w3m dump (github.com)
| mouse_ wrote:
| Nice work, awesome presentation
| x187463 wrote:
| Very cool. Though, I was waiting for the video to properly
| 'shake' the card.
| raincole wrote:
| Off topic, but where should one start learning writing physical
| simulation?
|
| Several years ago I ran into this project [0] and got overwhelmed
| even the algorithm can be written in 88 lines of C++. I realized
| that out of all CS topics, physical simulation is probably the
| one I knew the less (not saying I'm a compiler/database expert or
| something, but at least I've implemented a toy compiler and some
| basic data structures used in database. When it comes to physical
| simulation my bran just draws a blank.)
|
| [0]: https://github.com/yuanming-hu/taichi_mpm
| maccard wrote:
| Rigid body simulations are much much simpler. There's a
| siggraph course from 2001 [0] which is a bit of a dense read
| but it will bring you all the way up to a full blown rigid body
| simulation and understanding the math behind it too.
|
| [0] https://graphics.pixar.com/pbm2001/pdf/notesg.pdf
| beardyw wrote:
| Though in this case there's not much more than 500 points,
| which even if you scale up is manageable.
| maccard wrote:
| It's less about the number of points and scaling and more
| about understanding the fundamentals. Any sort of particule
| simulation (which is the easiest way to get into cloth,
| soft body and fluid dynamics) requires about the first half
| of that paper I linked anyway.
| aDyslecticCrow wrote:
| Ive done one myself. Very fun and very valuable project, with
| alot of optional deapth.
|
| Solar system simulation is another fun one, leaning more into
| nummerical differental equations solving.
| Cthulhu_ wrote:
| One thing that helped me was doing some tutorials for pico-8,
| an intentionally 'weak' game platform, one of which is a
| platform game with a simple / understandable inertia / gravity
| simulation (jumping, running left/right; think Mario). It was
| understandable enough with an x / y position for the character
| and a delta-x / delta-y representing their current speed. Every
| frame the dx / dy would get changed depending on player input
| and/or character state.
|
| Ex: if player presses jump button, set state to 'jumping' and
| dy to 1. Every frame, dy = dy * 0.9. When dy <= 0, set state to
| 'falling'. Every frame, dy = dy * 1.1 until dy = 1 (terminal
| velocity). Then add some collision detection.
|
| I think those basics are also behind the simpler physics
| simulations, the 'falling sand' types would be ideal for an
| application like this.
| wizzwizz4 wrote:
| Gravity is constant acceleration (in most games). Your
| algorithm is broken.
| maurits wrote:
| For statistical mechanics, I really liked [1]. Comes with loads
| of python programs.
|
| To see what might peak you interest, the videos in [2] could be
| a good starting point.
|
| [1]: https://www.coursera.org/learn/statistical-mechanics
|
| [2]: https://matthias-
| research.github.io/pages/tenMinutePhysics/i...
| ethan_smith wrote:
| The Nature of Code by Daniel Shiffman is an excellent entry
| point - it teaches fundamentals of physics simulations with
| clear examples in Processing/p5.js.
| stormfather wrote:
| Just go to Perplexity or something like that, its well trodden
| ground. And essentially, what you're doing is discretizing the
| relevant differential equations and getting that to run in a 2D
| or 3D cellular automaton.
|
| I'll give you a simple example. For diffusion of heat between 2
| points, the rate of change (first derivative) is proportional
| to the difference in temp between them. So you make an update
| rule for points on a grid that says "calc the average
| difference of a cell's temp with that of its neighbors,
| multiply by some constant, and that is the amount to update
| this cell at this time. Run that for every cell in parallel,
| many times." Then you tack on a visualization and you can watch
| the heat diffuse. A fun example would be the cooling of the
| proto-Earth. You can watch the crust form.
|
| Heat diffusion is a good starter problem. So is gravitational
| interaction.
| IIAOPSW wrote:
| Probably what you want is "numerical methods" and
| "computational physics".
|
| "Physical simulation" is a very broad scope, so your code for
| simulating fluids is going to be very different from your code
| for simulating planetary orbits, and at times it may feel a bit
| ad hoc. But at its foundation physical laws are written in
| differential equations and linear algebra.
|
| So whatever algorithm lets you numerically integrate several
| inter-related variables is going to be broadly applicable to
| simulating any physical phenomena. At the simplest end of the
| spectrum you just naively approximate integration by brute
| force. Eg at each step just update your physical state
| variables by doing velocity += acceleration, position +=
| velocity. This is called Euler's method, and while simple, it
| accumulates unacceptable errors rather quickly in most
| circumstance. The more advanced approach is to use a method
| like Runge Kutta. In circumstances where you have some known
| property, like say energy conservation, you can implement a
| method which explicitly imposes the constraint. This is good
| for cases where the motion is highly periodic as it prevents
| the numerical error from accumulating exponentially in orbits
| that spiral out of control.
|
| Of course at some point you'll have to grapple with the issue
| of if you are simulating trajectories of free particles or
| values of neighboring grid points in a field. This question of
| how best to encode physical systems and simulate them cuts to
| the heart of physics.
|
| I'll leave it at the old cliche "information is physical"
| dawnofdusk wrote:
| Essentially all physics simulations are either particle based
| or based on integration of differential equations (although in
| a computer both approaches involve a discretization which makes
| them somewhat computationally similar). You can consider
| reading through Numerical Recipes which is sort of the bible
| for this stuff for physicists, but it is aimed at scientific
| audiences with weak CS background. Something like Computer
| Simulation of Liquids by Allen could be a good start too. Let's
| be clear that the approach I'm talking about here is focused
| more on physical correctness: if you are a game designer it's
| not important that your fluid simulations are physically
| correct and more that it _looks_ physically correct to a
| player, and there are a variety of more heuristic techniques
| for something like that.
| pornel wrote:
| For water simulation, look towards learning compute shaders.
|
| Eulerian (grid-based) simulation is one of the classic
| examples.
| RMDNZ wrote:
| Amazing. Just don't show it to Patrick Bateman.
| ducktective wrote:
| "I can't belllieeeve RMDNZ preferred L-Johnson's card to mine"
| tetris11 wrote:
| Practically pregnant with electric potential
| bookofjoe wrote:
| "Silian Rail"
| rwmj wrote:
| Would love to see more information about how it was built. He
| must have worked with a company that can do the surface mount
| assembly?
| Retr0id wrote:
| You can get boards like these made for single-digit dollars per
| unit* even at prototype scale, through companies like jlcpcb.
|
| *I haven't looked at the specific parts for this board, the
| LEDs look nice and could be a little pricey.
| rwmj wrote:
| Boards, but can you get the pick and place and the soldering
| done? I wouldn't want to be soldering that many LEDs by hand!
| mk_stjames wrote:
| Every major chinese PCB supplier has offered very
| affordable PCB assembly ("PCBA") for several years now
| where you give the gerbers for the boards along with a BOM
| with part numbers from a mutual supplier catalog and p'np /
| solderpaste mask data and they will load up a p'np machine
| and oven run a small batch of boards for you.
|
| e.g.:
|
| https://jlcpcb.com/smt-assembly
|
| https://www.pcbway.com/pcb-assembly.html
| Retr0id wrote:
| That price is including PCBA. Without it would be <$1/board
| Cyan488 wrote:
| Electronics can be surprisingly easy and cheap to build these
| days. He designed the circuit and layout with software called
| KiCAD (free and open source) then submitted the designs to a
| fabrication house - probably a popular offshore one - that
| easily can handle that level of board and component placement
| complexity. It would probably cost only a few hundred to build
| and ship, with 1 month turnaround time.
|
| You can also hand-assemble surface mount parts by applying
| solder paste carefully to the pads, then placing all the
| components on the paste and heating the board until all the
| solder melts. That would have very time consuming for all those
| LEDs!
| Cthulhu_ wrote:
| There's also some homebrew pick-and-place machines and
| soldering ovens, but that's probably a bigger upfront
| investment than the offshore companies can offer.
| burnt-resistor wrote:
| As long as there aren't surprise 50% tariffs.
| alnwlsn wrote:
| This was something I had to look into earlier this year. We
| found that even if tariffs were 200-300%, JLC and PCBway
| are still half the cost of domestic USA board houses, while
| also somehow providing half the leadtime. They are an
| absurdly good deal.
| burnt-resistor wrote:
| Yep. And if you go to Shenzhen, some shops will take on
| varying amounts of board design and prototyping for you.
| It's possible to get boards fast and for cheap, like less
| than a few days and even cheaper when the goal is larger
| quantities for semi-serious products.
|
| For a few hobby or toy things, the fixed rate board
| stuffing shops are the way to go.
| FinnKuhn wrote:
| I remember William Osman (who established Open Sauce)
| talking about how they manufactured the badges for the
| convention, which are mostly just one large pcb, and how
| they looked into having them made in the US but there
| were no companies even offering the same kind of service.
| So it is not just that the Asian suppliers are cheaper,
| it is also that there isn't really a competitive US made
| alternative even if you were willing to pay more for it.
|
| Here is the link to the episode (without a timestamp):
| https://www.youtube.com/watch?v=S78lYvjo2JQ
|
| And this is how the badges looked/worked: https://www.dig
| ikey.com/en/maker/tutorials/2025/assembling-y...
| alnwlsn wrote:
| >He must have worked with a company that can do the surface
| mount assembly
|
| He did (there are centroid files in the production folder,
| which tell the board house where to put the components), but
| you'd be surprised at how possible it is to assemble something
| like this by hand. You won't believe me, but I find it easier
| than through-hole soldering (because you don't have to keep
| flipping the board over).
|
| But there's a 99.9% chance this was done in-house at JLC or
| PCBWay.
| phirks wrote:
| Indeed, JLC for this one, though I did start off by hand
| assembling the first version with a 3D printed jig to locate
| the LEDs.
| bobsmooth wrote:
| No need to reinvent the wheel. Hand assembling all those
| leds looks like a nightmare.
| JKCalhoun wrote:
| Yeah, wondering how the LEDs were aligned so precisely. Some
| kind of silicone grid-like jig to hold them while the solder
| reflows? Or is it just pick & place robotics doing what they do
| with precision?
| triactual wrote:
| The surface tension of the solder will pull them into
| alignment if the pad shape and solder volume are correct.
| ChrisMarshallNY wrote:
| Very nice, but probably a bit too expensive to just hand out.
|
| I knew a chap that had a similar hardware business card (I don't
| remember exactly what it did, but it wasn't as cool as this one).
|
| I remember that his card was pretty scuffed up, and he insisted I
| give it back, after he handed it to me. Bit weird.
| Cthulhu_ wrote:
| How much does it cost? The guest passes for hacker conferences
| are full-on computers these days, if this is in the same price
| bracket it would be a great idea for those.
| 4gotunameagain wrote:
| There's a BOM, you can find out. Plus some peanuts for the
| PCB :)
|
| Now whether you get it populated or not..
|
| https://github.com/Nicholas-L-Johnson/flip-
| card/blob/main/ki...
| unwind wrote:
| Just as a point of interest perhaps for folks who are not
| familiar with PCB design and modern electronics: the "huge"
| matrix of 21x21=441 LEDs would, with the specified LED from
| the bill of materials (BOM) cost all of $6.
|
| That is based on the price for low quantity (1-500 pieces)
| though; if you were to build more than one board you would
| buy more LEDs, pushing the per-LED price (way) down. You
| can get 4,000 LEDs for $30.'
|
| Edit: here is the LED in question, from the BOM [1].
|
| [1]: https://jlcpcb.com/partdetail/C497920
| whartung wrote:
| I don't know, I struggle with a light switch, but that
| doesn't look like board someone took home with a box of parts
| and a soldering iron to make at home.
|
| Are there services that you can send the BOM and board files
| too, and not only do you get the PC board back, but it's
| populated? Will they do that for a onesy-twosy thing like
| this?
|
| Then all you have to do is supply the battery and download
| the firmware (however that is done).
| bkettle wrote:
| Yes, I've done it for a batch of 10 with
| https://jlcpcb.com/smt-assembly for around $10/board
| including the PCB
| nilamo wrote:
| >$10 per business card is extremely high, though.
| vFunct wrote:
| Not if you're at a trade show in an industry where a
| single deal can net millions of dollars, and a small
| booth might cost $15k just for the space for a few days.
|
| There's definitely an entire business available for
| expensive trade show merchandise, including electronic
| business cards. People routinely give away shirts and
| other merchandise that cost far more than $10..
| hypercube33 wrote:
| I half expected this to have a button/mode to show custom QR
| codes...
| mcdonje wrote:
| That's a good idea!
| nine_k wrote:
| Could as well display the name and/or email, if rotated just
| so.
| phirks wrote:
| I tried, that's why it's 21x21. Still haven't managed to get
| it to read.
| hturan wrote:
| I might be wrong, but you might need need (at least) a
| 23x23 LED matrix to have a white border around the outside
| to give it the contrast needed (the "quiet zone", since QR
| data is black).
| chamomeal wrote:
| Maybe you wouldn't give em to just anybody, but anybody who
| gets one is guaranteed to remember you!
|
| I'd probably even keep it in my desk to play with. After a few
| weeks I'd accidentally have this guy's email/linkedin memorized
| for eternity
| ChrisMarshallNY wrote:
| This is true.
|
| I remember a story linked from here, recently, where a
| designer submitted a CV that was a custom-made widget of some
| kind.
|
| He got the job.
| physix wrote:
| In the way back days when we submitted our CVs on paper, I
| always cut mine to a smaller size than letter, in a branded
| folder. People tend to stack things with the smaller items
| on top. I don't know if mine actually was on top of the
| stack, but I can say that I basically always got the
| contract.
| ASalazarMX wrote:
| I used to subtly watermark mine with nerdy silly
| diagrams, in the hopes that someone noticed the hints of
| color and gave them a second look. I even ran a plain vs
| watermark experiment, and the watermark had almost double
| the response.
|
| Another trick was adding a "Valid until <YEAR> in the
| cover". It seems counterintuitive that a CV expires, but
| it made a few companies approach me for an updated CV.
| xp84 wrote:
| I believe Sears famously used that same move (probably
| close to 100 years ago) to cause their catalogs to be
| stacked right on top of the Montgomery Ward one!
| xp84 wrote:
| I'm just imagining interviewing a candidate for a job
| involving embedded systems and this dude pulls this out at
| the end and says "If you have any other questions, my email's
| right on there."
|
| What an absolute baller this guy is.
| nine_k wrote:
| (This assumes that the guy passed through the resume
| filters and advanced to the in-person stage, which is not
| that easy. Should work on a video call though.)
| CubicalBatch wrote:
| Still has to respond "no" on the post interview scorecard
| because the given solution didn't use the optimal
| ObscureLeetCodeAlgorithm
| codeflo wrote:
| I mean, the candidate can design and build innovative
| custom hardware, but do they remember an obscure
| impractical algorithm from a second semester CS course?
| No? Obviously not a fit for this company.
| conductr wrote:
| I am thinking how most of the people I get business cards
| from are people I've already invited in to my office and are
| discussing some potential business relationship. They've
| often flown to my city, staying in a hotel, paying for
| transport, meals, etc. The impression they make during that 1
| hour meeting is paramount and I think this is certainly going
| to leave a lasting impression. Most of those business cards
| just get tossed into a drawer or trash bin, I bet people keep
| this one on their desk a play around with it.
| computomatic wrote:
| This matches my experience fairly accurately _except_ for
| the one guy I met at a housewarming who handed out cards to
| _everyone_. It was so weird - I haven't seen anyone do that
| in real life. He had a shop that repairs chipped
| windshields.
|
| And you know what? About 8 months later my windshield got
| sprayed by gravel. That guy got the business (he's a friend
| of a friend after all, and I had his number in my wallet).
|
| I'd say the issue isn't that cards are outdated. It's that
| people aren't using them correctly.
| NikolaNovak wrote:
| I had an ad on Facebook marketplace for a synthesizer.
| The guy who bought it gave me his business card - cloud
| architect for a competitor. He didn't give it to me
| because we were in similar field - we had a pleasant
| conversation over shareEd hobby and he gave it to me
| then, _after_ which I realized we were in same field, so
| clearly he gave them around a lot.
|
| If I consider changing jobs, or if I need those very
| particular services he's getting a call :-).
| conductr wrote:
| Definitely still a market for regular cheaper business
| cards for stuff like this. I regularly keep cards of
| people like this were I might need their service in the
| future, but they don't need to be fancy at all and I
| don't think it really adds much value when they are. The
| market for "good service" in trade type labor that I'd
| always hire a guy I have even a weak social connection
| with over some random person I found online. I feel like
| there's a higher chance of them not price gouging and
| caring about the workmanship.
|
| But, I don't think he'd be handing out $20 BOM cards that
| freely. I was more validating that there is still
| probably a market of people where $20 cards might make
| sense. As in the example I posed, a business card isn't
| providing any additional information. By the time I meet
| these people in my office, we've already exchanged emails
| and had some conversations on the phone and are
| acquainted. That's what led to the in-person meeting. I
| know their names and have them in my contacts.
|
| But, just as it felt like a social faux pas to receive a
| business card at a housewarming party, I think it also
| feels like a faux pas to meet someone in a business
| environment (where you are the selling party) and not
| give out a card during the initial first handshake
| interaction. This is a pretty low volume and high value
| moment for that person so a $20 card is no big deal and
| could easily make sense.
| ChrisMarshallNY wrote:
| I have what I call my "Victorian Calling Cards." I'm
| retired, and have no need to advertise or boast.
|
| They are fairly fancy moo.com cards, with my name, email,
| and cellphone. Nothing else.
|
| On the back, is a fancy "dragon head" logo (the one you
| see, if you look at most of my social media accounts). It's
| actually my old artist signature. It's over a burnt umber
| gradient.
|
| People like them, and use them.
| DonHopkins wrote:
| I'd include a sad tomagotchi that after a week or so guilt
| tripped you into giving it back, its heart broken, missing its
| original owner.
| bee_rider wrote:
| That's a funny way to try and get people to get back in touch
| with you, haha.
| CGMthrowaway wrote:
| Feed your animal by calling me once a month to check in
| (and get the monthly "food code")
| Aurornis wrote:
| > but probably a bit too expensive to just hand out.
|
| These are generally done as portfolio projects. It's driving a
| lot of traffic to the website.
|
| Producing a small number to hand out to potential freelance
| clients or job prospects is also common.
| eitally wrote:
| I wouldn't even necessarily give one to anybody. If you're
| looking for a job just point to this block post in your
| resume/site and that's equally impressive.
| akoboldfrying wrote:
| Or give out a regular paper business card with a QR code on
| it pointing to your resume website...
|
| _snicker_
| Tempest1981 wrote:
| Giving the actual card though leaves a feeling of guilt...
| sort of like those old surveys you would receive in the mail,
| with a $1 bill included. A hyperlink is forgettable.
| SkyMarshal wrote:
| Just put a QR code on the front that transmits a vCard. Or a
| way to make the LEDs on the back display a QR code. Then you
| can still show people your digital business card, even let them
| hold it and play with it, but it's still obvious the idea is
| for them to scan the QR code and hand it back.
| nosignono wrote:
| If you ask for it to be handed back, it's not a business card.
| It's a toy.
| saretup wrote:
| Exactly my thought. Just make it a desk toy.
| mytailorisrich wrote:
| You don't hand out business cards to everyone, only to those
| who deserve one.
| DonHopkins wrote:
| Instead of a business card, I'd love an ultrathin pleasure card
| you can refill with virtual beer and virtually drink! You could
| input your weight, and it could track you BAC!
|
| I made "PalmJoint", a beamable Palm pleasure card for CodeCon
| 2002, when everybody was beaming their contacts around by IR at
| conferences, I would beam an interactive doobie simulator a bunch
| of people could play together in a circle. Each person gets their
| own doobie, and you can have contests to see who can virtually
| smoke theirs the quickest, or keep it lit for the longest time. I
| never get around to implementing an IR token passing network:
|
| https://donhopkins.com/home/images/PalmJoint.png
|
| https://donhopkins.com/home/PalmJoint/Src/PalmJointMain.cpp
|
| Some conferences of the era had kiosks with IR LEDs that beamed
| out a Palm app with a conference map and schedule, which would
| have been great to hijack for beaming out PalmJoints instead.
| serf wrote:
| small ad-hoc networks like that with IR and early bluetooth
| were a lot of fun.
| DonHopkins wrote:
| For beaming a lit joint around, you would definitely need an
| acknowledgement that it was safely passed, lest it drop on
| the floor! But how would you prevent duplication if several
| people received the same joint? I'd just mark that bug
| "Intended Feature: Will Not Fix."
|
| The Bluetooth Bong was a vast improvement over the MIDI Bong.
|
| MIDI aftertouch on the carburetor was a nice improvement over
| your grandfather's old Serial Acoustic 300 Baud ASCII Bong,
| but the Bluetooth Bong HID has a much higher bandwidth,
| multitouch chording, accelerometer tilt tracking, modular
| monophonic splash resistant microphone, and they weren't as
| easy to accidentally knock over because they were wireless.
| An extremely important feature if you have cats around.
|
| But nothing beats a high-end spill-proof Roo 802.11be NVB
| (Network Video Bong) with fully submersible IPX8 smoke
| resistant stereo mics.
| Cthulhu_ wrote:
| I love it; I bought a secondhand Palm just before smartphones
| became a thing for cheap and had a lot of fun with it. I wonder
| if I still have it somewhere and whether it still works, I
| haven't seen it in ages though so probably not.
| catapart wrote:
| Ha! That's pretty cool.
|
| My first thought with this card was that it could be "gamified"
| into something that kids would probably love. A clique-y,
| social thing where kids could "pour" some of their fluid into
| another's card, with NFC or something. User preference colors
| that don't change when "poured" could help indicate how many
| different people have interacted with your card.
|
| But enough spitballing. There's no killer idea there. Just
| something I'll be amused to see show up as a value-add for some
| other kind of toy, or whatever.
| DonHopkins wrote:
| Liquid Pokemon Eggs and Sperm! Gotta catch it all!
|
| Then you can lay the fertilized eggs at any GPS coordinate to
| gestate and hatch later on.
|
| That could start a whole genre of AI (Artificial
| Insemination) Life Simulation games.
| fennecfoxy wrote:
| Until hackers get in and add Pokemon STDs >>
| DonHopkins wrote:
| Thus the Pokemon Plug-In STD SDK.
| fennecfoxy wrote:
| Stuff like that is dead now btw (yes, it makes me sad too).
| Kids have iPhones; the idea is great but can just be an app.
| Which tbf makes more sense because you get the benefit of imu
| & everything else for that behaviour.
|
| Remember those little LCD cube block toys with the stick
| dudes that lived in 'em, then when you plug 'em together they
| interact? Those were the days.
| DonHopkins wrote:
| The Movable Feast Machine (movablefeastmachine.org)
|
| 44 points by mekaj on Nov 20, 2015 | hide | past | favorite
| | 11 comments
|
| https://news.ycombinator.com/item?id=10600001
|
| The T2 Tile Project:
|
| https://www.youtube.com/channel/UC1M91QuLZfCzHjBMEKvIc-A
|
| Artificial Life Creation T-0 and Launching - T2sday Update
| 3135:
|
| https://www.youtube.com/watch?v=O8kOkLPwNNw
| postcert wrote:
| Those little cube world blocks were neat:
| https://corporate.mattel.com/brand-portfolio/cube-world
|
| Maybe I grew out of the age range or maybe the whole market
| of silly knick-knacks has died out but they definitely
| drove my interest in all things electronic.
| QuiCasseRien wrote:
| I love when people don't have to talk to explain how the hell
| they are expert in a domain.
|
| This is a very good example, nice work !
| 5- wrote:
| i absolutely love the form factor!
|
| a similar one was beamu (eink screen, nrf52 with bt):
| https://nicgardner.com/2020/05/09/beamu-first-impressions/
|
| (this was an actual product, if a bit pointless. i have one
| still)
|
| any others?
| TechDebtDevin wrote:
| Do you use any of the features? This is kinda cool, I love when
| people pack way too many features into a single product :P
| 5- wrote:
| didn't really buy it for the advertised features, although
| networked tic-tac-toe works fine. :-)
| abdullahkhalids wrote:
| This is so cool. I wish something like this had the ability to
| load your debit/credit cards into it. Advantages over using the
| card directly or a wallet app on your phone.
|
| 1. You don't voluntarily give your financial transaction info
| to big tech.
|
| 2. Your card details are hidden. So if your wallet gets stolen,
| less danger of fraudulent transactions.
|
| 3. Carry one heavy card instead of many light ones.
|
| 4. Don't have to memorize the pin of all the cards. Or the pin
| just shows on the mini screen after finger print
| authentication.
| OisinMoran wrote:
| If you like this, you'll also love Mitxela's fluid simulation
| pendant [0], and likely all of his work! I'm consistently
| astounded by how informative and enjoyable his stuff his. He
| shares so much, so freely and it's so well produced, with a
| lovely voice to boot. Inspirational! Watch his vids, read his
| write-ups or both! We need more people like this.
|
| [0] https://mitxela.com/projects/fluid-pendant
| unwind wrote:
| That was very clearly mentioned and linked in the article, too.
| OisinMoran wrote:
| Ahh, today it is my turn to fail the online reading
| comprehension test! My bad, I'm just very into Mitxela.
| elictronic wrote:
| Guessing he found it from the reddit post where he mentions
| it in lower parts of the comment chain but not in the actual
| post. The project itself does clearly mention it but I had
| the same reaction when I first read the post remembering the
| mitxela project clearly. https://www.reddit.com/r/embedded/co
| mments/1mkkd4z/my_busine...
| OisinMoran wrote:
| I actually found him originally from his incredible clock:
| https://mitxela.com/projects/precision_clock_mk_iv
|
| Which was posted here a while back:
| https://news.ycombinator.com/item?id=44144750
|
| I'm a sucker for a novel clock concept, and the level of
| detail he's operating at is beautiful to witness. I
| actually have a collection of cool clocks here:
| https://lynkmi.com/oisin/Clocks
| nirava wrote:
| +1 for mitxela, dude never ceases to amaze
| msephton wrote:
| The circle works much better for the fluid simulation.
| mananaysiempre wrote:
| And now I can't stop thinking about those circular LCDs and
| OLEDs they sell in China as (evidently if unofficially)
| devboards for not-overly-smart watches, thermostats and such.
| msephton wrote:
| I bought one recently and none of the provided code samples
| would compile. Zero support.
| wkat4242 wrote:
| Wow that's a nice design.
|
| PS1200 for one though.. oof.
| bookofjoe wrote:
| All 24 sold out very quickly, within hours.
| wkat4242 wrote:
| Nice one. 28800 pounds :O
|
| For most of us makers it's very hard to make money as our
| things sell for so little that it's like 3EUR per hour to
| make them. Kudos to this guy, he really does his marketing
| right.
| fidotron wrote:
| The typical Chinese sources have been selling "digital hourglass"
| type ornaments that work like this for a while.
|
| There was a whole game based on this sort of thing back on the
| Acorn Archimedes: Cataclysm
| https://www.youtube.com/watch?v=3Byyz1Vlv8w It got remade for the
| 360, but the original was regarded at the time as surprisingly
| impressive for the machines it was running on.
| DonHopkins wrote:
| Is there a Digital Disco Ball?
| fidotron wrote:
| You could make a bad analogue of such a thing using WLED -
| although as many people have observed it has a tendency of
| turning anything anywhere into looking like a vape shop.
|
| The problem is so much of the effect of a disco ball is
| irregular directional beams reflecting off it, which would be
| hard to do.
| bookofjoe wrote:
| https://www.amazon.com/LED-Disco-Ball-NuLights-
| Lighting/dp/B...
|
| https://www.youtube.com/shorts/E8rzln1gUBg
| DonHopkins wrote:
| Wow what a cool retro fluid simulation game!
|
| Oxygen Not Included simulates a whole bunch of different kinds
| of fluids and gasses, and has a sandbox mode and debug tools.
|
| I love using it as a kidpix-like painting tool, just to see how
| all the different materials interact.
|
| https://youtu.be/U0MevBWyfS8?t=295
| gcapu wrote:
| Amazing project, but the font on the back of the card is gross.
| Nevermark wrote:
| That's cred, man. Real cred.
|
| Wack font. Circuits exposed. Pixels with fat borders between
| them. An ugly charging port. But more stuff, packed into a
| small sleek volume than reasonably possible. Working perfectly.
|
| That's not Jobs. Oh, no. It's effing Woz.
|
| The guy is a true _hardware_ engineer.
| gcapu wrote:
| For the most part I agree, but the purpose of a business card
| is to be read. You can barely read that text.
| phirks wrote:
| The render is pretty gnarly, but it's not quite that bad in
| person
|
| https://github.com/Nicholas-L-Johnson/flip-
| card/blob/main/me...
| gcapu wrote:
| The card is so impressive that it doesn't matter much,
| but I think that if you remove half of the text in that
| card and make it very legible it would burn your name
| into people's brain.
| Nevermark wrote:
| The card should not have any text on it, but show his
| info on the screen when the card is first shaken, and
| after it has been held still for 4 seconds, before going
| to sleep after another 10 seconds of no motion.
| denysvitali wrote:
| It sort of reminds me of those research professors that have
| received multiple awards and their website is an unstyled
| HTML page with 4 links
| recipe19 wrote:
| Sort of, but if the objective is to get hired for a hardware
| design job, I think that even the font aside, the overall
| aesthetics of the PCB aren't great. There are several places
| where component text overlaps other markings, some components
| are slightly offset from others for no reason, the pattern of
| stitching vias is pretty chaotic... I think it's actually the
| software part of it that's most worthwhile.
| phkahler wrote:
| It would be cool to have a USB C connector that goes through the
| PCB so total height is that of the connector and not
| board+connector.
|
| Like this one:
|
| https://www.adafruit.com/product/5180?srsltid=AfmBOopEIapZEq...
|
| But with supports along the sides that could solder one the top
| and/or bottom of the PCB. You'd have a notch cut out for the
| connector.
| throawayonthe wrote:
| It is.
|
| rather it's even smaller, it simply has the inner part of a usb
| c connector - exactly the thickness of the pcb
|
| similar to https://github.com/cnlohr/ch32v003_3digit_lcd_usb/
| ciaranmca wrote:
| Thought the same but from what I can see those are somewhat
| uncommon, presumably you are unable to affix them to the board
| as securely as the typical connectors
| echelon_musk wrote:
| The images in the GitHub show that the card has this.
| cameron_b wrote:
| In the implementation, the design uses a 'card edge' type
| connector with the whole PCB fitting into the constraint of the
| thickness of the center blade of the USB-C connector. So when
| charging, the board slots into the cable-end connector, and
| when not charging there is only the PCB. The PCB has cut-outs
| for the cable-end connector to fit into the PCB -- so like
| you're saying, but even thinner.
| throawayonthe wrote:
| that's awesome, but i think since it's a business card the text
| on the back should be more legible (nicer font and/or bigger)
| stusmall wrote:
| Agreed. I'd never hire this embedded system engineer to do
| graphic design. /s
| kuschkufan wrote:
| Impressive, very nice. Let's see Paul Allen's card!
| mrcwinn wrote:
| This beats the Bateman card. Excellent work!
| latexr wrote:
| But does it beat the Joel Bauer business card? It took 25 years
| to design!
|
| https://youtube.com/watch?v=4YBxeDN4tbk
| donohoe wrote:
| If they used a sans-serif font then they would have nailed it
| bschwindHN wrote:
| That and the overlapping silkscreen hurt to see, but otherwise
| a super cool project. Although they're very minor things that
| don't technically matter, it can give off certain impressions
| to people.
| queuebert wrote:
| Not nearly as tasteful as Paul Allen's card.
| xp84 wrote:
| disagree, a nice serif font is more distinctive with most of
| everything using a very tight cluster of boring sans-serif
| fonts.
| donohoe wrote:
| In that case I will add that this particular serif font was
| also a poor choice out of the variety of serif fonts out
| there.
| tiagod wrote:
| I sort of like it. Looks like a Neon Genesis Evangelion episode
| card
| NoSalt wrote:
| We getting our stories from Reddit now?
| augergine wrote:
| You're going to get downvoted obviously but this appeared on
| Embedded (or electronics?) and then made its way here. It's a
| bit telling the actual hacking communities are on "that awful
| site" that's so beneath us, meanwhile our pristine HN is full
| of gushing AI ads as front page hacker material.
| NoSalt wrote:
| I only mention this because this was posted here at,
| approximately, 08:00 EST 2028-08-08, and posted on Reddit at,
| approximately, 00:00 EST 2028-08-08.
| augergine wrote:
| They'd rather post there than here. https://www.reddit.com/
| r/embedded/comments/1mkkd4z/my_busine...
| uticus wrote:
| No issues mentioned with battery being exposed on both terminals?
| Seems like easy short hazard.
| MobiusHorizons wrote:
| Is a cr2032 shorting it is not dangerous, it can't supply the
| current to get hot enough do any real damage.
| uticus wrote:
| It says rechargeable, maybe a CR2032 size but prob lithium
| chemistry. Even a small size could create quite a hazard if
| shorted.
| AnotherGoodName wrote:
| The C in CR2032 means lithium fwiw. As in it's lithium
| either way.
|
| The LiR2032 (rechargable lithium) are slightly higher
| voltages but pretty much the same total energy.
|
| Fwiw if you ever have electronics that require 3V minimums
| the LiR2023 is better than the CR2032 since it's 3.7V vs 3V
| in the same form factor. It's common knowledge that the
| ESP32 for example can glitch on a CR2023 since it needs 3V
| minimum but it'll actually run fine on a LiR2032.
| MobiusHorizons wrote:
| Yep, the rechargeables of this form factor are also pretty
| safe. They just don't have much current capacity, as they
| are meant for long life (years) and long current draw.
| bookofjoe wrote:
| State of the art in 2009:
|
| https://www.tokyoartsandspace.jp/en/creator/index/B/124.html
| moechofe wrote:
| This will finish in the trash at some point like any other
| business card, but, good job.
| Kapura wrote:
| point of order: these are thicker than normal business cards.
| snickerdoodle12 wrote:
| [flagged]
| FinnKuhn wrote:
| To be fair it fits in with the Github and LinkedIn links.
| denysvitali wrote:
| He's an hardware engineer, not a software engineer.
|
| After many years of self-hosting an email server I also came to
| the realization that it's not worth the hassle (in terms of
| maintenance / problems) and I switched to Proton Mail.
|
| Using a custom domain with Proton Mail is not free (and all the
| other alternatives I know of are the same) and there's little
| advantage other than having a nice name. I think for a HW
| Engineer this is good enough.
| snickerdoodle12 wrote:
| I wouldn't recommend self-hosting email to anyone, but the
| expense of paying Proton Mail is absolutely worth the peace
| of mind (you are in control of your email & can effortlessly
| switch email providers) and professional appearance.
|
| We're talking about someone handing out $17/ea business cards
| here.
| cvsv wrote:
| I was expecting a regular business card where the paper was so
| thin it flowed like fluid.
| wkat4242 wrote:
| > One of the more difficult features was the rechargable battery.
|
| Flat ones do exist. I have one eink TOTP card that's no thicker
| than a normal credit card.
|
| And also an airtag style tracker that's about twice as thick.
| Maybe it uses the same kind of battery.
| bookofjoe wrote:
| O.4mm thick rechargeable battery:
|
| https://www.lithium-polymer-battery.net/ultra-thin-lithium-p...
|
| Standard credit card: 0.76mm thick
| uticus wrote:
| seems dangerous to have terminals of battery exposed, shorting
| (and with rechargeable, burning) hazard
| spacedcowboy wrote:
| Some conformal coating spray would probably be all that's
| needed.
| physicsguy wrote:
| I like this one: https://michaeldriver.co.uk/The-Business-car-d-1
| nabilt wrote:
| For those that want more details on how the software works, this
| guy goes into a bit more detail for his version
|
| Fluid simulation pendant https://mitxela.com/projects/fluid-
| pendant
|
| https://www.youtube.com/watch?v=jis1MC5Tm8k
| dmitrygr wrote:
| One note for the readers here: an electronic business card has a
| _VERY LARGE_ effect on those you give it to. More than I expected
| when I made mine. It is surprisingly effective. Even if the BOM
| is $30, it 'll pay for itself in the ease it adds to a job hunt
| easily
| msarnoff wrote:
| Surprise no one's mentioned yet that the firmware is written in
| Rust. As someone who's struggled with getting started with
| embedded Rust (the landscape seems to be changing quite a lot?)
| it looks like a good example.
|
| Also it's a bit startling to see floating-point code used so
| freely. Shows how rapidly the capabilities of MCUs have
| developed. 15 years ago, doing floating point on a
| microcontroller would be unspeakable /s
| Jweb_Guru wrote:
| Yeah embassy has improved tons recently. This is because
| embedded Rust is receiving a lot of investment from industry,
| embedded engineers desperately want a real C alternative there.
| bookofjoe wrote:
| Interview with the
| maker:https://usesthis.com/interviews/tim.jacobs/
| phirks wrote:
| That's actually not the same guy. He made the pendant that this
| project is based on.
| bookofjoe wrote:
| My bad: "That's actually not the same guy. He made the pendant
| that this project is based on."
|
| THANK YOU phirks for the correction. Much appreciated.
| SequoiaHope wrote:
| Beautiful design! I want to say as a maybe helpful review point
| that I see overlapping silk in a few spots. Ideally it would be
| nice to clean that up, possibly removing all designators which
| for my personal preference would work, but some people might like
| to see those. Also I would choose a more playful font for the
| back text but I like playful. This is an excellent project,
| nicely done! I'm doing a lot of RP2350 LED work right now, I'll
| have to see if I can run your code on the pendant I am designing.
| W3zzy wrote:
| It's not white, it's bone.
| thrance wrote:
| Now, let's see Paul Allen's ultrathin business card that runs a
| fluid simulation.
| _Microft wrote:
| If you are curious what PCB designs or schematics look like, you
| can use an online viewer for KiCad files to find out yourself:
|
| https://kicanvas.org/?github=https%3A%2F%2Fgithub.com%2FNich...
|
| @creator of the card (phirks?): have you considered further
| interactivity or maybe using the LED matrix for showing text or
| other information?
|
| You could use touch buttons for control as they basically add
| nothing to the BOM?
|
| Edit: this is of course really awesome as it is
| phirks wrote:
| I was thinking of throwing in a game like Tetris with just
| accelerometer controls. That'll be after I find a job though.
| Numbers were actually the first things I displayed, I actually
| still have all the code to display them still sitting unused.
|
| Text has been less of a success. Having the letters be easily
| legible takes more space than I would have thought, and the
| small pixel fonts don't look great with the big spacing between
| the LEDs. Maybe some scrolling text would look good, but I
| haven't focused on it too much. I tried getting a QR code
| displayed, but it didn't want to scan.
|
| For buttons, I'm kind of married to the idea of no buttons. The
| accelerometer does recognize clicks and double clicks in
| different directions, so that might be useful for something.
|
| I encourage anyone who wants to fork/contribute/post issues on
| this to do so and I'll try to be a good maintainer.
| _Microft wrote:
| Thanks for the detailed reply. I actually like the idea of
| using the accelerometer as input device and the design choice
| of using no buttons.
|
| What's the update rate of the LED matrix if I may ask? Maybe
| the combination of an accelerometer and the LEDs lends itself
| to a persistence of vision display?
| echelon wrote:
| > That'll be after I find a job though.
|
| I can't imagine you'll be on the job market for long (and I
| certainly hope not).
|
| This is such an amazing looking for work ad, I'd imagine
| you'll get snapped right up.
|
| Major kudos on this. It's amazing!
| delichon wrote:
| Advantages of a business card sized hollow box partially filled
| with water: * more realistic fluid motion *
| cheaper, easier build * easier to debug
|
| Disadvantages: * risk of wet butt when you sit
| down * less joy of doing hard things
| kazinator wrote:
| Disadvantages: * excessively fast fluid motion
| at card scale
| N2yhWNXQN3k9 wrote:
| increase viscosity of said fluid
| kazinator wrote:
| It doesn't work that way, unfortunately. The virtual fluid
| represented by the LEDs does not move anything like syrup.
| It's like looking at a small image of water sloshing in a
| big tank.
|
| To get of fluid to behave that way on the scale of several
| inches, the fluid would have to be massive (very dense)
| while simultaneously gravity would have to be reduced.
| bullox wrote:
| > the fluid would have to be massive (very dense) while
| simultaneously gravity would have to be reduced.
|
| /joy of doing hard things intensifies
| wedesoft wrote:
| You can use two different fluids instead of water and
| air.
| jrowen wrote:
| * less joy of doing hard things
|
| Have you tried to fabricate such a box? I wouldn't be so sure.
| bravesoul2 wrote:
| * no rust
| chr15m wrote:
| Unless the case is iron.
| animal531 wrote:
| I love good finger toys at my desk to keep my ADD busy while
| I'm working. They need to be:
|
| - Light: If they make a clanking noise every 5 seconds when you
| pick them up and put them down its just distracting.
|
| - Plastic: There are other materials that work, but in general
| metals and fabrics react too strongly with your fingers over
| time, whereas plastic can be easily cleaned.
|
| Having a little water window isn't a problem, but the water is
| also not as directly cool looking. Usually in the '90s you'd
| get those mixed color oil/water toys where the colors would
| make them stand out more, but shaking them would mix the
| substances causing them to lose function.
|
| As such the electronic version is quite durable in comparison.
| mhb wrote:
| Starting point: Ocean waves in a bottle
|
| https://www.youtube.com/watch?v=W4jbx5WLhy4
| pfortuny wrote:
| It also solves a fluid mechanics problem much faster and more
| accurately than de digital one!
| wvlia5 wrote:
| they should've added this card in that American Psycho scene
| modeless wrote:
| > board edge usb-c port
|
| This is awesome. I bet we see a lot of these in the future once
| people realize it's possible to have a USB-C port on your board
| with no extra parts and zero soldering.
| lbourdages wrote:
| That must be very fragile! Gotta be careful when unplugging,
| pulling very straight.
| noveltyaccount wrote:
| I thought this was one of the most impressive parts of the
| design, had no idea this was possible.
| phirks wrote:
| >Amazing project, but the font on the back of the card is gross.
|
| >It sort of reminds me of those research professors that have
| received multiple awards and their website is an unstyled HTML
| page with 4 links
|
| >If they used a sans-serif font then they would have nailed it
|
| >this particular serif font was also a poor choice out of the
| variety of serif fonts out there
|
| >that's awesome, but i think since it's a business card the text
| on the back should be more legible (nicer font and/or bigger)
|
| Ok, for real though, can someone just tell me what font to use?
| We can all see this isn't my strong suit and now you're in my
| head.
| Inityx wrote:
| My defaults are sans-serif Helvetica or Roboto, serif Roboto
| Serif, and monospace Fira Code
| N2yhWNXQN3k9 wrote:
| _swoons_
| wavemode wrote:
| You should see the font on Paul Allen's card.
| strogonoff wrote:
| A few business card typography tips off the top of my head:
|
| -- White on black (inverse) is less legible, so all else equal
| compared with black on white the font should be bolder and/or
| bigger for equivalent readability. (Using caps or small caps is
| also OK in display text like titles, if it reads easier.)
|
| -- Legibility is also impaired by visual noise around the text
| (it's not a single color but there is some pattern, for
| example). Compensate for that, too.
|
| -- Unless you really know what you are doing, stick to one
| font. You can use bolder/lighter variants of the same font.
|
| -- Never compress fonts vertically or horizontally. Instead,
| pick a different font. Many fonts have condensed/compressed
| alternatives, or there is also Impact if you want it.
|
| -- Use white space. Padding lets it breathe.
|
| -- Use typographic features. Em dashes (separate them by thin
| spaces), bullets.
|
| > Embedded Design Hardware [?] Firmware
|
| or
|
| > Embedded Design -- Hardware, Firmware
|
| vs.
|
| > Embedded Design - Hardware/Firmware
|
| That said, everything except the first two is subjective. A
| relaxed vibe of "don't give a damn about it" might be strategic
| if you are good at what you do (and crucially it is not
| design), as long as your card is legible and does its function.
| phirks wrote:
| Is this any better? I hid the vias
|
| https://github.com/Nicholas-L-Johnson/flip-
| card/blob/main/me...
|
| https://github.com/Nicholas-L-Johnson/flip-
| card/blob/main/me...
| strogonoff wrote:
| I personally think it is better and I like it a lot more.
| On the other side the concise "Shake Me" is fun, and
| "Powered by Rust" makes sense there. Curious how would it
| look when in physical form...
| phirks wrote:
| Thanks for all the help. I'll be ordering this soon and
| I'll be sure to post it.
| thrown-0825 wrote:
| Awesome project, but why is this considered "ultrathin"?
|
| I would think a business card that is as thick as a usbc port +
| pcb would be considered pretty thick.
| cortesoft wrote:
| It's not as thick as a usbc port, look at the picture of them
| charging... the usb plug is much thicker than the card.
| thrown-0825 wrote:
| ah I see, its still several times thicker than a business
| card though.
|
| so is it ultrathin relative to a phone?
| pornel wrote:
| The simple box-shaped container and low framerate/low gravity
| simulation doesn't show off what the FLIP algorithm can do.
|
| The algorithm is a more expensive combination of two simulation
| methods to support both splashes and incompressibility, but the
| benefits are barely visible in the simple container.
| m00dy wrote:
| lol, if you look at the firmware, it is essentially a bunch of
| if-else statements, rather than very complex simulation code.
| 404human wrote:
| Cool toy or business card? Either way, it's unforgettable.
| mightysashiman wrote:
| Any way to buy one maybe?
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