Relax and float down stream

[austin_dern]

One thing I like about having a kerspillion miles on my frequent flier card and flying out of Changi Airport in Singapore is when I would get to the airport early enough -- which, alas, I didn't manage this time, partly from misjudging when I should wake, partly from everyone in line having issues (it is good form when travelling to assemble your loose items into a container -- a piece of ``luggage'', to use the vernacular -- before reaching the check-in counter; while the attendant may generously give you a cardboard box and packing tape for your belongings, you are earning no friends behind you) -- they invite me to the ``SATS Terminal Club'', a cozy spot with buffet food and drinks, free newspapers and magazines, and serious-looking businessmen wondering what this scraggly guy in shorts and a T-shirt is doing there. I've been on these 800-hour flights before, and I'd rather be in comfortable, unconstraining clothes. I suppose if I had meet someone right after a little flight from, say, New York City to Washington I might dress in a work outfit. But after seven hours to Tokyo, nine to San Francisco, and another five to Newark you're not going to be in shape to meet with anyone, and if the person you're meeting won't give you a couple hours to wash and sleep that person's no decent host. Maybe they're slipping in a little more baggage in suit pockets and the like.

A scene from Tokyo-Narita airport, as I stood by a pillar waiting for my flight: a guy sat in the lounge seat next to mine and plugged in his ThinkPad, and apologized for sprawling the power cord around one of my carry-on pieces. A few minutes later a woman came up and asked if that was my computer; I pointed out the apparent owner to him. She held up the American-style power cord for her laptop and asked, ``the voltage here is OK?'' He nodded, ``Yeah, they think of everything here.'' I had thought Japan was on the US-style 120V/60Hz power. Still, it would be a thoughtful airport to include power plugs for the various major species, so maybe they did just think of everything.

In San Francisco I got in far enough ahead of time that I was able to watch the flight before mine at that same gate. The guy running that flight to Orange County kept making announcements about how he had his own way of running things and he appreciated everyone's ``participation'' as he deployed his very special concepts of boarding. I don't believe this was just him making a weird little grab for petty power; there was some kind of announcement about a mistake with boarding passes and seat assignments that had to be straightened out. Unfortunately, the gate speaker system was obscured by the airport speaker system warning that the Official Homeland Insecurity Alert Status was Orange, and the gate guy didn't pause his announcement to let the other announcement play through. I was surprised San Francisco continued with the Security Color Codes, though; I thought everybody gave up pretending to care about those after Bush won in 2004. Maybe San Francisco never got Tom Ridge's memo about them.

Trivia: The Ford Model A's appearance shortly before Christmas 1927 was accompanied by a $1.3 million advertising campaign. Source: Anxious Decades: America in Prosperity and Depression, 1920-1941, Michael E Parrish.

Currently Reading: An Old-Fashioned Christmas, Robert Benchley.

Comments

[orv.livejournal.com]

I got curious, so I looked it up. Japan's system is apparently a mutant that is sort of, but not quite, like the U.S. one. The outlets are physically identical, or nearly so. But they use a nominal voltage of 100V, not 120V. Also, the frequency varies -- 60 Hz in western Japan and 50 Hz in eastern Japan. This seems kind of perverse for such a small country.

Most modern laptops, fortunately, don't care. They use switching-type power supplies that aren't very picky. The one for my laptop is marked "100-240V, 50-60 Hz." The reason the exact voltage and frequency doesn't matter is the first thing a switching supply does is rectify the incoming voltage to DC.

[austin-dern.livejournal.com]

Huh ... that's even more bizarre than I would have imagined. I had the vague idea they stuck to US voltages (at least within error margins; my understanding was the voltage was at least early on only expected to be accurate within about ten percent) due to some early 20th-century marketing deal, but I haven't got any references on the development of the electrical system on hand anymore, but the frequency variation is weird.

I always wondered why my Mac power bricks just had that replaceable plug for US, Singapore, and other genres of plugs. Very convenient for replacing just the faulty part, certainly, but otherwise a little mystery to how it all works.

[orv.livejournal.com]

It's actually pretty simple in concept. In a switching-type power supply, you rectify the incoming AC to DC, then chop it on and off (this is the "switching" part) to make a high frequency square wave. You step that down with a small transformer, then smooth it out into DC again. To regulate the voltage, you vary the "on" time of the chopper circuit.

The biggest advantage here is the transformer can operate at a very high frequency, usually around 30 kHz, instead of 50 or 60 Hz. Since the amount of core steel you need in a transformer is inversely related to the frequency, the transformer ends up being much smaller and lighter. Also, since you're rectifying the incoming power immediately, the input frequency doesn't matter. Finally, because the voltage is being regulated by a chopper that's always either on or off, instead of by a linear regulator, far less energy is wasted as heat. (A Commodore 64 power supply is an example of a linear design -- they were bulky and infamously hot-running.)

The main disadvantage is that switching supplies produce a lot more RF noise than linear supplies. Better designs are shielded to cut down on this.

[austin-dern.livejournal.com]

Oh, huh, all right. I always did wonder just what changed that the Commodore 64 power brick was enough to warm a small city while the Mac bricks I can let my foot rest on for a while before I come to my senses.