I bought the last of the expensive components for this project today: an Exide Pro Comp Super HDX Off-Road/Deep Cycle Battery (whew!). It's forty-five pounds of high-tech battery goodness, and I was relieved to find that it fit perfectly into the space I had reserved for it. I have been waiting to finish mapping out the electronics bay until I had this battery, since it's big and heavy and can only go in one place. I had thought I might have to build a tray to hold the battery in place, but now I think I can just use some eye-bolts and heavy-duty rubber bungee straps. The amp will have to be mounted on the outside after all; I had thought there might be room inside, but it's clear now that it would be too tight a squeeze. That's OK; I'll just bolt in onto the side panel that partially encloses the electronics compartment.

My friend Michael and I did some beer-enabled brainstorming last night and came up with a rigid-but-swivelling hitch design that will allow me to steer the trailer more effectively, eliminating the shimmy problem, and will let me use my brakes to slow down both bike and trailer. It's really quite a simple design, so I'm confident that it will work, and it should make the whole experience rather less stressful than it would have been had I tried to use a length of rope.

The disco ball light I ordered turned out to require 12V AC power, not DC, so I cancelled the order. This leaves me a rather skimpy lighting situation for this weekend, since it's too late to mail-order anything else in time; but I'll make do with what I have. There really don't seem to be many battery or 12VDC-powered options for disco balls, so I may end up buying an inverter anyway (ugh).

I'm still hoping to have this thing finished in time for Critical Massive next weekend. It will be a lot of work, and there are still a bunch of parts to buy (including, most critically, the battery), but I think I can pull it off. The pressure is kind of fun, actually.

I put the second base coat on the body today, and a first coat on the wheel outriggers. Now I am covered in flecks of paint and my right wrist aches. The carpentry was fun, and the wiring will be fun, but this part is just work and I am ready to be done with it. Perhaps I will feel more enthused once I start painting on the silver finish coat: this white primer stuff is boring.

I hung the outriggers from the overhead rafter on bungee cords, so that I could paint all sides at once and let it all dry instead of having to take two passes. I hope nobody walks in there in the next day or two, because the scene is a little ominous: suspended right at eye level as you walk in is this row of things, pure white hunks of bolted-together wood without apparent function; it reminds me a little of one of those walk-in meat freezers you see in horror movies.

Nobody has yet walked in while I am working, and so far as I can tell nobody else has visited the basement at all since I began my project. I was a little nervous at first, because I didn't exactly ask anyone's permission to use the work space, and I had worried that someone would walk in on me, take offense, and complain to the managers. But I seem to be the only person in the building who is using my storage locker for anything but long-term stowage, so I pretty much have the basement to myself.

The laser projector arrived today, and of course I plugged it in immediately. It works pretty well. The laser is very responsive to the audio; it's kind of like watching a laser version of an MP3 player's visualizer mode. The only settings are a pair of knobs adjusting the projector's sensitivity to each audio channel, which is just fine with me; I want something I can stick on the end of a pole and forget about. The image is a bit small, but the size of the picture fluctuates according to the audio volume, so it could be that I just need to fix the levels so the gadget gets a hotter signal.

Now that the construction is finished, I'm starting to think more about lighting. I'm going to mount blacklights along the two rear outriggers, a strobe light and a colorball underneath the laser platform, and various other blinky things sitting on the top platform. I need to put enough gadgets on top of the stereo that people don't think it's somewhere to sit, at least; and I don't think it will take too much to make this contraption visible at quite a distance.

Here's an interesting microphone preamplifier circuit; it's a bit more complex than I would need, since it supports either an electret or a dynamic mic element, but it looks like it might not be that hard to modify.

Here's a 12V DC voltage converter for $3.95; like one of those universal wall warts, except it's designed to work on DC power. This will be useful; the amplifier needs 12 volts, the laser needs 9 volts, the strobe and other lights use 6 volts, and the MP3 player expects 5 volts... instead of wiring up a separate battery pack for each device, I'll just get a bunch of these converters and run them all on the 12V main battery.

I've been working hard on the rave machine over the last few days, though progress has not been as visible as I would usually like. There are a number of tricky design problems involved, relating to various limits of space, time, volume, power, and money, pushing against my desire to make the finished product as exciting, noisy, and visually impressive as possible. I finished the laser platform and its collapsible pole last night, and built about half of the speaker enclosure. I've solved the wheels problem - I'm going to use ten-inch pneumatic hand-truck tires - but I still need to actually build the swivels and mounting brackets, and I'm still trying to figure out what the electronics box is going to look like.