Archive for the ‘Projects’ Category

More Citations and a Camera Mount Field Test

Saturday, March 15th, 2008

Here are a couple updates regarding previous projects. I've been spending free time lately reading, but I should have some new stuff soonish.

[citation needed] stickers have been slowly showing up in new places. I've still got a number left, so if you want a few, just send me an email or a message via Flickr. A few from around Tempe and San Francisco are in the Flickr tag pool:

Inclusive community [citation needed]I'm willing to bet I've had something similar

I especially dig this one from Flickr user cutlerite:

Boise State ROTC

Reason Magazine also recently published a short article about the project, in their March issue. Don't be afraid -- they're much nicer Libertarians than some of the Randroids I've met!

I also finally had a chance to really test my bicycle camera mount -- the lead-up to the Game Developers Conference had left me with little time for biking anywhere other than work. I went riding with Matthew and took a few shots as well as this video:

On a side note I don't recommend trail riding with this particular mount -- the constant jostling broke the conduit hanger I was using to mount the tripod head. Luckily it's the cheapest piece at only 50 cents, but the weight of the assembly demands something a bit sturdier than cheap plastic if you're going to be navigating bumpy terrain!

Drunkpong: An excuse to make a USB Breathalyzer

Tuesday, February 19th, 2008

You're throwing a party for the Game Developers Conference and you think it would be cool to have a custom game. What's the natural response? How about Pong that adapts its difficulty based on how drunk you are!

Among my numerous interests is custom hardware for games and interactive art. When my friend and coworker Matthew Wegner suggested the idea of making a breathalyzer peripheral for a party game at GDC, how could I respond with anything but, "Hahahaha, Hells YES! I am ON that!"

I started by researching the various consumer breathalyzers. In the end I decided to hack the Alcoscan AL2500. It provides readings within a reasonable error tolerance and costs about $30 on Amazon -- much cheaper than fuel cell meters. Upon opening it up, I found that it's set up pretty simply. It's driven by an ATMEGA48V-10AU microcontroller, with the semiconductor sensor connected to an analog input, and digital outputs that drive a simple seven-segment style LCD.

Alcoscan AL2500 BreathalyzerBoard, back. Simple AVR microcontroller with sensor as an analog input and LCD as digital outputs

As I saw it, there were basically two options for obtaining the data from the breathalyzer and sending it to the computer. On the one hand, you could read the analog value from the breath sensor, or on the other hand, you could reconstruct the LCD digits from the digital outputs. Since the analog circuit driving the sensor was a little complicated and beyond my expertise (and I'd procrastinated enough that learning more before GDC was out of the question), I decided to reconstruct digits. I first followed traces on the PCB to find which pins on the microcontroller were driving the LCD. I then systematically grounded each pin while turning the unit on to determine which pins drove which LCD segments.

Mapping out which pins control which LCD segmentsPin cross reference for AVR microcontroller and LCD

I then soldered wires to the relevant LCD outputs on the board (the connectors were nice and big compared to the microcontroller pins). I spent a bit of time determining which outputs from the LCD I wanted to read. As it turns out, you only need five segments from a seven-segment digit to determine the numerical value of the digit -- the bottom and bottom right segments are superfluous (see Matt Mets's recent post, who solved the problem independently). I ran a total of eleven wires -- two digits for the BAC level and one wire for the "Wait" indicator -- into digital inputs on an Arduino Diecimila. The Arduino code ended up pretty simple -- it reconstructs two digits and the status of the "Wait" indicator and transmits these serially via USB.

You only need to observe five segments of a seven-segment display to know which number is displayedSoldering more wires - first digit done

I then read the serial data in using the Java RXTX library and spit it into a text file, which I then read in from Unity. The game then makes the paddle size larger the drunker you are!

Waiting for the player to use the breathalyzerPlaying with Player 1 significantly drunk

The hardware is of course begging to be used in other ways -- how about a program that locks you out of Ecto and your forum accounts when you're right trashed? No more embarrassing comments that you can't take back! I may go back and make a more sophisticated game in the future -- Pong was about the right scope for the single day of development time I had left after handling the hardware and serial transmission!

I'll have the game up for play at the 9Bit indie games party Tuesday night -- if you're at GDC just find folks from Flashbang, Gastronaut, or ThatGameCompany to get an invite and drink tickets! I'll post an Instructable and some more information about the software when time permits. Extra special thanks to Becky Stern and Matt Mets for their advising on the hardware interface!

A Quick Release Bicycle Camera Mount

Sunday, January 27th, 2008

Since buying my bike, I find myself cycling pretty often and I usually bring my camera along to take pictures. Usually taking photos involves stopping and fumbling around in my backpack for the camera -- not an ideal situation. Naturally, the first thing I started thinking about after buying the bike was, "How can I mod this to make it uniquely mine?" While looking through Instructables for ideas, I found instructions for a bicycle camera mount. It dug it, and it had the benefit of being cheap, but was a little feature-anemic. Specifically, it couldn't tilt at all, so would result in unlevel pictures on my bike, and it wasn't easy to remove the camera -- you had to unscrew it from a bolt for unmounted shots. I immediately thought of tripods with quick release plates and decided on a simple remake using a tripod head. I made and attached it this weekend, with pretty excellent results! Now I can make photos while biking and easily transition to hand-held shots when I see something cool on the roadside!

I published an Instructable for anyone interested in making one, and have a photoset up on Flickr.

PartsDrilling the bracket to attach the mounting bolt
Finished bracket with cotter pin screw insertedFinished mount assembly, front
A sample photo taken along a canal - it's pretty level!

[citation needed]

Tuesday, January 1st, 2008

It's no secret that I'm a big Wikipedia fan -- I've got a serious case of NADD and about half my browser tabs at any given time are Wikipedia articles. One of my favorite quirks about the site are the little [citation needed] tags that users can place in an article, indicating that a dubious claim needs a reference. One day an idea struck -- what statements are more dubious or outright ridiculous than those in advertisements? Thus, an OM project was born. I had 250 8x2 inch stickers printed, which I handed out to friends, who circulated them further. In true wiki fashion, the final placement of the stickers is a collaborative effort, now distributed and anonymous. If anyone sees one somewhere, please make a photo! I've been tagging my photoset on Flickr with citationneeded and wikiffiti -- more should start showing up in the next few weeks. I'm also providing the source Photoshop file (or as pdf) for anyone who wants to print their own batch. Note that you may have to resize the canvas or change the image mode to CMYK depending upon the print service used.
Update: A few people have asked via Flickr about printing services. I found via google, and ended up using them simply because their minimum order size was 250 instead of 500 -- there may be better or cheaper options available. They simply have a quote form you fill out, then you upload your file (such as the CMYK one above). Very painless overall.

Lavatory warning [citation needed]Protecting and Preserving Our Neighborhoods [citation needed]
Crime-free housing [citation needed]WikiffitiWikiffiti

Sun Jars

Sunday, December 16th, 2007

I saw an Instructable for these neat LED-lighted jars some time ago - I thought it would be cool to make a couple to leave in my room. It's a very simple hack - you gut a solar garden lamp, replace the LED if desired, and then place the parts into the lid of a large-mouth jar. Then simply do something to diffuse the light emitted - I used a glass frosting paint but you could just as easily add in a sheet of tracing paper or the like. I ended up making four - they turned out very nice, and I gave two away at the Phoenix DIY Meeting. Full Flickr photoset.

Really, there weren't many construction photos to take, but here's the garden lamp guts being epoxied to the jar lidsThe energy of the sun, collected in jars!

LED Bike Helmet

Wednesday, November 28th, 2007

After getting my new bike, it was clearly project time. But what to do first? There are plenty of interesting things to do with a bike, but what cinched it was my light being stolen. I decided to mod my helmet by adding LEDs, so that I'm more visible to cars and other cyclists at night, and as a backup against light failure or misappropriation. (also, mental masturbation - LEDs make anything cooler) I followed Becky's Instructable for the most part, with a few modifications of my own. The basic idea is to use conductive paint to draw traces for the circuit, then attach the LEDs, battery, and switch with conductive epoxy, and finally use regular epoxy and a clearcoat to weatherproof everything. The switch used is a magnetic reed switch, activated by a magnet tethered to the helmet's strap anchors. Full photoset on my Flickr account.

Testing the circuitMasking for conductive paint
Final configuration on my head - BackThe original design had a magnet with a hole in the center - I epoxied a small loop of wire to the magnet I had
Final configuration on my head - FrontA final touch