Recreating The Pop Ball

Those who were kids in the 80s may remember a sweet little toy called the Pop Ball. A simple rubber hemisphere, this rubber cup could be turned inside out and thrown on the ground, where it would hit and bounce sky high whilst knocking itself right side out. The black ones worked particularly well, and were the first to be banned from [electrosync]’s school along with yo-yos, slap bracelets, and any number of toys that eventually became weaponized by enterprising children.

An industrial Vegemite injection-molded version that only kind of worked.

You can still find Pop Balls today, but they don’t work nearly as well as they did originally because of a lower Shore hardness in the rubber. Naturally, as an adult with futuristic toys at hand, [electrosync] just had to try re-creating the ’80s version. But it wasn’t easy.

They started by studying the patents and anything else they could find. They even managed to get a hold of Peter Fish, the original creator of the Pop Ball, to get some questions answered about the things. According to Peter, the black Pop Ball was made from recycled rubber and worked almost too well. Peter sent [electrosync] an old-stock Pop Ball, which they used to modify their CAD design.

It’s easy to root for [electrosync] throughout this journey, which consists of many failed prints and injection molding attempts. At last, they are able to at least recreate the snap of the modern Pop Ball once they finally found the right filament — the extremely elastic Recreus Filaflex 60A TPU. Of course, it wasn’t all lollipops and rainbows from there, because the filament is notoriously difficult to print with, but [electrosync] made it work. Check it out after the break.

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Bit-Serial CPU: Ultra-Tiny VHDL-Based CPU With Forth Interpreter

Soft cores for FPGAs come in many different flavors, covering a wide range of applications. The Bit-Serial CPU (bcpu) soft core presented by [Richard James Howe] is interesting for taking up just about the most minimal amount of resources (23 slices, 76 LUTs) while providing the means to run a Forth-based (eForth dialect) interpreter. To this CPU core a UART can be added (92 LUTs), as well as other peripherals.

As [Richard] states, the entire core with UART fits in 73 slices (220 LUTs) on a Spartan 6, while requiring a single port BRAM (block RAM). It features a 16-bit accumulator and lacks features such as interrupts, byte addressability and function calls, but those are not required to run the eForth interpreter. The main purpose of this soft core (other than the challenge) is to have a UART-programmable core that can be slotted in any FPGA design. For more serious requirements [Richard] also has the H2 SoC, which can run full-fat FORTH.

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Tetris Goes Round And Round

You’ve probably played some version of Tetris, but [the Center for Creative Learning] has a different take on it. Their latest version features a cylindrical playing field. While it wouldn’t be simple to wire up all those LEDs, it is a little easier, thanks to LED strips. You can find the code for the game on GitHub.

In all, there are 5 LED strips for a display and 13 strips for the playing area, although you can adjust this as long as there are at least 10 rows. The exact number of LEDs will depend on the diameter of the PVC pipe you build it on.

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Tiny Motion Detection Alarm Does The Trick

If you have mischievous children or forgetful elderly in your life, you might want to build a couple of these tiny motion detection alarms to help keep them out of harm’s way. Maybe you want to keep yourself out of the cookie jar. We say good for you.

But you could always put one of these alarms on a window, a drawer, or anything else you don’t want opened or moved. The MPU6050 3-axis IMU makes sure that any way the chosen item gets jostled, that alarm is going off.

As you may have guessed, there isn’t much more to this build — the brain is a Seeed Xiao ESP32-C3, and there’s a buzzer, a battery, a switch, and a push button to program it.

The cool thing about using an ESP32-C3 is that [gokux] can use these for other things, like performing a task when motion is detected. If you do want to build yourself a couple of these, here are step-by-step instructions.

If you’d rather detect motion in the vicinity, here’s a PIR-based solution.

apple airtag being opened to remove the sounder

Apple AirTag: Antitheft Or Antistalking?

Occasionally, the extra features added to a product can negate some of the reasons you wanted to buy the thing in the first place. Take, for example, Apple’s AirTag — billed as an affordable way to link your physical stuff to your phone. If some light-fingered ne’er-do-well wanders by and half-inches your gear, you get notified. The thing is, the AirTag also has an anti-stalking measure, which after a while, notifies nearby iPhones, should the tag move but not be near your iPhone!

In a recent video, [David Manning] explains that this feature is great for preventing the device from being used to track people. But it also means that if said thief happens to own an iPhone, they will be notified of the nearby tag, and can find it and disable it. So in the end, it’s a bit less useful as an anti-theft measure!

The solution is to pop the back off the tag and yank out the little sounder module from the rear plastic. You lose the ability to locate the tag audibly, but you gain a little more chance of returning your stolen goods. Apple could easily remove this feature with a firmware update, but it’s a matter of picking your poison: antistalking or antitheft?

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Want To Learn Binary? Draw Space Invaders!

This was the week that I accidentally taught my nearly ten-year-old son binary. And I didn’t do it on purpose, I swear.

It all started innocently enough. He had a week vacation, and on one of those days, we booked him a day-course for kids at our local FabLab. It was sold as a “learn to solder” class, and the project they made was basically a MiniPOV: eight LEDs driven by a museum-piece AVR ATtiny2313. Blinking lights make a pattern in your persistence of vision as you swipe it back and forth.

The default pattern was a heart, which is nice enough. But he wanted to get his own designs in there, and of course he knows that I know how to flash the thing with new code. So I got him to solder on an ISP header and start drawing patterns on grids of graph paper while I got the toolchain working and updated some of the 2000’s-era code so it would compile.

There’s absolutely no simpler way to get your head around binary than to light up a row of LEDs, and transcribing the columns of his fresh pixel art into ones and zeros was just the motivation he needed. We converted the first couple rows into their decimal equivalents, but it was getting close to dinner time, so we cheesed out with the modern 0b00110100 format for the rest. This all happened quite organically; “unintentional parenting” is what we call it.

While we were eating dinner, I got the strangest sense of deja vu. When I was around ten or eleven, my own father told me about the custom fonts for the Okidata 24-pin printer at his lab, because he needed me out of his hair for a while, and I set out to encode all of the Hobbit runes for it. (No comment.) He must have handed me a piece of graph paper explained how it goes, and we had a working rune font by evening. That was probably how I learned about binary as well.

Want to teach someone binary? Give them a persistence of vision toy, or a dot-matrix printer.

(Art is from a much older POV project: Trakr POV — a hack of an old kids’ toy to make a long-exposure POV image. But it looks cool, and it gets the point across.)

You Got Fusion In My Coal Plant!

While coal was predominant in the past for energy generation, plants are shutting down worldwide to improve air quality and because they aren’t cost-competitive. It’s possible that idle infrastructure could be put to good use with fusion instead.

While we’ve yet to see a fusion reactor capable of generating electricity, Type One Energy, the Tennessee Valley Authority, and Oak Ridge National Lab have announced they’re evaluating the recently-closed Bull Run Fossil Plant in Oak Ridge, Tennessee as a site for a nuclear fusion reactor. One of the main advantages for siting any new generation source on top of an old one is the ability to reuse the existing transmission infrastructure to get any generated power to the grid. Overhead satellite view of a coal-fired power plant next to a heat map showing the suitability of terrain in the region for siting a nuclear power plant

Don’t get too excited as it sounds like this is yet another prototype reactor that will be the proof-of-concept before construction of a reactor that can produce commercial power for the grid. While ambitious, the amount of investment by government entities like the Department of Energy and the state of Tennessee (>$55 million) seems to indicate they aren’t just blowing smoke.

If any of this seems familiar, you might be thinking of the Department of Energy’s report on placing advanced fission reactors on old coal sites. A little fuzzy on the difference between a stellarator and a tokamak? Checkout this explainer on some of the different ways to (non-explosively) do fusion on Earth.