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a community for 18 yearsMODERATORSmessage the modsdiscussions in r/electronics<>X1 Weekly discussion, complaint, and rant thread126 · 22 comments This is how I organize my breadboard projectsFirst Project!299 · 25 comments My custom 3 byte SRAM on a breadboard14 · 1 comment heres my 4 bit calculator progress183 · 43 comments Lightning hit close by and fried the chip.561 · 27 comments DIY Raspberry Pi Oscilloscope115 · 6 comments Soviet PSO2-08 dekatron decimal counter90 · 33 comments Warning about ordering directly from FNIRSI.166 · 34 comments digikey packagingWelcome to Reddit,the front page of the internet.Become a Redditorand join one of thousands of communities.×153115321533GalleryI built a fully self-powered computer in actual credit-card size (~1mm thick) (old.reddit.com)submitted 9 days ago by krauseler120 commentssharesavehidereportPreviousNextBack to Grid ViewPreviousNextBack to Grid ViewPreviousNextBack to Grid ViewFor years, devices like the RbPi have been described as “credit-card sized”.
And of course the message is rather the footprint, but at some point I became obsessed with taking that idea one step further:
What would it take to build something that is literally sized like a credit card?
I've got a slight feeling that you really don't seem to like questions here, but I hope this rhetorical one is okay :P
That question slowly escalated into months of experiments to find solutions for things where default methods won't work. I can't use large, rigid components, connectors, and find a way to make my own custom flexPCB.
And after months of tinkering, I made the first prototype. Fragile, but it works within the goal of not exceeding 1 millimeter. Somehow, news pages have picked this up and described it as "revolutionary" which is a bit far fetched, but I feel flattered 🤭
To be fair, 'computer' might be a little overstatement, but it's technically perfectly within the definition of one. If you should have suitable words for it that sounds cool, feel free to suggest ^^
The prototype includes:

ESP32-C3FH4 w/ WiFi & BLE
NFC read/write
1.54" 200*200 E-Paper display
ultra-thin LiPo battery including charging circuit and power path management
accelerometer

Finding small/thin enough components wasn't really the main challenge, mechanical stability was. Solder and general material fatigue, pressure distribution (particularly focused pressure) and other strain related issues were the real problem.
This doesn't even include battery protection and some other things to solve.
At this scale, the project turned into a weird mix of electrical, mechanical and chemical engineering.
A few things that became clear over time:

preventing strain is much easier than surviving strain
tiny real-world tolerances start dominating the entire design near the physical limit
many “thin enough” components stop being thin enough once assembly is considered
FPC connectors are basically obsolete, forcing me to get creative and solder each single wire for each 0.5mm pitch pad one by one.

The prototype is fully self-powered and running from its internal battery.
I documented a large part of the engineering process, including the process of etching my own flexPCB, on my GitHub repo.
And yes, it's not like this thickness is a necessity, going just 0.5mm thicker would probably have saved me months of engineering. This entire project was probably motivated way too much by the 'disbelief' factor 😄
I am curious on your thoughts on this! :)

all 120 commentssorted by: besttopnewcontroversialoldrandomq&alive (beta)Want to add to the discussion?Post a comment!Create an account[–]the_rodent_incident 40 points41 points42 points 9 days ago (2 children)You know what would be an absolute banger?
The card which is a little bit thicker (2-3mm), but it has e-ink displays over it's whole surface.
It can not only be used for payments but as a high-security reusable ID card.

permalinkembedsavereportreplyload more comments (2 replies)[–]1Davide 92 points93 points94 points 9 days ago (16 children)Does it have any input/output? Or is it just a programmable display?

The prototype is fully self-powered

I don't think it's self-powered. It's powered until the battery is discharged.
To be self-powered, it would require a solar panel or extract power from the environment (vibration, RF energy in the air).

permalinkembedsavereportreplyload more comments (16 replies)[–]sceadwian 8 points9 points10 points 9 days ago (2 children)The batteries the weakest part, it makes this pretty dangerous to leave kicking around. There's no real way to fix that though without going to a double thick card at least and that's just ruins the charm of this.

permalinkembedsavereportreplyload more comments (2 replies)More commentsMore from r/electronics  Hide558559560GalleryDIY Raspberry Pi Oscilloscope (old.reddit.com)submitted 3 days ago by hapemask27 commentssharesavehidereportloading...296297298GalleryMy custom 3 byte SRAM on a breadboard (i.redd.it)submitted 1 day ago by KrisMakesRandomStuff25 commentssharesavehidereportloading...186187188GalleryLightning hit close by and fried the chip. (old.reddit.com)submitted 2 days ago by hremmingar43 commentssharesavehidereportloading...162163164Generaldigikey packaging (i.redd.it)submitted 4 days ago by Useful_Major856334 commentssharesavehidereportloading...126127128GalleryThis is how I organize my breadboard projects (old.reddit.com)submitted 11 hours ago by Big-Rent690522 commentssharesavehidereportloading...113114115GallerySoviet PSO2-08 dekatron decimal counter (old.reddit.com)submitted 3 days ago by AltCtrlGraphene6 commentssharesavehidereportloading...899091GeneralWarning about ordering directly from FNIRSI. (i.redd.it)submitted 4 days ago by AdministrativeElk62833 commentssharesavehidereportloading...131415Galleryheres my 4 bit calculator progress (youtu.be)submitted 1 day ago by Maestro_gaylover1 commentsharesavehidereportloading...012Weekly discussion, complaint, and rant thread (self.electronics)submitted 8 hours ago by AutoModerator - announcementcommentsharesavehidereportloading...Comments, continued...[–]Cheap_Protection_359 12 points13 points14 points 9 days ago (15 children)That's so cool. What you planning to use them for?

permalinkembedsavereportreply[–]HalcyonKnights 15 points16 points17 points 9 days ago (6 children)I recommend trade show swag, there are tons of companies that would love to give these out with an ad real on them.

permalinkembedsaveparentreportreply[–]krauseler[S] 14 points15 points16 points 9 days ago (5 children)I think the hardware would be way to expensive for an ad-gift. But the idea is cool, I'd imagine premium companies with high value customers would like to use this, or some kind of memberships that come with a customized animation-like graphic 😄
That's interesting for sure!

permalinkembedsaveparentreportreply[–]HalcyonKnights 6 points7 points8 points 9 days ago (4 children)You'd be surprised (or at least I was).  I've seen some shockingly complex things being given away.  It just depends on the shows industry.

permalinkembedsaveparentreportreply[–]otakunopodcast 6 points7 points8 points 9 days ago (1 child)Also, manufacturing can be optimized, etc. so that making a thing cheaply and at scale is financially feasible. Things like USB flash drives, power banks, etc. were probably expensive back in their early days, but now even these are given out routinely as trade show swag.

permalinkembedsaveparentreportreply[–]krauseler[S] 2 points3 points4 points 9 days ago (0 children)That's a very good point and actually even today not far off.
It wouldn't be something for this type of version, but if it would be built with a cheap MCU, no wifi, primary cell/coin cell, maybe electrochromic segment displays, it might only cost a few bucks to make.

permalinkembedsaveparentreportreply[–]krauseler[S] 1 point2 points3 points 9 days ago (1 child)Guess it depends on the target group. Like conversion rate + CLV and so on. If I'd run a company, I wouldn't spend that kind of money if I have a 5% chance of earning back the money spent. But of course it also has to do with branding I guess.

permalinkembedsaveparentreportreply[–]HalcyonKnights 2 points3 points4 points 9 days ago (0 children)Yeah, the last trade show I attended was for Big Pharma, so their profit margins are pretty safe. It definitely would not be for businesses without a massive corporate ad budget

permalinkembedsaveparentreportreply[–]krauseler[S] 1 point2 points3 points 9 days ago (7 children)Thanks! 😄
Honestly, the use case as physical wallet is a bit boring - I'd be more interested in out of the box use cases. Pentesting, smarthome, maybe 2FA OTP generator and so on would be so cool for this

permalinkembedsaveparentreportreply[–]orbit99za 2 points3 points4 points 9 days ago (6 children)F2a would be a great IDEA

permalinkembedsaveparentreportreply[–]krauseler[S] 1 point2 points3 points 9 days ago (4 children)It would need a practical way to transfer the OTP code though, no way I'm typing it there haha
The logical way would be some kind of smartphone NFC or bluetooth transfer, but that would need a bit more care to ensure security and might be a lot more effort to develop

permalinkembedsaveparentreportreply[–]stalagtits 5 points6 points7 points 9 days ago (1 child)Optical transmission using a photodiode might work. Data could be sent from a smartphone or computer display by placing the sensor on the screen and flashing a box of pixels to transfer the data.
If you kept the box smaller than the size of the credit card computer, there would be no real risk of eavesdropping.

permalinkembedsaveparentreportreply[–]krauseler[S] 1 point2 points3 points 8 days ago (0 children)That's a sick idea, I like it!
Very minimalistic, but if the final config is going to have NFC terminal, it might be obsolete.

permalinkembedsaveparentreportreply[–]Botlawson 1 point2 points3 points 8 days ago (0 children)Display a QR code?

permalinkembedsaveparentreportreply[–]aramiks 0 points1 point2 points 7 days ago (0 children)Since you are already using ESP32C3 why not use BLE or SoftAP to connect over wifi and transfer the secret?

permalinkembedsaveparentreportreply[–]john_ftq 0 points1 point2 points 8 days ago (0 children)Well, there are lots of them, working on cr2032 practically forever. Banks provide them. Getting obsolete with usage of a bank app for 2fa

permalinkembedsaveparentreportreply[–]Mawoka 5 points6 points7 points 9 days ago (1 child)This is really awesome! Especially the solder job on the e-paper and the fact you've made the flex PCB yourself, as if just designing this thing wasn't hard enough!

permalinkembedsavereportreply[–]krauseler[S] 5 points6 points7 points 9 days ago (0 children)Thank you! 🙏🏻
It's not like a normal flexPCB wouldn't have done the job, it would have been so much better. But I really hate the cycle of waiting for the fab, shipping, dealing with customs, just to find out it's not working.
I think it was just the factor of exploring the technique, which was a really cool experience!

permalinkembedsaveparentreportreply[–]DiceThaKilla 2 points3 points4 points 9 days ago (3 children)All these questions and nobody’s asked the important one: can it play doom?

permalinkembedsavereportreply[–]krauseler[S] 2 points3 points4 points 8 days ago (2 children)I should really start to count, this is getting hilarious. On all the discussions and chats about this project, the good old doom question is being asked at least the 10th time or so 😂
And yes, it theoretically can run DOOM, but only if you're willing to enjoy the buttery smooth 0.7-ish FPS.

permalinkembedsaveparentreportreply[–]MarinatedTechnician 0 points1 point2 points 8 days ago (0 children)You KNOW you have to run "Bad Apple" on it now, right?

permalinkembedsaveparentreportreply[–]stuih404 2 points3 points4 points 9 days ago (2 children)Here we meet again

permalinkembedsavereportreply[–]krauseler[S] 2 points3 points4 points 9 days ago (1 child)Hello sir, do you want to exchange business cards? What a coincidence that I've got my one at hand, it talks to you 😛

permalinkembedsaveparentreportreply[–]stuih404 0 points1 point2 points 9 days ago (0 children)Did you already think about how you wanna do the wireless charging coil?

permalinkembedsaveparentreportreply[–]Aggressive-Bike7539 2 points3 points4 points 9 days ago (1 child)This is so cool. This could drive the display in cereal boxes from Minority Report https://www.youtube.com/watch?v=7ESr3cph8mA

permalinkembedsavereportreply[–]krauseler[S] 0 points1 point2 points 9 days ago (0 children)Thanks!
That's funny. I mean, what's high tech today might be cheap in the future. If you told somebody in the early 2000s that we started to replace barcodes with little circuits aka NFC chips, that would have been unbelievable.

permalinkembedsaveparentreportreply[–]ImaginationToForm2 2 points3 points4 points 9 days ago* (0 children)Wow that's pretty cool. I've made an ARGB matrix in KICAD and had it made by JLCPCB but I don't know enough for your board yet. I've been learning to know what I need for a USB-C Port and a ESP32. I still want to learn about charging circuit. To power one project I want to use 2 sets of 2 18850 batteries in parallel.

permalinkembedsavereportreply[–]bmaa_77 2 points3 points4 points 9 days ago (1 child)Make sure if goes (when!) to mass manufacture, to be sturdy enough so won’t be another ewaste plague . Great work!

permalinkembedsavereportreply[–]krauseler[S] 2 points3 points4 points 8 days ago (0 children)Thank you so much!
I hope so. I mean you could argue that this is the very point of this card, replacing boarding passes, membership cards and all that stuff.
If it lasts for weeks or months with one charge, the battery will likely survive decades of usage. So if humanity still uses QR codes and NFC then, you're future-proof with this lol

permalinkembedsaveparentreportreply[–]Isometric-Toadstone 2 points3 points4 points 9 days ago (1 child)make a credit card sized keyboard to go with it next :P

permalinkembedsavereportreply[–]krauseler[S] 0 points1 point2 points 8 days ago (0 children)That'd probably be even easier than this one lol

permalinkembedsaveparentreportreply[–]deskpro256 2 points3 points4 points 9 days ago (2 children)Hey, great work, once again! I saw on a comment you are thinking about a new or different batteries, I just remembered an old GreatScott! video about LCBs Lithium Ceramic Batteries. Might as well take a look, they can bent, be punctured, be cut off with scissors and "should" be safe. Love to see a similar idea come to reality.

permalinkembedsavereportreply[–]krauseler[S] 3 points4 points5 points 8 days ago (1 child)This comment literally brought me back into the rabbit hole of FLCBs. And I can right away say: These would literally be the ideal batteries in virtually all aspects. They are thin, flexible, safe, you can even puncture and cut them and they will not only not explode, but even still work, which is crazy.
It unfortunately looks like these batteries either never got to mass market or disappeared, perhaps due to lacking demand.
You can be sure if I ever get the chance to have them, this would be my 1st choice by a big margin.

permalinkembedsaveparentreportreply[–]deskpro256 1 point2 points3 points 8 days ago (0 children)Yea, I tried looking for a second and couldn't see anything about those in their page. My tinfoil hat says it was too good and got 'cancelled' :D

permalinkembedsaveparentreportreply[–]Holkr 2 points3 points4 points 8 days ago (1 child)This is wicked cool

permalinkembedsavereportreply[–]krauseler[S] 0 points1 point2 points 8 days ago (0 children)😎

permalinkembedsaveparentreportreply[–]DelilahsDarkThoughts 2 points3 points4 points 8 days ago (3 children)I would be very careful with that lipo pouch. Those little guys can be very sensitive to heat and wear, I would surround that with a thin metal casing. Not a lot, but enough to disperse a dendrite eruption or a puncture.

permalinkembedsavereportreply[–]Sad-Impression-407 1 point2 points3 points 6 days ago (0 children)Agree, a small sacrifice would make a great improvement on safety.

permalinkembedsaveparentreportreply[–]krauseler[S] 1 point2 points3 points 5 days ago (1 child)Metal sheet proteection is already in the works, more info on the Git repo 😄

permalinkembedsaveparentreportreply[–]DelilahsDarkThoughts 0 points1 point2 points 5 days ago (0 children)oh, good.

permalinkembedsaveparentreportreply[–]tupikp 2 points3 points4 points 8 days ago (1 child)Can it run Doom?

permalinkembedsavereportreply[–]krauseler[S] 0 points1 point2 points 5 days ago (0 children)It may.

permalinkembedsaveparentreportreply[–]KaptainKugelkopf 2 points3 points4 points 8 days ago (1 child)
 I feel flattered 🤭  

flattened*

permalinkembedsavereportreply[–]krauseler[S] 0 points1 point2 points 8 days ago (0 children)That too.

permalinkembedsaveparentreportreply[–]r3drocket 2 points3 points4 points 8 days ago (2 children)That is pretty cool!
I fantasized about a small credit card GPS powered global map in a form factor like this. The idea is you have solar power a small microcontroller that could load map tiles from flash storage and show you were you are.
The goal is to mitigate the risk of a phone battery dying, and leaving you without knowing where you are.
Anyways this is cool!

permalinkembedsavereportreply[–]Odd_Independent8521 0 points1 point2 points 7 days ago (1 child)We can build it if you want us to do?

permalinkembedsaveparentreportreply[–]krauseler[S] 0 points1 point2 points 5 days ago (0 children)It would be possible, but I don't think this is an ideal form factor for something as power hungry as GPS

permalinkembedsaveparentreportreply[–]gokkor 2 points3 points4 points 5 days ago (2 children)Hmm, if you can find a way to add a finger print sensor then this could be a very good platform for FIDO key + 2FA + offline password manager + crypto wallet that you can always carry with you. I'd pay for that.

permalinkembedsavereportreply[–]krauseler[S] 1 point2 points3 points 5 days ago (1 child)A capacitive fingerprint sensor is indeed very possible. But I am not sure I want to go down that liability route. There are always disclaimers, but I feel like you can be sued even if it's not really your own fault if any breach happens...
I may consider it, but not sure if I'd present it as secure, even if it would be.

permalinkembedsaveparentreportreply[–]gokkor 0 points1 point2 points 5 days ago (0 children)I think you could just provide the hardware and let the open source world do it's magic. Regardless of finger print sensor, this is a cool gadget to have in your wallet and I'd like to get one for myself :) My eye sight is not what it used to be so I'll not start soldering stuff that small myself :) You did a great job with soldering the screen by the way!

permalinkembedsaveparentreportreply[–]defineReset 1 point2 points3 points 9 days ago (1 child)Very nice. What is the battery capacity?

permalinkembedsavereportreply[–]krauseler[S] 0 points1 point2 points 8 days ago (0 children)On this particular prototype, it's 30mAh. I intentionally used a smaller one to have more space for debugging. The final unit will likely have either 58mAh or 70mAh. With the right firmware, it could last months without charging.

permalinkembedsaveparentreportreply[–]GoldenDvck 1 point2 points3 points 9 days ago (1 child)hey there, considering how many ‘fits in your wallet’ type products that can be made from this, have you tested how it holds up in wallets (sometimes people sit on their wallets in their back pocket), sometimes wallets are packed tight with cards. Also would putting in a vibration motor be possible? or any kind of vibrating mems, maybe a larger battery?

permalinkembedsavereportreply[–]krauseler[S] 0 points1 point2 points 8 days ago (0 children)Interesting questions, let me address them one by one:
- I am currently actually working with the proper prototype, this one is the first "ugly" prototype, which is so fragile that it might break if you look at it the wrong way. Home etched PCB isn't a joke lol. Anyways, this is the major challenge, not fitting components. The display and battery are both designed to tolerate a reasonable amount of bending. But it is important to note that tolerating does not mean you should bend it. For the flexPCB, the strategy is clearly to avoid mechanical stress instead of trying to withstand it, which is practically just not realistic. Structural weak points and "islands" around larger ICs make sure solder joints don't experience any bending force in the first place.
- Actually, haptic feedback is technically possible. An actual motor is basically impossible, but a custom linear actuator can theoretically fit in. The problem is rather the axis. The mass would move along the width or length, but not along the height, which would have likely been the most relevant one if you imagine it laying on a table or being flush in your pocket. A side to side vibration won't really reach the correct axis.
- A larger battery is planned anyways. I used a smaller 30mAh battery for this prototype so I have more space for debugging. The final Muxcard will likely have 58mAh or 70mAh, depending on which model I will be able to fit into the final design.

permalinkembedsaveparentreportreply[–]Thin-Bobcat-4738 1 point2 points3 points 8 days ago (2 children)perfect size for a skimmer

permalinkembedsavereportreply[–]krauseler[S] 0 points1 point2 points 8 days ago (1 child)Pentesting on steroids. But this is a card itself, you'd be targeting terminals but not really cards I assume. In any way, I really hope if at all, this will be used for ethical hacking but can't prevent people from doing sketchy stuff with it besides saying please, please, pretty please ^^

permalinkembedsaveparentreportreply[–]Thin-Bobcat-4738 0 points1 point2 points 8 days ago (0 children)do you experience with building deep inserts?

permalinkembedsaveparentreportreply[–]LateralThinkerer 1 point2 points3 points 8 days ago (1 child)Saw this on Hackaday - very cool!!
https://hackaday.com/2026/05/11/this-credit-card-computer-follows-all-dimensions/

permalinkembedsavereportreply[–]krauseler[S] 0 points1 point2 points 5 days ago (0 children)It's an honour to be featured on Hackaday, never thought one of my projects would one day end up there ^^

permalinkembedsaveparentreportreply[–]constrobot 1 point2 points3 points 8 days ago (1 child)That's really great

permalinkembedsavereportreply[–]krauseler[S] 0 points1 point2 points 5 days ago (0 children)Thank you! 😄

permalinkembedsaveparentreportreply[–]fayyazORahmed 1 point2 points3 points 8 days ago (1 child)I didn't read the whole thing but this looks amazing

permalinkembedsavereportreply[–]krauseler[S] 0 points1 point2 points 5 days ago (0 children)It's okay, the project is definitely eye catcher compatible for those who just want to read the headline 😃

permalinkembedsaveparentreportreply[–]NootNottPortier 1 point2 points3 points 7 days ago (1 child)I definitely love the idea !
Incredible work and project

permalinkembedsavereportreply[–]krauseler[S] 0 points1 point2 points 5 days ago (0 children)Thank you so much!

permalinkembedsaveparentreportreply[–]V2kuTsiku 1 point2 points3 points 7 days ago (1 child)Doom. Does it run Doom?

permalinkembedsavereportreply[–]krauseler[S] 0 points1 point2 points 5 days ago (0 children)It does, at <2fps

permalinkembedsaveparentreportreply[–]TNTqwe 1 point2 points3 points 6 days ago (1 child)Thats soo cool

permalinkembedsavereportreply[–]krauseler[S] 1 point2 points3 points 5 days ago (0 children)Thanks!

permalinkembedsaveparentreportreply[–]Weekly-Republic-5642 1 point2 points3 points 5 days ago (0 children)Wild

permalinkembedsavereportreply[–]ConsciousLife2119 1 point2 points3 points 5 days ago (0 children)run DOOM?

permalinkembedsavereportreply[–]chumbuckethand 0 points1 point2 points 8 days ago (3 children)What are the pc specs?

permalinkembedsavereportreply[–]krauseler[S] 0 points1 point2 points 8 days ago (2 children)ESP32-C3 with WiFi and BLE, NFC with both emulation and terminal/reading, IMU, touch buttons and of course the super low power E-Paper display. 😄

permalinkembedsaveparentreportreply[–]chumbuckethand 1 point2 points3 points 8 days ago (1 child)No I mean storage space, processor speed, ram size, etc

permalinkembedsaveparentreportreply[–]McDonaldsWitchcraft 2 points3 points4 points 8 days ago (0 children)it's not a computer, as I pointed out in a separate post. They said they will "change the title" to be accurate but it seems they reposted it without changing the title.

permalinkembedsaveparentreportreply[–]wensul 0 points1 point2 points 8 days ago (1 child)I'm skeptical.

permalinkembedsavereportreply[–]krauseler[S] 0 points1 point2 points 8 days ago (0 children)You should be.
But if there’s anything on your mind feel free to ask. Not sure if that is allowed, the mods on this reddit seem to have a problem with questions for whatever reason :p

permalinkembedsaveparentreportreply[–]Twigsxi 0 points1 point2 points 8 days ago (1 child)Came here because of self-powered claim. Still really cool but now I think you have a new goal post.

permalinkembedsavereportreply[–]krauseler[S] 0 points1 point2 points 5 days ago (0 children)My mistake, I meant to say battery powered which is more accurate.

permalinkembedsaveparentreportreply[–]ElfMage83 0 points1 point2 points 8 days ago (2 children)Why not call it the OmniCard?

permalinkembedsavereportreply[–]krauseler[S] 0 points1 point2 points 5 days ago (0 children)I get what you mean, but doesn't flow that well imo

permalinkembedsaveparentreportreply[–]Suitable-Report-8712 0 points1 point2 points 5 days ago (0 children)OmniCard? Honestly, for a product that manages to pack WiFi, BLE, NFC, an e-paper display, and a battery into a package less than 1 millimeter thick, that name is probably spot-on.
But it sounds like you’ve done a lot of research on this?

permalinkembedsaveparentreportreply[–]QuantumKrishna 0 points1 point2 points 7 days ago (1 child)What is the working for this device

permalinkembedsavereportreply[–]krauseler[S] 0 points1 point2 points 5 days ago (0 children)How exactly do you mean? How it's working?

permalinkembedsaveparentreportreply[–]Danitosaurio 0 points1 point2 points 7 days ago (1 child)Yooo that’s crazy. Good job 👍🏼

permalinkembedsavereportreply[–]krauseler[S] 0 points1 point2 points 5 days ago (0 children)Thanks, gave my best 😄

permalinkembedsaveparentreportreply[–]The_Movie_Hub 0 points1 point2 points 5 days ago (1 child)What is the motherboard its currently using?

permalinkembedsavereportreply[–]krauseler[S] 1 point2 points3 points 5 days ago (0 children)You mean MCU? Power? If you mean power, it's not optimized for efficiency yet, will likely use roughly 10uA at sleep and around 30mA on display updates.

permalinkembedsaveparentreportreply[–]chaosgremlin11 0 points1 point2 points 5 days ago (0 children)Can it run doom?

permalinkembedsavereportreply[–]Ducati_Dude_0 0 points1 point2 points 5 days ago (0 children)Imagine showing this to some dude in the 60's

permalinkembedsavereportreply[–]Andre13480 0 points1 point2 points 5 days ago (0 children)Does it run doom?

permalinkembedsavereportreply[–]Optimal_Air6483 0 points1 point2 points 4 days ago (0 children)This is so cool!

permalinkembedsavereportreply[–]istarian 0 points1 point2 points 4 days ago* (0 children)Similar things have been attempted before, at least by companies, but it's obviously challenging to cram much into so small a space.
https://en.wikipedia.org/wiki/REX_6000
^ PC Card sized PDA
https://www.youtube.com/watch?v=XX_wOOvByPs
^ not a computer per se, but an fm radio receiver crammed into a credit card sized shell

Looks like a pretty good start for doing it on your own.

permalinkembedsavereportreply[–]Away-Software7116 0 points1 point2 points 4 days ago (0 children)That is impressive and it encourages the good competetion.

permalinkembedsavereportreply[–]A_Clever_Ape 0 points1 point2 points 4 days ago (0 children)Whoa! Now THIS is cool!

permalinkembedsavereportreply[–]GreatGrape5514 0 points1 point2 points 4 days ago (0 children)What is the capacity of the battery?

permalinkembedsavereportreply[–]gryphusZero 0 points1 point2 points 3 days ago (0 children)this is so cool to see, especially as it is done as a hobby at home not at the manufacturing facility. I saw your plans for the future and they look solid! Keep up the good work, and most importantly, have fun doing it!

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The presented material revolves around the experience and subsequent engineering discussions surrounding the creation of a fully self-powered computer housed within a physical dimension approximately one millimeter thick, based on a credit card size. The initial motivation for this project stemmed from challenging conventional limits, pushing the boundaries of miniaturization, and exploring novel solutions for electronics within extremely constrained physical envelopes.

The prototype incorporated specific electronic components, including an ESP32-C3FH4 for processing, NFC read/write capabilities, a 1.54 inch 200x200 E-Paper display, an ultra-thin LiPo battery with integrated charging and power path management, and an accelerometer. The critical engineering challenge extended beyond simply fitting components; the primary obstacles involved mechanical stability, dealing with material fatigue, managing pressure distribution, and designing a custom flexible printed circuit board (flexPCB). As the designer noted, mechanical strain proved to be the most difficult factor to manage, leading to the realization that preventing strain was more feasible than attempting to withstand it, forcing a shift in design strategy to avoid mechanical stress entirely.

The process required a multidisciplinary approach, merging electrical, mechanical, and chemical engineering principles. The designer experimented with material choices to create the flexPCB, realizing that standard methods were inadequate, which necessitated hand-soldering individual connections for each circuit trace due to limitations in flexible connector technology. The project highlighted that achieving ultra-thinness does not automatically guarantee manufacturability or reliability, as assembly considerations often add complexity that negates the perceived advantage of size.

Discussions within the community focused heavily on the implications of this extreme scaling. Feedback centered on the feasibility of the "self-powered" claim, with some questioning whether the device truly operates autonomously or if it merely runs until battery depletion. Other technical concerns addressed power management, particularly ensuring the system could operate reliably in real-world conditions, and the necessary physical protection for the internal battery to mitigate hazards. Furthermore, concerns were raised regarding potential future applications, such as developing highly secure, portable hardware, such as utilizing the device for two-factor authentication or cryptographic wallet functions, necessitating input/output methods like NFC or Bluetooth for data transfer.

The dialogue also touched upon potential future iterations and material science advancements. Suggestions included exploring the use of flexible lithium ceramic batteries (LCBs) due to their inherent flexibility and safety characteristics, which could offer solutions for achieving further miniaturization and robustness. Regarding functionality, there was debate over whether such a constrained device could perform complex tasks, with some speculative ideas regarding its potential for running sophisticated software, such as video games, while others focused on minimizing functionality to enhance security and practical utility. Ultimately, the project served as a testament to the challenges and innovations involved in integrating advanced electronics at the absolute physical limits of material science and mechanical engineering.