Fluid Simulation Pendant Teaches Lessons In Miniaturization

January 13, 2025 by Dan Maloney 3 Comments

Some projects seem to take on a life of their own. You get an idea, design and prototype it, finally build the thing and — it’s good, but it’s not quite right. Back to the drawing board, version 2, still not perfect, lather, rinse, repeat. Pretty soon you look around to discover that you’ve built ten of them. Oops.

That seems to be the arc followed by [mitxela] with this very cool fluid simulation pendant. The idea is simple enough; create a piece of jewelry with a matrix of tiny LEDs that act like the pendant is full of liquid, sloshing about with the slightest movement. In practice, though, this project was filled with challenges. Surprisingly, [mitxela] doesn’t seem to number getting a fluid dynamics simulation running on a microcontroller among those problems, at least not to a great degree. Rather, the LED matrix seemed to cause the most problems, both in terms of laying it out on the 25-mm diameter PCB and how to address the LEDs with relatively limited GPIO on the STM32 microcontroller. The solution to both was diagonal charlieplexing, which reduces the number of vias needed for the 216-LED matrix and allows the 0402 to be densely packed, along with providing some tolerance for solder bridging.

And then there’s the metalworking heroics, which no [mitxela] project would be complete without. This seems to be where a lot of the revisions come from, as the gold-plated brass case kept not quite living up to expectations. The final version is a brass cup containing the LiR2450 rechargeable battery, a magnetic charging connector, and the main PCB, all sealed by a watch crystal. The fluid simulation is quite realistic and very responsive to the pendant’s position. The video below shows it in action along with a summary of the build.

If you want to catch up on [mitxela]’s back catalog of miniaturized builds, start with his amazing industrial ear adornments or these tiny matrix earrings. We’re also fond of his incredible shrinking MIDI builds. Continue reading “Fluid Simulation Pendant Teaches Lessons In Miniaturization” →

How Nyan Cat Was Ported To UEFI

January 13, 2025 by Lewin Day 12 Comments

The Unified Extensible Firmware Interface (UEFI) took over from the classical BIOS some years into the new millenium. It’s typically used for running a computer at the basic pre-OS level, and most of us don’t even notice it past boot time. However, you can do some neat things in this space—you can even port over Nyan Cat if you’re talented like [Cornelius].

*That’s fun. Set your friend’s computer to boot into this instead of their OS by default and see how long it takes them to figure it out.*

Yes, Nyan Cat is now available as a UEFI application, running via the EFI Simple Text Output Protocol. [Cornelius] approached this creation by first learning Rust, before progressing to the Hello World stage. Before long, the computer was booting up to display a simple text message with no OS required.

From there, creating the Nyan Cat animation required figuring out how to display it as a bunch of dancing characters, which is where the Simple Text Output Protocol came in. Nyan Cat was really the perfect animation for the UEFI environment, since its simple pixel art style was easily recreated with text. With a bit of work, the animation came together, with a remarkable resemblance to the original artwork.

All that’s missing is a routine to play the music over a PC speaker; only, those are hardly a thing anymore. A pity! In any case, if you’ve been cooking up your own nifty UEFI hacks, don’t hesitate to drop us a line!

Fraens’ New Loom And The Limits Of 3D Printing

January 12, 2025 by Elliot Williams 8 Comments

[Fraens] has been re-making industrial machines in fantastic 3D-printable versions for a few years now, and we’ve loved watching his creations get progressively more intricate. But with this nearly completely 3D-printable needle loom, he’s pushing right up against the edge of the possible.

The needle loom is a lot like the flying shuttle loom that started the Industrial Revolution, except for making belts or ribbons. It’s certainly among the most complex 3D-printed machines that we’ve ever seen, and [Fraens] himself says that it is pushing the limits of what’s doable in plastic — for more consistent webbing, he’d make some parts out of metal. But that’s quibbling; this thing is amazing.

There are mechanical details galore here. For instance, check out the cam-chain that raises, holds, and lowers arms to make the pattern. Equally important are the adjustable friction brakes on the rollers that hold the warp, that create a controlled constant tension on the strings. (Don’t ask us, we had to Wikipedia it!) We can see that design coming in handy in some of our own projects.

On the aesthetic front, the simple but consistent choice of three colors for gears, arms, and frame make the build look super tidy. And the accents of two-color printing on the end caps is just the cherry on the top.

This is no small project, with eight-beds-worth of printed parts, plus all the screws, bearings, washers, etc. The models are for pay, but if you’re going to actually make this, that’s just a tiny fraction of the investment, and we think it’s going to a good home.

We are still thinking of making [Fraens]’s vibratory rock tumbler design, but check out all of his work if you’re interested in nice 3D-printed mechanical designs.

Continue reading “Fraens’ New Loom And The Limits Of 3D Printing” →

Try A PWMPot

January 8, 2025 by Al Williams 15 Comments

[Stephen Woodward] is familiar with digital potentiometers but is also familiar with their limitations. That spurred him to create the PWMPot which performs a similar function, but with better features than a traditional digital pot. Of course, he admits that this design has some limitations of its own, so — as usual — you have to make your design choices according to what’s important to you.

Perhaps the biggest limitation is that the PWMPot isn’t useful at even moderately high frequencies. The circuit works by driving two CMOS switches into an RC circuit. The switches’ inverted phase tends to cancel out any ripple in the signal.

Continue reading “Try A PWMPot” →

Mechanical Calculator Finds Derivatives

January 6, 2025 by Al Williams 10 Comments

We like mechanical calculators like slide rules, but we have to admit that we had not heard of the Ott Derivimeter that [Chris Staecker] shows us in a recent video. As the name implies, the derivimeter finds the derivative of a function. To do that, you have to plot the function on a piece of paper that the meter can measure.

If you forgot calculus or skipped it altogether, the derivative is the rate of change. If you plot, say, your car’s speed vs time, the parts where you accelerate or decelerate will have a larger derivative (either positive or negative, in the decelerate case). If you hold a steady speed, the derivative will be zero.

Continue reading “Mechanical Calculator Finds Derivatives” →

Front and rear views of a lander circuit sculpture that retrieves weather data and displays it on a screen.

Landing Soon: This Beautiful Weather Display

January 3, 2025 by Kristina Panos 5 Comments

All wiring is beautiful, except when it isn’t. But is there anything more lovely to behold than circuit sculpture? Once again, [Mohit Bhoite] has made this process look easy like Sunday morning. This time, he’s created a weather display in the form of a lander.

This lander runs on the Particle Photon 2, which connects over Wi-Fi and retrieves the weather forecast for the day, along with sunrise and sunset times and wind conditions. Everything is beautifully displayed on a vertically-oriented Adafruit 170×320 TFT screen.

There’s also a pulse-density microphone (PDM) breakout board and a buzzer, and the build is capped off with a red 0805 LED. We’re not sure what the feet are made of, but they sure make this lander cute (and accurate).

All the project logs are picture-rich, which is really the most we could ask for when trying to imitate this level of greatness. This is apparently an ongoing project, and we’re excited for the end result, although it looks fairly complete from here.

Do you want to bend it like Bhoite? Then be sure to check out his Hackaday Supercon talk on the subject.

A LoRa Rain Gauge From The Ground Up

December 26, 2024 by Dan Maloney 4 Comments

It’s a fair bet that most of us have a ton of wireless doo-dads around the house, from garage door remotes to wireless thermometers. Each of these gadgets seems to have its own idea about how to encode data and transmit it, all those dedicated receivers seem wasteful. Wouldn’t it be great to use existing RF infrastructure to connect your wireless stuff?

[Malte Pöggel] thinks so, and this LoRa rain gauge is the result. The build starts with a commercially available rain transmitter, easily found on the cheap as an accessory for a wireless weather station and already equipped with an ISM band transmitter. The rain-collection funnel and tipping-bucket mechanism were perfectly usable, and the space vacated by the existing circuit boards left plenty of room to play, not to mention a perfectly usable battery compartment. [Malte] used an ATmega328P microcontroller to count the tipping of the bucket, either through the original reed switch or via Hall Effect or magnetoresistive sensors. An RFM95W LoRa module takes care of connecting into [Malte]’s LoRaWAN gateway, and there’s an option to add a barometric pressure and temperature sensor, either by adding the BMP280 chip directly to the board or by adding a cheap I2C module, for those who don’t relish SMD soldering.

[Malte] put a lot of work into power optimization, and it shows. A pair of AA batteries should last at least three years, and the range is up to a kilometer—far more than the original ISM connection could have managed. Sure, this could have been accomplished with a LoRa module and some jumper wires, but this looks like a fantastic way to get your feet wet in LoRa design. You could even print your own tipping bucket collector and modify the electronics if you wanted.