Tetris Joins Minecraft And DOOM In Running A Computer

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

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

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

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

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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You Can Now Fix Your Deere

Over the last few years we have brought you many stories about John Deere tractors, and how their repair has been locked down such that only manufacturer-authorised technicians can work on them. They’ve become a poster child in the battle for the right to repair, a symbol of the worst practices. Finally now we can bring you some good news of sorts, as the agricultural giant has signed a memorandum of understanding with the American Farm Bureau Federation to ensure that their products will henceforth be repairable by people without Deere approval.

We can’t imagine that Deere will have taken this step willingly, and while we’d like to imagine that consumer protests in favour of right-to-repair have hit their mark, we’re guessing that it’s more of an economic pressure at work alongside the threat of legislation outside their native America. If farmers getting caught out waiting for a Deere van to arrive while their crop withers in the field wasn’t enough, when the price of a second-hand tractor without the DRM outstrips that of a newer one with it, eventually the sales of new tractors will also suffer.

So this is good news, and we’re guessing that other agricultural manufacturers doing the same DMCA practices will now follow suit. But it’s not a complete victory. The problem starts not with the DMCA restriction itself, but with the extension of the machine’s computer system into every part, including those many parts which simply don’t need it. It’s not a complete victory if anyone can now use the software to register a new hydraulic valve with the system; instead that hydraulic valve should not have to be authorised in the first place. It’s this creeping unnecessary complexity which is the true enemy of right-to-repair, and we shouldn’t forget that.

Header image: Dwight Sipler, CC BY 2.0.

3d printed tiny gym in a box with mirror and led strip lighting

Get Pumped For This Miniature Gym

[Duncan McIntyre] lives in the UK but participated in a secret Santa gift exchange for his Dutch friends’ Sinterklaas celebration. In traditional maker fashion, [Duncan] went overboard and created a miniature gym gift box, complete with flashing lights, music and a motorized lid.

[Duncan] used [TanyaAkinora]’s 3D printed tiny gym to outfit the box with tiny equipment, with a tiny mirror added to round out the tiny room. An ATmega328P was used as the main microcontroller to drive the MP3 player module and A4988 stepper motor controller. The stepper motor was attached to a drawer slide via a GT2 timing belt and pulley to actuate the lid. Power is provided through an 18V, 2A power supply with an LM7805 providing power to the ATmega328P and supporting logical elements. As an extra flourish, [Duncan] added some hardware audio signal peak detection, fed from the speaker output, which was then sampled by the ATmega328P to be able to flash the lights in time with the playing music. A micro switch detects when the front miniature door is opened to begin the sequence of lights, song and lid opening.

[Duncan] provides source on GitHub for those curious about the Arduino code and schematics. We’re fans of miniature pieces of ephemera and we’ve featured projects ranging from tiny 3D printed tiny escalators to tiny arcade cabinets.

Video after the break!

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