Intro

Urbana is an annual fundraiser hosted by Dharma Developments where proceeds raised support community programs with the goal of preventing homelessness in Ottawa. This year, URBANA is helping Action Housing / Action-Logement, an Ottawa-based charitable organization that assists low-income individuals and families to find and maintain safe, affordable and adequate rental housing.

Each annual Urbana hosts an artistic feature from local artists.  This year, Dharma contacted Deb and I for an interactive lighting installation by The Latest Artists.  The theme of “an on-going light for housing rights” was developed by integrating our medium of light with the need for the awareness of housing (and other social/charitable) issues to remain front and center: these issues don’t simply get solved with single instances of involvement or donation, but require constant attention to address.

This theme lead to the proposed installation: a large lighting structure, architecturally-inspired, requiring on-going crowd interaction to propagate its behavior, or,” keep the lights on.”

Some Google Sketchups were created:

This first sketch shows the six foot structure with an assortment of illuminated windows, akin to an apartment tower at night, w/ residents inside watching tv.  The planned interaction for this mode was to have the crowd turn on the windows by touching them, after which the window remains lit for a period of time before turning off again; constant interaction is needed to keep the piece illuminated.

The sketch below shows off the full color (RGB) capabilities of the piece. Animations like this could be used in a game play mode to signify winners:

Read on for technical details of the project and to see the finished piece . . .

Design + Fabrication

Fabrication was key to this project, for providing a robust, polished product.  With the help of Flux Lighting, we finalized the structure design and they provided some exciting renderings:

The bare structure

Structure with acrylic windows installed

The illuminated piece

In parallel to the design and fabrication of the structure, the electronics and lighting were designed and assembled.

The greatest technical challenge was making each window individually touch responsive.  Our first impulse was to have an IR transmitter/emitter pair behind each window to sense a hand blocking the window; this was quickly put to rest by trying to fire IR through the acrylic only to have it bounce directly back and flood the sensor, making it only useful for detecting the acrylic windows themselves.  Perhaps a combination of IR and IR-response cameras would do the trick, but we avoided this approach due to complexity and space issues inside the structure.  The thought of wiring up individual piezo elements to each window, or some sort of physical switch, was too labour-intensive seeing as there are a total of 120 windows.

The most promising and scalable solution seemed to be capacitive touch sensing.  We originally thought of using a dedicated chip like this, but after learning about the CapSense library — which works with minimal external parts on an Arduino — we decided to test a mock-up touch surface.

The advantage of the capacitive sensing was that we could use a row/column matrix arrangement, thus only needing 11 sense electrodes for the 30 windows of each fixture side (five for the columns, and six for the rows).  This conveniently used 11 of the Arduino digital pins, while leaving the two serial pins free for communication.  Four dedicated Prototinos were used, one for sensing the windows on each side of the fixture.

In consideration of budget vs. labor, Shiftbrites were used for the lighting.  Each window has a single Shiftbrite mounted behind it, allowing for full color (RGB), individual control of each window’s illumination.

Based on a previous project by Macetech, makers of Shiftbrites, we used lighting louvers as a substrate to mount the lights on.  Here’s a pic of our assembled “light cage:”

With lighting and touch sensing in place, we focused on a control scheme, deciding on an external control scheme, allowing the fixture’s behavior to remain easily reprogrammable.  Our specific arrangement made use of a custom computer-based control panel written in Processing.

Here’s a schematic the control scheme:

The top row shows the four Shiftbrite panels that make up the four walls of the light cage; the 120 Shiftbrites are controlled by a single Prototino, connected to an XBee (and breakout adapter).  The bottom row shows the four acrylic panels, each having a capacitive sensing matrix connected to a corresponding Prototino and XBee/breakout combo (I attempted to utilize serial messaging between the touch sense controllers with a single XBee to take care of all the messaging for the four sides, but I obtained much better results using individual XBees than ironing out my own protocol).  On the right is a laptop, running the control software, and communicating with the touch panels and the light cage: the touch panels only send data to the control software when a touch is registered, and the control software then processes that information and sends appropriate commands to the light cage; calibration and debugging messages can also be sent between the control software and the touch panels and light cage.

Here’s an early pic of the control software and corresponding lights:

When the galvanized steel structure was available from the fabricators, it was time to assemble everything.  This stage took a considerable amount of time since all the elements had exact mounting points that had to be accurately drilled to match the precise machining of the structure.

The below pic shows one of the window touch panels mounted to the inside of its corresponding structure wall:

You can clearly see the row/column touch electrodes; each intersection corresponds with the middle of a window, so when someone touches a window, which particular one can be determined from the corresponding row/columns registering a touch.  This arrangement worked surprisingly well (after debugging some grounding and interference issues caused by the metal structure itself).

Here’s a pic showing three assembled sides of the structure while the power to the light cage is checked and double-checked:

The light cage is attached to a steel plate that mates with the top of the structure, so it literally hangs in the middle of the inside of the structure, each light aligned with a specific window.

The below pic better illustrates how I actually felt getting everything together under the tight deadline for the debut of the piece at Urbana:

In situ

After getting everything assembled and tested, it then all had to be torn down again for transportation to the event.  I think once re-assembled and powered up at the venue, the final result was well worth the effort:

Installation view

detail view

The crowd also seemed to enjoy it and it certainly made for an interesting conversation piece:

We were pretty proud as well:

The Latest Artists (Deborah + Andrew O’Malley)

. . . and Aksash Sinha of Dharma Developments was very happy w/ the literal and illuminating tie-in to the evening’s cause:

Andrew + Deborah O’Malley and Akash Sinha

Afterthoughts

So what did we learn?

Timeline management of supply chain and fabrication is crucial.  Thank goodness for overnight shipping and a highly helpful and skillful fabrication team.

Capacitive sensing is touchy!  A major problem we encountered was tuning the capacitive touch system.  The circuit exhibited varying behavior between all environments from proof-of-concept to final integration with the structure.  We experienced noise problems when using the touch panels near the lights, and further interference when the arrangement was placed into the metal structure (common grounding solved most of these issues — subject to a blog post all their own).  The biggest downfall to this sensitivity was experienced during the move from studio testing to the actual venue: in the studio we had to use sensitive settings to obtain usable touch data, while once in the venue, the control software was receiving so much touch data that it became overwhelmed and couldn’t control the lighting exactly has planned.

Shiftbrites are simple in theory — the control data gets passed along nicely from the controller to each respective light along the chain — but have many practical caveats: power needs to be injected along the chain to keep things stable; the power supply used has implications; a long chain of Shiftbrites seems very susceptible to interference/glitches on the data lines, resulting in unwanted behavior (solved largely in software); and you must be very careful interconnecting Shiftbrites as they are easily damaged irreparably (make sure to order a contingent stash!).  Diffusion needs to be well thought-out as well.

Next plans?

We received a lot encouraging feedback on the fixture from the Urbana crowd and several offers of interest to host it at other events/venues, so we’re currently considering these options along w/ plans to tour the piece around other events/festivals where it can be programmed to compliment their themes.

In the meantime, we’ll be refining the control software and programming/capabilities of the fixture.  We also hope to improve the internal light cage, as it was quite fragile for transportation/installation; along with adding a grid of  blinds inside the structure to better isolate each Shiftbrite’s light output to it’s specific window as we experienced a bit of light overlap between windows.

Stay tuned for updates . . .

Acknowledgments

Writing this summary, I’d like to thank Deb for taking this on with me as one of our more complex projects as The Latest Artists to date.

Together, we’d like to thank the team at Dharma Developments for inviting us to participate in Urbana 2011; we’ve been keen to work on something inspired by the evolving, ambient light patterns of apartment towers at night, and Urbana 2011 provided the perfect impetus to get a project like this started.

Big thanks to Dan and Caleb at Flux Lighting for all their interest in, enthusiasm for, and enabling of this project on the fabrication side.

Garrette at Macetech was extremely helpful with his knowledge of Shiftbrites and seems very comitted to helping customers get their ideas up and running.

Thanks also to the City of Ottawa, their funding and support has also been instrumental in realizing this project.

Further reading

The Ottawa Citizen covered the event here, and if you’re still hungry for more pics, there’s another album here.

Alongside work by Aili Kurtis, Paul Schibli, Guy Lavigueur, Jennifer Gibbs, Reid MacLachlan, John Roth, and Tony Broderick, I’m debuting work exploring new themes for me: a light piece controlled by the colour of the sky.

The light patterns displayed by Sky Spectrum are directly related to the current sky conditions above Ottawa’s Peace Tower.  Every few minutes, the sky portion of the Hill Cam is analysed to reveal the average red, green, and blue components present in the sky.  The light fixture responds according to the various relationships between these values, presenting an altered view of the sky above, revealing colour details and relationships invisible to the naked eye.

The literal reference to the sky is echoed by the graphic processing portion of the piece which takes place on a remote webserver, in essence utilizing “cloud computing.”

Most of the work indeed takes place on my webserver, where a PHP script analyses the current Hill Cam pic with the GB library.  A small hardware module (hidden in the gallery) consisting of an Arduino development board and ethernet shield fetches the data from the web every few minutes, and sends the data via XBee radio to the light fixture, which is controlled by a custom board with an ATmega328 (running the Arduino bootloader), TLC5940 for driving the LED strips, and an XBee.

The code is only preliminary at this point, and I plan to analyse the daily data collected from the sky to make a growing library of light patterns and blends.  I’m also excited about how scalable the concept is, and look forward to working with this idea on a larger scale.

The Phenomena exhibition runs until Feb. 27, so if you’re in the Ottawa area, please drop by CUBE Gallery (1285 Wellington Ave., W) to check it out.  The best time to view Sky Spectrum is between 4 and 6 pm when the sun is setting and the sky changes relatively quickly

It already feels like I have more projects than the time to complete them   I’ve secured an “artist in residency” position with NYC Resistor, where I have open access to their space, including all the electronics tools I’ll need along with some cool fabrication tools, including a laser cutter.

[ more after the break ]

While here, I’m planning to work on the software for the upcoming light cube:

along with developing an open-source clock kit around the Electric Window 3 platform:

including a nifty enclosure fabbed on the laser cutter, or perhaps even the Makerbot, which will be aided by the convenience of Makerbot Industries and NYC Resistor being neighbors in the same building:

In addition to my self-guided residency at NYC Resistor, I’ll also be interning at Eyebeam Art and Technology Center in the Chelsea district of Manhattan:

[ pic from Flickr ]

At Eyebeam, I’ll be working with Hernani Dias, developing new hardware for his Refarm the City project.  A large portion of his project revolves around series of electronic boards which are responsible for monitoring and automatically feeding small urban farms (gardens).

[ pic from Hernani's blog ]

Specifically, I’ll be working on a board which visualizes data collected from a farm/garden with a reconfigurable LED display; the main idea being the ability to monitor data remotely without having to use a computer — a great overlap with my personal lighting projects which I’ve been long wanting to make internet-enabled.

And what of DJ/VJ’ing you may ask?  Well, Deb is here in NYC with me, and we indeed have a few things lined up.  The first being a performance this Saturday, July 17, at Disorient’s Compressor VI event.

So much to do, so little time . . . literally!

This presented a perfect opportunity to experiment with interactivity and sensor input for my Electric Window 3 platform.

After sketching out several 1-button game ideas, I decided to move forward with some simple particle systems, controlled by users through their interaction with a single button added to an Electric Window 3 fixture.  Thus was born Electric Window 3B:

[ more info and VID after the break ]

Each time the button is pressed, a new particle (represented by a single LED) is born.  The speed of each new particle is based on the average time between previous births.  Thus, the system has a form of “memory” shaped by previous users.

There are several variants of the particle systems in terms of particle behavior: particles either constantly scroll across the screen and wrap around at the borders; bounce back and forth (or up and down) within the screen; or travel both up and down and side to side, creating the opportunity for collisions.  In the latter case, when the particles collide, they both die.  In all cases, the particle system only has room for so many particles, so after a certain number of births (via button presses), the system resets.  This teases users to find a balance between a “boring” system of few particles versus creating a busy/dynamic system at the risk of killing the whole thing.

The guiding principle was to create an engaging, evolving display from a simple set of rules and user input.

Here’s a video demo:

The curators — Heather Kelly of Kokoromi and Peter Kirn of Create Digital Music/Motion — accepted the piece into the exhibition which took place on March 11-13 2010 at the Gray Area Foundation for the Arts.

I’m now planning to implement particle system animations into future Electric Window 3 fixtures, and more generally, start adding time-based behavior and user input (both direct via buttons etc., and indirect via motion sensors, etc.) to my light fixtures.

It’s always great to have a specific project like this to nudge one along and try out some new ideas and add a new angle to one’s work

This work was generously supported by the art funding program of the City of Ottawa.

Chinatown Remixed runs from May 8 to June 8, 2010, in Ottawa’s Chinatown district. This is the second year for the annual “art walking tour,” where local businesses, restaurants, and shops open their doors to collaborate with artists, providing art “exhibtions in unusual places.”

Last year, Deb and I made a “Chinatown Remixed” sign from electroluminescent (EL) wire, where the various syllables were individually lit, trigged by pedestrian and auto traffic detected by an ultrasonic sensor (see this previous post for details).  This year, the sign is hanging in Umi Cafe (610 Somerset St. W.), although this time driven by random sequences instead of the sensor.

Our new contribution to this year’s event is a window installation at the Oriental Charm gift shop (653 Somerset St. W.):

The installation includes a few light boxes from the Electric Window 4 series:

The main attraction, however, is a group of new Electric Window 3 light boxes, that in addition to their usual geometric and video game -inspired patterns, display messages from Twitter:

[After the break: how it all works and pics of opening day ]

By tagging Twitter messages (Tweets) with the hashtag #CTRM, anyone with a Twitter account can add messages to the installation archive. Between the various animations displayed by the boxes, the boxes query Twitter for new messages (tagged with #CTRM), and if a new message is found, the strobe lights flash and the new message is displayed across one of the boxes:

If no new messages are found, an older, archived message from the #CTRM stream is displayed, but without strobes: the strobes are only used to excitedly punctuate new Tweets

The technology

Here’s a block diagram of the system:

[ bigger version here ]

Starting at the left, there are 4 LED SCREEN light boxes, each with a corresponding STROBE light (only 1 of each is shown). Each LED SCREEN light box has an XBee radio which allows it to communicate wirelessly with the master CONTROLLER. When one of the LED SCREEN light boxes needs a new text string to display, it sends a request via XBee to the master CONTROLLER.

In addition to an XBee radio, the master CONTROLLER also has a WiFi chip which connects wirelessly to the internet (via a wireless router provided by the venue, not shown). When the CONTROLLER receives an XBee request for a new text string, it sends a command to execute a custom PHP script hosted on my website; after a short delay, the CONTROLLER reads the contents of a txt file also hosted on the website.

The PHP script requests the #CTRM stream from Twitter.com, and formats the results for display on the LED SCREEN, it also archives the messages locally on my website; if there is a new Tweet, this is placed in the txt file that the CONTROLLER reads, otherwise an archived message is placed in this txt file. The PHP script also filters the Twitter messages for a list of unapproripate keywords to avoid vulgarities.

If the master CONTROLLER returns a new message to the LED SCREEN, the STROBE lights are also activated for a few seconds to indicate a new message.

The motivation of having the LED SCREEN boxes connected wirelessly to the CONTROLLER was to be able to install the system on-site without having to run a wired serial bus between all the light boxes and the CONTROLLER. Cost was the main motivation for using multiple XBee points connected to one WiFi/ethernet point rather than adding WiFi to each LED SCREEN box. WiFi was chosen for the CONTROLLER so I didn’t have to worry about its placement relative to the internet connection.

Ideally, the STROBE lights would be wirelessly controlled also, but these were a last minute addition to the system — after discovering them in a local dollar store (!) — and are simply wired directly to, and controlled by, the master CONTROLLER with individual power connections; this saved the time, effort, and cost of developing a network to control them, or modifying the LED SCREEN boxes to support them as peripherals. An improvement for the next iteration, perhaps . . .

The exhibtion

Prior to the opening, Deb and I installed the Twitter-enabled boxes within the already-colourful window display at Oriental Charm:

The WiFi controller is located below the display; unfortunately I didn’t take time to snap any pics of it before installing the system so I’ll have to add those later.

Deb designed a great instructional poster for the installation, so we hung that in the window as well:

Here’s the press release we sent out as well, which succinctly describes what to expect from the installation.

On opening day, we did lots of demos, showing people how to add messages to the archive and have them displayed on the boxes:

For those without a Twitter account, or a Twitter-enabled phone (of which there were many), we had a laptop on hand for people to participate through our Twitter account:

Overal, people got a kick out of participating by contributing their own content to the exhibit, and enjoyed the near-immediate gratification of seeing their messages appear with the strobe lights.

We were amused when a friend from Toronto started sending in some “amusing” tweets.

The exbition runs until June 8, 2010. If you’re in the Ottawa area, please check it our for yourself and add some messages! Oriental Charm is located at 653 Somerset St. W., near Bronson, right beside Shanghai Resto.  You can of course participate from anywhere, though, by Tweeting w/ #CTRM

Here’s a few more pics; being a lighting installation, it’s best viewed at night!

Happy to have everything installed, we’re already working on bright ideas for next year

We’d also like to thank the City of Ottawa for its gracious support of this project.

This post assumes some knowledge of PCB etching methods and is an account of my experience with the toner transfer method. If this is new to you, you may have to get Googling on a few of things mentioned here. That said, I’ve linked to the sites I found most useful during the process.

Intro

Up until now, I’ve been hand wiring all the the circuits for my Electric Window series.

It’s a fairly straightforward process to build the circuit on a piece of protoboard, and for an Electric Window 3 circuit, it takes about two hours. The bottleneck of this process is preparing all the connecting wires (shown in white in the above photo) and ensuring all the interconnections are correct, ie, connecting the right components to the right pins of the microprocessor and the power and ground points.

While I find this process efficient/adequate for one-off circuits and prototypes, it gets monotonous when making multiple copies of the same circuit.

For our recent contribution to the Chinatown Remixed exhibition, Deb and I (working as The Latest Artists) envisioned a series of Electric Window 3 light boxes, displaying various animations along with text from Twitter via a wireless internet connection. I decied to use this as an opportunity to finally learn how to etch PCBs.

I’d previously been intimidated by the PCB etching process for similar reasons as Collin from Make:

There seemed to be a steep learning curve, as I’d yet to use electronic CAD software such as Eagle, and the actual etchning process seemed finicky and messy.

After watching Collin’s video, a few others on YouTube, and reading some on-line tutorials (found via Google), I decided to attempt etching with the toner transfer method, since I already have a laser printer and clothes iron.

[ More after the break . . . ]

Schematic capture and circuit layout

The first order of business was to electronically capture the schematic and create the board layout.

I knew I’d be creating a single-sided board for the sake of simplicity, so I created a rough layout by hand — based on my existing hand-drawn schematic (not shown) — to get an idea of where the components should best be and which microprocessor pins were best to avoid crossing wires and/or requring jumpers:

As I said, rough, but it was enough to get going.

While there are plenty of software alternatives, free and otherwise, for schematic capture and PCB layout, I decided to go with Eagle because a) it’s free to use for 3″ x 4″ boards, and b) there’s an abundance of resources/help out there for it.

I used this helpful tutorial and parts library from Sparkfun to get going with the program, and soon enough I had my first CAD schematic:

I then moved onto the PCB layout portion and used the auto-route feature to start the intimidating process of trace layout. With a bit of additional tweaking by hand, I had a layout I was happy with. I originally designed the board to be 3″ x 1.5″ but that resulted in tight traces and traces running really close to microprocessor pin connections. Being unsure of the tolerances/accuracy of the etching process to come, I decided to give the circuit more margin and ended up with a 3″ x 2″ board:

Toner transfer

Although I’d repeatedly read that glossy or photo paper was best to print the circuit for transfer onto the copper board, I didn’t have any of these fancy papers on hand, and didn’t want to make a trip to the store if I didn’t have to. So I decided to try it with regular paper.

I readied my otherwise unused clothses iron:

Naturally I didn’t turn it on until resting it on its back, and I wish more turorials were explicit about whether or not you should have water in there or not. The answer is no.

I cut my copper board to size and used a sponge to clean it with isopropyl alchohol (a 70% solution from the drug store).

I grabbed a scrap piece of wood to do the ironing on:

and it didn’t work. After several attempts to iron the circuit pattern onto the pattern from regular paper, it just wouldn’t stick. Whenever I’d move the iron around, the paper would slip and the result would be a smugged circuit pattern on the copper board.

I really didn’t want to make a run to the store for special paper, so I consulted Google instead. I found this great article explaining how you can use glossy magazine paper, the principle being that the laser toner doesn’t stick very well to it, thus making it easy to transfer onto the copper — the same principle behind using special glossy or photo paper I’d previously read about.

I set to work with the cheaper and more easily available magazine paper I already had around, trimming it to fit my printer before making a few prints of the circuit:

Back to the ironing board:

and it stuck! The paper stuck pretty much immediatly after applying heat with the iron, and I was able to move the iron around and evenly heat the entire circuit. Soon I could see the traces through the paper:

I let the board cool a bit, then put it in a sink of warm water. The magazine paper came off very easily, and the traces didn’t budge or scratch away. I’d read that you need to let the paper soak for 5-10 minutes before it’ll come off the board, but I found with the magainze paper it only needed to soak for 2 or 3.

I’d also read that you need to press really hard while ironing, and iron for 5 or more minutes. I’m not sure so much force and time are required with the magazine paper technique, as I ended up with a few smudged traces:

Specifically, there were a few pads that had shorted together on the transfer:

Using an X-Acto knife, I was easily able to scrape spaces between the pads before etching.

Etching

Now the fun part: etching with chemicals!

I decided to use ferric chloride since I didn’t want to mix my own etchant with ammonium persulphate and water, or the like.

I bought some handy etching trays with corner spouts at the local electronics store, and with some chemical resistant gloves, got set up in the utility sink:

Rubber gloves on from this point: I filled one tray with water for rinsing, and I poured about a centimetre (0.4″) of etchant into the other one. I put the circuit board, traces up (more about this later), in the etchant, and let it soak for about 15 minutes. Not much seemed to be happening, so I decided to try the scrubing technique described in Sonodrome’s great tutorial video:

It worked like a charm, the exposed copper started to come off the board, while the circuit traces held up well, even against fairly rigorous scrubbing. Caution needed to be taken at this step to avoid splashing etchant around, though!

Here’s the etched board with the toner still in tact. I think it looks silver/white from remaining fibres of the magazine paper:

Next I used isopropyl alchohol and a sponge (seperate from the one I used to scrub with etchant) to clean off the toner. Some of the pads had smugged edges, faithful to the smudged transfer image, but the board had no short or open circuits:

Drilling and assembly

I trimmed to board to length, and drilled the holes. Since I aready have a Dremel tool, I bought the Dremel drill press attachment and a package of small bits. I also bought the Dremel keyless chuck to accomodate the smaller bits.

Despite not being carbide bits, as recommended by many tutorials for drilling PCBs, they worked fine, and didn’t break or noticeably dull.

Lastly, I populated and soldered the board:

Not the most photogenic, but totally functional I wanted to tin the board, but the local shop where I got my supplies didn’t have any tinning materials.

Initial impressions

So, did I save any time!?

Let’s compare. I takes me 2 hours to make this circuit from protoboard. I’m familiar enough with the circuit that I don’t need to keep refering to the schematic, the real time taking tedium of this method is cutting all the connecting wires.

To learn Eagle and create the PCB layout, I spent about 6 hours. Since this was my first time through the process, I’m not sure how much of this time I should count against the protoboard method.

Etching and drilling, including the necessary clean-up of nasty chemicals was about an hour the first time through. Again, part of a learning process.

Soldering the circuit took only around fifteen minutes, though.

For one circuit board, this definately didn’t save any time.

Rinse and repeat

I needed 3 more boards for the Chinatown Remixed installation, so I did all these in a second etching session.

I made a few modifications to the layout, to run the traces clearer of the microprocessor pads, and to move the programming header (bottom centre) away from the LED screen connector (upper left) to make it easier to program the board when attached to the LED screen (glad I didn’t make all 4 like this!).

Here’s the 3 boards after ironing the toner transfer to the copper:

I did the 3 boards seperately instead of together on one larger boards to experiment with the timing of various steps of the process. This time around, some of my traces broke, so I repaired these with a black Sharpie marker.

All the boards etched successfully, including the portions repaired by the Sharpie. Next, I drilled them: all the small holes first, followed by large holes; I did this in case I accidentally drilled a large hole with a small bit, allowing me to enlarge it if necessary.

Next impressions

So, did I save any time across multiple boards?

The answer is yes! Although, for this circuit I only saved about 15 minutes per board compared to the protoboarding method (not including the time spent learning Eagle). However, I assume there would be more time savings with more complex boards.

That said, I do feel that I saved labour. Soldering each circuit together on a protoboard, making sure to correctly wire each connection requires considerable mental attention, in contrast to the “dumb labour” required to etch and drill the boards, followed by the comparatively easy task of populating the boards without having to handwire all the interconnections.

Another advantage to the PCB method was that Deb and I could work in parallel to solder the boards together.

I also imagine I’ll shave some time off as I become more proficient with the process, so I’ll definately continue to etch my own PCBs!

Some tips

I would highty recommend the use of glossy magazine paper for printing your circuit designs on: it’s cheap/free; you probably have some already; and it comes off in water very easily and quickly.

If you use glossy magazine paper, I found that a lot of ironing pressure wasn’t required, just be firm. I also found it only took about 3-4 minutes (for a 3″ x 2″ board) to do the transfer. More time can actually start to smudge the transfer, as discussed above. You’ll have to experient with this.

High speed steel (HSS) bits seem to work fine. I ordered some additional bits from Digikey for drilling the PCBs, since I’ve read so many times that anything other than carbide bits will dull very quickly when drilling PCBs. I’ve found the HSS bits to work well so far. Bare in mind I’ve only done about a half dozen boards. However, I have yet to break a bit and the bits are much cheaper than carbide. I just bought a bunch of bits to compensate for any dulling. For the price of one carbide bit, I was able to buy 3 HSS bits.

If you are not agitating (ie, constantly moving) the board in etchant, place the board traces up. I’ve heard that putting the traces face down enlists gravity to help remove the etched copper, but I found the ridges on the bottom of my etching tray started to leave lines on my circuit when I didn’t agitate.

The finished product

If you’ve read this far, you’re probably curious about the final product these circuit boards belong to!

They’re used to drive LED displays from Sure Electronics, for a series of Electric Window 3 light boxes in a public art installation.

The following picture shows 3 of the Sure displays cascaded, and the driver circuit with an XBee radio attached:

The XBee is used to wirelessly query a WiFi-enabled master controller (not shown) for strings of text to display, from Twitter; this post has a clear explanation of the final installation.

The black, rectangular connector on the bottom-left of the driver circuit mates directly with the LED display, as shown below:

The dangly bit on the bottom left is the power connector.

Next these units were installed in custom-made, acrylic enclosures:

Here’s some “still on the bench” shots of the finished boxes:

The deadline for this project didn’t permit time for better photos of the final boxes before installation on-site, so stay tuned for more pics and videos.

Thanks for checkin’ all this out, all the best with your circuit etching endeavors!

TWITTER ACTIVATED LIGHT BOXES ON DISPLAY AT ORIENTAL CHARM GIFT SHOP [ 653 SOMERSET ST. W., OTTAWA ] FROM MAY 8 – JUNE 8 2010

Ottawa (Ontario) – You won’t want to miss it! Ottawa’s second annual Chinatown Remixed event is happening Saturday, May 8, from 2-5 p.m.

Walk the streets of Somerset West as you take in dazzling contemporary local art, mixed in with Chinatown’s traditional shops and restaurants.

One of the highlights of this year’s festival is an interactive lighting display by The Latest Artists — Ottawa’s dynamic artistic duo, Andrew and Deborah O’Malley.

The Latest Artists have created Twitter-enabled light boxes. These unique pieces feature custom-built circuits and hand-made acrylic frames.

Using a mobile phone, audiences will be able to interact with the art by sending messages to Twitter (using the hash tag #CTRM).

Thanks to creative custom software, audience messages will be instantly displayed as text scrolling across the lightbox screens. Strobe lights, placed near the boxes, will flash when the message appears, altering audiences their Tweet is coming through.

When no one is sending a Tweet, the light boxes will display scrolling fortune cookie messages, lucky numbers, and animated geometric patterns. Previous Tweets will also be saved and randomly displayed, serving as an archive of audience experiences over the month-long event.

Giving audiences the ability to comment and connect through lighting art with Twitter is a novel interactive experience, providing global reach to the local Chinatown Remixed event.

The Latest Artists’ twitter-enabled light boxes will be on display at the Oriental Charm Gift Shop (located at 653 Somerset Street West) from May 8 – June 8, 2010.

This series revolves around a matrix of 16 LEDs with individually controlled brightness and fading, making it an organic/analog sibling to the 3.xx series which uses LED screens with a large group of on/off, or binary/digital behaving pixels.

Development of this series was fairly straightforward, extending on the work done for the Orion light boxes last spring, with the hardware based on the TLC5940 LED driver, controlled by an Arduino (and using Alex Leone’s great TLC library).

On the software side, it became an exercise of “how much content can I write for 16 LEDs?”  Although the Orion boxes simply simulate a twinkling star field, the orderly grid of Electric Window 4.xx demanded more than mere randomness.

So I wrote a series of pattern-generating functions using sinusoidal values to create soothing waves, adapted some of the grid-filling patterns from Electric Window 3.xx, along with a few other routines that specifically address the 4 x 4 grid of this series by randomly toggling the brightness values of rows and columns to create evolving greyscale patterns.

Diffusing the LEDs with acrylic gives the display a nice ghostly aesthetic.   Here’s a video of the results:

For demonstration purposes, the video shows the patterns changing quite quickly, but in actuality, the pattern speeds vary between slow and serene and speedy and frantic.  I’m really happy with the results, and this is one of my favorite series so far.

The finished pieces are 5″ x 7″ x 2″ and will be individually numbered:

I plan to make a batch of these in various other colours; and although I really like the monochromatic look, I’m sure an RGB version isn’t too far off.

I’m also considering getting a custom PCB made based on this design so I can easily scale it to bigger grids for bigger fixtures.

In the meantime, for anyone interested in a fully assembled piece, I’m also offering these at my on-line shop.

We were pretty pleased with our first attempt at constructing and gluing a 3D object from acrylic.

The LED matrix and controller are from SeeedStudio, and the next steps for us will be to develop content for the LEDs, and refine the acrylic enclosure design.

Another consideration will be whether to stick with a corded DC adapter for power, or go with (rechargeable) batteries.  The pro for a DC adapter is that it takes no additional space in the enclosure, while the flip-side con of batteries is that the extra space required in the enclosure may affect the aesthetics.  Batteries will also need to be recharged or changed as a trade-off for going cordless.  What would you prefer (let me know in the comments)?

Here’s a few more pics:

And a last one for scale:

More pics and video to come as things develop here in the lab!

]]> http://technoetc.net/blog/2010/01/31/light-cube-prototype/feed/ 4 http://technoetc.net/blog/2010/01/24/electric-window-3-03/ http://technoetc.net/blog/2010/01/24/electric-window-3-03/#comments Sun, 24 Jan 2010 23:03:25 +0000 ao http://technoetc.net/blog/?p=212 With the inspiration of using acrylic as an artistic/structural medium mixed with the notion of baring it all in terms of circuit board exposure, as outlined in this previous post, I set about to realize the next entry in the Electric Window 3.xx series with a new perspective:

[ Build details and more photos after the break . . . ]

Before assembling the circuit board, I painted the perf. board black:

The circuit is basically an Arudino-loaded Atmel microprocessor with a ribbon connector to the LED screen, and a programming header (the spikey thing along the lower right) for loading new programs to the microprocessor.

The perf. board accepted the acrylic paint well, and the resulting circuit matched well w/ the LED screen:

The circuit board and LED screen were then mounted on a small sheet of white pressboard, over which I mounted a translucent red acrylic sheet of matching size . . . et voila!

The content is similar to previous entries in the 3.xx series, with various drawing and screen filling routines:

Extrapolating from the above pattern, I think a Tetris routine should be in the works, perhaps alongside autonomous pong

Of course, each piece receives its individual label:

I was quite pleased with how this version turned out and will continue to offer the open-concept acrylic style as an enclosure option for future Electric Windows.  I’m also starting to source coloured stand-offs and hardware, particularly black, so if you have any suggestions in this regard, please let me know!

Another concern is where to add an unobtrusive power switch.  I’m hesitant to mount a switch along the side of these pieces, particularly on the framed versions, as I think it would look horrible sticking out one of the sides:

Perhaps I can find an in-line switch that works with the thin power cords I’m using . . . although, once these things are internet-enabled, owners could just program them to turn on and off at convenient times