Boombox Doorjam Plays Your Theme Song When You Step in the Ring

Although many of us may have had childhood aspirations to be a famous wrestler in the WWE, not very many of us will ever realize those dreams. You can get close, though, if you have your own epic intro music theme that plays anytime you walk into a room. Although it’s not quite the same as entering a wrestling ring, [Matt]’s latest project will have you feeling just as good whenever you enter a room to your own theme song.

The core of the build consists of a boom box with an auxiliary input. The boom box is fed sound via a Raspberry Pi which also serves as the control center for the rest of the project. It runs Node.js and receives commands via websockets from a publicly accessible control server. The Pi is also running Spotify which allows a user to select a theme song, and whenever that user’s iBeacon is within range, the Pi will play that theme song over the stereo.

The project looks like it would be easy to adapt to any other stereo if you’re looking to build your own. Most of the instructions and code you’ll need are available on the project’s website, too. And, if you’re a fan of music playing whenever you open a door of some sort, this unique project is clearly the gold standard. It might even make Stone Cold Steve Austin jealous.

Taking a U2F Hardware Key from Design to Production

Building a circuit from prototyping to printed circuit board assembly is within the reach of pretty much anyone with the will to get the job done. If that turns out to be something that everyone else wants, though, the job gets suddenly much more complex. This is what happened to [Conor], who started with an idea to create two-factor authentication tokens and ended up manufacturing an selling them on Amazon. He documented his trials and tribulations along the way, it’s both an interesting and perhaps cautionary tale.

[Conor]’s tokens themselves are interesting in their simplicity: they use an Atmel ATECC508A specifically designed for P-256 signatures and keys, a the cheapest USB-enabled microcontroller he could find: a Silicon Labs EFM8UB1. His original idea was to solder all of the tokens over the course of one night, which is of course overly optimistic. Instead, he had the tokens fabricated and assembled before being shipped to him for programming.

Normally the programming step would be straightforward, but using identical pieces of software for every token would compromise their security. He wrote a script based on the Atmel chip and creates a unique attestation certificate for each one. He was able to cut a significant amount of time off of the programming step by using the computed values with a programming jig he built to flash three units concurrently. This follows the same testing and programming path that [Bob Baddeley] advocated for in his Tools of the Trade series.

From there [Conor] just needed to get set up with Amazon. This was a process worthy of its own novel, with Amazon requiring an interesting amount of paperwork from [Conor] before he was able to proceed. Then there was an issue of an import tariff, but all-in-all everything seems to have gone pretty smoothly.

Creating a product from scratch like this can be an involved process. In this case it sounds like [Conor] extracted value from having gone through the entire process himself. But he also talks about a best-case-scenario margin of about 43%. That’s a tough bottom line but a good lesson anyone looking at building low-cost electronics.

Air-Powered Top Only Possible on a 3D Printer

One of the major reasons anyone would turn to a 3D printer, even if they have access to a machine shop, is that there are some shapes that are not possible to make with conventional “subtractive manufacturing” techniques. There are a few more obvious reasons a lot of us use 3D printers over conventional machining such as size and cost, but there’s another major reason that 3D printers are becoming more and more ubiquitous. [Crumbnumber1] at Make Anything’s 3D Printing Channel shows us how powerful 3D printers are at iterative design with his air-powered tops. They incorporate fan blades that allow you to spin the top up to very high speeds by blowing air down onto it.

Iterative design is the ability to rapidly make prototypes that build and improve upon the previous prototype, until you’re left with something that does the job you need. Even with a machine shop at your disposal, it can be expensive to set up all of the tooling for a part, only to find out that the part needs a change and the tooling you have won’t work anymore. This is where 3D printers can step in. Besides all of their other advantages, they’re great for rapid prototyping. [Crumbnumber1] made a box full of tops and was able to test many different designs before settling on one that performed above and beyond everything that came before it.

The video below is definitely worth checking out. The design process is well documented and serves as a great model for anyone looking to up their rapid prototyping game.

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Scratch-Built EV From Hoverboards

Electric vehicles are everywhere now. Even though battery technology hasn’t had the breakthrough that we need to get everyone out driving an electric car, the price for batteries has dropped enough that almost anything else is possible. The hoverboard was proof of this: an inexpensive electric vehicle of sorts that anyone who was anyone in 2015 had. Taking his cue from there, [Harris] used off-the-shelf parts normally used for hoverboards to build his own battery-powered trike.

The trike is homemade from the ground up, too. The H-frame was bolted together using steel and lots and lots of bolts. Propulsion comes from a set of hub motors that are integrated into the wheels like a hoverboard or electric bicycle would have. Commonly available plug-and-play lithium batteries make up the power unit and are notably small. In fact, the entire build looks like little more than a frame and a seat, thanks to the inconspicuous batteries and hub motors.

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Chair Dances Like No One Is Watching

Although it might be more accurate to say that this chair dances because no one is watching, the result is still a clever project that [Igor], a maker-in-residence at the National Museum of Decorative Arts and Design in Norway, created recently. Blurring the lines between art, hack, and the ghosts from Super Mario, this chair uses an impressive array of features to “dance”, but only if no one is looking at it.

In order to get the chair to appear to dance, [Igor] added servo motors in all four legs to allow them to bend. A small non-moving dowel was placed on the inside of the leg to keep the chair from falling over during all of the action. It’s small enough that it’s not immediately noticeable from a distance, which helps maintain the illusion of a dancing chair.

From there, a Raspberry Pi 3 serves as the control center for the chair. It’s programmed in Python and runs OpenCV for face detection and uses pigpio for controlling the leg servos. There’s also a web interface for watching the camera’s output and viewing its facial recognition abilities. The web interface also allows a user to debug the program. [Igor]’s chair can process up to 3 frames per second at 800×600 pixels.

Be sure to check out the video after the break to see the chair in action. It’s an interesting piece of art, and if those dowels can support the weight of a person it would be a great addition to any home as well. If it’s not enough chair for you, though, there are some other more dangerous options out there.

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Tiny House Forecasts Weather

Before the information age, it wasn’t quite as easy to glean information about the weather. Sure, there were thermometers and barometers and rhymes about the sky, but if you lived in or near Germany back then you might have also had access to something called a “weather house” which could help predict rain. [Moritz] aka [Thinksilicon] found one of these antequated devices laying around, and went about modernizing it. (Google Translate from German)

A traditional weather house is essentially a hygrometer housed in an intricate piece of artwork. Two figures, typically a man and woman, are balanced on a platform that is suspended in the middle by a small section of horsehair. When the humidity is low, the hair tightens up and turns the platform one way, and when humidity is high — suggesting rain is coming — it turns the other way. When the man comes out of the house, it predicts rainfall.

To get the weather house upgraded, [Moritz] outfitted the front with an OLED display which replaced the traditional thermometer. Instead of using horsehair to spin the figures he installed a small servo on the platform. The entire house is controlled by an ESP8266 which pulls data from the Open Weather API and spins the figures based on the information it receives.

Much like unique clocks, we enjoy interesting weather indicating/forecasting builds. This one’s right up there with using squirrels to predict the weather, or having a small weather-recreation right on your bookshelf.

Simple Clock from Tiny Chip

If you haven’t jumped on the ESP8266 bandwagon yet, it might be a good time to get started. If you can program an Arduino you have pretty much all of the skills you’ll need to get an ESP8266 up and running. And, if you need a good idea for a project to build with one of these WiFi miracle chips, look no further than [Ben Buxton]’s dated, but awesome, NTP clock.

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