[Jamie] decided to build a generator, and Lego is his medium of choice. Thus was created a fancy levitating generator that turns a stream of air into electricity. 

The basic concept is simple enough for a generator—magnets moving past coils to generate electricity. Of course, Lego doesn’t offer high-strength magnetic components or copper coils, so this generator is a hybrid build which includes a lot of [Jamie’s] non-Lego parts. Ultimately though, this is fun because of the weird way it’s built. Lego Technic parts make a very crude turbine, but it does the job. The levitation is a particularly nice touch—the build uses magnets to hover the rotor in mid-air to minimize friction to the point where it can free wheel for minutes once run up to speed. The source of power for this contraption is interesting, too. [Jamie] didn’t just go with an air compressor or a simple homebrew soda bottle tank. Instead, he decided to use a couple of gas duster cans to do the job. The demos are pretty fun, with [Jamie] using lots of LEDs and a radio to demonstrate the output.  The one thing we’d like to see more of is proper current/voltage instrumentation—and some measurement of the RPM of this thing!

While few of us will be rushing out to build Lego generators, the video nonetheless has educational value from a mechanical engineering standpoint. Fluids and gases really do make wonderful bearings, as we’ve discussed before. Video after the break.

Another day, another Internet-connected gadget that gets abandoned by its creators. This time it’s Jooki — a screen-free audio player that let kids listen to music and stories by placing specific tokens on top of it. Parents would use a smartphone application to program what each token would do, and that way even very young children could independently select what they wanted to hear.

Well, until the company went bankrupt and shutdown their servers down, anyway. Security researcher [nuit] wrote into share the impressive work they’ve done so far to identify flaws in the Jooki’s firmware, in the hopes that it will inspire others in the community to start poking around inside these devices. While there’s unfortunately not enough here to return these devices to a fully-functional state today, there’s several promising leads.

It probably won’t surprise you to learn the device is running some kind of stripped down Linux, and [nuit] spends the first part of the write-up going over the partitions and peeking around inside the filesystem. From there the post briefly covers how over-the-air (OTA) updates were supposed to work when everything was still online, which may become useful in the future when the community has a new firmware to flash these things with.

Where things really start getting interesting is when the Jooki starts up and exposes its HTTP API to other devices on the local network. There are some promising endpoints such as /flags which let’s you control various aspects of the device, but the real prize is /ll, which is a built-in backdoor that runs whatever command you pass it with root-level permissions! It’s such a ridiculous thing to include in a commercial product that we’d like to think they originally meant to call it /lol, but in any event, it’s a huge boon to anyone looking to dig deeper in to the device.

But wait, there’s more! The Jooki runs a heartbeat script that regularly attempts to check in with the mothership. The expected response when the box pings the server is your standard HTTP 200 OK, but in what appears to be some kind of hacky attempt at implementing a secondary OTA mechanism, any commands sent back in place of the HTTP status code will be executed as root.

Now as any accomplished penguin wrangler will know, if you can run commands as root, it doesn’t take long to fire up an SSH server and get yourself an interactive login. Either of these methods can be used to get into the speaker’s OS, and as [nuit] points out, the second method means that whoever can buy up the Jooki domain name would have remote root access to every speaker out there.

Long story short, it’s horrifyingly easy to get root access on a Jooki speaker. The trick now is figuring out how this access can be used to restore these devices to full functionality. We just recently covered a project which offered a new firmware and self-hosted backend for an abandoned smart display, hopefully something similar for the Jooki isn’t far off.

Music consumption has followed a trend over the last decade or more of abandoning physical media for online or streaming alternatives. This can present a problem for young children however, for whom a simpler physical interface may be an easier way to play those tunes. Maintaining a library of CDs is not entirely convenient either, so [JakesMD] has created the Yaydio. It’s a music player for kids, that plays music when a card is inserted in its slot.

As you might expect, the cards themselves do not contain the music. Instead they are NFC cards, and the player starts the corresponding album from its SD card when one is detected. The hardware is simple enough, an Arduino Nano with modules for MP3 playback, NFC reading, seven segment display, and rotary encoder. The whole thing lives in a kid-friendly 3D printed case.

Some thought has been given to easily adding albums and assigning cards to them, making it easy to keep up with the youngster’s tastes. This isn’t the first such kid-friendly music player we’ve seen, but it’s certainly pretty neat.

The Etch A Sketch is a classic children’s toy resembling a picture frame where artwork can be made by turning two knobs attached to a stylus inside the frame. The stylus scrapes off an aluminum powder, creating the image which can then be erased by turning the frame upside down and shaking it, adding the powder back to the display. It’s completely offline and requires no batteries, but in our modern world those two things seem to be more requirements than when the Etch A Sketch was first produced in the 1960s. Enter the Tilt-A-Sketch, a modern version of the classic toy.

Rather than use aluminum powder for the display, the Tilt A Sketch replaces it with an LED matrix and removes the stylus completely. There are no knobs on this device to control the path of the LED either; a inertial measurement unit is able to sense the direction that the toy is tilted while a microcontroller uses that input to light up a series of LEDs corresponding to the direction of tilt. There are a few buttons on the side of the device as well which allow the colors displayed by the LEDs to change, and similar to the original toy the display can be reset by shaking.

The Tilt-A-Sketch was built by [devitoal] as part of an art display which allows the visitors to create their own art. Housed in a laser-cut wooden enclosure the toy does a faithful job of recreating the original. Perhaps unsurprisingly, the Etch A Sketch is a popular platform for various projects that we’ve seen before including original toys modified with robotics to create the artwork and electronic recreations that use LED displays instead in a way similar to this project.

Nerf blasters typically fire small foam darts or little foam balls. [Michael Pick] wanted to build something altogether more devastating. To that end, he created a rocket launcher with an advanced air burst capability, intended to take out enemies behind cover.

Unlike Nerf’s own rocket launchers, this build doesn’t just launch a bigger foam dart. Instead, it launches an advanced smart projectile that releases lots of smaller foam submunitions at a set distance after firing.

The rocket launcher itself is assembled out of off-the-shelf pipe and 3D printed components.  An Arduino Uno runs the show, hooked up to a Bluetooth module and a laser rangefinder. The rangefinder determines the distance to the target, and the Bluetooth module then communicates this to the rocket projectile itself so it knows when to release its foamy payload after launch. Releasing the submunitions is achieved with a small microservo in the projectile which opens a pair of doors in flight, scattering foam on anyone below. The rockets are actually fired via strong elastic bands, with an electronic servo-controlled firing mechanism.

We’ve featured some great Nerf builds over the years, like this rocket-blasting robot.

LEGO! It’s a fun toy that is popular around the world. What you may not realize is that it’s also made to incredibly high standards. As it turns out, the humble building blocks are good enough to build a interferometer if you’re so inclined to want one. [Kyra Cole] shows us how it’s done.

The build in question is a Michelson interferometer; [Kyra] was inspired to build it based on earlier work by the myphotonics project. She was able to assemble holders for mirrors and a laser, as well as a mount for a beamsplitter, and then put it all together on a LEGO baseboard. While some non-LEGO rubber bands were used in some areas, ultimately, adjustment was performed with LEGO Technic gears.

Not only was the LEGO interferometer able to generate a proper interference pattern, [Kyra] then went one step further. A Raspberry Pi was rigged up with a camera and some code to analyze the interference patterns automatically. [Kyra] notes that using genuine bricks was key to her success. Their high level of dimensional accuracy made it much easier to achieve her end goal. Sloppily-built knock-off bricks may have made the build much more frustrating to complete.

We don’t feature a ton of interferometer hacks around these parts. However, if you’re a big physics head, you might enjoy our 2021 article on the LIGO observatory. If you’re cooking up your own physics experiments at home, don’t hesitate to drop us a line!

Thanks to [Peter Quinn] for the tip!