Log The portaNUC - turning a NUC into a UMPC handheld system

[Choidebu]

I'll save you the hassle of rolling out your own ups solution.

My opinion since couple years ago: below 100W application, just get a powerbank that supports PASSTHROUGH charging.

This means you can charge your device while the powerbank itself is charging. Look for powerbanks with dc out. Something like this.

Once you're happy with it disassemble and fit to your case.

 

[CC Ricers]

I'll save you the hassle of rolling out your own ups solution.

My opinion since couple years ago: below 100W application, just get a powerbank that supports PASSTHROUGH charging.

This means you can charge your device while the powerbank itself is charging. Look for powerbanks with dc out. Something like this.

Once you're happy with it disassemble and fit to your case.

Is there a power bank with pass-through charging that supports up to 60W and that fits the tiny form factor I'm going for? Disassembling it would help, but I'm also trying to fit this hardware inside a footprint about the size of a 7-8 inch netbook lol. And remember the motherboard must also fit there too.

That size constraint I feel is gonna dictate how much I use the DIY approach. It would be about the size of this other home-made handheld device (not counting the controller parts). But it can be somewhat thicker though, like 30 to 35mm.

I don't need too much capacity... I'd be satisfied if I can manage to get 70-80 watt-hours for now, which is 2 hours of usage assuming a constant 35-40W load (this is what I measured at the wall for gaming and benchmarks).

I was also reading @timginter 's thread on making a portable PC and while his power requirements are larger, my approach would have been a downsized version of what he had planned. I was thinking of a 4S pack with 18650 or 21700 cells. Excluding the balance board, this is generally the footprint I want to achieve for power components (in total square cm/in, the dimensions can be made flexible). NUCs take a wide voltage input so no step-up or down converter is necessary.

 

[Choidebu]

Dc out powerbanks do usually comes in larger sizes, yes, because they are marketed as 'laptop powerbank'.

If you are concerned about dimensions, I think it's trivial to disassemble and reconfigure the cells; e.g. reduce the number of paralel groups, 4p to 2p etc.

Being laptop powerbank 60W should be trivial. Only downside I see is that neewer models tend to use usb-c so a pd negotiatior might be needed and prob incur some efficiency loss.

 

[CC Ricers]

Dc out powerbanks do usually comes in larger sizes, yes, because they are marketed as 'laptop powerbank'.

If you are concerned about dimensions, I think it's trivial to disassemble and reconfigure the cells; e.g. reduce the number of paralel groups, 4p to 2p etc.

Being laptop powerbank 60W should be trivial. Only downside I see is that neewer models tend to use usb-c so a pd negotiatior might be needed and prob incur some efficiency loss.

I think I know what you mean, I've also seen people take apart battery packs from discarded laptops to use the cells for their own configs.

For adapting USB-C, do you mean like a fast-charge trigger to spoof the charger such as this one? If this would work, that should easily fit in my build. I would probably integrate the outlet as part of the case or use a removable barrel connector like a patch cable.

 

[CC Ricers]

In the meantime I will be moving forward with buying a 7" IPS display for the handheld.

There are many 7" touch screen displays mainly designed for Raspberry Pi and general purpose use. They are all similar but with subtle differences in ports and circuit layout. Lamentably, all of these are not slim enough to fit in my project. It was hard to find the thickness of these displays, but a few listed in the specs as 15mm including the ports. I settled for a non-touch display because it was a very good price, and in a thinner case. Plus, it has speakers!

While I could just get a bare 7" display with control board, all the boards I've seen for these displays are too bulky for my needs and take up too much room that would used better for power or cooling.

I will add a touch screen overlay later on. By this time I would work on a custom frame for the screen anyways, so that the overlay fits with the screen.

 

[CC Ricers]

I have now received the monitor. I've already used it several times just to test it out and see how to navigate on Windows and Linux on such a small screen.


The monitor really is quite thin at 9mm. It's still not a touch screen panel but adding one should not add more than 1 or 2mm to the profile.

The casing is all metal. Two pieces, one solid piece that is milled out with screw holes and openings, and a metal sheet screwed onto the back. There's one good reason it's not plastic and you'll see why.

This just needs 4 Philips screws to remove the back. Control board is on the right, with a nice, slim profile, and the monitor buttons are on the left. There is a thermal pad (top right of the speakers) that sits above the main IC of the board when closed. This IC uses the back metal side as a heatsink.

If I were to completely remove the monitor from its casing I will need to use a different heatsink to stick on the IC, because the monitor does get warm to the touch when in use.


I have gotten two Samsung 4GB RAM sticks now, so the benchmark score is with dual-channel RAM.

The picture is very clear, great viewing angles given that it's an IPS panel. Just don't expect a smartphone quality panel here, it's still a LCD not a AMOLED. It was hard to take good pictures as it's so bright it just washes everything else out. While the monitor options let you change the brightness, contrast, and color balance, there doesn't seem to be a way to adjust the brightness of the backlight. It's always this intense.

The speakers were pretty disappointing, however. When plugged into the wall, the monitor speakers didn't sound that loud even at maximum volume. Still hard to hear some things in media players where you can push its maximum past 100%. I also have plugged in the monitor's USB power to one of the USB ports of the computer. The manual doesn't suggest it, but it does power the monitor fine (I have measured 5W powering it at the wall).

When it's powered by USB, the speakers begin to buzz and crackle in a matter of minutes. Could be from ground loop interference. I guess this is why the manual doesn't mention plugging it to one of the USB ports of the computer.

I may have to unplug the speakers for this build and figure out what I'll have to do for sound. There are better speakers for DIY projects but they can also draw more power, and I'll have to be mindful of that in a battery-powered setup.

 

[CC Ricers]

I'm gonna bite the bullet and buy some 18650 batteries for a battery pack. Possibly 3000 or 3500 mAh with at least 10A of discharge. And a battery management system to keep them balanced.

Going to use the daisy chain method to connect the BMS with the load and DC charging port.

 

[CC Ricers]

Looks like I'll kill two birds with one stone this time. I'm just going to buy this rechargeable 3000 mAh pack for now. It already has battery cells connected in series with BMS plus a USB charging port (which would be convenient to power the monitor with). And as @Choidebu suggested I can just take it apart as I customize the build further.

Also, I'm kind of at a crossroads of how I will design the case.

I could either go for a handheld system design which is just controller joysticks and buttons with the screen in the middle like the Aya Neo or the numerous Pi-based handhelds, or go with a mini laptop design like the recent GPD Wins. If I go the laptop route, controller buttons will be optional and I can use a mini Bluetooth keyboard for built-in input.

The design I choose to go with will totally depend on how well I can arrange the power source, screen, cooler, and motherboard with the most efficient use of space. However, I'm interested to see what other peoples' opinions on are on what their preferred form factor is.

 

[CC Ricers]

This is how I would like to position the main components in a handheld layout. The CPU heatsink cooler is offset to the side of the motherboard for a slimmer profile, with the screen height easily taking up the same height as both the other components.

The I/O ports are exposed well but the power jack isn't. A custom bezel is required for the screen in order to make it usable.

You can see here that the bezel of the screen takes up some height. If I were to remove it I might be able to shave off a few mm. Possibly.

For the cooling, the heatsink will have to be connected with another metal piece for heat transfer. Somewhere along the lines of a 2mm to 3mm thick strip made of aluminum or copper with thermal paste to make the contact between the metal parts. I actually don't know how effective this would be for cooling. It's something I would have to test out for myself.

 

[Valantar]

This is how I would like to position the main components in a handheld layout. The CPU heatsink cooler is offset to the side of the motherboard for a slimmer profile, with the screen height easily taking up the same height as both the other components.

The I/O ports are exposed well but the power jack isn't. A custom bezel is required for the screen in order to make it usable.

You can see here that the bezel of the screen takes up some height. If I were to remove it I might be able to shave off a few mm. Possibly.

For the cooling, the heatsink will have to be connected with another metal piece for heat transfer. Somewhere along the lines of a 2mm to 3mm thick strip made of aluminum or copper with thermal past to make the contact between the metal parts. I actually don't know how effective this would be for cooling. It's something I would have to test out for myself.

Looks great! Two points of feedback:
- Is the cooler positioned to exhaust downwards or upwards when handheld? The pics make it look like it's pointed downwards, which would make it very easy to block the exhaust if supporting the system on anything, so hopefully I'm just reading the pic wrong.
- A flat, thin piece of metal will do a very poor job of heat transfer - even over a relatively short distance the thermal resistance of something like copper is far too high for such an application. I would recommend you get a vapor chamber or "flat heatpipe" (they're called that on Aliexpress and similar sites some times) for shifting the cooler to the side. Something like this, perhaps?

 

[CC Ricers]

Looks great! Two points of feedback:
- Is the cooler positioned to exhaust downwards or upwards when handheld? The pics make it look like it's pointed downwards, which would make it very easy to block the exhaust if supporting the system on anything, so hopefully I'm just reading the pic wrong.
- A flat, thin piece of metal will do a very poor job of heat transfer - even over a relatively short distance the thermal resistance of something like copper is far too high for such an application. I would recommend you get a vapor chamber or "flat heatpipe" (they're called that on Aliexpress and similar sites some times) for shifting the cooler to the side. Something like this, perhaps?

That's some good feedback.
The cooler exhaust would point upwards when the unit is held, like the Nintendo Switch. Or, when sitting on a flat surface it will point away from you.

Side note: I don't even think intake holes are necessary for the back side because in the NUC case the cooler is on the top side, but there are no intake holes in the top cover. It gets intake from openings on the sides.

That's good to know about the heat transfer. So I guess it's heatpipes or nothing then. Thanks for the AliExpress link as it makes finding them much easier. I also heard about "Coolpipes" which are very thin and flexible that can be stuck to any metal surface and @aquelito used them before for some of his builds. Maybe that's just a brand name for the same pipes you mentioned?

Also, how would you fasten those pipes down. I can make my own mounting bracket to line up with the holes but I'm afraid of the pipes sliding around underneath them, between the thermal paste and pads.

 

[CC Ricers]

I've decided to go with a handheld mini PC layout, like GPD Win 3 and Aya Neo. Just with older hardware. It's no Vega, but the iGPU should be able to handle most PC games around 5 years or older fairly well with 600p and 720p screen resolutions on the small screen.

This form factor means there's now the added challenge of integrating physical controller buttons into the case and have it be detected as a XInput device. I will achieve this with a tiny Arduino board that stays powered on with USB.

Here's one possible layout using my NUC board and a similar cooler (I couldn't find the exact NUC cooler but has same outer dimensions), with how it might look arranged with a 4S1P battery setup.

Overall length: ~250mm, height: 110mm

The physical controls will be next to the left and right edges, laid above the motherboard and batteries. Keeping mind of the overall thickness of the whole thing I estimate around 30mm will be needed to fit all the face buttons and joysticks.

 

[Valantar]

I've decided to go with a handheld mini PC layout, like GPD Win 3 and Aya Neo. Just with older hardware. It's no Vega, but the iGPU should be able to handle most PC games around 5 years or older fairly well with 600p and 720p screen resolutions on the small screen.

This form factor means there's now the added challenge of integrating physical controller buttons into the case and have it be detected as a XInput device. I will achieve this with a tiny Arduino board that stays powered on with USB.

Here's one possible layout using my NUC board and a similar cooler (I couldn't find the exact NUC cooler but has same outer dimensions), with how it might look arranged with a 4S1P battery setup.

Overall length: ~250mm, height: 110mm

The physical controls will be next to the left and right edges, laid above the motherboard and batteries. Keeping mind of the overall thickness of the whole thing I estimate around 30mm will be needed to fit all the face buttons and joysticks.

Looks great, really looking forward to seeing how this turns out! Will you be disassembling the screen to slim down the build? I'm also curious about why you're choosing 18650s rather than something like an RC Li-Po pack - is it just for the sake of convenience and modularity, or are there other advantages?

 

[CC Ricers]

Looks great, really looking forward to seeing how this turns out! Will you be disassembling the screen to slim down the build? I'm also curious about why you're choosing 18650s rather than something like an RC Li-Po pack - is it just for the sake of convenience and modularity, or are there other advantages?

Yep, I already took the screen out of its frame so the profile can be as slim as possible. I'm ditching its speakers for now- see if I can find a fix around that otherwise the sound will be with headphones only.

It's mostly for convenience as I have found some 12V battery packs that have 18650 cells, charging circuit and BMS already built in. When I'm confident enough with how it's working, I can take it apart and put its components inside my case.

I might pursue LiPo batteries later on when I decide to build a pack from scratch. Maybe not from an RC pack- the RC batteries I've seen that are 4-cell and 3000mah and higher are too long. A form factor like this is much better- the longest side doesn't exceed the case width of 110mm and I can still stack 4 of them together.

 

[Valantar]

Yep, I already took the screen out of its frame so the profile can be as slim as possible. I'm ditching its speakers for now- see if I can find a fix around that otherwise the sound will be with headphones only.

It's mostly for convenience as I have found some 12V battery packs that have 18650 cells, charging circuit and BMS already built in. When I'm confident enough with how it's working, I can take it apart and put its components inside my case.

I might pursue LiPo batteries later on when I decide to build a pack from scratch. Maybe not from an RC pack- the RC batteries I've seen that are 4-cell and 3000mah and higher are too long. A form factor like this is much better- the longest side doesn't exceed the case width of 110mm and I can still stack 4 of them together.

Could something like this be an alternative for speakers? They're from the most recent DIY Perks video where he used them on a DIY portable monitor build.

 

[CC Ricers]

Could something like this be an alternative for speakers? They're from the most recent DIY Perks video where he used them on a DIY portable monitor build.

That may work if I can find a good spot to place it in. Same wattage and impedance as the stock speakers, but looks better built. Just gotta replace that JST 2 pin connector with a 4 pin to plug it.

There's a chance there's actually something wrong with the something in the screen's board because of the overwhelming hum that is drowning out the speaker sound. And when I listen through it with headphones on the screen's 1/8" jack, I get that loud hum too. Meanwhile the sound is perfectly fine with no unwanted noise in the NUC board's audio jack.

 

[CC Ricers]

I found this mini USB speaker that looks like it would be better to go with. Obviously it will occupy a USB port but I can use one of the internal headers to leave more external ones free.

Post update: instead of trying to figure out how to add a custom length heatpipe to move the cooler to the side, I think it would be easier to adapt a laptop heatsink with a pipe of the appropriate length and mount it with custom brackets. I went with the heatsink cooler for a Dell XPS 13 9350. Its CPU is a i5 6200U, very close to what I'm using, and the same TDP so it should work all right.

 

[CC Ricers]

Some work is still being done with this build, but progress has been slow because not a lot of new parts have been ordered yet. I did receive my laptop cooler, though, and it seems like it will work great. Its fan is the same diameter as the stock fan, but it won't be usable without an adapter, because the pins are a slightly smaller pitch. I'll probably stick with the stock fan.

I have measured the hole spacing of both the motherboard and laptop heatsinks, and with that I designed an adapter piece that will act as a spacer with the CPU to support the new heatsink.

Here's a render showing a mock placement of the parts inside a roughly shaped shell (bottom piece). The battery management board will go underneath the cooler, where the heat from the MOSFETs can be pulled away with the fan.

I also got some 4-pin Picoblade cables to use with the internal USB headers of the board.

One of the headers will be used for the screen. I soldered the wires to a USB micro connector as a replacement for the bulky USB cable that came with it.

And it's a success, the screen powers on with the new cable. I don't think the data wires are necessary for this screen, but for completeness I soldered them too. Now I just need to get a ribbon HDMI cable to completely reduce the clutter.

Next is the new heatsink. Here's a mockup of the heatsink placement with some very roughly placed aluminum pieces (totaling approx. 4mm in height) as a proof of concept with setting the heatsink. First with the heatsink only:

Then I slapped on the aluminum pieces with some thermal paste to line up the height to where the spacer would be.

This clearly isn't adequate for actual use. The metal is rough with a brushed finish and the heatsink isn't secured to anything. Not to mention the fan can't reach the fins to blow out the heat. But I was curious to see how well that heatpipe would draw away the heat. So I booted it up, to the BIOS.

Here's the actual system running with the rush job heatsink. The CPU temperature on the BIOS was 57C and climbing up to 65C. Yes it's on the hotter side but at least it works. I'm looking forward to see what actual performance temps are when I get the proper cooler setup done.

Making the spacer and getting the screws to attach everything with the cooler is my next priority. It's not clear from the pics, but the profile is indeed narrower. I have reduced it by about 5mm compared to the stock cooler

 

[Choidebu]

Great progress!

 

[CC Ricers]

Great progress!

Thanks!

Aside from the cooling, I need to start setting up power management. That's going to be the most high stakes part of this project. If I can get it to run on battery power, even as a pile of disassembled parts, the rest of the build should go much more smoothly.

One of my influences has been Project Scout, which is another x86 PC that was put inside a portable case with built in power and controls. He had Destiny 2 running on it, 3 years ago.

Unfortunately, he hasn't given updates on that anymore and moved on to other DIY projects. It runs on similar hardware though so it's a good reference point on what I could expect for power efficiency and performance.

Battery placement

Something else I noticed about the renders of that device is that the screen protrudes farther out than the handles. Maybe it's to fit the batteries in the middle of the case? I have the batteries located in the handles. The only thing that might be an issue with that is being able to fit the PCBs for the controls, especially the joysticks.

Controller input

Still on the fence whether to go full custom hardware with the help of a micro board like Teensy or Arduino, or disassemble a third party controller and try packing that one in. Weighing some pros and cons here:

Custom controller

Pros: Use the exact hardware and firmware I want, could even make it toggle between "mouse + keyboard" and "gamepad" modes if desired for better control over the desktop programs

Cons: Requires a wired USB connection which can take one away for something else like speakers or touch screen input. While Bluetooth support is possible it's also more difficult to program with a DIY controller project.

Third-party controller

Pros: Hardware is (usually) plug-and-play. You can have one as a Bluetooth device so it doesn't need to take up a USB port. That means a USB touch panel is more possible.

Cons: Requires manual disassembly. Using it like a mouse + keyboard requires third-party software. For BT controllers they also need to do their own power charging.