Sunday, December 8, 2013

Twinkle, Twinkle, Arduino...

Francois Chambard has built a lamp into the espresso counter for Happy Bones, our upcoming café. The plan is to have the lamp respond to customers putting money in the tip jar. I have an Arduino-controlled dimmer working, but Brandon LeNoir is working on the sensor. Until we integrate, I wanted the light to do something autonomously. Mapping notes to light levels (higher is brighter, lower is dimmer), and testing with a UM Project lamp, the system now plays Twinkle, Twinkle, Little Star.

The only other issue is that the whole setup looks a lot like a bomb...

Saturday, December 29, 2012

Two-Letter Scrabble Words

One of +Dave Goldberg’s many skills is that he’s a stellar Scrabble player, and one of his secret weapons is knowing all 101 valid two-letter Scrabble words. This lets him make words alongside other words, picking up the scores of the old and new words – and counting the letters in the new word twice. It's a bit tedious learning the two-letter words, so I built to train myself. You’ve already learnt three of them – ‘go’, ‘jo’ and ‘za’ are the only valid two-letter words starting with ‘g’, ‘j’ and ‘z’ respectively. Click on the valid words, but not on the others – and hover over a word to see its definition. Here’s to higher-scoring Scrabble games!

Wednesday, July 25, 2012

Three Containers

The New York Times Wordplay blog posted this puzzle.

Spoiler alert! Stop reading now if you're going to try to solve the puzzle yourself.

I ended up spending long enough on it that I manually created the complete tree of water-in-glass configurations (thank you to Beckett Madden-Woods for a correction):

Each node is a different combination of water quantities in each glass – respectively the 20, 15 and 7 ounce glasses. An edge represents pouring one glass into another glass – the source glass and the destination glass, where A = 20 oz, B = 15 oz, and C = 7 oz. So A → C means that water is poured from the 20 oz glass into the 7 oz glass.

The depth of the node is the minimum number of pours required to get to that configuration. The puzzle solution, "10,10,0" is surprisingly deep – there are two very long branches, and it takes 15 pours to get to the solution. Incidentally, every amount of water from 0 oz to 20 oz is present in a glass somewhere in the tree.

I did this manually – please let me know if you notice an error!

Thursday, February 3, 2011

2004 Google New York portrait from the Empire State Building

Nearly seven years ago, Google New York was based in Times Square (we're now in a much cooler location in Chelsea). We had a nice view of the Empire State Building, which meant that we should also have been able to see our office from the ESB. The question that came up over our communal lunch table was: “what focal length lens would we need to take a portrait of all 20 engineers from the top of the ESB?” After some initial confusion about the mathematics of optics, we came up with the answer: about 4000mm. That's a big lens! Fortunately, Michael Riley had a 2000mm astronomical telescope, and I had a digital SLR (Nikon D1x) with a DX-size sensor, which meant that once I bought a physical adaptor, we had a 3000mm focal length camera. Maureen Marquess called the ESB and found out that we could bring the bulky telescope up to the observation deck as long as we were finished by the time it was opened to tourists. The only remaining challenge was getting Michael Riley up that early – he's most productive in the wee hours of the morning – along with the other engineers. But on October 23, 2004, the stars aligned, and Michael and I went up to the (very windy) observation deck with 25mm, 105mm, 450mm and 3000mm lenses:





Clay Bavor stitched these photos together to create this zooming movie:

Sunday, March 14, 2010

Pixels by the square foot

We're renovating an apartment, and Ghislaine Viñas, a friend and interior designer, suggested a mosaic for the wall of a powder room. We looked at mosaics, but they're (a) expensive, and (b) a big commitment – what if you don't like it when it's done? So I thought: wouldn't it be great to have a mutable mosaic – some kind of wall of tile-sized pixels that you could put in any pattern you wanted?


White and RGB LEDs are becoming pervasive – the Oscars had many LED panels on stage showing images and patterns. But they're expensive and power-hungry: e.g. 100-300W for a 2 s.f. panel. Todd Holoubek tracked down Chimera, which consists of LEDs (white or RGB) at a 10mm pitch, individually addressable, on boards that can be cut to any shape. The BMW Museum uses them to great effect. But they turn out to be $650/s.f. all-up.

Plasma and LCD TVs

Here's a spreadsheet of various cheap TVs and their cost per square foot. Bottom-line: a 50" 720p plasma is $170/s.f. This includes $500 for a computer to drive the screen. If you drive it with a cheap device like a DVD player, the cost is $100/s.f.

This seems plausible (and cheaper than mosaic), but there are two problems: power and borders.

Power. 50" plasma screens consume about 300W. If you had a wall of ten screens, you'd generate 3kW of heat. I wondered whether the nominal power usage was real, and whether turning down the brightness would help. so I plugged one into a Kill-A-Watt electricity usage monitor. Sure enough, about 270W. I turned down the brightness, and this dropped to 130W. Unfortunately, the image looked gray and washed out: I couldn't figure out how to drop the brightness without killing contrast. And in any case, 130W is still a lot.

Borders. How closely can you put plasma screens together? If you remove the bezels, could you make it look like a seamless wall (for example, if you put translucent glass in front)? For this, I needed to dismantle the screen. It weighs 75 lb, most of which is a big hunk of glass. I have to say, I'm not a fan of heavy, fragile things... The metal back panel comes off easily (after removing about 30 screws), but it's a cheaply-cut pressed sheet with sharp edges, and I sliced my finger open on it. Having staunched the bleeding, I removed some wires to speakers, IR receiver, etc and undid some more screws:

You can see the driver boards around the periphery, with ribbon cables going to the screen.

Once I lifted the (heavy, fragile) screen out, I could see the edge:

(the ruler, in addition to measuring, demonstrates the beauty of New Zealand native wood...) From the edge of the image to the edge of the glass is about 30mm. So even if you had the bare panels butted up against each other, you'd have 60mm between the images. Not seamless.

Physical pixels

So now I'm driven to desperation. I started thinking about physical mosaic-substitutes. Imagine an x-y plotter that could place lego pieces to create a piece over a few hours. With an automatic color-sorter, it could then take the old pieces out and build a new one. One problem is that there aren't many lego colors.

Or you could build a wall of clear vertical tubes and fill each tube with beads, varying the color to build up the image. Or if you could figure out how to thread the beads on a wire, you could do it even more finely and accurately, with less space between the columns. Then you'd just need an x plotter: the order you drop them in gives you y.

You build a paint plotter, but that would get messy, and not easy to reuse; you'd have to have an easy way to paint over (or maybe you'd get big sheets of white paper, or a huge dry erase board).

I have seen the future, and it is running late

Maybe the time for the huge, low-power image wall has not yet arrived. Let me know if you have ideas that I haven't thought of!

Saturday, October 10, 2009

Boston Butt Telemetry

Another slow-cooked pork weekend...

We were given a Big Green Egg by Martin & Andrew Farach-Colton. The Egg is great at high-temperature grilling like steaks, but comes into its own for slow cooking, like pulled pork. Last time I did this and posted progress on Facebook, Bharat Mediratta wanted more data: specifically, a chart of temperature versus time. Last time, I bought a Redi-Chek (see how appealing a product name is when you misspell it in several ways?) remote thermometer: the transmitter has a probe that goes in the pork, and you can keep track of the internal temperature within a hundred or so feet with the remote. This time, I used Gawker, time-lapse software for the Mac, to track the temperature overnight, then replayed the movie (yeah, low-tech) to fill in a Google spreadsheet.

Here's the temperature chart:

You can see the plateau at about 170˚F from 4:30am to 8:00am. According to collected wisdom on the internet, this is when the fat and connective tissue break down. I prefer to think of it as a phase change of the Pork molecule, analogous to heated water pausing at 100˚C while all the energy goes into creating water vapor. I don't know the chemical formula for pork, but it sure must involve some tasty elements!

This time around, I had the Egg configured just right, so it maintained a constant 215-ish˚F all night, and I didn't have to wake up multiple times to adjust the vents. It was done in less than 12 hours, so must have been a bit smaller than the one I cooked last time.

Oh, and it tasted great...

Sunday, March 1, 2009

Beautiful Coffee

Inspired by the new "bottomless" ("naked", "crotchless") portafilters at Google New York, I bought one for home. Seeing the espresso emerge from the filter in its syrupy, chocolate-flecked-caramel essence is a thing to behold. I highly recommend clicking on the images for the full effect: