Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

A Minimum Viable Computer, or Linux for $15

bbenchoff.github.io

Post reply on HN
Print view View original

361–370 of 408 posts

Re: A Minimum Viable Computer, or Linux for $15

#361

Post by desireco42 »

miav wrote: post #222

> It costs $10,000 USD to build one of these > The ten thousandth one costs $15 As a software engineer, I'm used to being able to build essentially whatever I want, with the only cost being my time. I'm often unpleasantly reminded that software is an outlier in that regard and as soon as physical items are concerned, especially hardware, it turns out that manufacturing even a simple thing is prohibitively expensive i…

Yes that is true, but only thanks to huge reliance on OPEN SOURCE. :) Without it, no tools, no infrastructure, no nothing.

Re: A Minimum Viable Computer, or Linux for $15

#362

Post by antoinealb »

aidenn0 wrote: post #313
Teknoman117 wrote: post #299

Earlier quoted context omitted.

You can even run 4-layer impedance controlled boards that support BGAs for ~$60 and get 10 of them. Problem is I now have a bunch of unpopulated PCBs I don't really intend to use. I made a few PCIe x1 to SMA adapters for an FPGA devkit - even building a single one and considering the rest of the PCBs as write-offs was less than a quarter the price of premade ones.

Can you verify good flow of solder on a BGA without an x-ray? Do you just reflow it for the prescribed time and see if it works?

It is already the way you do it for parts like QFN (at least the way I do it): if it works then all good! If it does not, then heat it up again. I heard BGA is actually pretty simple as you cannot apply too much paste, but I don't have so experience with it.

Re: A Minimum Viable Computer, or Linux for $15

#363

Post by hypertele-Xii »

gmiller123456 wrote: post #246
hypertele-Xii wrote: post #184

Earlier quoted context omitted.

Why not?

You can't hold it and type at the same time, this device has to be sitting on a surface to type.

How so? You can hold it with both hands and type with your thumbs. Or hold it in one hand and type with the other.

Re: A Minimum Viable Computer, or Linux for $15

#364

Post by rikelmens »

renonce wrote: post #200

In China we buy second-hand Redmi 2 for 60RMB each (roughly $9.5). Can be bought in quantities. Fully functional with 2GB RAM+16GB eMMC, and battery, touchscreen, WiFi, Bluetooth, camera, and even 4G support. It's not built from scratch like this one, but if you are just looking for something cheap, then this price is insane.

Where can one outside from Chime buy these phones (in bulk) ?

Re: A Minimum Viable Computer, or Linux for $15

#366

Post by schwartzworld »

throw10920 wrote: post #275
renonce wrote: post #200

In China we buy second-hand Redmi 2 for 60RMB each (roughly $9.5). Can be bought in quantities. Fully functional with 2GB RAM+16GB eMMC, and battery, touchscreen, WiFi, Bluetooth, camera, and even 4G support. It's not built from scratch like this one, but if you are just looking for something cheap, then this price is insane.

Amazing that we went from this potato[1] for $12 in 2013 to that Redmi 2 in 9 years. Now, you said that you buy the Redmi second-hand, but still - the leap is amazing. [1] https://www.bunniestudios.com/blog/?page_id=3107

If you threw a a Qwerty keyboard and command line on that thing, it would be on the front page of HN right now

Re: A Minimum Viable Computer, or Linux for $15

#367

Post by fest »

aidenn0 wrote: post #313
Teknoman117 wrote: post #299

Earlier quoted context omitted.

You can even run 4-layer impedance controlled boards that support BGAs for ~$60 and get 10 of them. Problem is I now have a bunch of unpopulated PCBs I don't really intend to use. I made a few PCIe x1 to SMA adapters for an FPGA devkit - even building a single one and considering the rest of the PCBs as write-offs was less than a quarter the price of premade ones.

Can you verify good flow of solder on a BGA without an x-ray? Do you just reflow it for the prescribed time and see if it works?

If the board layout permits it, you can inspect the outside balls around the perimeter- if they are fine, the inside ones will most likely be fine as well. Sometimes, a small piece of front-surface mirror can be used to inspect the sides of the chip obscured by taller components.

Even PCBA companies usually just place and reflow the chip and may only use x-ray to validate the initial build- and then rely on process consistance + functional testing at the end of line.

Re: A Minimum Viable Computer, or Linux for $15

#369

Post by kragen »

watersb wrote: post #355
webmaven wrote: post #329

Earlier quoted context omitted.

> I'm fairly decent with clay, always wondered if I could make something like a raspberry pi case with sculpey. The short answer is yes you can, but it's a PITA. Among other problems you have to deal with shrinkage and drooping. I'd only use that approach for a quick and dirty prototype that just needed to hold parts together and survive rough handling. A better option is to build a case from parts you cut out of a s…

> A better option is to build a case from parts you cut out of a sheet of plastic (anywhere from 1mm on up) that you then glue together. Not a bad way to go, but I found that for hand assembly, I had a really hard time with the glue out of control; I probably needed a better applicator than the default tube of epoxy. Instead, I would go with VHB (Very High Bond) tape. Also weird to use, if you are using the thin 1mm…

I don't know anything about this stuff, but from YouTube I'd think other options would include:

- machine a form out of wax or delrin (or clay), pour a silicone mold, and then pour liquid plastic into the mold, either a not-yet-polymerized resin such as a thin epoxy, or a molten thermoplastic;

- similarly, but use plaster instead of silicone and burn out the form in a kiln before pouring (not applicable for clay);

- 3-D print the case, and if you don't like the layer lines, smooth them out with either a coat of paint or by smoothing an ABS print with acetone vapor;

- 3-D print a form for molding.

Even for injection molding, you might start with an aluminum mold, which won't last as long as hardened steel but will cost a lot less.

But I don't know anything about this stuff so maybe it's not applicable to this case?

Re: A Minimum Viable Computer, or Linux for $15

#370

Post by vaxman »

There should be some industry-subsidized program where upon (a) it’s free to 4th-7th graders and available for pickup at local stores using a thumbprint; (b) it should have free packet connectivity to Internet, perhaps through something like Sidewalk, the FindMy network and the piggyback WiFi networks that cable coNpanies [sic] have started installing into the neighbor’s “WiFi routers” to support their new CLEC+ mobile service; (c) if a youth spends enough time working on one in certain ways (perhaps a minimum of two hours per day on average in Emacs/Mu/VIM or certain types of nCurses variants of Jupytr, Mathematica, VisiCalc, SQLiteStudio, etc… as verified by signals emitted to the Cloud from the ROM/BSP), then they receive eligibility to go pickup a progression of “snap-on” upgrades (7” LCD, storage, 5GUW, etc), eventually (after thousands of hours) leading to a “snap-on” compatible rPi400 as they’re getting ready for high school. Yeah, it’s pretty anemic compared to where we really should be as a society right now, but it’s a lot more realistic than giving out locked-down $300 iPads equipped with MDM and supporting infrastructure to 4th graders that starve during the Summer (when school lunches are closed).
Post reply on HN