Wednesday, January 7, 2009

The UV LED microcontroller bracelet

I have been thinking about soft circuits for a while now. Its interesting to think about electronics as they relate to clothing, as well as building circuits with no solder, just knots. At about the same time i had come across "magic beads", which are white beads that change colors when exposed to UV light. Apparently they are one of the least expensive ways to reliably detect UV, and have some scientific use. but mainly they are sold by science education stores to teach kids about sun protection. The beads retain their dark color for a bit after the UV light source is removed, so the idea came up to make a slow refreshing solid state display out of beads and UV leds. This got mashed up with the soft circuit idea, and the ultimate raver cancer device was born!

I found some UV led's from a china importer for really cheap, and decided to use the arduino minipro from sparkfun as the microcontroller. it has such a small form factor, and is completely integrated so no external parts are needed besides power. Theres also a CR2032 battery holder from sparkfun, and a magnetic conductive snap (also from sparkfun. can you tell i love this place?). I took each bead and made a cut through it, and fit the LED through two of them.

Using conductive thread (sparkfun), and a piece of leather as a board I experimented with how close you could get the traces together in a sewing machine. The leather made a surprisingly good circuit board. the critical part here is to use the conductive thread on the *bottom* bobbin, not the main bobbin. you get a perfectly flat "wire" with a nice little thin wrap around it. This stuff frays like *crazy*, and was a giant pain in the ass to work with. Id almost recommend hairspraying over it lightly or something once you finally get it with no shorts.



So after many hours of carefully..... okay, im lying. I totally had my sewing machine master roommate sarah sew this for me. I laid it out with a ruler and had her sew over the traces. It was unusually fun designing the circuit traces, this is why i am a nerd. Its sort of hard to tell, but the microcontroller will go on the right, and there are 10 UV led's that run down the center of the bracelet.

the LED's were attached by wrapping the wire very tightly around each lead, and sealing it with a drop of glue. I had high hopes to make the entire thing with no adhesives of any sort, but the fraying was really frustrating me.

Here you can see the first few leads of the microcontroller attached. they were attached just by stitching through the hole in the board a few times around the leather. it looks fantastic, and was very solid. You can also see the detachable mini USB programming header.


Here it is! It is very very difficult to take videos and photos of this thing. all of my cameras react very badly to the UV light, even with playing with UV filters. There is no flickering to the eye, that is an artifact of the camera. It has ten individually addressable LED's, with the full power of the arduino behind them. This program reads from a stored sine wave table to do fakie PWM on all 10 pins. Sadly, the beads do not hold their color for very long since the UV is not that strong coming out of the led's. its bright, its just not enough of the ideal wavelength. The effect is pretty damn cool anyways though. i cant see actually wearing this, but it was a cool way to explore these technologies. Its pretty amazing how advanced of things you can make these days at home with fifty bucks and a few hours time.

Sunday, June 22, 2008

Casio EX-F1 remote shutter mod

So, the last thing most people do with a brand new $1000 camera is start cramming a screwdriver into stuff and popping it open. Luckily, I was stupid so you dont have to be! In this case, stupidity paid off bigtime. Turns out the remote shutter release isnt some fancy schmancy USB device, its just three wires! Casio even conveniently labeled them for me: GND, Half-Shut, Shutter!

Thanks for the labels!

Just a simple single sided board, nothing hiding on the back.

Now.. to find out where to get some of those funky USB connectors.

Thursday, May 22, 2008

High Speed: Cheese grater 300/600/1200 demo

This is my cheese grater in the sink under running water. Between these shots, the camera remained in the same position. only the FPS setting and the lighting were adjusted. as you can see, the higher the speed, the smaller the frame size.
300 FPS. 10 seconds=1 second of RL

600 FPS. 20 seconds=1 second of RL

1200 FPS. 40 seconds=1 second of RL

Something about the 1200 clips really appeals to me. Its like a tiny window into into a bizarre world you encounter every day, but are not able to appreciate. I cant wait to explore it more!

High Speed: Bic lighter

Notes: 1200FPS in a moderately lit room. First video I took. High speed videos unsurprisingly require a LOT of light. Even fire seems a little dim

Casio EX-F1

For the last several years I have been fascinated with high speed photography. Even rental of equipment capable of higher than 60fps has been cost prohibitive for me. With casio releasing one of the first consumer high speed video cameras, I couldn't resist jumping on the opportunity to experiment more with the format.

Friday, January 4, 2008

Nintendo DS MicroSD card storage solution

For the last few years ive come to know the joys of having a DS flash cart. Imported games, fantastic homebrew, emulators galore. No need to carry a giant stack of games with you, just grab the DS and go! Ive gotten so used to the idea of carrying around all of my games right inside the DS, that when I finally outgrew my 2gb microSD card I realized I had no place to put the second one! Its truly impossible to find a place to store those tiny memory cards. After pondering it for a while I finally came across a solution that was so obvious, I cant believe it wasnt the first thing that came to mind. use microSD card slots!

I ordered up a few of the "click-in click-out" style microSD solder-on surface mount components from for $1.13/each. hot glued them to the inside lid of the DS, and bam! instant 4 gig memory expansion. The slots of course dont work, but they keep the card in place just fine, the lid still closes, and they blend in nicely. I slapped one in each corner, but there seems to be enough room for at least 5 of them in there with the lid still able to close.

Hope someone else finds this as useful as I did!

Saturday, December 22, 2007

Yak hat

This is the first hat i ever knitted. It was made with "Shokay" 100%
Tibetan yak fiber. This all started when someone told me that yak
fiber was one of the softest and warmest fibers you could get, but
you couldn't get it because of the extreme pain in the ass it is to
gather. Yaks cannot be shaven and must be combed to gather fiber.
Apparently a couple of harvard grads noticed the demand for fiber,
yet an abundance of very poor Tibetan yak farmers. So they started
the shokay yarn company and here we go!

This stuff costs $32 for 3.5oz of worsted weight yarn. The hat ended
up using 1.5oz of yarn, so i am quite happy with the overall cost. The
hat is warm, and extremely soft. It seems a little delicate though,
there are lots of "pills" that form on the surface with wear.

The pattern was made from several generic hat patterns i found. cast
on 8, every other row tbl on all end stitches on each of the 4
needles until cap fits head, knit until its long enough.