The team at Eschelle Inconnue wanted to “trace a sound cartography of Islam” in Marseilles, France, so they came up with a clever little GPS walking tour powered by an Arduino, MP3 playback module, and a surface transducer speaker.

The team used a Processing app to define geographic areas where each MP3 file would play. An Arduino on the build queries a GPS module and selects the audio file from an MP3 playback module. This isn’t uncommon, and a lot of large outdoor museums (think battlefields) have similar setups.

Determining which audio to play at what location is fairly easy, but that’s not what makes this build special. Instead of simply hooking up a pair of headphones to the build, the team decided to use a surface speaker that turns just about any solid material into a speaker. From the writeup, this is supposed to, “diffuse sounds by giving the illusion to collect them, to listen to the words of the walls, the whisperings through the materials” but we think it’s just a great way to have several people listen to the same audio file at the same time.

Filed under: arduino hacks, gps hacks, portable audio hacks

[John Boxall] of Little Bird Electronics was thinking about combination locks, and how one might improve or at least change the way these locks work. Traditional combo locks can be implemented in a variety of ways, most of which we are all familiar with. Standard rotary padlock and keypad-based electronic safes work just fine, but he was interested to see how one might implement a single button combination lock.

[John] determined that the best, if not only way, to build this sort of lock would require him to measure button press intervals. In his case he decided to monitor the intervals between his button presses instead, but the concept is the same. He first tested himself to see how accurately he could press and release the button, leaving a one-second space between presses. After looking at the results he determined that he would need to incorporate at least a 10% margin for error into his code in order to compensate for human error.

He then created an Arduino sketch to test his idea, defining a set of key press intervals that could be used to ‘unlock’ his imaginary vault. It worked quite well, as you can see in the video demo below.

Now we’re not suggesting that you lock up your mind condition My Little Pony collection or your illegal arms stash with this type of lock, but it could be useful as an extra failsafe for certain projects/gadgets that you want to keep all to yourself.

Filed under: arduino hacks, security hacks

Some friends of mine have a house in the mountains in Steamboat Springs, Colorado.  In the winter they dig a luge track in the (many feet of) snow in their yard and have timed sled races to see who can make it down the fastest. They call it the Mario Cup. I went out there last week with my buddy Mario (a member at Artisan’s Asylum and the namesake of the race) and we made some improvements to the system. Details below.

As you can see, the luge is several hundred feet long and on the side of a mountain, so it’s tough for a person with a stopwatch to know when to start and stop the time.  Here I am testing the track before we had finished it; at the end, I’m a tiny little dot in the snow.

Mario and his girlfriend also helped calibrate the track.

Recently, the competition has become fierce and the accuracy of a stopwatch-wielding human isn’t enough to conclusively pick a winner.  So we automated it.

We designed a system so a “race official” would start the clock by hitting a button on a controller, which would sound a loud countdown of beeps and then start the clock.   The luger would take off from the start line down the track.  Arduinos hooked to sensors would detect when the luger passed the start, midpoint, and finish lines.  The arduinos were also connected to Xbee radios to communicate the time at which the racer passed by.

It took a while to sort out which sensor would work best.  We tinkered around with tilt sensors, photointerrupters, Hall effect sensors, and proximity sensors.  We ended up with plain old photoresistors wrapped in plastic wrap, sealed with tape, and buried in snow under an upside-down disposable plastic food container.  That way, the luger would slide right over the sensor, block the bright white light coming off the snow, and trigger the arduino to note the time and send it back to the controller.  Here we are setting up the sensors and tuning them in fast forward.

And here I am, soldering up voltage dividers in the snow. Potentiometers are difficult to find in Steamboat, but the snow keeps beer cold while you resolder new resistors, so I’m calling it a wash.

Finally, we got the sensors tuned just so.

The timing data was sent by radio back to the controller, which showed the time on an LCD display.

 

Now truth and justice will prevail in the Steamboat Backyard Luge Association races.  More information can be found here: http://mariocup.tumblr.com/

Next steps for the project include adding in two sensors at the start, midpoint, and finish so we can know the luger’s speed at each point, and adding in some fancy blinding-bright luxeon 1-watt LEDs to give the luger a proper starting signal like a christmas tree at a drag race.  Any excuse to go back will do.

It seems everybody has a different interpretation of the perfect alarm clock. [Loic Royer's] alarm clock is not the loudest, or the smartest, but does have some interesting features. By monitoring several environmental factors like temperature, air quality, humidity, dew point, and your own sleep patterns, this alarm clock can determine the best moment in the morning to wake you up.

The main sensor is a wireless accelerometer with the theory being: the more you move in your sleep, the closer you are to a conscious state. The other sensors assist in picking the perfect moment, and awaken you with the sound of birds chirping.

For now all we have is the source code and the list of hardware, but for anyone wanting to try, a circuit diagram wouldn’t be too hard to figure out on your own. Check after the rift for some more videos.

Setting the clock:

Different sensors:

Wireless accelerometer:

This XKCD comic takes a playful swipe and almost everything, including the Arduino. We’ve heard people claim that we have some sort of favoritism toward Arduino, and we don’t. People just submit a LOT of projects with them. But there is one point that we’ve seen a few times that should be addressed. In our categories we have an “Arduino hacks” section. That will not be going away, again, because we get so many submitted. However, shouldn’t we also add some categories for other stuff? Should there be a “pic hacks” category, or maybe just “microcontroller hacks” category?

Let’s not making this an Arduino bashing thread. Instead, give us some good ideas on other categories you would like to see for sorting.

[via littlebirdceo]