Saturday, June 20, 2009

LED Tree

It isn't too bright (I used a 4 AA battery supply, so about 6V, and there are 52 LEDs in parallel on the tree), but it does provide a nice ambient kind of glow to a dark room (you almost can't see it in the light). That was the goal, I guess, and I put in a Joule thief circuit in hopes that it would extend the battery life a little, though I'm not feeling up to actually testing it.

Though this one was a bit of a pain, I have some ideas on how to improve on the design and I'm definitely going to make some more similar LED artstuffs in the future.

EDIT: So like I thought, it is pretty much for certain that the Joule thief is kind of silly in this circuit, because it doesn't seem to actually be doing anything useful. Also, the lifetime on the lamp isn't too great. It'll last through a whole night, I guess, but come up kind of dim in the morning. If you turn it off for a bit it gets brighter again, but near the end of the battery life that extra brightness doesn't last long. One day in the future, when I have completed a number of EE and physics courses and have hopefully gained some understanding of what it is I'm trying to do, I will redesign the guts of this tree.

Thursday, June 11, 2009

Joule Thief + Another Fridge Magnet

So the main, big project I'm working on now is getting kind of frustrating, and I thought I'd take a break tonight with a few quick projects.

I started with a empty box of chocolates from Trader Joe's. It had an adorable design with a porthole in the middle, and I had to use it somehow. Using a dremel I cut the bottom of the box off, and then I glued on three magnets with super glue. The top fits snugly onto the bottom, so all that was left was to find a picture for my picture frame.

Big Daddy character copyright 2k, of course.

Anyhow, since that project had just about two steps, I needed something else to do. Half an hour on instructables (an amazing site, by the way) reminded me that I had always wanted to build a Joule Thief. It is a remarkably simple project, but I still feel proud of myself.

You basically need an NPN transistor (2N3904), an LED, an old battery, a small toroid magnet, a 1kohm resistor, and thin wire. Optionally, you'll want a AA battery holder and a switch. I already had everything except the toroid.

Of course, the Radioshack store people had no idea what I was talking about when I asked for the toroidal magnet thing, so I found the part number myself. If you have to go to Radioshack and pay their inflated prices, here it is. Note you can probably try to use the 273-108 if you can't find the 273-109 in stock.

The 2 AA battery case leaves plenty of room to house the battery and the innards (in the second battery's place). It is a little black and boxy, but you can decorate it with stickers and such.


Thursday, June 4, 2009

Mobile Robots

And now, for robots! To start, we have a basic obstacle-avoiding, color-detecting robot. He was the final project for my ENGR 150 class, a basic intro to robotics class that was definitely worth taking. He navigates with a SICK LMS 200 laser rangefinder, and sees color with a basic webcam. His brain is a laptop, and his body is a Pioneer. Oh, and we used whatever sound files we found already on the laptop (from somebody else's project), hence the robot's lingual confusion. (Also, sorry that it is unedited...I ripped these from facebook, and I couldn't get them to import into iMovie.)

And finally, more robots! This is a robot from the lab where I work, a CREATE roomba from iRobot with a webcam and a Netbook. A quick google search shows that this is getting to be quite a popular robot setup: relatively cheap, very easy to use, and versatile. This guy also hooks up to a Garmin GPS, not shown. (There's no sound in the video, by the way).

So yeah, I that's all I have for now, but there is some pretty awesome stuff in the works, which I hope to show you soon!