At Hack a Day, we don’t throw the term genius around lightly. We’re obligated to bestow that title on [Don Gilmore] for his amazingly simple self-tuning piano. To appreciate [Don]‘s build, you need to realize that just because a piano has 88 keys, that doesn’t mean it has 88 strings. Treble notes have three strings per key while tenor and bass notes have one or two strings each. This usually comes out to more than 200 strings per piano, and [Don] can bring them all up to tune in under a minute.

[Don]‘s system needs to perform two functions. The first one is sustaining the strings so the computer can ‘hear’ the strings. He does this with a magnetic sustainer that is a lot like an E-Bow. To bring the strings up to the right pitch, there are small heaters underneath the pin block. Running a little bit of current through these heaters allows [Don] to decrease the temperature of each string and lower the pitch.

This tech reminds us of the Gibson Robot Guitar, a self-tuning guitar that does it’s trick with motors in the tuners. The Gibson didn’t do well on the sales floor, given that everybody and their mom can tune a guitar. Pianos, though, are another story. [Don] is looking for investors to bring his idea to market, and we hope to see it on the floor of a music shop sometime in the future.

After a few months of eager waiting, [Brook Drumm] has finally released the files for his paradigm-shifting 3D printer, the Printrbot. If you didn’t order one of these during the Kickstarter, you can now print your own set of parts.

[Brook] gave his Printrbot to the world last November with the promise of being extremely cheap, extremely easy to build, and having a relatively high print quality. The simplicity of the Printrbot was amazing, which probably led to the Printrbot getting $830k worth of funding on the initial Kickstarter. Although the files for the 3D printed parts are out in the wild now, there still aren’t any instructions on how to build it apart from a Flickr slideshow.

[Brook] promised to release the files for the Printrbot much earlier, but we’re guessing he’s been busy printing and assembling  the 1200 Printrbots that were claimed in his Kickstarter. While we’re on the subject of cheap 3D printers, [Richard Sum], the English gent behind the SUMPOD sent in a link of one of his $600 printers milling MDF and extruding for seven hours straight. We’re on the cusp of Star Trek-style replicators here, people.

If you’ve ever wanted your own self-driving car, this is your chance. [Sebastian Thrun], co-lecturer (along with the great [Peter Norvig]) of the Stanford AI class is opening up a new class that will teach everyone who enrolls how to program a self-driving car in seven weeks.

The robotic car class is being taught alongside a CS 101 “intro to programming” course. If you don’t know the difference between an interpreter and a compiler, this is the class for you. You’ll learn how to make a search engine from scratch in seven weeks. The “Building a Search Engine” class is taught by [Thrun] and [David Evans], a professor from the University of Virginia. The driverless car course is taught solely by [Thrun], who helped win the 2005 DARPA Grand Challenge with his robot car.

In case you’re wondering if this is going to be another one-time deal like the online AI class, don’t worry. [Thrun] resigned as a tenured professor at Stanford to concentrate on teaching over the Internet. He’s still staying at Stanford as an associate professor but now he’s spending his time on his online university, Udacity. It looks like he might have his hands full with his new project; so far, classes on the theory of computation, operating systems, distributed systems, and computer security are all planned for 2012.

Apparently, there’s some sort of sporting event being televised this weekend that has been historically used as an excuse to buy a big-screen TV. [Joel] wanted a huge-screen TV on the cheap, so he converted an overhead projector to something he can use with his XBox.

Using a bare LCD panel with an overhead projector is a decades-old hack we’ve covered before. The basic idea is fairly simple, but we’ve never seen anything that could be considered a semi-permanent build. [Joel] started his project by picking up a surplus overhead projector for $25 and routing a cutting board to mount the LCD in. The bulb in the projector added a lot of heat, so three small fans are used to blow air between the projector glass and the LCD display.

[Joel] started off looking at the LumenLab DIY projector project, but considered that to be a terrible amount of work with a fairly high initial investment. If you don’t count the few LCDs [Joel] burned through while building his project, his projector was built for under $100. We’re loving the result and are sure it will be much appreciated at [Joel]‘s LAN parties.

[Arpad] has spent quite a bit of time reverse-engineering a home automation system, and, as he is quick to point out, presents the information learned for informational purposes only. He’s really done his homework (and documented it well), looking into the US patent application, and figuring out how the protocol works.

If you’re wondering how someone is able to send a signal over an AC sine wave, at least one technique is the proprietary [Universal Powerline Bus]. This works by sending precisely times pulses in conjunction with the wave that would exist normally. Given the correct software on the other end, this can then be decoded and used for whatever data transfer is necessary.

Although as engineers and technologists, we certainly don’t condone stealing patents,  part of point of one is that others are allowed to learn your secrets in exchange for some legal protection. [Arpad]‘s motivation in doing this is that the technology is only widely available in the US with our puny 120 VAC 60Hz power. With this knowledge, he’s been able to transfer it to work with European 230 VAC 50Hz.

[Yuhin Wu] wrote in to let us know about the Automated Recycling Sorter that was built with a group of classmates at the University of Toronto. They entered it the school’s student design contest and we’re happy to report that it took first place.

The angled sled has been designed to separate glass, plastic, and metal containers. The first sorting happens at the intake area. A set of moment arms are used to weed out the glass bottles. Since there are several of them in a row, a larger and heavier plastic container will not be falsely sorted and the same goes for smaller glass bottles.

With the glass out of the mix the team goes on to separate metal and plastic. An Arduino was used for this purpose. It senses an electrical disturbance caused by a metal can passing through the chute and actuates a trap door to sort it. Plastic has no effect on this sensor and slides past the trap to its own sorting bin.

Don’t miss both demo videos which we’ve included after the break.

Have you ever seen an LED display made out of routers? [Sean] took eight Netgear routers and made an 8×4 display out of them. Because that wasn’t cool enough, a very small version of Conway’s Game of Life was added to the build.

Each router is running a copy of OpenWrt, a Linux distro meant for limited hardware. Instead of an 802.11 protocol, each router runs the B.A.T.M.A.N. advanced mesh protocol. This protocol allows each router to communicate with all the other routers.

Instead of each router receiving data from a master, the routers calculate each step in the Game of Life independently.  Once the routers communicate their initial states, each router is responsible for displaying its four LEDs for each new generation. In the video after the break, you can see [Sean]‘s routers calculating random Game of Life boards. Sadly, we didn’t notice a GoL oscillator being randomly generated, but with a 4×8 play field even a Glider wouldn’t last very long.

Another week has come and gone and that means that it is time for our week in review. These are the top posts that have been viewed at Hackaday in the past week.

Coming in at first place is a post about a project by [Red Jones] and [Brian Kast] of Sandia labs. Ethical issues aside, this is a pretty cool project. They have developed a bullet that can be shot out of a smooth-bore gun that can hit within eight inches of a target one kilometer away. That is pretty amazing. It does this magic with an 8-bit processor. This takes the microcontroller wars to a whole new level. Are they using Microchip, Atmel or (gasp) something else?

In second place is a follow up post to our post asking how to control three LEDs with three switches, all in series. That post, although it was posted in December 2011 came in at number three. Getting back on topic though, this week’s post shows how he did it! Not only that, but it shows the extent that he went to when making it. There is footage through the eyepiece of a microscope showing him building one!

Want to use LiPo batteries in your next project but are afraid to use them? Here is a post where [Paul] shows off a circuit that he built that can charge LiPo batteries using a MCP7813 chip from Microchip.

Finally, rounding out the five is a post about a blog that was taken down but luckily not before the IEEE made a copy of it. This blog was made by a robot operator working at the Fukushima nuclear plant and detailed their ongoing cleanup operations there.

The sales team in [Chuck’s] office is a pretty competitive bunch as you might expect, and they decided that they wanted a system which would allow them to challenge one another during their weekly meetings. The competition involves answering questions posed by their manager, but hand raising only works for so long – they needed a definitive way to tell who “buzzed in” to answer a question first.

Since [Chuck] only had a short bit of time and a tiny budget to work on, he opted to find the easiest solution to the problem, which was an Arduino-based game show buzzer system. The game display is built from an Arduino, some LEDs and an Altoids tin, while the buzzer pushbuttons were salvaged from an old radio broadcast console.

Now, when a question is posed, the salesman can buzz in to answer, knowing that only the quickest person’s button click will be registered. When it’s time for another question, the host simply clicks his buzzer to reset the console.

While it’s not quite as fancy as this game buzzer system we featured a while back, [Chuck] says it does the job perfectly and was cheap to boot.

Continue reading to see a short video of the office game buzzer system in action.

This coffee table is a real show-piece. It’s got a smoky glass surface that is hiding the LCD screen within. But what fun would it be if it could only play video? The rest of the enclosure houses all the parts necessary to make this living room centerpiece into a computer.

After the break you can see a video showing off each step of the build process. It starts by ridding the screen of its enclosure, and using what’s left to determine the size of the wood frame for the table. With the display firmly in place [Nate] sets to work position, mounting, and developing cooling solutions for the motherboard and the rest of the bits. He does nice work and ends up with a table that we’d be proud to feature in our homes.

Now he’s got a lot of computing power and a huge display, but isn’t something missing? How hard do you think it would be to add touch sensitive input to this? We’re wondering if the overlays used to make those Android touchscreens could be mounted on the underside of the glass? 

Build log photos:

Short demo:

[Thanks Mathew]

If you’re one of the hordes whose Xbox 360 died the fiery death associated with the RRoD you may be wondering what to do with that multi-hundred dollar door stop you’re left with. Why not salvage the parts for other uses? If you’ve ever wanted to use your wireless controller with a computer here’s a way to pull out the RF module and reuse it.

The concept is simple enough, there’s a daughter-board in the Xbox 360 which hosts the RF module for wireless controller connectivity. Once you extract it from the carcass of the beast, you just need to find a way to read and push the data to your computer. Any USB enabled microcontroller will do, in this case an Arduino nano was chosen for the task. A bit of level converting was necessary to interface with the device, but nothing too involved.

It sounds like at first there was an issue with syncing a controller with the hacked module, but as you can see in the clip after the break that problem has been solved.

[via Build Lounge]

What’s better than one amazingly acrobatic quadcopter? How about a swarm of acrobatic micro-quadcopters? It’s not a rhetorical question, but an experimental reality. A team at the University of Pennsylvania are showing off their latest round of hovering robots which can move in formation and alter their orientation as a swarm.

You may remember us salivating over the unbelievable stunts the team pulled off with a single ’copter back in 2010. That device needed a sophisticated camera installation to give provide feedback, and this uses the same framework. But we don’t that detracts from the achievement; it’s simply a future hurdle for the project.

The video after the break shows some of the stunts the slew of whirring devices are capable of. Watching them move as a grid, and even landing simultaneously, we can’t help but think of the Dog Pod Grid from Neal Stephenson’s book The Diamond Age. It was used as a protection system, keeping unwanted flying intruders out. Doesn’t sound so far-fetched any more, does it?

http://hackaday.com/2010/05/28/quadcopter-acrobatics-like-nothing-weve-seen/

Agonize no more over stripping the insulation off of tiny wires like those used in ribbon cables. For years we’ve used razor blades to do this, as the tiniest wires don’t have a slot on our trusty wire strippers. But often we cut all the way though the conductor (or many of the strands) when doing so. [Bjbsquared] came up with this design that will alert you when you’ve hit the conductor.

It uses the two metal razor blades as electrodes in the LED circuit. When anything metal connects the two, the LED will be illuminated. This way you know you’ve cut far enough, and should be able to tug the insulation off of the wire. This image only shows half of the printed unit, a second piece covers up the inner workings, and helps keep stray fingers away from the edges of the blades.

Overkill? We don’t think so, and we hope everyone will agree this is a wonderful design.

[via Reddit and Gizmodo]

[Alan] was unimpressed by the cheap ticking egg timers that grace many of our kitchens. He decided this was an execllent opportunity to ply his skills with microcontrollers. He built this kitchen timer complete with an enclosure and audible alarm.

The device is Arduino based, which makes driving the graphic LCD quite easy thanks the libraries associated with that platform. As you can see above, his user interface makes use of virtual buttons – three tactile switches whose function is listed at the top of the display.

But we think the alarm sound really earns this a place in his kitchen. He used the same hardware as that that Super Mario Bros. Toilet project to play classic video game sounds when your soufflé needs come out of the oven. We haven’t come across them ourselves, but apparently there’s a line of key chains for sale in Japan (yes, we need to plan a trip there!) that have the tunes programmed into them. They’re easy to crack open and it beats dealing with a speaker and amp circuit.

It’s really amazing what you can find at military surplus shops. [David] just built a radiation detector out of a DT-590A scintillation probe originally made to test if Air Force bases were contaminated with Plutonium. Who says nothing good came out of massive nuclear arsenals?

DT-590A / PDR-56 Gamma ray probes were made obsolete by the US Air Force a few years ago and they’re trickling into military surplus stores around the country and the Internet. [David] found the manual for this probe and put together a little circuit to drive this x-ray sensor. The build uses an ammeter as a simple dial, and includes a piezo speaker for the prerequisite Geiger counter ‘clicks.’

[David] also threw up a post on converting this x-ray probe into a general purpose Gamma probe, effectively making it a Geiger counter for the really dangerous radiation. You could always use your smart phone for the same task, but recycling military hardware imparts a good bit of geek cred.

[Andrew] and his brother had some time (and a lot of ping pong balls) on their hands, so they decided to have some fun and built a remote-controlled ping pong ball turret.

Arduino aside, the turret is cheap and easy to build as [Andrew’s] writeup explains. The firing mechanism was constructed using a pair of foam wheels and motors, which is used to launch the ping pong balls much like a baseball pitching machine. The balls are stored above the wheels in a cardboard tube and released by a mechanical flap when triggered.

When [Andrew] is ready to release the turret’s payload, he sends a command to his computer over VNC, which relays the command to the Arduino over a serial connection, triggering the flap. While the control scheme could certainly benefit from direct, wireless phone-to-Arduino communications, it seems to work well enough for [Andrew's] needs.

Check out the video dramatization below to see [Andrew] “surprise” his brother with a hail of ping pong balls after the jump.

Retro is in the air today as [John] has tipped us off about a new game he has written for the Tandy Color Computer (CoCo), The game, inspired by the homebrew game DOWNFALL for the Atari Jaguar, features what looks like snappy game play, lots of bright colorful animation and has just entered the Alpha stages. The blog page above sheds some insight on what it takes to make a game for these old 8 bit wonders, cause no matter how easy it sounds, you do have to do some dancing to get even the simplest of things working correctly on such limited resources.

The game was part of this years Retrochallenge which is typically held in January, which we recommend checking out if you want your fill of random projects for old computers. From building an Apple I replica kit, to making a soccer game for a SGI system, getting a 5160 XT online or just noodling with a KIM, there is plenty of interesting projects to keep you occupied during the afternoon.

Join us after the break for a quick video of Fahrfall, the fun looking CoCo Game.

Even though we’ve seen dozens of Kinect hacks over the years, there are a few problems with the Kinect hardware itself. The range of the Kinect sensor starts at three feet, a fact not conducive to 3D scanner builds. Also, it’s not possible to connect more than one Kinect to a single computer – something that would lead to builds we can barely imagine right now.

Fear not, because Microsoft just released the Kinect for Windows. Basically, it’s designed expressly for hacking. The Kinect for Windows can reliably ‘see’ objects 40 cm (16 in) away, and supports up to four Kinects connected to the same computer.

Microsoft set the price of Kinect for Windows at $250. This is a deal breaker for us – a new Kinect for XBox sells for around half that. If you’re able to convince Microsoft you’re a student, the price of the Kinect for Windows comes down to $150. That’s not too shabby if you compare the price to that of a new XBox Kinect.

We expect most of the builders out there have already picked up a Kinect or two from their local Craigslist or Gamestop. If you haven’t (and have the all-important educational discount), this might be the one to buy.

It might just be a case mod, but we love [Eduard]‘s take on a modern Macintosh LC (translation). The donor motherboard came from a disused home server, and the LC came from [Eduard]‘s childhood memories of playing Glider and The Incredible Machine.

The case was donated from a venerable Macintosh LC, manufactured circa 1990. The original LC had a Motorola 68020 CPU, which [Eduard] upgraded to an Intel Atom board. It was a somewhat tricky build – he adapted a 90 Watt power supply from a piece of old office equipment to power the new Intel board. With a great deal of very careful Dremel work, the old-school Apple logo was modified into a power button for the new computer.

For frequent readers of Hack a Day, it’s no surprise that we’ll grab up any old Apple or Mac build. [Kevin] built a weather station and analog joypad for his Apple IIc, We’ve seen custom Mac ROM SIMMS, and of course [Sprite_tm]‘s amazing SE/30 emulation. If you’ve got something that will send our 68k senses tingling, send it on into the tip line.

As a boy scout properly acculturated into the DIY philosophy, [Adam] really wanted to get his hands on the new Inventing merit badge. The merit badge required solving a problem, so of course a pinewood derby instant replay system was the obvious solution.

After thinking through a few solution paths like a radio-controlled camera that follows the cars, [Adam] settled on a system that would replay the pinewood derby cars crossing the finish line.  [Adam]‘s father found a cheap and readily available Playstation Eye camera that can record 60fps video for this task. [Adam]  used a laser/photodiode/Arduino setup to detect when a car was crossing the finish line. A bit of Processing code supplied by his father records the relevant 60 frames of video and plays them at 5fps on a projector for the enthralled spectators.

We suspect that a similar setup could be used if [Adam]‘s den wanted to try the rain gutter regatta or oft-forgotten space derby next year. Check out [Adam]‘s instant replay system after the break, or join us in the comments for the inevitable argument over who had the best pinewood derby car.