A Solar-Powered Wristwatch With An ATtiny13

March 13, 2024 by Maya Posch 22 Comments

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 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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The Short Workbench

March 13, 2024 by Al Williams 36 Comments

Imagine an electronics lab. If you grew up in the age of tubes, you might envision a room full of heavy large equipment. Even if you grew up in the latter part of the last century, your idea might be a fairly large workbench with giant boxes full of blinking lights. These days, you can do everything in one little box connected to a PC. Somehow, though, it doesn’t quite feel right. Besides, you might be using your computer for something else.

I’m fortunate in that I have a good-sized workspace in a separate building. My main bench has an oscilloscope, several power supplies, a function generator, a bench meter, and at least two counters. But I also have an office in the house, and sometimes I just want to do something there, but I don’t have a lot of space. I finally found a very workable solution that fits on a credenza and takes just around 14 inches of linear space.

How?

How can I pack the whole thing in 14 inches? The trick is to use only two boxes, but they need to be devices that can do a lot. The latest generation of oscilloscopes are quite small. My scope of choice is a Rigol DHO900, although there are other similar-sized scopes out there.

If you’ve only seen these in pictures, it is hard to realize how much smaller they are than the usual scopes. They should put a banana in the pictures for scale. The scope is about 10.5″ wide (265 mm and change). It is also razor thin: 3″ or 77 mm. For comparison, that’s about an inch and a half narrower and nearly half the width of a DS1052E, which has a smaller screen and only two channels.

If you get the scope tricked out, you’ve just crammed a bunch of features into that small space. Of course, you have a scope and a spectrum analyzer. You can use the thing as a voltmeter, but it isn’t the primary meter on the bench. If you spend a few extra dollars, you can also get a function generator and logic analyzer built-in. Tip: the scope doesn’t come with the logic analyzer probes, and they are pricey. However, you can find clones of them in the usual places that are very inexpensive and work fine.

There are plenty of reviews of this and similar scopes around, so I won’t talk anymore about it. The biggest problem is where to park all the probes. Continue reading “The Short Workbench” →

Custom Library Rescues Good LoRa Hardware From Bad Firmware

March 13, 2024 by Dan Maloney 17 Comments

The range of hardware that comes on some dev boards these days is truly staggering. Those little LoRa boards are a prime example — ESP32 with WiFi and Bluetooth, a transceiver that covers a big chunk of the UHF band, and niceties like OLED displays and plenty of GPIO. But the firmware and docs? Well, if you can’t say something nice, don’t say anything at all. Or better yet, just roll your own.

Of course that doesn’t hold true for all the LoRa dev boards on the market, but [Rop] certainly found it to be the case for the Heltec HTIT-WB32LA. This board has all the bells and whistles and would be perfect for LoraWAN and Meshtastic applications, but it needed a little help getting it over the line. [Rop]’s contribution to this end is pretty comprehensive and is based on his fork of the RadioLib library, which incorporates a library that greatly reduces wear on the ESP32’s flash memory. In addition to full radio support, the library supports all the hardware on the board from the pushbutton to the display, power management and battery charging, and of course the blinkenlights.

[Jop] includes quite a few example applications, from the bare minimum needed to get the board spun up to a full-blown spectrum analyzer. It’s a nice piece of work, and a great give-back to the LoRa community. And if you want to put one of these modules to work, you’re certainly in the right place. We’ve got everything from LoRaWAN networks to the magic of Meshtastic, so take your pick and get hacking.

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

March 13, 2024 by Kristina Panos 21 Comments

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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