So, quick status report before I sleep. I haven’t been getting enough sleep, so I’m kind of wiped out right now.  My day went like this: school, talk to professor, eat, school, work on next iteration of coilgun, break an ott light, eat greasy food, go to a concert, made a smoothie, and tried to hack a quickie robot before realizing that I am an idiot and have no place on this earth. So.

School was fine: day on which nothing is due, which is good. Talking to a professor, I now have a smaller chance of being rejected outright by USC. Next iteration of the coilgun will have multiple stages, and we almost have it all set up, but the charging system we’re using seems to have broken over winter break. However, we got the arduino-controlled firing system working, and have a separate 328 chip on a breadboard acting as our arduino, since we fried our last one. Great fun. There were more than a few instances in which I had an LED plugged in the wrong way, so I had no idea it was working.

After we found out that we were hungry as heck and needed to eat, my fellow hacker left, and since I couldn’t figure out how the ott stand was screwing with wall power, I just plugged the bulb directly into the wall. Of course that was a bad idea, and now everyone should know that while the stand doesn’t screw with the voltage, it almost definitely tamps down the current available, probably through the inductor-looking thing. Fortunately, it did not blow up, which was my realistic worst-case scenario fear. It does have a crack in it, and who knows what’s in the lamp, so I might wake up tomorrow morning as some horribly mutated thing. If that happens, I recommend ceasing all attempts to hack such lamps; don’t worry about me, I’ll have done it FOR SCIENCE. Right.

Since that lamp is gone, I’ll probably have to mash up a system of LEDs to aleviate my current lighting situation. Maybe. LEDs can be not so great for lighting, so I guess I’ll try it and see how it turns out.

Friday cafeteria food has a theme of greasiness, which is unfortunate. I’m already pretty unhealthy, which I will have to rectify. Talked to fellow humans, and saw a pianist play some pieces I have not heard before. He was pretty good, but not quick kick-ass.

After the concert, I tried to stick together a very simple robot. It’s a differential drive, that derives obstacle avoidance through 2 dpst switches that switch the polarity of the motor when switched. It’s pretty simple in theory, and should’ve been simple in practice, but I have no working robot that can scuttle around and keep me happy. After 1.5 hours of working on that, I decided to switch to my pre-amp, but I looked at the schematics, the bottom of my perf-board, and now I’m here to tell you all that I need more solder. I’ll have to find if there’s a radioshack nearby.

Basically, nothing got done. Some groundwork got laid, but I have nothing to show. Yet. I’m not sure what I’m going to do next week. Yet.

As noted before, Ze Local Awesome-blowing-stuff-up club, of which I’m the Benevolent Dictator for Life, has created the initial iteration of a coilgun. Behold!

I can already hear the complaints about the lack of video of the thing actually firing, but I have an excuse: our benevolent email-writer for life, managed to kill a vital component while trying to make a would-be version 0.2 (this also explains why nothing is connected to anything else). So, no video until we finish up version 0.2, which should be soon.

For those of us unfamiliar with what a coilgun is, and who are familiar with physics, a coilgun is essentially a big electromagnet. For those of us who are not in the physical conspiracy, but still want to know what they’re looking at, a quick physical primer: first, the big cylinders are capacitors, which store electricity, only to quickly dump all that electricity through the coil. With all this electricity moving around in circles through the coil, a magnetic field is created, which then draws magnets or pieces of metal through the coil, sending them flying.

Well, okay, you should forgive me: this is the first iteration of the documentation associated with the coilgun, too. I’ll try to update the descriptions and inner workings better as we go, especially since we managed to do very little math on this coilgun. We’ll probably do more and more math/analysis as we go, too.

So, finally, some gory details: we have a capacitor bank of 4 capacitors in parallel, rated for 200V and 1200uF. The coil was made with 24 gauge magnet wire, for a coil density of who knows what, since we weren’t keeping track, and we’ve already taken most of it apart. The coil is wrapped around some 6 inches of 1in diameter PVC piping, and we used a high voltage, high current rated thyristor as a switch. With the capacitors charged up to 195V, we shot a magnet around 70cm straight up into the air, which is not too bad for doing absolutely no math. Maybe I’ll talk about our throwing-together process in later posts.

For the next iterations, we’re thinking about using a high-voltage transistor instead of a thyristor, for better control of the current: once a thyristor is turned on, it passes current, and continues passing current until there’s not enough voltage to keep it turned on. A transistor passes current only when there’s some voltage applied at the base. (Note: I know this is a bad explanation, especially when I use terminology on several different levels. As I hinted at before, I’m trying to apply some agile methodology to blogging, and maybe it’ll stick). Also, we’re looking into thicker magnet wire, and a way to power the circuit directly from the AC grid.

And I’m sorry about the crappy photos: the camera phone idea is good, but the cameras still don’t hold up well when you want crisp details.

So, the coilgun fires! I will (hopefully) post with more information soon.