Robotic Mouse Toy Built For Cats

Cats are nature’s born hunters. Whether its rodents, insects, or lasers, they’ll pounce and attack with ruthless efficiency. Built to challenge a cat, or perhaps merely to tease it, Sourino is a robotic mouse built with common off-the-shelf parts.

A test subject appears unamused.

So named for the combination of Souris (French for “mouse”) and Arduino, the project is driven by an Arduino Nano. Hooked up to three sets of ultrasonic transducers, this gives the robot mouse much improved obstacle avoidance abilities compared to using just a single transducer front-and-centre. The ‘bot can navigate basic mazes or household floors with ease. A pair of geared motors are used for drive, using simple skid-steering to turn corners. It’s all packed in a 3D printed enclosure, which mounts the various components and exposes the ultrasonic sensors. There’s even an IR remote enabling mode selection or full manual control.

While the ‘bot lacks the speed and agility of common house mice, it’s nevertheless a project that teaches plenty of valuable lessons. We’re sure [Electrocat01] picked up plenty of skills in robotic navigation, mechanical design and 3D printing along the way. Creating robot mice is actually a competitive field, as we’ve seen before. Video after the break.

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Video Compression Explainer — Like We’re Five-Year-Olds

[Ottverse] has an interesting series in progress to demystify video compression. The latest installment promises to explain discrete cosine transforms as though you were five years old.

We’ll be honest. At five, we probably didn’t know how to interpret this sentence:

…the Discrete Cosine Transform takes a set of N correlated (similar) data-points and returns N de-correlated (dis-similar) data-points (coefficients) in such a way that the energy is compacted in only a few of the coefficients M where M << N.

Still, the explanation is pretty clear and we really liked the analogy with the spheres and the stars in a constellation.

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A New Spin On A Medical Test

Most of us can say that we have taken an obsolete hard drive out of a computer and felt it was a waste to toss it in the e-waste pile. Some of us have children’s drawings hung on the fridge with actuator magnets, or maybe a vast spreadsheet suspended on a steel filing cabinet. Let us not forget that there is also a high-speed, low-noise motor in there. On some models it is separate from the PCB, so grab an Electronic Speed Controller (ESC), your microcontroller of choice, and make yourself a salvaged HDD centrifuge like [Cave Man] has. His build uses the tray as a chassis, but he modeled and printed a new face in the same style as the original.

On top, he has an OLED screen for displaying the requested speed, measured speed, and runtime. Next to the display is a four-button pad with a customized legend for setting parameters. The video after the break shows the machine running through its paces. This version accommodates the tiny capillary tubes, microhematocrit tubes, for processing raw blood. This test can calculate the packed cell volume, which professionals use to determine things from dehydration to anemia.

There are other builds out there where people have modified an old drive into the kind of centrifuge that accepts larger diameter tubes, but this was a shining example of what is possible. One good turn deserves another, so we recommend a desktop bio-lab companion, or enlist some LEGO Mindstorms to help out.

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Laser-Etching Photos On To Eggs

CNC machines are every maker’s dream. Capable of churning out accurate parts from CAD designs with a minimum of manual labor, they’re a great tool to have in the workshop. Alternatively, you can use them for more entertaining pursuits. [Leo]’s project is one of the latter – etching greyscale photos on to eggs.

The first thing you’ll need is an egg-compatible CNC machine. The Eggbot is a popular option, else a fourth-axis on an existing machine can also do the job as in [Leo]’s case. Coupling the egg is a delicate task, for which some rubber paper rollers are salvaged from an old printer and put to work. Then, a laser needs to be fitted to the CNC head, and the egg depth mapped with a probe to ensure the entire etching is in focus. Then it’s simply a matter of loading up an image, and turning the greyscale data into the relevant G-code to burn it onto the egg.

Using eggs coated in black ink, the results [Leo] achieves are impressive. The eggs would make an amusing Easter gift, or serve as a great cheap way to teach students about CNC techniques. Obviously, eye protection is a must, and be sure to mount your laser securely to avoid any unintentional exposures. Video after the break.

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Building A Heavy Duty Open Source Ventilator

Since the COVID-19 pandemic started, we’ve seen several attempts to create homebrew ventilators designed to address the shortage of these lifesaving machines. Unfortunately, most hackers aren’t terribly experienced when it comes to designing practical medical equipment. So while many of the designs might have appeared functional on the workbench, there’s little chance they’d get used in any official capacity.

The open source DP Ventilator is still clearly the product of a couple plucky hackers, but we think it shows a level of design maturity that’s been missing in many of the earlier attempts. Made primarily with 3D printed components, this mechanical device is designed to operate a hand-held manual resuscitator; essentially standing in for a human operator. This makes the design far less complex than if it had to actually pump air itself, not to mention safer for the patient since the resuscitator (often referred to as an Ambu Bag) installed in it would be a sterile pre-packaged item.

In the video after the break, you can see just how much thought and effort has been put into the device’s touch screen interface. With a few quick taps the medical professional operating the DP Ventilator can dial in variables such as breathing rate, pressure, and volume to match the patient’s needs. While the Arduino Mega 2560 at the machine’s heart wouldn’t pass muster for any regulating body in charge of medical devices, we think with a few more tweaks, this design is getting close to something that might actually be able to save lives.

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A Tale Of Tutor Texts

Have you ever had one of those books that let you choose your own adventure? You know, the book will say “The bully tells you to hand over the secret message. If you want to run away, turn to page 48. If you want to fight him, turn to page 70.” While this is normally a staple of children’s literature, there were a series of training books known as Tutor Texts that used the format to teach technical topics.

In fact, one of these books was my first introduction to computer programming more years ago than I care to admit. But it wasn’t just computer programming. There were titles from the same publisher about trigonometry, slide rules, and even how to play bridge. I own four of these old books and it got me to thinking about how we deliver information on the web. Maybe these books were ahead of their time.

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Hackaday Podcast 082: DJ CNC, NFC Black Box, Sound Of Keys, And Payin’ For 3D Prints

Hackaday editors Elliot Williams and Mike Szczys check in on the best hacks from the past week. All the buzz is the algorithm that can reverse engineer your house keys from the way they sound going into the lock. Cardboard construction goes extreme with an RC car build that’s beyond wizard-level. Speaking of junk builds, there’s a CNC mill tipped on its side grinding out results worlds better than you expect from something made with salvaged CD-ROM drives. And a starburst character display is a clever combination of laser cutting and alternative using UV-cured resin as a diffuser.

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct download (~65 MB)

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