Tuesday night’s Broken City LabOffice Hours were successful, but as usual, all too short. Spending the majority of the time in Lebel’s wood shop, we started working on our LED sign, but still have a long ways to go with it. We cut plexiglass, drilled holes, and started soldering—I think we’ll continue next Monday and Tuesday night at Office Hours. Lots of photos of the whole process after the jump.
On Monday morning we set out all of the stuff that we figured we would need to start figuring out how to make an LED sign (+ some other things that aren’t really necessary for this project). We cut wires, soldered, used resistors, and mocked up a circuit on a breadboard and it was really, really fun. Lots of photos after the jump.
I got the needed resistors right before Christmas, though hadn’t had a chance to post this yet. As you can see, there’s a 270Ω resistor, a 9V battery, and a 10mm LED working… along with the resistors, I got a 9V power supply, so we can make signs and run them off the wall, rather than relying on a ton of batteries. As I’m unsure about just how long a whole bunch of LEDs could run on battery, I suppose depending on the size of the batteries this could vary… connecting a bunch of D batteries to add up to 9V will certainly last longer than one of these alone.
Spent last night around the table with my brother, the high school physics teacher, trying to figure out how one might calculate the resistors and type of battery that would be needed in a circuit powering 200 LEDs.
I know there are some calculators online, as Mike had suggested earlier, but because I really don’t know the first thing about electricity, I think I was probably confusing the problem… as well, our Internet connection was down, so we were googless. However, as you can see above, we eventually came out with the right number.
Then I found this formula earlier tonight…
(SupplyVoltage – LEDForwardVoltage)/ NominalLEDCurrent = ResitorValue
Then I ordered a whole bunch of 270 ohm resistors and a 9v wallwart from Jameco to hopefully get these LED projects moving forward.
I found this little gem while aimlessly seaching instructables for a good recipe for General Tao’s tofu.
“Shoefiti” is a necessary element of any urban space. They are of particular interest to me due to the various myths and truths surrounding them, be it an informal murder memorial, a drug users annotation, or the hijinks of a common ruffian. When we seem them, we attach our preconcieved purpose (in my experience, this purpose was birthed out of schoolyard lore) as we walk by allowing that ephmeral space to feel differently than the space that came before it and after.
Creating an ethereal version, speaks to the magic surrounding this urban act.
Jim Campbell’s Home Movies is a large-scale video installation consisting of hundreds of LEDs that render films spanning four decades into nearly illegible light and shadow. Seems like a good fit for such a cold night.
Oh, and I now have in my possession 200 10mm LEDs.
In a post on MAKE about how to embed 720p videos from YouTube, I found this great, short video about the history of LEDs and some quick notes at the end about the simplest way to make them work. I’m on the case of looking into getting a bulk order of LEDs from DigiKey.
Oh, and to embed 720p video (when available) add this to the embed source &ap=%2526fmt%3D22 or add this to the url just to watch a video on the YouTube page in 720p &fmt=22 … adding &fmt=18 will make any video play in high-quality h264 encoding.
Although I’d imagine that we could find a better message, the technology is dead simple and very cool results. MAKE also has an upcoming Halloween Special Edition issue… probably too late for us to accomplish a lot this year, but good thing to keep in mind for next year!