The final version will probably have a black/smoked case with a choice of red or green LEDs.

Not sure if the buttons will be on the side or the bottom yet — which would you prefer?

A few more pics from the prototyping stage of DOTKLOK (see my introductory blog post here.

I’ve soldered my prototyping circuit together:

Next up: a user interface (buttons!) and writing lots of time animations . . .

DOTKLOK will be an open source clock kit with multiple time-telling animations, some literal like the simple display above, and others showing the passage of time through abstract patterns, following on from my Electric Window 3 series.

The inspiration for this clock is to combine a bunch of cool ways to show time — such as in a sentence, with words, or retro game displays — along with my own original animations, while providing a platform on which others can further develop cool timepieces.

Thanks to a great RTC1307 tutorial and library by Adafruit, I was interfacing with the clock chip faster than expected, and soon had a rudimentary sketch up and running:

The font’s not too hot, but it’s the default one I had from the Electric Window 3 software.  I’ll be developing several special time fonts and and animations over the next few weeks, along with designing a cool laser-cut acrylic case to round out a kit that’ll be great for both those who want to hack and mod the clock, and those who simply want to plug it in and enjoy.

[ Eyebeam bio ]

Working with Hernani Dias on the Re:Farm project (see my previous post for some more info about the Re:Farm project), my first objective is to create the PCB for the Re:Farm On The Wall module, a data visualization module using an LED display to present data away from the computer screen.

[ details after the break ]

Here’s Hernani’s original sketch for displaying the soil moisture level from 6 sensors:

This design uses 7 LEDs to display the soil moisture level for each of 6 sensors (42 in all). The design concept has been formalized as seen below:

The module still has 7 LEDs for each sensor (or farm/garden), but with the addition of LEDs between the groups (for a total of 48) to create a complete circle which can be used with other templates, such as the one below, for visualizing other data such as temperature or humidity:

Ideally, the board will also incorporate a stepper motor to drive a needle (like a speedometer) for an additional data channel.

I’m going to first concentrate on the LED display. Since the board will make use of an ATMEGA microcontroller (Arduino) chip and an XBee radio (to receive the data), real estate on the approx. 3″ x 3″ board is already a bit tight, so I am currently researching Charlieplexing, an LED driving scheme which allows N*(N-1) LEDs to be directly driven by N pins of the microcontroller. 8 data pins from the microcontroller can thus be used to control the 48 LEDs since Charlieplexing with 8 pins allows control of up to 8*7=56 LEDs.

At The Next HOPE conference this past weekend (blog post about the conference forthcoming), Jimmie P. Rogers was demo’ing and selling his LoL (Lots of LEDs) Shields for the Arduino. He has a great post about his work with Charlieplexing which I’m currently consulting. Talk about serendipity!

In a way, the overlap between the needs of Hernani’s project and my own interests in lighting and internet-enabled lighting fixtures is serendipitous as well.  It’s great to be working on a project that is seemingly so diverse from my own projects, yet has so much overlap on the technical side.

It’s also been interesting to observe Hernani’s design approach/philosophy which stems from his graphic design background.  It seems like everything starts from the aesthetic: the documentation for the project has some of the nicest component diagrams I’ve seen; and even his calendar is created in Illustrator

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.

You can visit the post here.

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!