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standard power
Wednesday, October 8 2003
The weather for the past several days has been in the 50s and even 40s, but today it was up at the comfortable ideal of 72 (all those are, of course, from the Fahrenheit scale; we Americans prefer to keep our religion, measurement systems, food, cell phones, and music primitive). The day had more the feel of a warm day in winter than it did the resumption of the warm season. Something about the fragrance of the air had changed.
The good weather inspired me to finally do some work on the communication and entertainment systems in my pickup truck. I've had a CB radio ready to install in it for some time, and yesterday I also got an antenna for it. While I was at it, I wanted to make it so I could easily plug my MP3 player into the truck's stereo, whose own arbitrary music system, a tape player, is non-functional. I thought I could just tap into the inputs on the final amplification stage, as I have done in the past with other radios (such as the boom box I had strapped to the dashboard "towel hanger" of the Punch Buggy Green).
Once I had the stereo out of the dashboard, I realized I was never going to tap into anything with the tape deck in my way. So I tried simply removing it, but something in the tape player's most basic electronics (we're talking switches and solenoids here) was necessary for the radio to do anything, and it looked like I wasn't going to be able to remove it after all, not without investing hours of sleuth work.
I'm old enough now to regard time as money, so I solved my dilemma by simply buying a replacement car stereo for $100 at the store whose name implies there is no better buy. I didn't get the $30 extended warranty the Best Buy guy tried to pressure me into getting. I know all about that racket - extended warranty are almost all profit for a company. Besides, it's rare that I buy something that works and don't proceed to void the warranty immediately with some sort of custom modification.
I spent most of the late afternoon installing the new car stereo, whose form factor was exactly half that of the old stereo, giving me more than enough room to also install the CB radio directly into the dash. I stacked everything up loosely in the dashboard hole, since none of the hardware that would have allowed things to be bolted into place seemed to match up.
The new stereo comes with a built-in CD player, but I was actually more interested in the fact that it had auxiliary inputs allowing me to connect my MP3 player. Ideally, though, I'd also want some way to power the MP3 player, which requires five volts at two amps.
So I built a little power supply using a pair of 7805 power regulators (one of which I'd salvaged from an old color monitor) to convert the 12 volt vehicular electrical system to five volts. As I was building this system, I had an idea. Instead of building a single five volt supply that is only capable of powering my MP3 player, why not build a generic five volt power supply that can drive any of my five volt equipment? In fact, why not terminate the new truck power supply with the same connectors that have become the default standard in my laboratory, the four-conductor cables that come out of every computer power supply and are used to deliver power to hard drives and CD-ROMs? I use computer power supplies for most of my low-voltage laboratory projects (including such non-electronic applications as electroplating), so I can always count on these when I'm at home. In a pinch, I can also find them in any place where there are desktop computers. Even when I was in South Africa and I could find no other source of suitable power, I scrounged together a camera recharge using a Macintosh power supply.
So I made a power supply for my truck that takes the 12 volts of the truck's electrical system and converts it into a standard computer power cable. I also made an adapter that converts the computer power cable connector into the coax power connector used by my MP3 player. Now I can hook this MP3 player up to any of the several computer power supplies in my laboratory, the connector in my truck, or (in a pinch) to the power supply of anybody else's computer.
But I didn't stop there. I took a perfectly-good plug-in power adapter and cut the cable in half, then I attached standard computer power supply connectors on either end of the slice (one male, the other female). It's a very small adapter that supplies five volts at an impressive 2.3 amps. Now that it has a "standard" connector, I can use it to power either my camera or my MP3 player, depending on which "adapter" I use. Eventually I expect to convert all my other five and twelve volt equipment to use these sorts of connectors. By taking charge of my equipment in this way, I no longer am a slave to arbitrary connectors on grab bag of bulky power bricks, all of which must be carried when traveling. I can pick the one power supply I need and then a handful of adapters cables.
This brings me back to a subject near and dear to my heart: the importance of standards in our lives. To a larger degree than we think, we are manipulated by standards: how fixed they are, how they are changed, and who owns the rights to them. We wouldn't even be here if it weren't for the multi-billion-year-old open standard used to encode our genes. But even in a context as simple as a household, it's important to make a decision about a standard and then stick to it, at least until it becomes a serious burden. For example, my standard of small-range digital storage is the Compact Flash memory card. I will not buy a camera or a PDA that uses anything else. Keeping track of two different varieties of memory card introduces complexities that are easily avoided simply by adhering to the use of a single kind. Similarly, dealing with the differences in power supplies between a vehicle and a household has its own headaches, but at least now I can count on the increasing ubiquity of a certain kind of low-voltage connector.
While I was rummaging around for parts to build my truck's new five volt power supply, I was listening to Terry Gross interview Bill O'Reilly on her program Fresh Air, because I'd been alerted that O'Reilly would throw one of the bully tantrums he's been throwing ever since Al Franken came down to Earth to show the Vast Right Wing Conspiracy that they have, in the words of Rob Halford, another thing coming. The prospect of Terry Gross causing anyone to throw a tantrum was such a lure that I managed to get Gretchen to come into the laboratory and listen along with me.
I'd never heard much from O'Reilly before, but this interview showcased his personality well. He sounded to me like a guy with a lot of pent-up aggression and a dangerous inferiority complex. Not only do I think encountering him in a darkened alley would be an unpleasant experience, but it's surprising that a guy so clearly on the edge of stability manages to maintain a career. From all reports, though, it seems he's becoming unglued with increasing regularity. I mean, come on, if Terry Gross can cause you to storm off in a huff, you've got serious emotional problems. She was admittedly more confrontational than usual, making the time she tried to get Paul McCartney off the subject of his poetry seem like Orrin Hatch's interrogation of Clarence Thomas.
Mind you, I don't feel this way about all right wing gasbags I hear interviewed. Whenever I've heard Rush Limbaugh interviewed by others, he's come across as a gentleman and, if not a scholar, then at least capable of a modicum of sensitivity and reflection. But it might have just been the Oxycontin talking.
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