Beating Simon

Virtually everyone has played Simon, that electronic memory game from the 70s, but who among us has actually beaten it? That was the goal of [Ben] and his 7-year-old daughter, and after a year of work, an Arduino, some servos, and a few Lego bricks, they’ve finally done it.

Instead of the large original Simon, [Ben] is using a key chain version of the game: much smaller, and much easier to build a device to sense the lights and push the buttons. The arms are made from Lego bricks, held up with rubber bands and actuated with two servos mounted on a cutting board.

To detect Simon’s lights, [Ben] connected four phototransistors to an Arduino. The Arduino records the pattern of lights on the Simon, and activates the Lego arms in response to that pattern. [Ben]’s version of Simon has only a maximum of 32 steps in the final sequence, but that still means each game takes 528 button presses – and a lot of annoying beeps – to complete.

Videos below.

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[Afrotech]’s Guide To Class D Amplifiers

classd

Hang around in any of the many guitar or audiophile forums or discussion boards for long enough, and eventually you’ll come across the arguments over amplifier topologies. One of the more interesting and useful of these classes of amplifier is class d – they’re extremely efficient and when well designed can sound pretty good. [Afrotech] is here to show you how they work, and how to build a 15 Watt amp using a $3 class d amplifier chip.

The very definition of an amplifier is taking a low power signal and transforming it into a high power signal. A great way to modulate a high power signal very quickly is by modulating a square wave with pulse width modulation. A class d amplifier takes a low power input signal, uses it to modulate the duty cycle of a high power square wave, and with a little filtering, amplifies the low power input.

To demo this, [Afrotech] used TI’s TPA3122 class d amplifier chip. It’s a pretty cheap chip for being a 15 Watt stereo amplifier, and the circuit is simple enough to build on a breadboard. With a few caps, resistors, and a pair of inductors, [Afrotech] built this one-chip amplifier that’s capable of powering some pretty big speakers. It’s also very efficient – no heat sink required.

Although class d amps are extremely efficient. there are a few people out there that say because the amplifier is basically a filtered square wave, you’ll be able to hear a difference in the audio over class a or class ab amplifiers. This led to the development of class t amplifiers, basically a class d amp with a higher switching speed (Megahertz for class t, a few hundred kilohertz for class d). Still, if you need a cheap amplifier for a DIY boombox or any other high power application, you could do a lot worse than a simple class d amp.

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Bluetooth Headphones For Hearing Aids

Cyborgs walk among us, but for the time being, it’s really only people with glasses, contact lenses, the occasional hearing aid and the infrequent prosthesis. As with all technology, these devices can be expanded into something they were not originally designed to do – in [Gertlex]’ case, the superpower of listening to music through his hearing aids. he gets a few strange looks from wearing a Bluetooth headset around his neck, but the power to turn his hearing aids ito what are effectively in-ear monitors is a great application of modified electronics.

[Gertlex] began with a Bluetooth headset, his hearing aid, a few resistors, some wire, a 3.5mm audio connector, and an absurdly expensive DAI cable. The DAI cable – Direct Audio Input – is a pseudo-standardized feature on many hearing aids. as its name implies, it allows the wearer of a hearing aid to pipe audio directly into their ear.

By cutting up one of these $50+ DAI cables, [Gertlex] was able to construct a DAI to 3.5mm adapter cable. From there, it was simply a matter of installing a 3.5mm socket on a Bluetooth headset.

It’s a brilliant build, with the most expensive component being the DAI connector itself. [Gertlex] has a few ideas for making these connectors himself – they’re really only three pins and some plastic – and we’re hoping he gets around to that soon.

 

The In-Circuit SD Card Switch

SDISP

For nearly every problem, it’s possible to engineer a solution, even if you’re dealing with an extraordinarily niche problem that might only apply to yourself. [Joel] wanted to be able to program the microSD card in his BeagleBone with a new bootloader or file system without removing the SD card from the target board. This is a peculiar requirement, and it’s highly doubtful a product or even a circuit exists for such a function. This meant [Joel] would need to roll his own board to accomplish the task.

The board is remarkably simple, housing a single microSD socket, two expansion headers for a microSD sniffer for a computer and an embedded board, an FTDI header, and a pair of 4-bit multiplexer/demultiplexers. The operation of the device is fairly straightforward: send a signal down the FTDI cable, and the board switches the onboard SD card from one device to another.

[Joel] has a video of his screen that shows him pulling off in-circuit SD card reading and writing. You can check that out below.

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Hackaday Links: June 8, 2014

hackaday-links-chain

Yes, dogfighting with RC planes is cool. You know what’s even cooler? RC jousting. Considering these eight foot long planes are probably made of foam board or Depron, they’ll probably hold up for a fairly long time. The perfect application of RC FPV.

Home automation is the next big thing, apparently, but it’s been around for much longer than iPhones and Bluetooth controllable outlets and smart thermostats. Here’s a home automation system from 1985. Monochrome CRT display panel (with an awesome infrared touch screen setup), a rat’s nest of wiring, and a floor plan drawn in ASCII characters. It’s also Y2K compliant.

Here’s an idea for mobile component storage: bags. Instead of tackle and tool boxes for moving resistors and other components around, [Darcy] is using custom bags made from polyethylene sheets, folded and sealed with an impulse sealer. It’s not ESD safe, but accidentally zapping a LED with an ESD would be impressive.

Need a stepper motor test circuit? Easy, just grab one of those Polulu motor drivers, an ATtiny85, wire it up, and you’re done. Of course then you’re troubled with people on the Internet saying you could have done it with a 555 timer. This one is for them. It’s a 555, some wire, and some solder. Could have done it with discrete transistors, though.

Someone figured out Lego Minifigs can hold iDevice charge cables. +1 for the 1980s spaceman.

Remember that “electronic, color sensing, multicolor pen” idea that went around the Internet a year or so ago? It’s soon to be a Kickstarter, and man, is this thing full of fail. They’re putting an ARM 9 CPU in a pen. A pen with a diameter of 15mm. Does anyone know if an ARM 9 is made in that small of a package? We’ll have a full, “this is a totally unrealistic Kickstarter and you’re all sheep for backing it” post when it finally launches. Also, this.

The Open Hardware Driver For CRTs

driverCRTs are the king of displays for any homebrew project. They have everything – high voltages, high vacuums, X-rays, and the potential for a vector display – that makes a project exude cool. Getting an old CRT up and running, though, that’s another story. Never rear, because now there’s an Open Hardware eletrostatic CRT driver for your next display.

[Eric] designed a driver circuit that should be able to send a picture to most 2″, 3″ and some 5″ electrostatic CRTs, the kind found in ancient TVs and oscilloscopes. The 1kV power supply uses a transformer usually found in a CCFL bulb, and is able to produce several milliamps. You’ll want to keep one hand behind your back when working on this.

The driver circuit takes a 0-3.3V analog signal for deflecting the beam along the X and Y axis. The amplifier has enough bandwidth to handle NTSC video, so displaying video along with vector letters and shapes is also a possibility with this circuit. Most of the files are available on the git, with three boards available to be ordered from OSHPark.
Thanks [Mike] for the tip.

Converting The Wacom Intuos Into A Cintiq

wacom

Wacom, purveyors of fine pen tablets for digital artists, basically have two product lines of pen tablets. The first, Intuos, is a great pen tablet that give an artist the ability to turn a computer into a virtual dead tree notebook. The second product line, the Cintiq, takes the same technology and adds an LCD to the mix, effectively turning a drawing tablet into a second display. [Bumhee] wanted a Cintiq, but didn’t want to pay the Cintiq price, leading him to install a display in his old Intuos tablet. It’s an amazingly simple build, making us think we’ll be seeing a few derivatives of his work in the future.

The display [Bumhee] used for this modification is a Retina display from an iPad. With the right adapter, you can easily connect one of these displays to a computer, giving you a very thin 2048×1536 9.7″ display. The initial tests to see if this mod would work on his tablet – removing the metal shield on the display, placing it on the tablet, and drawing – were a success, giving [Bumhee] the confidence to irreparably modify his tablet.

From there, the modification was a simple matter of cutting up the enclosure of the tablet, installing the display with a few screws, and installing a piece of glass over the display. Very easy, and it’s just about the only way you’re going to get a pen tablet with a small, high-resolution display for less than a thousand dollars.

Thanks [David] for sending this one in.