$1 million Google Tiny Box prize won

Belgian contenders The Red Electrical Devils have won the $1,000,000 Google Tiny Box prize.

There’s a .pdf of the paper describing their design here, but don’t bother trying to read it if the word “schematic” means nothing to you.

Google’s challenge was for a tiny, lightweight device that converts DC (the type of electricity that batteries and solar panels put out) to AC (the type of electricity that is most useful for doing work). Such devices are called “inverters” and improvements in inverter technology would obviously be useful for electric cars, home solar power systems, and many another thing.

The winning team exceeded Google’s minimum requirements to win by three times, creating a device that is ten times smaller than existing technologies while meeting all of Google’s other restrictions (such as 95% or better efficiency, air cooling, &etc.) It’s extremely impressive work.

Skunk works claims hot fusion breakthrough

Lockheed’s secret lab says they’ve solved the problem of hot fusion containment, and that they can build a 100 megawatt reactor small enough to fit on a truck in less than one year, with commercial prototypes in less than five years, and reactors available on the market in a decade.

Supposedly it took them only four years to work this out, which makes you think of Bussard’s talk to Google back in 2006, where he claimed that the only reason we didn’t have working fusion reactors was lack of will.

Hot fusion is a highly energetic, highly radioactive process but it does not generate extremely long-lived waste like conventional fission reactors do. A hot fusion reactor accident might do as much initial damage as a fission plant accident, but the long-term cleanup would be relatively simple; if we can’t have true cold fusion, hot fusion is still a big step up from coal or fission.

Craptacular Eskimo Fan

Heather bought another old fan at the Arden Fair a few weeks back. It’s a single speed oscillating Eskimo with aluminum blades from the late 1930s. It has a somewhat attractive pseudo-Deco design with a spiderwebbish pattern to the cage.

Dissassembly revealed not only unbelievably thick crud deposits (half an inch of greasy fur inside the casing) but also the cheesiest design and materials I have ever seen in an antique fan.
The shaft bearings are thin and very yellow, very little copper content. But not all of the bearings are even metal! Some of them appear to be made of greased cardboard. The stator windings are literally bound with masking tape, although the wire nuts are porcelain. Two of the gears in the oscillator box are made of masonite – steam-pressed wood fiber. The worm gears they engage are steel, so don’t grab the fan and prevent it from oscillating unless you enjoy the sound of masonite gear teeth snapping off. The blade is soft aluminum, so soft that sticking a finger into the cage will almost certainly unbalance it… two of the blades are already bent, so that it vibrates noisily and the main shaft sidles erratically in and out like a trombone slide.

Even without the blade mounted it still sounds like a gravel crusher and the main shaft wobbles all over the place, because the squirrel cage rotor has never been balanced and all the cheesy bearing surfaces are worn out. If you push the oscillator shaft bearing up into the housing with a penknife it’ll swing back and forth wildly, at surprising speed, until the shaft bearing flys back out and the gearing disengages. I guess with a 2-pole stator and a 15-pole rotor you can’t expect smooth operation? The fact that the oscillator must have fallen apart almost immediately is probably what preserved those masonite gears.

Generous and repeated use of PB blaster, WD40, degreaser, and ultrasonics have given this piece of junk an interesting wabi-sabi patina that I kind of like, so I’m thinking about replacing all the bearing surfaces with bronze, and seeing if I can reshape the blade to restore balance. Planishing fan blades is always a big challenge, though.

Time Domain Reflectometry visualized

Wikipedia provides this excellent graphic to help explain how you can determine where the fault is in a very long cable.

Reflection of an electric pulse back towards point of origin

Time delay reflectometry is a clever trick where you can calculate the location of an imperfection in a conductor by timing when the “bounce” returns, as long as you know the speed of signal propagation in the wire (which you generally do).

The impedance of the discontinuity can be determined from the amplitude of the reflected signal. The distance to the reflecting impedance can also be determined from the time that a pulse takes to return. The limitation of this method is the minimum system rise time. The total rise time consists of the combined rise time of the driving pulse and that of the oscilloscope that monitors the reflections.

Plumbers will note that the behaviour of the electric flow here is analogous to water hammer. I think it should be possible to find the distance to an obstruction in a pipe as a TDR calculation, as long as you know how compressible the fluid medium is.

240 VAC hurts

When I was much younger, I worked one summer as an Electrician’s Mate in a munitions plant. I was hired (and paid) as unskilled labor – fetch and carry, hold the flashlight, etc. – but the electricians I worked with soon discovered I had a pretty strong familiarity with electricity, mostly thanks to my father. I was good at soldering, I knew P=IE and E=IR and I could calculate resistances in parallel, and all that put me in a different category from the other helpers. So before long I was helping to wire breaker boxes, replacing outlets, and so forth.

I should point out here that my senior co-workers were not exposing me to unnecessary dangers by allowing me to do the more complex jobs. Among the tasks normally expected of unskilled helpers was weeding inside the caged-off areas around extremely high-voltage sources, tens of kilovolts, where a misstep could easily mean an ugly death. And of course we are talking about a factory that existed to create dangerous items and situations in the first place… it was never supposed to be a place where a person could blunder around unthinkingly and expect to survive. Unlike most American workplaces, staff there were treated as fully self-actualized human beings, capable of making life and death decisions routinely without reference to rulebooks. So as an employee, you were not just expected but required to understand what you were doing and required to do it safely. Once I had I proved to persons in a position to make such a judgement that I could work with electricity without harming myself or others, they permitted me to do so.

But maybe I got a little too cocky, being the only guy without a journeyman’s rating that was allowed to work with very little supervision. And maybe I was a little too bold, willing to volunteer for tasks the older, family men weren’t so quick to take on.

Anyway, there’s a small valley in the woods behind the plant that’s full of magazines. Magazines are these little concrete and steel shacks, made of six pre-cast panels held together solely by gravity. They’re kept from falling down by big galvanized steel pins at the corners; a crane drops each of the four walls onto the base slab, then a slab roof is dropped on top. Deep-buried wires provide electricity to each magazine’s electric heater and an air conditioner, and one slab wall has a thick steel door in it.

If the extremely powerful explosives stored in a magazine blow up, the blast berm around the magazine directs the force of the expanding gasses upwards into the air, and afterwards you bring a crane down and pick up the surviving pieces of the magazine and put it back together again.

Aerial shot of a small group of magazines

Aerial shot of a small group of magazines

Magazines are kept at very specific humidity and temperature levels, so it was often necessary to run the heaters and air conditioners simultaneously on humid summer days. You had to condense the moisture out of the air with the AC unit, which meant you had to run the heater to maintain temperature. These things run unattended for years, sometimes for decades, so there’s remote monitoring and alarms go off whenever a piece of equipment malfunctions or the temperature begins to creep outside allowable limits. And on some sort of schedule, a watchman would visit and sample the humidity with a sling psychrometer (I’m sure they use electronic hygrometers these days).

It must have been about 90 degrees outside the day I volunteered to fix the air conditioning in one of the magazines. I can’t remember how it came about that the A/C service guys determined that a relatively skinny person was needed to wriggle into the blisteringly hot space just below the roof of the magazine and replace a bit of control wiring with a soldering iron. I do remember that when they called the electrician unit, they were in a big hurry, because the temperature and humidity were already rising precipitously. None of us knew exactly what was in the magazine, but everyone was vaguely half-expecting an earthshaking BOOM accompanied by shattering windows throughout the plant.

This is what I learned that day.

#1) Most air conditioning systems (other than American window units) run on 240 volts. I have no idea why I ever thought otherwise, nor do I know why nobody told me the control circuitry for these particular AC units was running full voltage. But I had grown pretty blase about 120 volts, and didn’t take a lot of precautions while I was sliding around in the dark by the light of a weller gun.

#2) Although perfectly pure water is an insulator, and dry human flesh is a poor conductor, a sweaty human will spasm like a click-beetle if given a good old-fashioned electric shock. When I accidentally touched a live 240 lead my sweat-soaked body conducted enough juice into my muscles that I got bruises all over my body, particularly on my knees, elbows and the back of my head, which slammed into the top of the magazine at least once. But you can’t scream (or think, really) when you’ve got that much current passing through you… and nobody can hear you thumping around from outside of a steel-reinforced concrete box six inches thick.

#3) A healthy teenager can survive brief contact with 50 amps of 240 volt alternating current. (Due to the thrashing mentioned in lesson #2, my contact was extremely brief.) And within fifteen minutes or so, said teenager will be sufficiently recovered to lie convincingly about the incident if asked why the job took so long.

My mother still doesn’t know this ever happened, so don’t tell her.