Dev Board Watch Takes Path Of Least Resistance

Building your own watch or clock is kind of a maker’s rite of passage. Once upon a time, if you went with a wrist watch, you’d typically work on producing your own compact PCB with everything crammed into a typical watch form factor, maybe relying on a simple binary output for compactness and simplicity. Times have changed, however, and [Arnov]’s design is altogether different in its construction.

The build relies on a XIAO ESP32-C3 microcontroller board as the brains of the operation. It’s paired with the XIAO expansion board. It’s designed as a carrier for the ESP32-C3, giving it a bunch of IO that’s accessible over readily-accessible connectors. It also features a display, a real-time clock, and a battery — pretty much the three main things you’d need to add to an ESP32 to turn it into a watch.

Thus, with the electronics pretty much done, it was simply up to [Arnov] to turn the device into a watch. He achieved this by screwing the frame and strap of an old Casio watch to a 3D printed carrier for the XIAO expansion board. With that done, it was simply a matter of writing the code to show the time from the RTC on the display. There’s no connectivity features, no smart stuff going on — just the time and date for your perusal.

Some might decry the project for simply slapping a watch band on a devboard. Or, you could look at how this indicates just how fast and easy development can be these days. Once upon a time, you could spend weeks trying to find a cheap display and then further weeks trying to get it working with your microcontroller. Now you can spend $20, get the parts in a few days, and get your project blasting along minutes later.

If you’ve done an altogether more ornate watch build of your own, we’d love to see that, too. Show us on the tipsline!

A Solar-Powered Wristwatch With An ATtiny13

Wristwatches come in many shapes, sizes, and types, but most still have at least one thing in common: they feature a battery that needs to be swapped or recharged somewhere been every other day and every few years. A rare few integrate a solar panel that keeps the internal battery at least somewhat topped up, as environmental light permits.

This “Perpetual” wristwatch designed by [Serhii Trush] aims to keep digitally ticking along using nothing but the integrated photodiodes, a rechargeable LIR2430 cell, and a power-sipping face that uses one LED for each hour of the day.

The face of the perpetual wristwatch. (Credit: Serhii Trush)
The face of the perpetual wristwatch. (Credit: Serhii Trush)

The wristwatch’s operation is demonstrated in the linked video (in Ukrainian, auto-generated subtitles available): to read out the current time, the button in the center is pressed, which first shows the hour, then the minutes (in 5 minute intervals).

After this the ATtiny13 MCU goes back to sleep, briefly waking up every 0.5 seconds to update the time, which explains why there’s no RTC crystal. The 12 BPW34S photodiodes are enough to provide 2 mA at 0.5 V in full sunlight, which together keep the LIR2430 cell charged via a Zener diode.

As far as minimalistic yet practical designs go, this one is pretty hard to beat. If you wish to make your own, all of the design files and firmware are provided on the GitHub page.

Although we certainly do like the exposed components, it would be interesting to see this technique paired with the PCB watch face we covered recently.

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A dress is shown in three shapes: the original, a slightly-heated A-line version, and a close-fitting body con version.

4D Knit Dress Skirts Waste

Regular 2D sewing of anything is inherently wasteful. You can align the pattern pieces however you want, but there’s going to be wasted everything — thread, fabric, and interfacing — whether you get it right the first time or not. Never mind the fact that people tend to create a muslin (prototype) first using inexpensive fabric (like muslin) for the purposes of getting the fit right.

A few examples of the lines than can be created.

The MIT Self-Assembly Lab x Ministry of Supply have come up with a 4D garment construction technique that minimizes waste while being pretty darn cool at the same time. They’ve created a knit dress that combines several techniques and tools, including heat-activated yarns, computerized knitting, and 6-axis robotic activation. The result is a dress that can be permanently molded to fit the body however and wherever you want, using a heat gun mounted on a 6-axis robotic arm.

As far as we can tell, a finished dress does not come off of the machine in the short demo video after the break. It looks like it still has to be sewn together, which creates some potential for waste, but absolutely nothing like conventional methods.

This is probably the coolest dress we’ve seen since the one covered in LCD panels.

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LED Choker Is A Diamond In The Junk Pile

Isn’t it great when you find a use for something that didn’t work out for the project it was supposed to? That’s the story behind the LED strips in this lovely blinkenlights choker by [Ted].

The choker itself is a 15 mm wide leather strap with holes punched in it. According to [Ted], the hole punching sounds like the absolute worst and hardest part to do, because the spacing of the holes must be greater than that of the LEDs to account for flex in the strap. [Ted] tested several distances and found that there is little margin for error.

Controlling those blinkenlights is a Seeed Xiao S3, which fits nicely behind the neck in what looks like a heat shrink tube cocoon. [Ted] chose this because there was one lying around, and it happens to be a good fit with its LiPo charge controller.

The choker runs on four 300 mAh LiPo batteries, which makes for more bulk than [Ted] would like, but again, sometimes it’s about what you have lying around. Even so, the batteries last around two hours.

Sometimes it’s about more than just blinkenlights. Here’s an LED necklace that reports on local air quality.

LED Matrix Earrings Show Off SMD Skills

We’ll be honest with you: we’re not sure if the use of “LED stud” in [mitxela]’s new project refers to the incomprehensibly tiny LED matrix earrings he made, or to himself for attempting the build. We’re leaning toward the latter, but both seem equally likely.

This build is sort of a mash-up of two recent [mitxela] projects — his LED industrial piercing, which contributes the concept of light-up jewelry in general as well as the power supply and enclosure, and his tiny volumetric persistence-of-vision display, which inspired the (greatly downsized) LED matrix. The matrix is the star of the show, coming in at only 9 mm in diameter and adorned with 0201 LEDs, 52 in total on a 1 mm pitch. Rather than incur the budget-busting expense of a high-density PCB with many layers and lots of blind vias, [mitexla] came up with a clever workaround: two separate boards, one for the LEDs and one for everything else. The boards were soldered together first and then populated with the LEDs (via a pick-and-place machine, mercifully) and the CH32V003 microcontroller before being wired to the power source and set in the stud.

Even though most of us will probably never attempt a build on this scale, there are still quite a few clever hacks on display here. Our favorite is the micro-soldering iron [mitxela] whipped up to repair one LED that went missing from the array. He simply wrapped a length of 21-gauge solid copper wire around his iron’s tip and shaped a tiny chisel point into it with a file. We’ll be keeping that one in mind for the future.

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You Could Be Relatively Cooler In Diamond-Coated Clothing

We vaguely remember what we believe was a DuPont commercial in the late ’80s or early ’90s touting that one day, they would make clothing that could cool you. And sure, there is clothing that allows heat to escape — fishnet shirts come to mind most immediately — but a group of scientists at Australia’s RMIT University have applied a coating of nanodiamonds to cotton in order to make fabric that goes a step further, drawing heat away from the body.

While you may be picturing blinged-out blouses, the truth is that nanodiamonds are cheap and non-glittery. They bear the same carbon-lattice structure as regular diamonds, which gives them great thermal conductivity.

In order to create cooling fabric, the scientists combined nanodiamond powder with polyurethane and a solvent, and applied the solution to one side of a sheet of cotton via electrospinning. This technique uses electric force to spin charged threads up into the diameters of fiber. The other side was left uncoated so that it doesn’t draw in heat.

Studies showed that the treated samples released 2 to 3 ºC (3.6 to 5.4 ºF) more heat via the coated side throughout the cooling period. While a couple of degrees may not seem like much, it could mean the difference between using a fan or using an air conditioner to cool off further.

Another application could be to keep buildings from overheating. We’ve seen developments in that area, usually in the form of ultra-white paint.

Thermal Earring Tracks Body Temperature

If you want to constantly measure body temperature to track things like ovulation, you usually have to wear something around your wrist or finger in the form of a smartwatch or ring. Well, what if you can’t or don’t want to adorn yourself this way? Then there’s the thermal earring.

Developed at the University of Washington, the thermal earring is quite small and unobtrusive compared to a smartwatch. Sure, it dangles, but that’s so it can measure ambient temperature for comparison’s sake.

You don’t even need to have pierced ears  — the earring attaches to the lobe magnetically. And yeah, the earring can be decorated to hide the circuitry, but you know we would rock the bare boards.

The earring uses BLE to transmit readings throughout the day, and of course goes into sleep mode between transmissions to save power. Coincidentally, it runs for 28 days per charge, which is the length of the average menstrual cycle. While the earring at this time merely “shows promise” as a means of monitoring stress and ovulation, it did outperform a smartwatch at measuring skin temperature while the wearers were at rest.

This is definitely not the only pair of earrings we’ve got around here. These art deco earrings use flexible PCBs, and this pair will light up the night.