Build Your Own Two-Stage Water Rockets

August 22, 2018 by Lewin Day 15 Comments

Water rockets are one of the most fun and exciting science-adjacent activities one can take part in during the summer, and are popular with children and adults alike. Designs range from a bike pump with a cork in a bottle, up to significantly more advanced hardware. [Air.command]’s two-stage water rocket definitely fits into the latter category.

The build is initially somewhat confronting in its complexity, but after a thorough read-through the operating principles become clear. It’s an all-mechanical setup which relies on the weight of the upper stage and the initial acceleration of the rocket to keep the two stages coupled. It’s only when the first stage stops delivering thrust that a spring forces the two stages apart, and the upper stage rockets ever higher.

Parts-wise, everything is fairly accessible – with pieces cribbed from garden hose fittings, retractable pens and other household ephemera. It’s not the easiest thing to put together, but with perseverance and some tweaking and tuning, it’s definitely achievable for the home gamer, with no advanced tools or techniques required.

Now that you’ve got a two-stage rocket under construction, you might want to consider upgrading your launchpad. Video after the break.

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PC In An SNES Case Is A Weirdly Perfect Fit

August 18, 2018 by Tom Nardi 20 Comments

For better or for worse, a considerable number of the projects we’ve seen here at Hackaday can be accurately summarized as: “Raspberry Pi put into something.” Which is hardly a surprise, the Pi is so tiny that it perfectly lends itself to getting grafted into unsuspecting pieces of consumer tech. But we see far fewer projects that manage to do the same trick with proper x86 PC hardware, but that’s not much of a surprise either given how much larger a motherboard and its components are.

So this PC built into a Super Nintendo case by [NoshBar] is something of a double rarity. Not only does it ditch the plodding Raspberry Pi for a Mini-ITX Intel i5 computer, but it manages to fit it all in so effortlessly that you might think the PAL SNES case was designed by a time traveler for this express purpose. The original power switch and status LED are functional, and you can even pop open the cart slot for some additional airflow.

[NoshBar] started by grinding off all the protruding bits on the inside of the SNES case with a Dremel, and then pushed some bolts through the bottom to serve as mounting posts for the ASUS H110T motherboard. With a low profile Noctua CPU cooler mounted on top, it fits perfectly within the console’s case. There was even enough room inside to add in a modified laptop charger to serve as the power supply.

To round out the build, [NoshBar] managed to get the original power slider on the top of the console to turn the PC on and off by gluing a spring-loaded button onto the side of the CPU cooler. In another fantastic stroke of luck, it lined up almost perfectly with where the power switch was on the original SNES board. Finally, the controller ports have been wired up as USB, complete with an adapter dongle.

[NoshBar] tells us the inspiration for sending this one in was the Xbox-turned-PC we recently covered, which readers might recall fought back quite a bit harder during its conversion.

How The 8087 Coprocessor Got Its Bias

August 18, 2018 by Steven Dufresne 8 Comments

Most of us have been there. You build a device but realize you need two or more voltages. You could hook up multiple power supplies but that can be inconvenient and just not elegant. Alternatively, you can do something in the device itself to create the extra voltages starting with just one. When [Ken Shirriff] decapped an 8087 coprocessor to begin exploring it, he found it had that very problem. It needed: +5 V, a ground, and an additional -5 V.

His exploration starts with a smoking gun. After decapping the chip and counting out all the bond wires going to the various pads, he saw there was one too many. It wasn’t hard to see that the extra wire went to the chip’s substrate itself. This was for providing a negative bias to the substrate, something done in some high-performance chips to get increased speed, a more predictable transistor threshold voltage, and to reduce leakage current. Examining where the bond wire went to in the circuitry he found the two charge pump circuits shown in the banner image. Those worked in alternating fashion to supply a -5 V bias to the substrate, or rather around -3 V when you take into account voltage drops. Of course, he also explains the circuits and dives in deeper, including showing how the oscillations are provided to make the charge pumps work.

If this is anything like [Ken’s] previous explorations, it’ll be the first of a series of posts exploring the 8087. At least that’s what we hope given how he’d previously delighted us with a reverse engineering of the 76477 sound effects chip used in Space Invaders and then went deeper to talk about integrated injection logic (I²L) as used in parts of the chip.

JB Weld – Strong Enough To Repair A Connecting Rod?

August 18, 2018 by Lewin Day 26 Comments

JB Weld is a particularly popular brand of epoxy, and features in many legends. “My cousin’s neighbour’s dog trainer’s grandpa once repaired a Sherman tank barrel in France with that stuff!” they’ll say. Thankfully, with the advent of new media, there’s a wealth of content out there of people putting these wild and interesting claims to the test. As the venerable Grace Hopper once said, “One accurate measurement is worth a thousand expert opinions“, so it’s great to see these experiments happening.

[Project Farm] is one of them, this time attempting to repair a connecting rod in a small engine with the sticky stuff. The connecting rod under test is from a typical Briggs and Stratton engine, and is very much the worse for wear, having broken into approximately 5 pieces. First, the pieces are cleaned with a solvent and allowed to properly dry, before they’re reassembled piece by piece with lashings of two-part epoxy. Proper technique is used, with the epoxy being given plenty of time to cure.

The result? Sadly, poor — the rod disintegrates in mere seconds, completely unable to hold together despite the JB Weld’s best efforts. It’s a fantastic material, yes – but it can’t do everything. Perhaps it could be used to cast a cylinder head instead?

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A Surprisingly Practical Numitron Watch

August 16, 2018 by Tom Nardi 6 Comments

Regular Hackaday readers are surely familiar with Nixie tubes: the fantastically retro cold cathode display devices that hackers have worked into all manner of devices (especially timepieces) to give them an infusion of glowing faux nostalgia. But unfortunately, Nixie displays are fairly fragile and can be tricky to drive due to their high voltage requirements. For those who might want to work with something more forgiving, a possible alternative is the Numitron that uses incandescent filaments for each segment.

There hasn’t been a lot of prior-art that utilizes Numitrons, but that might be changing, given how fantastic this wristwatch created by [Dycus] looks. With a multi-day battery life, daylight readability, and relatively straightforward construction, the Filawatch is likely to end up being something of a reference design for future Numitron watches.

[Dycus] has gone through three revisions of the Filawatch so far, with probably at least one more on the way. The current version is powered by a ATmega328 microcontroller with dual 16-bit LED drivers to control the filaments in the KW-104S Numitron display modules. He’s also included an accelerometer to determine when the wearer is looking at the display, and even a light sensor to control the brightness of the display depending on the ambient light level.

If there’s a downside to Numitron displays, it’s their monstrous energy consumption. Just like in the incandescent light bulbs most of us have been ditching for LED, it takes a lot of juice to get that filament glowing. [Dycus] reports the display draws as much as 350 mA while on, but by lighting it up for only five seconds at a time it can be checked around 150 times before the watch needs to be recharged.

Its been a few years since we’ve seen a Numitron watch, and it’s interesting to see how the state of the art has advanced.

[via /r/electronics]

Raspberry Pi Foosball Scoreboard

August 13, 2018 by Tom Nardi No comments

Foosball, also known as table football, is a classic game from the 1920s that is completely devoid of the bells and whistles of modern gaming. Players control stoic little figures with the most simplistic of input devices in order to move a tiny ball to and fro on the playing field. So naturally, somebody thought they should add a Raspberry Pi to it and drag the whole thing kicking and screaming into the 21st century.

The team at [Matmi] spend a good portion of their down time huddled over a foosball table, but they found the experience was significantly less exciting for the spectators than the players. To add a little more pomp to their sessions they added a flashy display that not only shows the current score, but makes individual scores a bit more exciting by showing some celebratory confetti.

Micro switches mounted in the ball return tubes of the table allow the Raspberry Pi to know who scored and when. This information is picked up by the web-based scoreboard written in Vue.js and served out by nginx. The actual scoreboard is being displayed by a laptop that’s connected to the Pi over Wi-Fi.

If the software setup seems a bit convoluted, it’s because the project itself was something of a learning experience for HTML5 and web programming in general. Further updates are planned to streamline the system a bit to make it more self-contained, as well as adding more features to the scoreboard such as tournaments and randomized matches.

Interestingly, we’ve seen quite a few foosball hacks over the years. It seems these tables are somewhat ubiquitous in offices and hackerspaces. From turning it into an online-enabled experience to building an AI table you can play against, there’s plenty of ways to inject some new life into this nearly 100-year-old game.

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Modern PC Crammed Into An Original Xbox

August 13, 2018 by Tom Nardi 19 Comments

When the original Microsoft Xbox was released in 2001, one of the most notable features of its design was that it used a number of off-the-shelf computer components. Inside contemporary offerings from Nintendo and Sony you’ll see almost nothing but proprietary components, whereas cracking open the Xbox reveals an IDE hard drive, a customized PC DVD-ROM drive, and an Intel Pentium III CPU. Depending on which team you were on, the Xbox’s close relation to PC hardware of the day was either a point of honor or ridicule in the early 2000’s console wars; but regardless of politics, it ended up being instrumental in all of the hacks and mods the console got over its lifetime.

In that light, [P8ntBal1551] managing to jam a modern computer into the shell of an Xbox is like having the last laugh in this nearly two-decade-old debate. Wanting to build an HTPC that wouldn’t look out of place in his entertainment center, he figured the Xbox would make a suitable home for his Intel 4460 powered build. Not to say it was easy: getting all of the hardware and associated wiring inside the case took a bit of cheating, but the end result looks good enough that we’ll give him a pass.

The key to this project is the 3D printed structure inside the Xbox’s case that holds everything together. Painstakingly designed to align all of his components and cooling fans, it took over 58 hours to print just the base plate alone on his CR-10.

Even with all of his primary components installed, [P8ntBal1551] still had to wrestle with an absolute rat’s nest of wiring. He couldn’t find smaller versions of a number of the cables he needed, so he had to resort to some creative wire management to get everything packed in there. In the end, there was simply too much gear for the Xbox’s case to legitimately fit, so he ended up printing a spacer to fit between the bottom and top halves. Though in the end even this worked out in his favor, as it gave him a place to mount the integrated FLIRC IR receiver without having to cut a hole in the original front panel. The end product looks close enough to stock to be almost unnoticeable to the casual observer.

Its been a while since we’ve seen a hack for Microsoft’s original black and green monster, most of the Xbox projects we see are in relation to its significantly more popular successor. It’s always nice to see people keeping the classics alive in their own way.

[via /r/pcmasterrace]