Giving A Proprietary Power Supply The Boot

February 2, 2025 by 29 Comments

You’ve probably noticed that everywhere you go — the doctor’s office, hotels, or retail shops, there are tiny PCs everywhere. These small PCs often show up on the surplus market for a very good price, but they aren’t quite full-blown PCs. They usually have little option for expansion and are made to be cheap and small. That means many of them have custom and anemic power supplies. We aren’t sure if [bm_00] needed a regular power supply to handle a graphics card or if the original power supply died, but either way, the HP small-form-factor box needed a new power supply. It took some clever work to be able to use a normal power supply in the little box.

At first, we thought this wouldn’t be much of a story. The motherboard surely took all the regular pins, so it would just be a matter of making an adapter, right? Apparently not. The computers run totally on 12V and the motherboard handles things like turning the computer on and off. The computer also was trying to run the power supply’s fan which needed some work arounds.

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Wearables queen [Becky Stern] with a microcontroller and a speaker. And a skull!

Wearable Tech Tips Directly From The Queen

February 2, 2025 by 8 Comments

What’s the only thing cooler than building something electronic? That’s right — wearing it proudly for all to see.

But maybe you’re not into wearables. Maybe it’s because you’re afraid of sewing, or simply scared that you won’t be able to launder that blinkenshirt you’ve always wanted to make. Well, the undisputed queen of wearables — [Becky Stern] — has a bunch of beginner tips for making DIY wearables. She’s created dozens and dozens of wearable projects and matching tutorials over the years and has graced these pages many times.

As [Becky] points out, once you have your idea sorted, the next thing you need is the tools to get the skills to do the parts you don’t know how to do yet. Even if that’s almost all of it, then this is the guide for you. Importantly, [Becky] reminds us that we should only bite off what we can chew, and that ready-made modules and such are perfectly fine.

There are some tips here that may surprise you. For instance, [Becky] recommends against conductive thread for beginners who already know how to sew by hand, largely because of power delivery and other issues. She also is somewhat anti-lithium battery pouch, preferring instead to use a couple of AAs or a USB battery bank for the renewability aspect.

Be sure to check out the video after the break, which has these tips and more.
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Custom Smartwatch Makes Diabetes Monitoring Easier For Kids

February 2, 2025 by 21 Comments

Living with Type 1 diabetes is a numbers game. There’s not a moment in the day free from the burden of tracking your blood glucose concentration, making “What’s your number?” a constant question. Technology can make that question easier to ask and answer, but for T1D patients, especially the kids who the disease so often impacts, all that tech can be a distraction.

To solve that problem for his son, [Andrew Childs] built this custom T1D smartwatch. An Apple Watch, which integrates easily into the Dexcom CGM ecosystem, seems an obvious solution, but as [Andrew] points out, strapping something like that on a nine-year-old boy’s wrist is a recipe for disaster. After toying with some prototypes and working out the considerable difficulties of getting a stable BLE connection — the device needs to connect to his son’s iPhone to get CGM data — [Andrew] started work on the physical design.

The watch uses an ESP32-S3 on a custom PCB, as well as a 1.69″ TFT IPS display and a LiPo battery. The board also has an accelerometer for activity monitoring and a vibrator for haptic feedback. Getting all that into a case was no mean feat, especially since some degree of water resistance and shockproofing would be needed for the watch to survive. [Andrew] had a case made by a local 3D printing company, and he managed to source custom-cut and silkscreened glass for the face. The result is remarkably professional-looking, especially for a software developer who hadn’t really stretched his maker wings much before tackling this project.

[Andrew] doesn’t appear to have made build files available yet, although he does say he intends to open-source the project at some point. We look forward to that as it’ll be a big help to anyone trying to hack diabetes care. Until then, if you need a primer on continuous glucose monitoring, we’re happy to oblige.

Tiny RC Four-Wheeler Gets Chassis Upgrade For More Traction

February 2, 2025 by 9 Comments

[Azpaca] purchased a fun little toy car from Tamiya, only… there was a problem. The little off-roader wasn’t up to scratch—despite its four-wheel-drive, it couldn’t get over rough ground to save its life. Thus, it was time to 3D-print a better chassis that could actually get through it!

The problem was quite obvious. With no suspension and a rigid chassis, the vehicle would tend to end up with one or more wheels on the air on rough surfaces. To rectify this, [Azpaca] created a twisting chassis which would allow the wheels to better remain in contact with the ground. The design is relatively straightforward, and reuses much of the original drivetrain, including the simple brushed motor. However, with a pivot right behind the front wheels, it has much more traction on rocks and gravel, and can traverse these terrains much more easily.

Tamiya’s motorized toys aren’t particularly well known in the West, but it’s neat to see the community that exists around modifying them around the world. Design files are available for the curious. If you’re not down with mods, perhaps you’d prefer to print your own cars from scratch. Video after the break.

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Inside A Vintage Oven Controlled Crystal Oscillator

February 1, 2025 by 8 Comments

Crystal oscillators are incredibly useful components, but they come with one little snag: their oscillation is temperature-dependent. For many applications the relatively small deviation is not a problem, but especially for precision instruments this is a deal breaker. Enter the oven controlled crystal oscillator, or OCXO. These do basically what it says on the tin, but what’s inside them? [Kerry Wong] took apart a vintage Toyocom TCO-627VC 10 MHz OCXO, revealing a lot more complexity than one might assume.

Inside the insulated enclosure there is of course the crystal oscillator itself, which has a heating coil wrapped around it. Of note is that other OCXOs that [Kerry] took apart had more insulation, as well as other ways of providing the thermal energy. In this particular unit a thermistor is attached to the crystal’s metal case to measure its temperature and provide feedback to the heating circuit. The ICs on the PCB are hard to identify due to the conformal coating, but at least one appears to be a 74LS00, alongside a 78L05 voltage regulator which reduces the 12V input voltage.

As an older OCXO it probably is a lot chunkier than newer units, but the basic principle remains the same, with a heating loop that ensures that the crystal inside the unit remains at the same temperature.

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Using Microwave Heating To Locally Anneal CNT-Coated FDM Prints

February 1, 2025 by 19 Comments
The CNT coating between the layers is heated with microwaves to locally anneal. (Credit: Sweeney et al., Science Adv., 2017)

Layer adhesion is one of the weak points with FDM 3D printing, with annealing often recommended as a post-processing step. An interestingly creative method for this was published in Science Advances back in 2017, featuring the work of researchers at Texas A&M University and citing previous work by other teams. In the paper by [Charles B. Sweeney] et al, they describe how they coated PLA filament with carbon nanotubes (CNTs), resulting in this CNT being distributed primarily between the individual layers of polymer.

This is useful because CNTs are quite sensitive to microwave radiation, resulting in the conversion to thermal energy, i.e. heat. Compared to traditional annealing where the entire part is placed into an oven or similar, this microwave-based heating – or locally induced RF (LIRF) as they call this method – localizes the heat to the interface between two layers.

The advantages of this approach are that it doesn’t change the dimensions of the part noticeably, it’s faster and more efficient, and the annealing between layers approaches the strength of traditional manufacturing. Unfortunately not too much seems to have happened with this approach since then, but considering that both CNTs (single & double-walled) and microwaves are readily available, there’s not much standing in the way of replicating these results.

Could Non-Planar Infill Improve The Strength Of Your 3D Prints?

February 1, 2025 by 24 Comments

When you’re spitting out G-Code for a 3D print, you can pick all kinds of infill settings. You can choose the pattern, and the percentage… but the vast majority of slicers all have one thing in common. They all print layer by layer, infill and all. What if there was another way?

There’s been a lot of chatter in the 3D printing world about the potential of non-planar prints. Following this theme, [TenTech] has developed a system for non-planar infill. This is where the infill design is modulated with sinusoidal waves in the Z axis, such that it forms a somewhat continuous bond between what would otherwise be totally seperate layers of the print. This is intended to create a part that is stronger in the Z direction—historically a weakness of layer-by-layer FDM parts.

Files are on Github for the curious, and currently, it only works with Prusaslicer. Ultimately, it’s interesting work, and we can’t wait to see where it goes next. What we really need is a comprehensive and scientific test regime on the tensile strength of parts printed using this technique. We’ve featured some other neat work in this space before, too. Video after the break.

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