Arduino Hacks

3048 Articles

Cast A Shadow, Play A Note

December 15, 2013 by 3 Comments

Looking for a way to entertain friends and family this holiday season? Look no further than the Arduino-powered Photocell Piano. [Asahillis] has posted this Instructable for building a 6-note musical command center.

The piano uses photoresistors to turn each note on when the player runs their hand over it. Notes can be tuned independently using potentiometers on the front of the box. The hack uses two circuits: one to generate the tones, and a second to mix them. [Asahillis] adapted [Forest Mims III]’s timeless schematics for the 555 Tone Maker and the 741 Audio Mixer to create his Photocell Piano.

When the instrument is powered on, the code takes a 5-second reading of the ambient light, and sets a threshold based on its findings. Afterward, the first note will sound, indicating the piano is ready to be played. Each note has its own if-else statement that tells it to sound when its corresponding  photoresistor reaches a value below the set threshold (when the player casts a shadow). There’s a demo video included in the guide but we couldn’t embed it here.  Check out the demo video after the break.

If you prefer to rock out with your lights out, there’s always this impressive laser harp.

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Flying Spaghetti Monster Display

December 13, 2013 by 91 Comments

[Anthony Liekens], one of our favorite hackers from Belgium, recently completed this large (and awesome!) Flying Spaghetti Monster LED display!

With so many different holidays in December, [Anthony] decided he wanted his family to celebrate a slightly less traditional deity. The body is a massive 4′ by 8′ wooden board that we think [Anthony] cut out by hand, with a total of 300 RGB LEDs driven by an Arduino. Chicken wire mesh provides support for the LEDs in the FSM’s mouth and eyes. [Anthony] built everything in his very own backyard hackerspace called the Open Garage, which is a fantastic neighborhood hackerspace (and we should know—we stayed at his place during our European Hackerspace Tour!)

[Anthony] has a bunch of videos showing off the display on his personal YouTube channel, but stick around after the break for a quick sample that features the Flying Spaghetti Monster in the front window of his home.

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Arduino Controlled Beer Brewing Machine!

December 13, 2013 by 12 Comments

[the_meatloaf] just put the final touches on his fully automated beer brewing machine using an Arduino.

The project was part of his computer engineering degree, and it took [the_meatloaf] and two mechanical engineer friends a year to design and build the entire system from scratch. An Arduino Mega with a 4-button interface allows you to program, save, load, rename, and run up to 26 different recipes saved to the EEPROM.

An automated system like this removes most of the guesswork from an otherwise complex brewing process. The machine starts by heating the water in the first keg using a 2000W heating element, after which the water transfers into the mash vessel via servo valves, where it’s stirred by a mixing motor. The machine then drains the wort (the resulting liquid after mashing) and sparges (adds more water to the mash tun) the grains as programmed: thanks, [Chris,] for clarification! The wort is brought to a boil for the programmed amount of time, while a servo-controlled “hopper” automatically adds the hops.  Finally, a counter-flow heat exchanger rapidly cools the solution to room temperature using ice water, then dispenses the solution for fermentation.

Though [the_meatloaf’s] biggest project to date was quite the accomplishment, he unfortunately won’t get to enjoy it. The sponsors who covered the $1000 budget reclaimed the machine. Drat.

[via Reddit]

Hacking A Reader For Medical Test Strips

December 13, 2013 by 7 Comments

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[Rahul] works at a startup that produces cutting edge diagnostic test cards. These simple cards can test for enzymes, antibodies, and diseases quickly and easily. For one test, this greatly speeds up the process of testing and diagnosis, but since these tests can now be administered en masse, health services the world over now have the problem of reading, categorizing, and logging thousands of these diagnostic test cards.

The normal solution to this problem is a dedicated card scanner, but these cost tens of thousands of dollars. At a 24-hour hackathon, [Rahul] decided to bring down the cost of the card scanners by whipping up his own, built from a CD drive and an Arduino.

The card [Rahul] used, an A1c card that tests for glucose bound to hemoglobin, has a few lines on the card that fluoresce with different intensify depending on the test results. This can be easily read with a photodiode connected to an Arduino. The mechanical part of the build consisted of an old CD drive with a 3D printed test strip adapter. Operation is very simple – just put the test strip in the test strip holder, press a button, and the results of the test are transmitted over Bluetooth.

Not only is [Rahul]’s build extremely simple, it’s also extremely useful and was enough to net him the ‘Most Innovative Project’ prize at the hackathon in his native Singapore.

Portable Musical Stairs

December 13, 2013 by 8 Comments

musical stairs

[Amir] recently finished a pretty cool project — Portable Musical Stairs! He designed and built it so it could be temporarily installed in schools for musical therapy sessions with autistic children — a fun activity for all ages!

The system utilizes lasers and photo sensors that come with a built in digital output with a sensitivity potentiometer, which makes it super easy for the Arduino Leonardo to interpret. The reason they are using 2 by 4’s for the system is because of the width of the stairs. At 1.75m across, a laser misaligned by only 1 degree results in it being about 3cm off!

On the software end of things, the Arduino acts as a HID input to the computer to create the sounds. [Amir] has put together a free sound sampler on his website makeysoundy.com, and we must say, it’s pretty fun! You can assign notes to different keys, which makes it super easy to make a similar project to this!

Stick around after the break to see the stairs in action!

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Finally, An Animated GIF Light Painter

December 12, 2013 by 6 Comments

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Light painting, or taking a picture of a moving RGB LED strip with a very long exposure, is the application du jour of Arduinos, photography, and bright, glowey, colorful things. Hackaday alumnus [Phil Burgess] has come up with the best tutorial for light painting we’ve seen. It’s such a good setup, it can be used to create animated .gifs using multiple camera exposures.

The build uses an Arduino Uno, SD card shield, and Adafruit’s new NeoPixel strip with 144 RGB LEDs per meter. Despite a potentially huge mess of wires for this project, [Phil] kept everything very, very neat. He’s using an Altoids case for the ‘duino, an 8 AA-cell battery holder and 3A UBEC  for the power, and a wooden frame made out of pine trim.

Part of the art of light painting involves a lot of luck, exponentially so if you’re trying to make a light painted animated .gif. To solve this problem, [Phil] came up with a very clever solution: using a rotary encoder attached to a bicycle. With the rotary encoder pressed up against the wheel of a bike, [Phil] can get a very precise measurement of where the light strip is along one dimension, to ensure the right pixels are lit up at the right time and in the right place.

It’s a wonderful build, and if Santa brings you some gift certificates to your favorite electronics retailer, we couldn’t think of a better way to bring animated .gifs into the real world.

8-Track Tapes As A Storage Medium

December 10, 2013 by 42 Comments

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Before [Woz] created the elegant Disk II interface for the Apple II, and before Commodore brute-forced the creation of the C64 5 1/4″ drive, just about every home computer used cassette tapes for storage. Cassette tapes, mind you, not 8-track tapes. [Alec] thought this was a gross oversight of late 1970s engineers, so he built a 8-track tape drive.

This actually isn’t the first instance of using 8-tracks to store data on a computer. The Compucolor 8001 had a dual external 8-track drive, and the Exidy Sorcerer had a tape drive built in to the ‘the keyboard is the computer’ form factor. It should be noted that nearly no one has heard about these two computers – the Compucolor sold about 25 units, for example – so we’ll just let that be a testament to the success of 8-track tape drives.

[Alec] installed an 8-track drive inside an old external SCSI hard drive enclosure. Inside is an Arduino that controls the track select, tape insertion and end of tape signals. Data is encoded with DTMF with an FSK encoding, just like the proper cassette data tapes of the early days.

On the computer side of things, [Alec] is using a simple UNIX-style, pipe-based I/O. By encoding four bits on each track, he’s able to put an entire byte on two stereo tracks. The read/write speed is terribly slow – from the video after the break, we’re assuming [Alec] is running his tape drive right around 100 bits/second – much slower than actually typing in data. This is probably a problem with the 40-year-old 8-track tape he’s using, but as a proof of concept it’s not too bad.

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