Author Topic: DIY tablet computer, maybe.  (Read 2077 times)

Offline S. Heslop

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DIY tablet computer, maybe.
« on: July 11, 2018, 05:33:41 PM »
I've had alot of half baked ideas, unfinished projects, and false starts over the last couple years and this is one of them. No promises that this will go anywhere, and also keep in mind that I have no idea what i'm doing!


So here's a lifelong dream of mine - the ability to make my own portable computers. Mostly spurred by the endlessly disappointing world of pre-built portables. Some laptop designs were pretty good, especially the IBM thinkpads. But now every laptop manufacturer is chasing thinness to a riddiculous degree, leading to small non removeable batteries, cooling issues with more powerful hardware, and some of the worst keyboards and mice ever developed.

I was recently looking at those Microsoft Surface Pros, and as an art tool they almost seem ideal. There's similar offerings from other manufacturers with built in pen digitizers. But they all share the same issue - no buttons! That's the other part of modern portables that drives me nuts, the whole war on buttons. I figure it's some bean counter thing on saving money per unit, especially in building new tooling. But in digital painting you make alot of use of the undo shortcut. Some workarounds include running a program to put onscreen buttons on the edge of the screen, but then you're stuck fighting the palm rejection algorythm. Others are using external keypads. I think maybe some sort of clip on port expander style deal with some buttons could work. But then those tablets seem kind of expensive for something that'd take some fiddling to make useful

So naturally i've been thinking about making my own.

I found a forum dedicated to building pen tablet displays through various methods, and in the thread linked a fella made a couple of laptop displays work. I went and bought the same display, I believe, that he used.



I've yet to test if the display or its controller works. I'm a little hesitant to plug the suspicious Chinese circuit into any computers I own.

But I also bought a thin mini ITX motherboard that was going cheap on ebay a bit back. An ECS H81H3-TI2.



Which has an LVDS output, so i'm probably going to see if that Just Works first before worrying about using the Chinese board. I don't really understand LVDS and there's nothing in the manual about configuring it, but I believe some displays send configuration data over that hopefully the motherboard can handle.

I still need to assemble the rest of the hardware which will involve alot of Ebay Disappointment I bet. The board is limited to 8gb of ram and 4th gen CPUs, but that's also what I have in my desktop and the drawing program I use (Krita, excellent program and it's free) is mostly CPU rather than GPU dependant from what i've read.




So the real question is 'what shape?'

Whatever it is it's going to have to be quite chunky. I've collected a bunch of photos of old tablets and laptops from the earlier days of portables to hopefully inspire ideas. 


They're surprisingly hard to find, I figured there'd be more enthusiasm for cataloguing them. They were all marketed under the idea of you being able to Compute while standing up, with built in handwriting recognition. I don't think any of them were hugely successful.


I was first considering some kind of laptop.



Acer recently made a laptop convertible with this style of hinge, the R7. It got poor reviews and Acer prostrated themselves in front of the tech journalism world and made sure their next version was more in line with what everyone else was doing. But I think what they came up with was pretty clever, since it still gives you access to the keyboard while using the pen display. It's kinda similar to the arrangement i've got with the graphics tablet stand I made a bit back to save on desk space.

But it'd still be way too complicated to build, and I couldn't find a source for those thin keyswitches that supposedly exist. So I think a more 'normal' style of tablet would be the way to go.




It's still early days and I've got some other angles to think about. The reason i'm revisiting this project is becuse i've found myself needing to accurately ink a whole stack of drawings, and with the way i'd been doing it previously (going over the line 20 times and hitting undo till I get it right) it was taking way too long. It turns out that the overhanging graphics tablet stand isn't such a great idea since it gives you no forearm support, and while it works fine for rough sketching from the wrist it's hard to do long consistent lines.

So i'm considering some kind of unit that can dock into an angled table. And I might forgo batteries since that's something i'd have to really bodge together and is really outside of my abilities. Plus I don't think i've ever seen anyone use a laptop or tablet away from a wall socket!

The first priority will be making sure all the hardware works together though.

Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #1 on: July 11, 2018, 10:17:21 PM »
Hah. Been on a google adventure trying to find what the connector is for the wacom board. Turns out it's a 14 way Hirose DF19. Finding out what it even was was only half the battle, as the other was finding a source to buy one. The usual sites all have a 12 delivery fee for 20p worth of connector, radiospares didn't have any, ebay had a few jokers trying their luck. So I started looking at replacement cables, plugging part numbers in. Eventually found an entire different display for sale with a digitizer board and the cables + inverter included for 10 and went for that.

That whole bongofish forum is fascinating though. For anyone that isn't aware, Wacom is a company that makes graphics tablet digitizers for digital drawing - and for a long time they pretty much held the monopoly on them with the high prices that entails. They also sold obscenely expensive Cintiqs, a pen digitizer display. So you can draw directly on the screen. They've also been liscensing their technology to various laptop and tablet manufacturers. Recently some Chinese companies have been massively undercutting them but the driver support is spotty. But I love the idea of DIY alternatives undercutting them even further. In theory a 20 microcontroller, 10 surplus laptop display, whatever it costs for a sheet of acrylic to cover it, and 15 for a controller board could be all it'd cost to have an Official Wacom with fancy drivers equivalent. You could even skip the microcontroller if you can find a digitizer with a USB output instead of serial.

Offline JHovel

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Re: DIY tablet computer, maybe.
« Reply #2 on: July 12, 2018, 06:22:34 AM »
Nice plan and you now have me subscribed to your thread  :beer:
My interest isn't / wasn't in digital drawing but rather at sustained hand-held pen computing: working in a fast-paced clinic (in a prison health centre). I ended up with older Fujitsu 2300s which had native pen support with two 'mouse' buttons on them, a decent hand-hold on the side of the screen, USB, LAN and - using its PCMCIA ports - WLAN access.
Their relative thickness actually made them more comfortable in the hand than the much thinner tablet I use now at home (retired).
I have been interested in pen computing for decades in the health field, so I'm fascinated by what you develop for your profession.
If I may make a suggestion: don't be limited by what others are doing in terms of shape, consider 3D printing EXACTLY what you design - along with the option of changing things easily for Ver 2,3,4,5 until you have YOUR ideal.
Cheers,
Joe

Offline Brass_Machine

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Re: DIY tablet computer, maybe.
« Reply #3 on: July 12, 2018, 04:13:43 PM »
Oooh. This will be cool!

Watching!
Science is fun.

We're all mad here. I'm mad. You're mad.

Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #4 on: July 12, 2018, 04:58:31 PM »
That's interesting to hear a real world use for those older tablets. I was watching some old recordings of computer news TV shows to try find more tablets to look up and the sales guys always seemed to struggle to come up for good examples of their use. The one they kept going for was 'an estate agent could input a clinets information while standing and taking to them'.

Wish I did have a 3d printer though. I was thinking of leaving this whole project till after I build one since it'd make it alot easier, but I think I should be able to put something together with what I've got using wood and metal, even if it might look stupid. Even if it's entirely unrelated to tablets, the kinda look i'd like to go for is something like the Madsen LAR. Those forgottenweapons videos are pretty good if you've never seen them before, it's surprising how much history you can extrapolate from just looking at guns. But I think those rifles are the nicest looking mix of wood and metal i've ever seen. But i'd also settle for something clunky looking that just works!

Right now i'm trying to find a viable CPU. The motherboard i've got only supports the 4th gen intel Core CPUs which are still quite expensive for the higher end ones second-hand. I also would ideally want one with the lowest TDP rating possible since i'll only have a small heatsink. I might try get a cheaper low end one just to see if this stuff will work before I consider going all out.

Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #5 on: July 12, 2018, 08:30:26 PM »
Blargh, so much for cheap PC parts. Spent 50 on a 4 year old i5-4590T CPU that hopefully wasn't ran full blast since its manufacture. The i3 chips turned out to be more expensive than the i5 ones. By coincidence at least the motherboard I found uses the same range of chips as my desktop, and the processor I just bought is a little bit better than what i'm currently using. So assuming what arrives is functional I can shove that into this computer if all else fails.

The whole computer parts world is in a weird place at the moment, mostly because of bitcoins. Graphics cards are especially hard hit with the prices rocketing, although starting to come back down a bit as the hysteria fades, since most of the calculations are done on the GPU. I figure people must be buying up second hand CPUs and other hardware to assemble mining computers as cheap as possible, and perhaps people assuming that i3s are the cheapest option has people fighting over those before looking at the mid range chips.


There was that whole reveal a bit back that most of intel's performance gains in the last few years has been through removing security features. Which were eventually discovered by no-goodniks and had to be patched in, massively tanking performance on alot of chips. I hear intel has given up alot of its R&D, and focussed more on directly competing with ARM and the low power chips, so their desktop stuff has been somewhat stagnant and most of the developers have quit for hopefully better jobs. But maybe the performance changes have made the older chips seem just as good as the newer ones.

I think all I need now is an LVDS cable. I hate shopping.

Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #6 on: July 12, 2018, 11:04:37 PM »
Hope nobody minds these rambling posts!

The motherboards manual is pretty barebones on the info included. But in the diagram legend it says "LVDS connector (For All-In-One Specification)" so i've just looked up what all-in-one specification means. Intel has a big bunch of documents that are thankfully publically available outlining the thin mini ITX specification in more detail than I can understand. But right off the bat it says 40 pin LVDS when my screen uses 30, so that dashes all hopes of it just working right off the bat. Should've counted those pins to begin with!

LVDS is interesting. It's hard to find any info on it, along with inverters, but from what i've read it's barely a standard. It seems every manufacturer just changes stuff around even between models, as a joke, so little is interchangeable. But thankfully most displays are making a move towards eDP which is more standardized. But apparently really hard to make work right in a DIY sense since it's all RF black magic.

It's still exciting though, since a lack of standards is a big part of why DIY portables are uncommon. If I have some success with this build then it might not mean much to anyone else, since i'd be using a specific display model and specific digitizer model that might become hard to get ahold of if even just a few people decide they want to follow my steps and buy them up. I'd be surprised if that were to happen though. Hell i'll be surprised if this works at all!


So yeah i'll need to slap that Chinese board in the middle. But that runs off of 12 volts when the motherboard takes 19. I'd slap a buck converter somewhere in the line but I'm not sure if they'd have some kinda... whats the word. Transients? That might upset the motherboard.

Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #7 on: July 13, 2018, 02:18:52 AM »
Here's a concept. Dimensions are about 400x270x40mm so it's quite a big thing.



The general idea though is to have an aluminium or maybe steel plate for the top, an aluminium or steel band bent around into a kinda squareish shape for the sides, wooden bottom, then some kinda grip thing on the left with buttons. The idea is that there'll be some buttons arranged in a fan to match the arc of your thumb when holding the left. It'd probably end up so heavy and off to the side that picking it up one handed wouldn't be feasible, but resting it on your lap or on a table you'd likely still be holding it with a hand to steady it.

I got carried away a bit though and those tapered edges would be hard to build. Tapered sides are a classic feature of chunky electronics, they've been doing that for years to give the illusion it's thinner than it really is, and I think it's a vital part of making this look 'semi-professional'. But I could try out a stepped side, which is visible in some of those early tablets in the OP and looks more interesting

Offline awemawson

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Re: DIY tablet computer, maybe.
« Reply #8 on: July 13, 2018, 07:11:05 AM »
Simon,

Any chance you could limit your pictures to 800x600 pixels, so those of us without wide screen surround sound mega gaming pcs on steroids can see them WITHOUT having to go to the other side of the road ? Thanks

. . . oh welcome back by to way  :thumbup:

Andrew Mawson
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Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #9 on: July 13, 2018, 10:23:32 AM »
I did consider that, and made it an effort in the past. But with the world moving towards 4k i'm starting to consider regular HD to be getting old. Not that i'm in love with 4k. 1920x1200 is ideal, with pixels so small I cant see them with the display at a comfortable distance that doesn't require panning your neck around to see the edges. But I guess they've gotta make us buy new stuff somehow.

Offline awemawson

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Re: DIY tablet computer, maybe.
« Reply #10 on: July 13, 2018, 10:54:43 AM »
On a normal pc if the picture is as wide as you make it you have to use the slide bars to scroll about, but if there is more than one picture as soon as you move the first you've lost the scroll bars  :bang: It's also an unnecessary waste of band width . Some pictures (such as circuit diagrams for instance) sometimes need a higher resolution, but in the example of your picture above, no meaningful detail would be lost.

Here it is at a 800x600 pixel resolution and nothing has been lost !!!!
Andrew Mawson
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Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #11 on: July 13, 2018, 02:28:59 PM »
Going to a place tomorrow to pick up a mirror for some DIY work, i'll probably see if they can do 3mm tempered glass or know anywhere that might. I believe tempered glass has some light polarizing properties that might interfere with the display though, but maybe that's just car windows that are also laminated.

Offline vtsteam

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Re: DIY tablet computer, maybe.
« Reply #12 on: July 13, 2018, 09:36:43 PM »
Simon, sorry,  it really messes up my own screen when trying to read a thread if people use img tags with photos exceeding 800 pixels. Please consider either attaching them if larger, or keeping to the forum requested limit of 800 pixels for linked photos. I appreciate it, buddy.  :beer:
I love it when a Plan B comes together!
Steve
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Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #13 on: July 13, 2018, 11:43:32 PM »
It's starting to look a little Star Trek. I think its the button arrangement.



Still considering if this is the ideal way to go about it. I figure it'd be best if the plate glass is supported all around on a ledge that it's glued into, and the easiest way for me to make that would be with two layers of... perhaps aluminium. Prices might put me off when I check! Then the screen itself is just screwed on behind, saving it from taking any of the pen pressure.


Question is - how do I stick the two plates together. Welding would distort. It'd be too thin to hide screws. Loctite is expensive and I don't have a whole lot of faith in adhesives... maybe I could stick rivets in, ground flush, and paint the aluminium rather than anodize it. For starters I've never anodized before and that's a whole art from what i've seen, and paint/ filler could hide the seam.

Y'know I could probably make it at least 30mm narrower but I need that decorative strip! If I could rely on some kind of adhesive then I could replace the top plate entirely with the glass plate, but then i'd need to ditch that strip.


Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #14 on: July 13, 2018, 11:52:07 PM »
I think i've got it. If I move the black dots a few mm towards the screen then they line up with the band that goes around the edge, and that'd give load of engagement for some long countersunk screws and sandwich all 3 parts together. Then I can loctite those in and fill the holes with bodyfiller.

Offline PK

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Re: DIY tablet computer, maybe.
« Reply #15 on: July 14, 2018, 01:55:06 AM »
Quote
Question is - how do I stick the two plates together

I may be able to assist.
We make this product:http://www.soledigital.com.au/hibeam.html
on top of the LED board are three layers of acrylic of varying colour, opacity and thickness
They are (for the most part) held together with Weldon #16 glue, the exception being the front screen with it's border mask. The mask is created by just lasering through the cover paper, peeling off the outside part, sand blasting and 4 coats of Krylon fusion paint.
Once this is cured, we glue it into the stainless case with some neutral cure silicone.

Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #16 on: July 14, 2018, 08:21:08 AM »


Nice packaging guys.


Edit: Seriously I hate this shop. I got dragged in a few times last year when I was in the city more. It's got decor that says 'we think you're a bunch of idiot mental teenagers'.

Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #17 on: July 14, 2018, 08:25:53 AM »
Quote
Question is - how do I stick the two plates together

I may be able to assist.
We make this product:http://www.soledigital.com.au/hibeam.html
on top of the LED board are three layers of acrylic of varying colour, opacity and thickness
They are (for the most part) held together with Weldon #16 glue, the exception being the front screen with it's border mask. The mask is created by just lasering through the cover paper, peeling off the outside part, sand blasting and 4 coats of Krylon fusion paint.
Once this is cured, we glue it into the stainless case with some neutral cure silicone.

Thanks for the info. It is very tempting to go with acrylic. I have access to laser cutters through several angles too.

Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #18 on: July 14, 2018, 12:04:13 PM »
It never ends. I've been looking at power adapters. The big document recommends over 120 watts and the manual quotes 19V but all I can find are power supplies at 19.5V. I've got a 65 watt laptop one with the right connector at that voltage so after some thinking I decide I might as well try it. 19.5 is well within the usual +/-5% quoted.

Anyways there's no signs of life. I've probed the supply and unconnected it's putting out about 16 volts but that might be some standby/ no load thing. I guess I could try order a more suitable supply, they hover around 20-30 second hand. But boy these things all add up.


Edit: This is gonna turn into sunk cost fallacy.

Another Edit: So I've tallied up the price of things. I've been buying things here and there since the new year so i've not felt it as much as these few recent purchases. The current total is at 193.

I think it's generally seen as... uncouth or something to talk about price and money. But if someone says somethings cheap or expensive it's really a relative thing and it's hard to tell how they personally value things. For me 193 is definitely in the 'yowza!' territory.

Actual prices are probably important so people can see how much it's worth the idea of making your own mains power only tablet computer with a high chance of failure against just buying one. Plus calling it a tablet seems like a stretch if it's mains only. It's closer to an all-in-one PC really.

« Last Edit: July 14, 2018, 12:32:18 PM by S. Heslop »

Offline CrazyModder

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Re: DIY tablet computer, maybe.
« Reply #19 on: July 14, 2018, 02:06:37 PM »
I would not feel too bad. I have done so many projects like yours, where I thought "this seems so easy, I just need a few cheap components and can do the rest myself to end up at a Thing 1/10th the price and 10 times as nice for my particular needs".

A few decades later, I know that the guys which say "DIY = 10 times as much time, 10 times as much money, 1/10 quality" are mostly correct.

Does that stop me? Nah. It's a form of entertainment, and entertainment usually costs. I do tend to get a little wiser in that I tackle the difficult + cheap bits of new projects first now, so if I fail at that point in time, not much damage has been done. Also, I tend to wait until actually buying anything except raw material (wood, metal stock) as late as possible - that stuff so often ends up in a long-term storage box...

So, go on and build your tablet, looking forward to what you come up with in the end!  :beer:

Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #20 on: July 14, 2018, 04:32:01 PM »
Yeah I feel that. Alot of it is for its own sake, because I enjoy it despite the complaining, and to see whats possible.

I also consider it as a sort of installments thing. 20 here and there is alot more agreeable and easier to handle than dropping 500 all at once. Or worse than that, having to continue paying it off after I find all the shortcomings with the device.

Offline nrml

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Re: DIY tablet computer, maybe.
« Reply #21 on: July 14, 2018, 05:03:59 PM »
I am a huge fan of 3M VHB tape. They make a clear version for glass. I believe it is the the same acrylic adhesive most manufacturers use for bonding windows and windshields for everything from aircraft to cars. It is also extensively used in the construction of the Burj Al Arab hotel in Dubai. Once you stick it on, you can never get it off again.

It is also easier to apply than liquid adhesives.

Offline efrench

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Re: DIY tablet computer, maybe.
« Reply #22 on: July 14, 2018, 06:58:04 PM »
You can make Gorilla glass.

Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #23 on: July 14, 2018, 07:41:42 PM »
I am a huge fan of 3M VHB tape. They make a clear version for glass. I believe it is the the same acrylic adhesive most manufacturers use for bonding windows and windshields for everything from aircraft to cars. It is also extensively used in the construction of the Burj Al Arab hotel in Dubai. Once you stick it on, you can never get it off again.

It is also easier to apply than liquid adhesives.

That sounds ideal for sticking the glass down, and in general. I'll check it out.

You can make Gorilla glass.

I did look into that a bit back. The big advantage of chemical glass is that it can be really thin and flex a good bit before it breaks. Ideally i'd want thick enough glass that it shoudn't bend much with pen pressure applied.

Offline PekkaNF

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Re: DIY tablet computer, maybe.
« Reply #24 on: July 15, 2018, 05:35:41 AM »
I am a huge fan of 3M VHB tape. They make a clear version for glass. I believe it is the the same acrylic adhesive most manufacturers use for bonding windows and windshields for everything from aircraft to cars. It is also extensively used in the construction of the Burj Al Arab hotel in Dubai. Once you stick it on, you can never get it off again.

It is also easier to apply than liquid adhesives.

I bought a roll of Tesa 4965

https://www.tesa.com/en/industry/tesa-4965.html

pretty good, instant results

1. Store it on ziplock, or edges will atract fuss (my daughter stored it with some clothe and it sitill is fine for most uses, but not between two glass/plastic panels.

2. Getting backing off takes a little practice. I leave a little excess outside, surplus backing underside, apply tape, remove the backing on surplus side and cut off the "tail" before joining two panels together.

3. Sticks to everyting and only thing it did not work was sticking a shower handle holder on the tile on the bathroom, it had tilting load and it eventually crept. I have used it on the fixtures to hold material that is drilled, sawed, cut, routed, sanded and it has been nearly perfect. Only on latest ocassion I thinkt that I did remove all of it and it interacted with sprayable alcyd paint (some roughness).

Higbly recommeded instead of glueing.

Pekka

Offline awemawson

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Re: DIY tablet computer, maybe.
« Reply #25 on: July 15, 2018, 06:01:55 AM »


I think it's generally seen as... uncouth or something to talk about price and money. But if someone says somethings cheap or expensive it's really a relative thing and it's hard to tell how they personally value things. For me 193 is definitely in the 'yowza!' territory.

Actual prices are probably important so people can see how much it's worth the idea of making your own mains power only tablet computer with a high chance of failure against just buying one. Plus calling it a tablet seems like a stretch if it's mains only. It's closer to an all-in-one PC really.

Simon, price or cost is often highly relevant in these matters. If you're giving someone a present and discuss it's price, or bragging about your costly new car, then yes that's uncouth, but letting people know what is a realistic price in an engineering discussion I believe is absolutely fine
Andrew Mawson
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Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #26 on: July 15, 2018, 03:11:09 PM »
Boy howdy it's hot. I've been taking it easy and daydreaming about portables some more. I think the ideal device is probably the slider style phones they were coming out with before the stupid iphone ruined it and every manufacturer turned towards big solid cheap to manufacture touchscreen slabs.

Here's a doodle of a really bad idea for a chunky handheld games console.



Not a great idea at all really. I'll need to re-think it a bit. But something i've been hung up on for years is how... nice DSLR cameras feel. I think something with a similar form factor that's better than what I came up with might make a neat novelty device, if a goofy one. I believe those dirt cheap Rapberry Pi's are capable of playing the only game that matters - Doom (1993). Or more specifically the custom levels for Doom and its sourceports that people have been making for the last 25 years, refining their art. So it could be relatively cheap to slap together something silly some day.

Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #27 on: July 17, 2018, 03:02:49 PM »
This is going a bit slow since i'm still waiting on stuff to be delivered. The cable came today though.


Got a few things soldered onto this tiny Tiny board, including the 3V voltage regulator. It's the first time i've actually soldered anything surface mount and it wen't just fine. Probably helps that it's still on the large side of surface mount!


I really hope I got the right wires in the right holes. The guy i'm following was lucky enough to have them colour coded. I went over them a few times and labelled them. I could perhaps test it on my desktop PC but it took so much to get the weird Chinese drivers that came with my current graphics tablet working that I'm not keen on risking anything that might break them. They still stop working when I open certain programs.



Here's the setup I used to record the soldering. All those weird extra adjustments on the legs finally came in useful. Check out all that "useful looking junk" in the shelves.

Offline vtsteam

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Re: DIY tablet computer, maybe.
« Reply #28 on: July 17, 2018, 10:06:32 PM »
Now that's my kind of clutter!  :dremel:
I love it when a Plan B comes together!
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Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #29 on: July 17, 2018, 10:46:19 PM »
Now that's my kind of clutter!  :dremel:

I swear I just cleared the desk a week ago. I can't figure out where it comes from but its the same stuff every time.

Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #30 on: July 19, 2018, 12:16:46 PM »
Holy mackrel. New problems. So the new power supply seems to make the PC run. A connected CPU fan spins and a keyboard can toggle the caps lock etc LEDs. But no video over HDMI. It's the only video output aside from LVDS.

So I figure maybe I can get a beep code out of it to try narrow the problem down. So I pull the case speaker out of a very old computer that's been sitting in a corner for years but I can't find the header on this motherboard. It's got headers galore to meet the all-in-one thin mini ITX standard but no PC speaker header. It does however have some LDC debug card header, so I look that up and find nothing. But there's similar looking connectors (9 pin header) called LPC and lots of shoddy looking circuits from China.

Man I was really hoping something would just work. I'm hesitant to go out and buy even more stuff to maybe get this working, but i'm half tempted by that debug card just to see if it's the CPU and memory causing the issues. They seem a likely candidate since they were sent in a god damn paper bag.

I think I might have a plan B if I can't get this PC to work. And i'll definitely return those components on the grounds of shoddy packaging.



Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #31 on: July 19, 2018, 01:42:27 PM »
Here's the messy setup. Bar of aluminium as a temporary heatsink.



But just as I posted that last post a package arrived.



Kayzed1 sent me this cool laptop. Part of plan B was to gut it for parts but it's far too nice and useful. But it will give me a second computer to test the display and digitizer on without risking driver conflicts. It's got an older CPU but i'll also see how well it handles Krita.

Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #32 on: July 19, 2018, 02:14:54 PM »
That panel at least seems to work. Or rather it switches on, makes a weird buzz, then switches back off and repeats. I suspect it's becuse I was using a tiny .75 amp power adapter but it's all i've got on hand at 12 volts. Boot sales are the best option for finding power adapters so hopefully the weather holds till Sunday.

Cant find my USB cale that matches the Tiny board either. I'm glad they finally came up with a USB adapter that can fit in both ways - but it's a shame they left a wake of hundreds of variations of the smaller sized ones.

I think i'm done for now. Just running up and downstairs to fetch stuff in this heat is killing me. I think i'll start concentrating on the case next. Might go with plastic rather than aluminium. Prices are about the same and aluminium would probably be the better choice - but I have access to a laser cutter. At least I think I do. If I can get the front assembled then i'd feel more comfortable flinging this very delicate display about to test stuff.

Offline ddmckee54

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Re: DIY tablet computer, maybe.
« Reply #33 on: July 19, 2018, 04:32:21 PM »
Not sure that I didn't miss something, but is this "maybe tablet" just for funnsies - or are you planning on using it for a dedicated purpose?

Just askin'.
Don
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Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #34 on: July 19, 2018, 05:58:02 PM »
Not sure that I didn't miss something, but is this "maybe tablet" just for funnsies - or are you planning on using it for a dedicated purpose?

Just askin'.
Don

A bit of both. I've been wanting to do something like this for a while for various reasons. One is just to see if its possible. Earlier this year I was collecting some stuff to give it a shot, but ended up shelving it when I realised how expensive older generation CPUs still are. But right now i've found myself needing to ink a whole bunch of drawings as quickly as possible, and if all goes to plan i'll have even more in the future.

One of those Chinese pen tablet displays would probably be the most sensible option but I already had most of this stuff collected. Or at least I thought I did.


If I was going to take the DIY portable idea a bit more serious i'd be looking closer at stuff like those single board computers. Intel NUCs and all the weird stuff coming out like the UDOOx86. I might still in the future - especially as those boards are rapidly getting more powerful. I think whatever I come up with in this thread will be functional at best.

Offline krv3000

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Re: DIY tablet computer, maybe.
« Reply #35 on: July 19, 2018, 08:33:58 PM »
lol I shod put a pic on showing my work bench

Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #36 on: July 25, 2018, 10:06:09 AM »
Finally got something real done.


Not a straight edge in sight.

I'm going with steel and i've simplified the design a whole bunch since I want to actually get this finished. The steel is what I have on hand. I'm trying to stick to things I have now, like a keypad from an old mains powered calculator.



The idea is that the glass will be stuck to the steel - i'm gonna try that tape out. Then there's a plate behind the screen that screws into the front plate and holds the monitor in with some foam pads to act as springs so it's held flush against the glass but not with too much force. Then anything else will mount onto that rear plate.

The reason for the delay is that i've been caught trying to figure out how the font plate should look. Since once the glass is fixed to it I won't be able to drill any more holes in it I need to get that fully figured out.

Still thinking about how to join the sides of the box. I was thinking a few tack welds and hoping theres no serious distortions, but I figure i'd want the plate to still flex a bit to match the glass.


Oh yeah - does anyone know of any glass paint that sticks to glass really well? I want to mask the back of the glass off, the side that gets stuck down, with paint to hide the steel and tape behind it. Just searching for glass paint brings up arts and crafts type stuff.

Offline ddmckee54

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Re: DIY tablet computer, maybe.
« Reply #37 on: July 25, 2018, 01:41:07 PM »
So the glass plate will be on the outside of the tablet in front of the steel plate with the important hardware screwed on the back side of the plate with screws through it?  You want to effectively black out the screws and the steel plate by painting over those areas on the glass?

If the paint's going to be on the back side of the glass you don't really need to worry about the paint getting worn or scratched so just about any rattle can of paint should work - as long as the glass is clean and dust-free.  I think when they black out around the edges of automotive glass they etch the area they're going to paint to ensure a good bond for the paint.  However I don't think this tablet will need to survive the exposure to the elements that automotive glass needs to survive.

Don
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Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #38 on: July 25, 2018, 01:56:13 PM »
So the glass plate will be on the outside of the tablet in front of the steel plate with the important hardware screwed on the back side of the plate with screws through it?  You want to effectively black out the screws and the steel plate by painting over those areas on the glass?

If the paint's going to be on the back side of the glass you don't really need to worry about the paint getting worn or scratched so just about any rattle can of paint should work - as long as the glass is clean and dust-free.  I think when they black out around the edges of automotive glass they etch the area they're going to paint to ensure a good bond for the paint.  However I don't think this tablet will need to survive the exposure to the elements that automotive glass needs to survive.

Don

The problem i've got is that the glass is also going to be a structural part to some degree, since it'll stop the display falling out forwards. And whatever paint I use will be between whatever adhesive I use to stick it to the steel. I guess it's still not going to be taking a whole load of pressure from the display so I could do some tests with the rattle cans i've got. I'm just assuming any old paint would practically fall off the glass.

Offline awemawson

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Re: DIY tablet computer, maybe.
« Reply #39 on: July 25, 2018, 02:56:47 PM »
But the solvent in the adhesive may well react with the paint and either wrinkle it or not bond at all. You need to experiment with samples.
Andrew Mawson
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Offline PekkaNF

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Re: DIY tablet computer, maybe.
« Reply #40 on: July 25, 2018, 03:12:37 PM »
Think that painting the glass is risky...I remember one design that needed something like that and design was between etching the glass or masking it, sandblasting and painting with epoxy.

Is it possible to paint metal rim and all that hardware behind the glass black? Tape is pretty transparent and probably attaches better to painted metal than painted glass.

The Tesa tape I use seems to be compatible with most of the paints, but reacted with one 2k alkyd paint (blistering).

Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #41 on: July 25, 2018, 03:39:52 PM »
I'm glad I asked because I didn't even consider the tape reacting with the paint.

The hole in the plate was fairly crudely cut out, and I mesured the display wrong so there's a gap around the top and bottom too. I mean it's entirely concerns about how it looks so I could settle for this thing looking crude. I'm fairly sure it's going to anyways.

I took a closer look at those arts and crafts paints and it turns out they're a type you bake on in an oven, and are advertised as dish washer safe. So that's probably plenty strong. But worth testing with the tape.

Offline ddmckee54

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Re: DIY tablet computer, maybe.
« Reply #42 on: July 25, 2018, 05:06:52 PM »
Depending on how "nasty" the solvents are that you are going to use with this, then your best option would probably be to sandblast the areas that are going to be painted to provide some tooth for the paint.  Then using an epoxy paint should provide the best resistance to solvents.

Personally, I think I'd just try cleaning the glass REALLY well, painting it with a good quality brand rattle can paint and assemble it, maybe baking the glass at a very low temperature for a while to be sure all the solvents are driven off before assembly.  Worst case you've got to peel the tape off the steel plate before you try it again and maybe get some more glass.

Don
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Offline nrml

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Re: DIY tablet computer, maybe.
« Reply #43 on: July 26, 2018, 02:05:08 AM »
Instead of etching and painting the glass, why don't you get a vinyl sticker in the colour of your choice cut out on a plotter-cutter and stuck down. It would be cheaper, easier and probably tidier. It wouldn't need more than a good clean and degrease before sticking down. It wouldn't take you long to get a template drawn and emailed off to a sign-writer or similar on ebay. Vinyl stickers are used on plastics very widely. The probability of chemical damage occurring is far less than with paint.

Here is the 3M VHB tape design guide. They have a lot of very useful data sheets and videos if you do a quick search. http://multimedia.3m.com/mws/media/441448O/vhb-tapes-design-guide.pdf
Sorry for going on about it. I can't help feeling that it would be just the ticket for your project. Page 14 might be interesting to you.

Offline PK

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Re: DIY tablet computer, maybe.
« Reply #44 on: July 26, 2018, 02:18:14 AM »
Think that painting the glass is risky...I remember one design that needed something like that and design was between etching the glass or masking it, sandblasting and painting with epoxy.
Agree

We did a bunch of testing and what worked well for us was:
Sandblast
Paint immediately.
Paint
Paint
Paint
Cure for a long long time
Glue with a non rigid, non shrinking, neutral cure silicone. (I suspect tape with a little bit of thickness and flexibility would work better).

We've just (ie this batch) given the painting away and now bond a thin, opaque, layer onto the back to create the mask effect. It gets put in the squish-o-matic to force air bubbles out..

PK

Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #45 on: July 26, 2018, 03:32:30 AM »
Instead of etching and painting the glass, why don't you get a vinyl sticker in the colour of your choice cut out on a plotter-cutter and stuck down. It would be cheaper, easier and probably tidier. It wouldn't need more than a good clean and degrease before sticking down. It wouldn't take you long to get a template drawn and emailed off to a sign-writer or similar on ebay. Vinyl stickers are used on plastics very widely. The probability of chemical damage occurring is far less than with paint.

Here is the 3M VHB tape design guide. They have a lot of very useful data sheets and videos if you do a quick search. http://multimedia.3m.com/mws/media/441448O/vhb-tapes-design-guide.pdf
Sorry for going on about it. I can't help feeling that it would be just the ticket for your project. Page 14 might be interesting to you.

Sign vinyl is a good idea. I was thinking about some sort of thin plastic sheet last night and I don't know why I didn't think of self adhesive vinyl. I can get that from a regular hobby store and it'll probably cut fine with a ruler and scalpel.

I'm interested to hear about this tape though. And adhesives in general. I like the general idea of adhesives but outside of wood glues and loctite i've had nothing but disappointment. But i've got high hopes for this tape doing what I wished hot glues could.

Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #46 on: July 30, 2018, 11:22:40 AM »
Not a whole lot of progress. Still waiting on that glass. The guy that cuts mirrors, which are in the same order, is off work for personal reasons. I'm not in a huge hurry though since i've got a few other things i'm trying to get done.


The back plate is just solid right now, but once I figure out where things aught to go i'll start cutting bits out of it to lighten it.


The first attempt at these stand-offs were a complicated part with a thread cut in one end and a screw hole in the other. I made one before realising it'd be alot easier to just part the bar off, tap a hole through it, and use a bit of threaded rod on the bottom. Need to get some countersunk screws too.

Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #47 on: July 30, 2018, 01:17:49 PM »
Sides cut and welded on.


You can see how the stepped sides work. A sleek and modern device for 2018.


The top still seems to be somewhat flat as far as I can tell. It's as flat as that plywood bench at least. I found a cheap Clarke mig welder earlier this year with a broken trigger and i've not had an excuse to roll it out much till now. I'm getting a sooty weld which as far as I know means the gas flow is too high.

Offline awemawson

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Re: DIY tablet computer, maybe.
« Reply #48 on: July 30, 2018, 01:59:34 PM »
Simon,

Have you an idea what this is going to weigh? You may need muscles like Super Man  :clap:
Andrew Mawson
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Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #49 on: July 30, 2018, 03:01:47 PM »
Simon,

Have you an idea what this is going to weigh? You may need muscles like Super Man  :clap:

It's already pretty hefty and it's just the shell!

Offline vtsteam

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Re: DIY tablet computer, maybe.
« Reply #50 on: July 31, 2018, 10:51:21 AM »
I like it!  :thumbup: :clap:


Also, good to have on hand in case of a need for self defense. Remember Odd-Job and his hat?
I love it when a Plan B comes together!
Steve
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Re: DIY tablet computer, maybe.
« Reply #51 on: July 31, 2018, 10:55:31 AM »
I'd probably have tried riveting over those standoffs. Just put a shoulder on one end, make it a little long, and tap artfully with a ball pein hammer.

If you want to get fancy, lightly countersink the sheet metal, then rivet over the stud, and finally file flat.
I love it when a Plan B comes together!
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Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #52 on: August 01, 2018, 08:47:42 PM »
I'd probably have tried riveting over those standoffs. Just put a shoulder on one end, make it a little long, and tap artfully with a ball pein hammer.

If you want to get fancy, lightly countersink the sheet metal, then rivet over the stud, and finally file flat.

I considered that back when I was planning on making it from aluminium. My concern was hitting the top with a hammer possibly warping it, but that's probably less of a concern after switching to steel and welding it.

That magic tape arrived today. I went for GPH-060GF since it was the cheapest I could find. It's one of the lower strength varieties I think.



It's been like this all day. I can see its real strength is the foam core preventing it from 'peeling', but it's still pretty impressive.

I've found that with adhesives the real test isn't how strong it is trying to rip it apart, but instead how well it holds over time. Maybe if I was smarter the datasheets might already tell me that.

Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #53 on: August 04, 2018, 03:55:42 PM »
Green paint from a spray can because it's what I have. It's not very good paint and runs easily.


I did a little test and the tape seems to hold to it. But not sure how it'll work in the long run but I can't imagine it'll be too bad. I'll bake it in the oven for a bit tomorrow to hopefully drive off all the solvent.

The handle area is crudely carved out with a forstner bit. I've got that router table and templates would've done a nicer job. But it's currently buried behind my main bench with stuff on it.


I didn't really think too far ahead with the handle in terms of how I was going to actually attach it. Probably just going to glue the bottom piece on with a single screw in the middle, and then the top part can also screw on. I'll drill some holes through the bottom part to reach the screws for the top panel. I don't think I did a very good job with it. I don't think I did a great job with any of this really! But i'm more concerned about the function.

Offline PekkaNF

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Re: DIY tablet computer, maybe.
« Reply #54 on: August 04, 2018, 05:23:16 PM »
I do many projects same way. I call first iteration POC (Proof of concept). I think my daugter inherited it from me: For a anime sword, she did first some drafts, then drew it 1:1, then we made very crude model from pine board (just to see if the length is fine, parts look about right size etc.) then she whitled some parts to see how thy would be on 3D, because many stuff is very different on comics pages. AND THEN we started working on plugs to make moulds, to make parts....

I'm very happy to leave details to "next model"....until I am happy with basics. I guess my design process is recursive  :scratch:

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Re: DIY tablet computer, maybe.
« Reply #55 on: August 05, 2018, 10:51:11 PM »
I do many projects same way. I call first iteration POC (Proof of concept). I think my daugter inherited it from me: For a anime sword, she did first some drafts, then drew it 1:1, then we made very crude model from pine board (just to see if the length is fine, parts look about right size etc.) then she whitled some parts to see how thy would be on 3D, because many stuff is very different on comics pages. AND THEN we started working on plugs to make moulds, to make parts....

I'm very happy to leave details to "next model"....until I am happy with basics. I guess my design process is recursive  :scratch:

Yeah thinking about this, I think it's the way to go.

Tomorrow i'm just gonna stick that glass on, not bothering trying to blank the borders. My concern with vinyl is just how to get it evenly stuck down. I imagine a rectangle with thin borders would be a bit fiddly to get applied right. I also bought some of that glass paint but it's not very opaque, which I should've expected. A 'real' paint and sandblasting to get a better grip seems like the best way to go in that regard. But then the other problem is how to even line it all up with the active area of the display.

I'm probably also going to give the whole motherboard thing a miss since I'm not sure if it even works. And in reality it'd be more useful hooked up to my desktop. I'm just nervous about the thing dying at some point since it's getting pretty damned old at this point. I'd complain more about the lack of real progress in PC hardware over the last few years but really it's a great thing for not having to worry about biannual upgrades to still have a useful PC!

Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #56 on: August 06, 2018, 07:02:43 PM »
And I did exactly that.



That gap along the top may be because the display isnt sitting fully flat against the glass. I was hesitant to put foam on top of the circuit board since I figure that might be delicate. And I need to fuss a bit with getting the right amount, as well as making sure there's actually room for the display cable. And I need to double check the glass is actually flat before I try forcing the display against it.



The handle has a coat of shellac on it. I've heard that shellac when stored dissolved for a while becomes uncurable. But i've yet to have that problem with this bottle I dissolved a couple years back.



The keys are from an old electronic calculator - if it ain't obvious! Kinda wish I put them a bit higher up on the upper cluster though. That microcontroller has been through the wars so i'll be surprised if it still functions.


Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #57 on: August 07, 2018, 06:14:30 PM »


Got the back plate cut. More of an odeal than I expected. The only thing actually attached is the display controller board in the lower left. I'm going to mount it with studs so I can adjust the height to hopefully clear the connectors over the top of the motherboard.

Little concerned about the inverter. I figure that'd be a source of interference if its too close to anything important. I'm also a little concerned about the insulation on that shrink tubing, even though I doubled it up. It'll probably end up sitting on top of the hard drive, maybe with a bit of grounded tin in between.

All I've gotta make now is a few bushings to raise the motherboard up a bit... and then the heatsink. I also wish I thought a little further ahead and drilled holes into the case for the exit vent and input/ output sockets, since i'll need to take it all apart again.


The heatsink... you can buy heat pipes and I guess solder them. They seem like they might be tricky to solder but i've got a gigantic burner. For the fins i'm considering cutting up a whole bunch of pop cans to make the vanes and just holding them together with a press fit on the heat pipe, since that's how they seem to construct alot of the real ones. Maybe I could make a little swaging die too to punch and stretch the holes.

Also gonna look on ebay for a 12 volt adapter. I was hoping i'd find one at the boot sales. Then I can actually test to see if the display works before really worrying about going further on the computer side.

Offline nrml

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Re: DIY tablet computer, maybe.
« Reply #58 on: August 08, 2018, 05:05:09 PM »
Nice work. This is certainly a very unique project. I've never seen anything quite like this and I mean that in a good way.

Judicious use of guitar shielding foil should sort out interference problems.
How about arctic silver thermal epoxy for building the heat sink. It wont be as efficient as a soldered joint but is likely to be far less of a hassle to put together.

Offline krv3000

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Re: DIY tablet computer, maybe.
« Reply #59 on: August 08, 2018, 05:28:33 PM »
in a word brill

Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #60 on: August 08, 2018, 05:39:57 PM »
Nice work. This is certainly a very unique project. I've never seen anything quite like this and I mean that in a good way.

Judicious use of guitar shielding foil should sort out interference problems.
How about arctic silver thermal epoxy for building the heat sink. It wont be as efficient as a soldered joint but is likely to be far less of a hassle to put together.

That's not a bad idea at all. I've also seen heatsinks where the heat pipes are flat against the CPU with the plate holding them together on top, so maybe the loss in efficiency won't be a huge deal.

Wish I could tell if it was the CPU or motherboard that's at fault, if its even a fault at all. I'm considering putting that CPU inside my desktop since it'd be compatible but I kinda feel this computer is held together at this point by the dust caking the boards. I think Windows triggers the software protection if you switch CPUs out too but I only need to get as far as the POST.

Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #61 on: August 08, 2018, 06:22:31 PM »
I'm glad I did that even though it was terrifying. I thought i'd bent some pins on my CPU socket but i've got a foggy memory of thinking that when I first assembled the PC too - they just look weird.

So the CPU I bought is junk. Perhaps because it was sent in a paper bag but it might've been toast before that. I'll have to see if this place will accept it back without a fuss. What actually are my rights on this matter. I've never really pursued returning faulty items before but this one has me genuinely annoyed.

Thinking about bent motherboard pins. The first PC I ever tried to build I got sold a duff motherboard with a bent CPU socket pin. I was 13 or something at the time though so I couldn't really argue my point in returning it, and the guy insisted that I must've tried put the CPU in sideways or upside down or something. I got got.

Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #62 on: August 09, 2018, 04:57:04 PM »
12 volt AC adapter arrived today. I'm glad 12 volt adapters seem to be fairly standard in connector size.


I got so excited I forgot how to draw.

It's a TN display so the viewing angle isn't great.


You can also see where the top isn't entirely flat and the tape hasn't stuck. I managed to get some swarf into the gap too when drilling a dimple to clear a screw and it's now a permanent feature. Other problems are a fair bit of latency which could be from the controller board. I suspected something like that might happen.

And finally the cursor is... perfectly aligned. I think i'd like it offset a bit to the upper left of the pen nib to compensate for parallax and so the pen isn't actually obscuring it. The Wacom drivers are surprisingly sparse in features so i'd probably need to do that through the waxbee config thing for the microcontroller, which has some baffling options.

It's weird but i've gotten fairly used to my non display pen tablet and i'd consider not having your hand blocking the image a huge advantage. I actually find that a bit of a hassle when drawing on paper too, not that I do it alot.

Seems like alotta complaints. I'm really excited it works but there's still alot to fuss with to get it finished. I didn't ever expect it to replace my regular tablet though and so far it seems ideal for what I want it for - inking. Despite the screen latency the pen is very responsive with a good pressure ramp (or whatever you'd call it) and no jitter. Most of the wobbles in that doodle were from my hand sticking to the glass. You can actually buy cotton gloves for your ring and little finger to prevent that. They're often coupled with the commercial pen displays.

Offline awemawson

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Re: DIY tablet computer, maybe.
« Reply #63 on: August 09, 2018, 05:08:20 PM »
 :thumbup: :thumbup: :thumbup:
Andrew Mawson
East Sussex

Offline krv3000

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Re: DIY tablet computer, maybe.
« Reply #64 on: August 09, 2018, 05:46:20 PM »
nice

Offline nrml

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Re: DIY tablet computer, maybe.
« Reply #65 on: August 10, 2018, 02:15:16 PM »
Very nice indeed :thumbup:.

Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #66 on: August 12, 2018, 09:29:43 AM »
Thanks for the comments!


I've been kinda delaying doing more on this as I try figure out what I even want to do with it. Plus I need to go get some coaxial DC connectors and the cars booked in the garage for tomorrow.

Gonna give the PC part a miss for sure. I think the display really isn't very good. It's fine for what I need it for, but even as a proof of concept I don't think it'd prove much since it's such old technology. As a regular pen enabled display theres not much going for it as theres fairly cheap IPS pen enabled displays from China out now. And for the computer side of it the motherboard I've got is a few generations old and of a format that seems to have been ditched by the manufacturers.

It seems like intels NUCs and equivalents really took off though and are still making gains. I've heard they're becoming popular in offices for their small size and low power consumption. Intel are also releasing the occasional gaming oriented NUCs with hefty price tags and heftier power consumptions but i'm not sure if that's going to last since they get middling reviews and are more of a gimmick or curiosity than anything serious.

The obvious option would be to try get ahold of a somewhat modern laptop and borrow the internals from that. But again that won't prove much since whatever i'd make would be specific to that one laptop. I like the idea of standard motherboard sizes and connectors since it gives room to switch parts out, say if I start with an old and shoddy NUC to see if it'll work and then maybe save up to get the latest greatest thing.

As for displays. There's all kinds of stupidly high resolution IPS displays about now. I'm still taking a look through them to see whats available in spares. eDP has really caught on and theres a bunch of guys making way more compact controller boards for them. I think it's more of a pass through for regular displayport with a few extra bits for lighting the backlight, and while that kind of stuff is well beyond me but they openly post their designs to copy. Then the digitizer boards from older displays easily disconnect from the display itself, and perhaps if I can find one that matches the display size or is a little oversized then it'll fit behind a modern display just fine.

Either way I think the next thing will be making that 3d printer. Rapid prototyping is what they were designed for!

Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #67 on: August 12, 2018, 10:59:16 PM »
https://www.dfrobot.com/product-1728.html

Looks like this thing is set to release next month. It seems pretty good with built in eDP. Can't find actual board dimensions yet, but seems like something to keep an eye on. Edit: Dimensions are 79x115mm

I've also had no luck so far finding an affordable modern and relatively large IPS display with eDP. There might be a better way to serch for them, but i'm mostly trying to find various laptops and tablets that use them and looking up spares specific to those to then find the actual panel number from.

However the 9.7 inch ipad 3 & 4 displays are extremely available and relatively cheap. I guess because they sold so many there's skips full of broken ones to pull spares from. And this digitizer I already have is about the right size to match, being just slightly bigger. Could be a good way to assemble a more portable tablet.

Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #68 on: August 13, 2018, 01:58:51 PM »
Back to reality for a bit. Had a hard time sleeping last night so with the car in the garage I kept myself moving so I wouldn't calcify, and got a bunch done.


Made a stand and stuck that screen protector on. Went for a more upright stand (60 degrees) since it leads to a more comfortable posture than hunching over the thing. I put some rubber feet on the stand and with the weight of the device it doesnt move at all.

I also had it apart to drill holes for the two connectors at the top and... what a chore. If I thought a bit ahead I would've realised I could just put the connectors in the base and save myself having to drill some large holes in sheet steel with an incredibly fast but low torque drill and the wrong kinds of bits.


No matter what I tried I couldn't get all the dust off. I think just the act of wiping the screen was statically charging it and every speck and shard in the area flew onto where i'd wiped. This image also shows how the screen protector blurs the image a bit, but in a way that hides the pixels and gives it a cool look.


Messed around with the display settings a bunch and it vastly improved the image. The camera of course doesn't pick it up well but by default the greys were appearing extremely blue. Not as blue as in some of the photos though - I just forgot to hit the white balance. I'm also surprised that laptop can handle Krita's ~fancy brushes~. They give me a bit of trouble on my desktop if I go wild trying to fill an image with a complicated smudging brush so I didn't think the laptop would handle them at all, let alone as well as it does.


It also tucks neatly under the stand. This wasn't by design but i'm glad it fits!


I also cut apart an old test glove I had sitting on the desk to make one of those goofy tablet gloves. I thought they were for pedantic people that didn't want to get grease on their display, but it turns out it really helps stop your hand from chattering along the display surface.

So i'm back to feeling pretty pleased with how this is turning out. At some point I need to try program the arduino microcontroller to emulate keyboard shortcuts. It's soldered up but I don't know if it even still works. It was playing up last time I tried using it to mesure a potentiometer.


Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #69 on: August 14, 2018, 06:46:53 AM »
Boy i'm no good at scripting. What i've managed to create is a very dangerous USB device that when plugged in immediately starts hammering undo as fast as possible. I think i'm going to have to try disable the shortcut so I can actually reprogram the board.

Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #70 on: August 14, 2018, 09:11:34 AM »
Turned out the trick was to save and exit so there was nothing to undo before uploading the new program.

Seems like i've made some progress though. All my troubles were caused by a stupid syntax error in the if statement that made it ignore the query and just spam the function inside as fast as possible. I was puzzling over if the device was broken since I had a real hard time in the past trying to read a potentiometer value. So now I just need to copy this function 20 times for each shortcut I want to slap in.

Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #71 on: August 14, 2018, 11:17:12 AM »
Nice. Now it's working for reals. Got undo and redo set to keys. The problem I had is that theres a function to start the keyboard press, and a function to end that keypress. But because alot of the key combos share a key (ctrl) then having each individual function doing its own 'else - end key press' thing was mucking it up. So now i've got a bunch of integers to keep track of if a key has been previously pressed before running the release function once.

Or something. I'm not great at programming.

Now I just need to figure out what shortcuts are worth assigning to buttons.


Since the thing also works as a plain old digitizer with the display off, i'm considering the idea of ditching both my second desktop monitor and the old graphics tablet and using it to fill both roles. I'm always fighting for desk space so something you'd need to slide around and drag through the piled up junk wouldn't be ideal. Perhaps a cantilevered arm. But even if you could lock it it's not going to be very solid. Gives me something to think about while I type out this stupid function 15 more times.

Offline S. Heslop

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Re: DIY tablet computer, maybe.
« Reply #72 on: August 15, 2018, 08:05:41 AM »
I've been all about trying to find a damned displayport cable with no success.

It's something I get hung up on actually, that physical shops never stock anything small that they wont be selling at least one a day. But they could just shove one of them in the store room or on the bottom of a shelf and it'd justify my trip out and maybe make me want to visit that shop again. They're all wondering why the internet has killed the highstreet but the internet is innocent of that crime - the highstreet committed suicide.

That said I enjoyed the trip out just driving about. There's a new radio station thats some combination hospital and student radio, but I think they might be breaking the law since they're playing Good Music.

Offline Will_D

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Re: DIY tablet computer, maybe.
« Reply #73 on: Today at 08:39:47 AM »
There's a new radio station thats some combination hospital and student radio, but I think they might be breaking the law since they're playing Good Music.

I highly recomend Radio Nova in Dublin - plays our sort of music! Any station that plays Thunderclap Newman and the Doors has to be #1

https://www.nova.ie/radio-player

Will
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