Roll-On Deodorant Controller Heats Up Racing Game

January 10, 2023 by 24 Comments

What do you get when you combine roll-on deodorant containers and a soccer ball with an optical mouse and an obscure 90s Japanese video game about racing armadillos? Well, you get a pretty darn cool controller with which to play said game, we must admit.

We hardly knew they were still making roll-on deodorant, and [Tom Tilley] is out here with three empties with which to hack. And hack he does — after thoroughly washing and drying the containers three, he sawed off the ball-holding bit just below the business part and fit each into the roll-on’s lid. Then [Tom] constructed a semi-elaborate cardboard-and-hot-glue thing to hold them in an equilateral triangle formation. Out of nowhere, he casually drops a fourth modified roll-on ball over an optical mouse, thereby extending the power of lasers to the nifty frosted orb.

Finally, [Tom] placed the pièce de résistance — the soccer ball — on top of everything. The mouse picks up the movement through the middle roll-on, and the original three are there for stability and roll-ability purposes. At last, Armadillo Racing can be played in DIY style. Don’t get it? Don’t sweat it — just check out the brief build video after the break.

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The Intricacies Of Creating Fuel For Nuclear Reactors

January 10, 2023 by 51 Comments

All nuclear fission power reactors run on fuel containing uranium and other isotopes, but fueling a nuclear reactor is a lot more complicated than driving up to them with a dump truck filled with uranium ore and filling ‘er up. Although nuclear fission is simple enough that it can occur without human intervention as happened for example at the Oklo natural fission reactors, within a commercial reactor the goal is to create a nuclear chain reaction that targets a high burn-up (fission rate), with an as constant as possible release of energy.

Each different fission reactor design makes a number of assumptions about the fuel rods that are inserted into it. These assumptions can be about the enrichment ratio of the fissile isotopes like U-235, the density of individual fuel pellets, the spacing between the fuel rods containing these pellets, the configuration of said fuel rods along with any control, moderator and other elements. and so on.

Today’s light water reactors, heavy water reactors, fast neutron reactors, high temperature reactors and kin all have their own fuel preferences as a result, with high-assay low-enriched (HALEU) fuel being the new hot thing for new reactor designs. Let’s take a look at what goes into these fuel recipes.

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Tetris Joins Minecraft And DOOM In Running A Computer

January 10, 2023 by 6 Comments

There is a select group of computer games whose in-game logic is enough for them to simulate computers in themselves. We’ve seen it in Minecraft and DOOM, and now there’s a new player in town from a surprising quarter: Tetris.

One might wonder how the Russian falling-blocks game could do this, as unlike the previous examples it has a very small playing field. And indeed it’s not quite the Tetris you’re used to playing, but a version played over an infinite board. Then viewed as a continuous progression of the game it can be viewed as somewhat similar to the tape in a Turing machine.

The various moves and outcomes are referred to through a Tetris scripting language, so states can be represented by different sets of blocks and holes while logic elements can be be built up using the various shapes and the game logic. From those a computer can be built, represented entirely in Tetris moves and shapes. It’s a little mind-bending and we’d be lying if we said we understood every nuance of it, but seemingly it works well enough to run the game from within itself.. If it had the catchy music from the NES version, we’d declare it perfect.

Hungry for more? Here’s DOOM doing some adding, and of course Minecraft has a rich computing history.

TV personality and maker, Adam Savage, sits on a chair attached to a milk crate on wheels. It is situated inside an assortment of steel tubes forming the legs and body of a strandbeest walking machine.

Human-Powered Strandbeest

January 10, 2023 by 6 Comments

Once you’ve seen a strandbeest, it’s hard to forget the mesmerizing movement of its mechanical limbs. [Adam Savage] built a pedal-powered strandbeest in (more than) one day in full view of the public at the San Francisco Exploratorium.

One of the biggest challenges with building strandbeests is the sheer number of parts required to build a walking machine. It becomes clear rather quickly how big of an advantage the wheel is for part count on a device. Add in a few seemingly small design errors, and you might not have any forward motion at all.

[Savage]’s build takes us through all the ups and downs of this process, including lots of wrenching, welding, and more sneakers than Squitter the Spider could wear. The final product is unwieldy, impractical, and beautiful. What more could a maker ask for?

If you need more strandbeest goodness, check out this more practical strandbeest bicycle, this strandbeest Venus rover concept, or Jeremy Cook’s talk about designing strandbeest bots.

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Wipe On, Wipe Off: Make Your Own Rain Repellent

January 9, 2023 by 55 Comments

Once upon a time, we drove an old six-volt VW Beetle. One sad day, the wiper motor went out, and as this happened before the Internet heyday, there were no readily-available parts around that we were aware of. After briefly considering rubbing a potato on the windshield as prescribed by the old wives’ tale, we were quite grateful for the invention of Rain-X — a water-repelling chemical treatment for car windshields.

Boy would we have loved to know how to make it ourselves from readily-available chemicals. As you’ll see in the video below, it doesn’t take much more than dimethicone, sulfuric acid, and a cocktail of alcohols. [Terry] starts with dimethicone, which he activates with a healthy dose of concentrated sulfuric acid, done under the safety of an exhaust hood. After about 20 minutes on the stir mix-a-lot plate, [Terry] added ethanol and isopropyl alcohols. Finally, it was off to the garage with the mixture in a spray bottle.

After meticulously cleaning the windshield, [Terry] applied the solution in small areas and rubbed it in with a towel to create a thin bond between it and the glass. This creates a perfectly normal haze, which can be removed after a bit with a clean towel.

If you just love listening to your windshield wipers, at least make them move to a beat.

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IoT Archaeology Leads To API Resurrection

January 9, 2023 by 21 Comments

What happens when someone’s personal project is turned into a startup which becomes something of a publicity darling, then collapses with very little product shipped and takes all its customers’ money with it?

That’s the subject of a blog post from [Kevin Chung], who investigated the legacy of NYCTrainSign, a company whose product was an LED NYC subway sign and which has become a meme byword for a startup scam. Along the way he found himself reverse engineering its API, and eventually even purchasing the expired domain name to resurrect the API for any NYCTrainSigns that may still be out there.

Securing a second-hand NYCTrainSign, he dismantled it to see what made it tick. Inside the handmade wooden case was an array of LED panels, driven by a Raspberry Pi 3 and an Adafruit LED panel HAT. This gave pause for thought, as the component choice gives rise to a very high BoM cost which was unsustainable given their habit of steep discounts.

The software proves straightforward enough to reverse engineer, and since the original domain was for sale he bought it and set up a replacement API. Do you have one of the few signs that made it to customers? Now you can run it again.

The rest of the piece tells a tale that will be familiar to startup veterans: one of far too much marketing, too many bosses, and too little engineering to create a viable product. The founders remain tight-lipped about what happened and where the money went, but since there are few more efficient money pits than a badly-run startup, it’s more likely that ill-advised spending is to blame than someone running off with suitcases of cash.

If you’d like a public transit sign without the dodgy start-up, we’ve got you covered.

Clever Mechanism Makes A Linear Control From A Rotary Hall Sensor

January 9, 2023 by 81 Comments

Every once in a while we stumble across something so simple yet so clever that we just have to call it out. This custom linear Hall effect sensor is a perfect example of this.

By way of backstory, [Nixieguy], aka [The Electronic Mercenary], offers up a relatable tale — in the market for suitable hardware to make the game Star Citizen more enjoyable, and finding the current commercial joystick offerings somewhat wanting, he decided to roll his own controllers. This resulted in the need for a linear sensor 100 mm in length, the specs for which — absolute sensing, no brushes or encoders, easily sourced parts — precluded most of the available commercial options, like linear pots. What to do?

The solution [Nixieguy] settled on was to use a Hall effect sensor and a diametrally magnetized neodymium ring magnet. The magnet is rotated through 180 degrees by a twisted aluminum bar, which is supported in a frame by bearings. A low-friction slider with a slot captures the bar; moving the slider along the length of the control rotates the bar, which rotates the magnet, which allows the Hall sensor to measure the angle of the magnetic field. Genius!

The parts for the prototype sensor are all made from 0.8-mm aluminum sheet stock and bent to shape. The video below shows the action better than words can describe it, and judging by the oscilloscope trace, the output of the sensor is pretty smooth. There’s clearly a long way to go to tighten things up, but the basic mechanism looks like a clear win to us.

Hats off to [Nixieguy] for this one, which we’ll surely be following for more developments. In the meantime, if you need to brush up on the Hall effect, [Al Williams] did a nice piece on that a while back.

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