Hack a Day

A while back we saw the MintEye CAPTCHA system  - an ‘are you human’ test that asks you to move a slider until an image is de-swirled and de-blurred – cracked wide open by exploiting the accessibility option. Later, and in a clever bit of image processing, the MintEye CAPTCHA was broken yet again by coming up with an algorithm to detect if an image is de-swirled and de-blurred.

It appears we’re not done with the MintEye CAPTCHA yet (Russian, translation). Now the MintEye CAPTCHA can be broken without any image processing or text-to-speech libraries. With 31 lines of Java, you too can crack MintEye wide open.

The idea behind the hack comes from the fact that blurred images will be much smaller than their non-blurred counterpart. This makes sense; the less detail in an image, the smaller the file size can be. Well, all the pictures MintEye delivers to your computer – 30 of them, one for each step of swirl and blurring – are the same size, meaning the ‘wrong answer’ images are padded with zeros at the end of the file.

There’s a 31 line program on the build page that shows how to look at thirty MintEye images and find the image with the fewest zeros at the end of the file. This is, by the way, the correct answer for the MintEye CAPTCHA, and has a reproducibility of 100%.

So, does anyone know if MintEye is a publicly traded company? Also, how exactly do you short a stock?

Looking to build your own instrument out of plumbing and tape? [Scott] made his own set of Membrane Bagpipes out of PVC pipes, a plastic bag, and duct tape.

Bagpipes are made out of a few parts. The drones are pipes that are tuned to play a single note. They are tuned by the fixed length of the pipe. The chanter is a tube with finger holes. This lets you play various notes depending on which holes you cover. The blowpipe is used to fill the bag with air that will pass through the membranes on the drones and chanter. Finally, there’s the bag which stores air.

[Scott]‘s build uses PVC for the drones and chanter. The membranes are made out of cut up bits of plastic bags. Some crafty duct tape work makes up the bag, and seals it on to the various parts. A check valve is used to stop warm, duct tape flavoured air from blowing back into your mouth.

It’s pretty amazing what people can do with a few rolls of duct tape. The pipes aren’t exactly in tune, but they certainly work. Check out a video of them in action after the break.

[Samir] dabbles in hobby electronics and decided to put his skills to the test by building this portable gaming console (Note: this site uses an HTTPS address which cannot be used through Google Tranlator. It does work for the Chrome browser translator). The image above is a screenshot from his Breakout-style game. The paddle at the bottom is controlled with the touchscreen. You move it back and forth to keep the ball from traveling past the bottom edge (it bounces off of the red borders on the sides and top).

The main PCB is larger than the 3.2″ LCD footprint, but [Samir] made sure to include a lot of peripherals to make up for it. The board sports a Parallax Propeller chip to run the games. It interfaces with the SSD1289 screen (this is a cheap and popular choice) but that really eats up a lot of the IO pins. To control the game the touchscreen can be used as we’ve already mentioned. But there are two other options as well. There is an expansion port which uses a shift register (74HC165) to serialize the input. For prototyping this allowed [Samir] to use an Atari joystick. He also rolled a Bluetooth adapter into the project which we would love to see working with a Wii remote. Rounding out the peripherals are an SD card slot, audio jack for sound, and an RTC chip for keeping time.

There are several videos included in the post linked above. After the break we’ve embedded the game-play demo from which this screenshot was taken.

This telepresence upgrade lets an employee take part in the office from more than four thousand kilometers away. It’s an upgrade of their previous setup which used a laptop on a rotating platform to add a bit of control to the video conferencing experience. But all that original version could do was swivel, this one lets you drive your virtual self around for fifteen hours between battery charges.

The real work is in the base of the robot, as the audio and video are handled by a tablet independently from the locomotion. The team spent about four hundred bucks to throw the thing together. It starts with a hunk of plywood. Two 3A motors were mated with lawnmower wheels for the front of the bot. Dragging under the back of the base are a couple of casters that make it possible to turn without skidding. A motor shield and a WiFi shield for the Arduino make it possible to control the thing over the Internet. They even added some functionality on the client side to use a PlayStation 3 controller. Check out the completed machine in the clip after the break.

When we read “smaller paddles” we immediately thought of the physical controllers that you hold in your hands. But this hack alters the size of the virtual Pong paddles displayed on the TV screen.

We remember quite well the episode of That 70′s Show where Red and Kelso take apart their Pong machine to hack it. The video after the break which [Blues Image] put together shuffles scenes from that episode in with images of his hack. The characters are adamant that the game is too easy and reducing the size of the virtual paddles is the only thing that will make it fun again. After building his own hardware from the original schematics, [Blue Image] figured this challenge was worth a try.

His solution is in the form of two man-in-the-middle boards which insert a way to reroute the pins without altering the main board. One of the chips is used to draw the paddles, the other checks for collisions with the ball. By changing the pin-out the paddles are reduced from fifteen pixels down to seven.

[via Reddit]

In and of itself this mobile chicken coop is a pretty nice build. There are some additional features lurking inside which you don’t find on most coops. [Neuromancer2701] built-in a set of sensors which can be accessed wirelessly. It makes it a snap to check up on the comfort of the hens without leaving the couch.

At the heart of the sensor system is an Arduino along with an Xbee module. The build isn’t quite finished yet, but so far three sensors have been implemented. A thermistor is used to read the temperature inside the coop. To make sure there’s enough water, two sheets of foil tape were applied to the water reservoir. The CapSense library measures the capacitance between these plates which correlates to the water lever (we’ve seen this type of water level sensor before). And finally, there’s a sensor that can tell if the door to the coop is open or shut.

He’s having trouble automating the door itself. This can be pretty tricky, especially if you go for a super complicated locking mechanism like this one.

As we announced last Friday, we’ve got a brand new email list. Again, this isn’t another way to get our normal hacks, but a sneak preview of the videos we’re working on. Sign up  right over there in the right column —->, if you want to see what is coming, and would like to give us feedback and ideas on how to make the videos better.

We like this project for its sheer simplicity. After all, recreating the hardware in the controller for a modern gaming system is next to impossible. [Guillermo A. Amaral B.] had a bunch of parts sitting around and decided to try his hand at recreating an original Nintendo Entertainment System controller.

If you’re not familiar with the electronics inside this brand of retro gaming hardware you might be surprised to find that there’s barely any logic hardware at all. The chip in the middle of the board is a 4021 parallel to serial shift register. It connects to the buttons and uses the clock signal coming through the cable to pulse out the button states over a serial wire. So all that [Guillermo] did was lay out the chip with connects for each button.

In the image above his thumb is obscuring the 5-way switch used for directional control and select (center click). The yellow and green buttons serve as A and B, with the start button on the opposite side of the board due to a mistake in his board layout. He does have some future plans for this. He’s working on a Raspberry Pi project that will monitor and record the controller serial data so that you can play it back. It sounds like a player piano for video games.

Want to see a really small version of this? The same hardware in a smaller package was put together a couple of months ago to build the world’s smallest NES controller.

[via Adafruit]

The University of Kent’s hackerspace, TinkerSoc, recently had a talk on software-defined radio using an incredibly inexpensive USB TV tuner. Of course this is nothing new to Hackaday readers, but they did manage to build one of the best antennas for their TV dongle. It’s a discone antenna, and is perfectly suited for tuning into a whole bunch of really cool things such as weather balloons and aircraft transponders.

The idea discone antenna looks exactly like its namesake; a metal disk attached to a metal cone. Of course with the frequencies the RTL software-defined radio deals with, it’s rarely necessary to build antennas out of sheet metal. The team at TinkerSoc built their discone out of galvanized garden wire and attached it to the input of their TV tuner.

All the dimensions for their discone antenna were gleaned from [ve3sqb]‘s antenna design programs. Since TinkerSoc designed their antenna for 110 MHz, it ended up being pretty large. For higher frequencies, though, a discone antenna become fairly small and more than portable enough for a mobile rig.

Furby teardowns are a favorite of ours, and there’s nothing quite like flaying open a creepy talking deformed animatronic owl/hell beast. There’s a lot you can do with a set of screwdrivers and a pair of scissors, but it takes a real clever person to reverse engineer a Furby without any disassembly (Russian, here’s the translation).

The new Furby comes with an iOS and Android app that allows children to interact with the Furby by feeding it, giving it commands, and even translating the Furbish into English. These apps work by playing a WAV file encoded with commands that give the Furby something to eat, or tell it to dance a merry jig.

Commands are delivered with these WAV files by means of a 4-digit, 4-bit code, complete with checksums. There are ten bits the Furby actually responds on, meaning there are potentially 1024 different commands the Furby can accept.

[iafan] wrote a Perl script to listen in on the audio generated by the Android Furby app and correlated all the possible commands with actions taken by the Furby. Everything is up on a git, allowing anyone to play an audio file and control the Furby’s mood and actions.

With this it should be possible to remotely control a Furby, letting it dance whenever you receive an email, or making it angry whenever someone retweets you. It’s a lot more clever than just putting a Furby through a wood chipper, but considering how creepy these things are, we’re not going to say it’s better.

One of the more interesting use cases for the Raspberry Pi is exploiting its DSP capabilities in interesting ways. There’s a lot of horsepower inside the Raspberry Pi, more than enough to do some very interesting things with audio, all while being powered by a small wall wart adapter. [Pierre] over on the Pure Data mailing list has a proof-of-concept working that uses the Raspi as a guitar effects processor. The results are very encouraging – [Pierre] is able to use his Raspi as a delay, pitch shifter, and of course a classic flanger, phaser, and chorus with a latency of about 16 ms.

There are a few steps necessary to get low latency with the Raspi’s audio interface. [Pierre] is running his Pi headless, and allocated more RAM to the CPU.

If you’d like to try this out for yourself, [Pierre] has a tutorial for setting up Pure Data with the Raspberry Pi. He’ll be updating his blog soon with more tutorials and verified USB audio interfaces later.

Check out the processor in action after the break.