Like a lot of semi-urban computer enthusiasts who plan on living for a few decades after the onset of global warming, I have a few computers that are always on, and I wish that I could find an economically viable way of reducing the emissions generated as a side effect of the power they require. Also, when the hard times come and grid power gets flaky or drops out entirely, it would make the local warlord happy if I could use a computer to calculate optimal irrigation ditch depths, or the like. (Note to self: learn to use abacus while leisure time still exists.)

Typically, solar arrays in urban or suburban areas are tied by an inverter to the local power grid. Such inverters cost a few thousand dollars; they both allow excess power to be released to other consumers and enable the use of AC appliances without any modifications. I live in a rented property, so installing a large solar array on the roof with an inverter in the basement is not an option. But, maybe I could run a smaller array without an inverter for DC loads only.

DC vs. AC
Computers, generally designed to connect to AC power, have as their first component a switching power supply that turns AC from the wall into DC. If I had a solar array, it would output DC, which would be converted to AC by the inverter, and then back to DC by each computer’s power supply, losing energy at each step. I call this “dumb”– why not just run the computers off of the DC directly?

The problem is that if you run the computers just off DC from the solar panel, the computers die when the sun is occluded by a cloud or a planet (at night, for example).

An alternative architecture
The system I’m building has a 24 V DC power supply fed from the grid at its core. This will run in parallel with whatever solar panel I eventually set up. For starters, I have replaced the ATX power supply that came with my desktop with a DC/DC converter from Ituner.com. I then power that from a beautiful DIN-mount Sola SDN 10-24-100P supply that I got off Ebay for $33.00 ($45.82 with shipping).

For the DC/DC converter, I looked at the pico-PSU, but rejected it in favor of the slightly larger M2-ATX-HV.

The M2-ATX-HV had a few advantages:

The M2-ATX-HV is a bit bigger, but my PC case is pretty large, so that wasn’t a concern. Including all the cables and shipping, I paid $96.40 for the M2-ATX-HV– about $30 for the advantages listed above.

Stage 1 complete
The DC system has been working reasonably well for a few weeks now. Next, I have to find a cheap way to test current sharing with a solar panel, as I don’t want to commit the full $700 or whatever for a 180 W panel until I have more evidence that it will work. I’m off to the beach to start collecting sand for a little homebrewed Czochralski action.

After meeting Ubuntu zealots Alan Pope and Jono Bacon at Fosscamp this morning, I made the mistake of leaving my laptop screen unlocked within the range of these two dangerous characters while I went to the bathroom. What’s worse, I left a terminal window with a root prompt open on the desktop. (I don’t remember why– I think I was installing some software earlier.) When I got back, this so-called “Pope” had blown up the font size on my terminal window and added “rm -rf /” at the root prompt.

It was good for a laugh. Unfortunately, I didn’t have the poise to take a screenshot.

Later, it was revealed that the Bacon, not Pope, was the instigator, or so says Pope.

Note for the non-haX0rs in the audience (I guess that’s you, mom): “rm -rf /” is a command that recursively deletes all files in your filesystem. Incidentally, I did once execute that command on an OS X server that I was maintaining a few years ago. I needed to reinstall OS X for some reason, so I tried executing the legendary command. It was pretty sweet– various programs on the desktop crashed, services disappeared, and the machine was eventually rendered unbootable.

Anyway, I won’t make the mistake of leaving my laptop unprotected when Bacon is on this side of the Atlantic.

One other interesting note from Fosscamp– I talked to Ubuntu Linux founder Mark Shuttleworth for a few minutes after one of the morning sessions; he mentioned that the Dell Linux machines that I was so excited about a few months ago were actually Dell’s idea. I had assumed that the whole Dell Ideastorm business was more of a marketing exercise, while Dell and Canonical had actually been planning Dell PCs with Linux for a while. I guess I was wrong.

The Dell XPS 410n that I ordered on May 24th arrived this Saturday. After 10 years of using Linux, I was finally able to order a prebuilt computer from a major OEM without paying anyone for an operating system that I would delete shortly after unboxing. Instead of devoting half of Saturday afternoon to installing Linux, I had a working Linux system 19 minutes after opening the box. I think I probably spent more time picking a desktop background from Flickr than configuring the machine.

I didn’t spend any time installing the DVD drive into the case or washing thermal grease off my hands. I opened the case briefly to take a picture, but I don’t even know how many PCI slots I have. I can feel the freedom of blissful ignorance returning.

I half-expected Dell to screw up Ubuntu somehow– add idiotic icons to the desktop (offers to connect me to the internets, shortcuts to crippled versions of photo editing software, or similar). I’m happy to report that they seem to have gotten it right. The Ubuntu they delivered is difficult for me to distinguish from the Ubuntu I’ve been installing for the past few years. Synaptic is set up to use the ubuntu.com repositories. Compiz is disabled by default. The boot process seems faster, but that may be the new hardware. The 2.6.20-15 kernel was installed; Synaptic installed 2.6.20-16 during the first update.

Ubuntu wasn’t perfect– it did fail to identify my HP f2105 monitor’s maximum resolution of 1680 x 1050, and there was no way that a normal human would have been able to fix it. (I executed sudo dpkg-reconfigure -phigh xserver-xorg and selected the correct resolution to fix it.) Also, the option to enable the restricted Nvidia driver doesn’t work, but I haven’t gone beyond the normal-human level of effort yet.

(Update: after running a Synaptic update, I could enable the restricted Nvidia driver and turn on Compiz– no geek-level intervention necessary.)

Overall, I’m delighted with what Dell and the wealthy gentleman from Canonical have done. For me, 2007 is the year of the Linux on the desktop. I offer my sincere congratulations and thanks to the Ubuntu folks at Canonical and Dell.

Last week, after building my own computers to run Linux for about 10 years, I ordered a computer from Dell with Ubuntu Linux pre-installed. Don’t get me wrong– I have enjoyed at least 80% of the hacking, crashing X11 repeatedly, trying to disable X11, giving up and using the terminal window at 640 x 480, crashing X11 repeatedly, and so on. In the last 2 or 3 years, Linux has become solid enough that I rarely need to perform tasks akin to surgery. With tested hardware from Dell, instead of hardware randomly selected from different (non-Belkin) vendors, I’m betting that I may not need to edit xorg.conf at all!

As I prepare to enter the realm of normal people, the realm of adults who buy computers to get work done, who don’t know about lolcats or frist psot, HTTP redirection or ARP cache poisoning, SSH or even RSS, it’s time for me to pass on what I sincerely hope will become useless tips.

When your GUI goes crazy, the screen starts cycling on and off, or just searching for inputs eternally:

1. Use Ctrl-Alt-Backspace to stop the X server and drop to a command prompt. Then you can try looking at /etc/X11/xorg.conf to see what’s wrong and restart X using the command startx.

2. Enable sshd as soon as you can, so that something goes horribly wrong, you can still ssh into the machine and execute commands.

3. Use Ctrl-Alt-F2 (or higher F-keys) to cycle to additional terminal windows if, as was generally the case, X is screwed up.

Those three tricks have kept me going for tens, or maybe even hundreds, of hours of debugging.

So, maybe I’ll need these skills again when the hard times come and production of new computers grinds to a halt, but until then, I’m turning my attention to higher level tasks, like implementing a sun-tracking algorithm in Python.