Red Echo

November 30, 2011

I finished the ski pants last night, fancy trapezoidal belt loops and all. That was really rather a lot of work, but I’m delighted with the result. Now I want to go back and spiff up last year’s jacket to match – redo the collar, I think, and add a lining.

I’ll be showing them off at the ALTSpace open house tonight!

7.0″ TFT display, 24-bit RGB, 800×480 pixels. Might be useful for that dual-screen, eight-core microcontroller-driven laptop concept I keep flirting with.

November 29, 2011

awesome jetpack video

Yves Rossy is at it again, flying in formation with a couple of fighter-jets using a custom built delta-wing jetpack. It’s like watching a guy on a motorcycle race a couple of Formula-1 cars, except they’re all flying.

November 28, 2011

I got my motorcycle back today. It was a bit cold out but perfectly clear, and it was nice to ride around a little after work. The rear brake lever is adjusted a little strangely but the brake works fine. The new tire looks exactly as it should, and the new clutch works smoothly. Now that I have the machine back in hand – four weeks later! – I can finally replace the munched headlight with the eBay replacement that has been sitting on my shelf collecting dust.

I spent a couple more hours on the ski pants tonight. This project has definitely taken longer than I expected, but these pants are also the most complex garment I’ve ever constructed, and I’m pushing the finish level as hard as I know how. I want this garment to last for at least five seasons, and I want to feel comfortable and look stylish the whole time, so I’m taking my time getting it right. Tonight I inserted some darts into the waistband, stitched the inner seam down, and got about halfway through the belt loops (ballistic nylon trapezoids, lined with supplex – no raw edges exposed anywhere!). One more evening should be enough to finish the belt loops and cuffs.

November 26, 2011

ALTSpace open house on Wednesday

Air Light Time & Space is having an open house:
Wednesday November 30th from 7 pm til 10 pm
Wine and snacks will be served
Show-and-tell: bring something you have made, or something you are working on – let’s inspire each other!
Open to the community, please bring guests.
If this goes well we will make it a regular weekly event.

A.L.T.Space is located at 2318 E. Cherry Street, at the corner of 23rd Avenue, across the street from Garfield.
Look for the tall metal gate next to the row of garage doors – our door is at the end of the narrow courtyard on the right.

November 25, 2011

Progress on ski pants

All the major shell pieces are cut out. The articulated knees are finished and the rear pockets are sewn on. I’ve also made a lining: it’s a nylon / dacron / interfacing sandwich, quilted together. I haven’t decided whether it will have elastic cuffs independent of the shell, or whether the shell & lining cuffs will just be sewn together.
Next I will make some zippered front pockets, and I should have enough time to sew up the main body seams tonight. That’ll leave the zipper fly, the waistband, and the cuffs for tomorrow.

I spent a couple of hours working on shop improvements today, too. The heat in the south half of the space was not working, and it was uncomfortably chilly in there last night. We’d been talking about installing programmable thermostats anyway, so I bought a pair. Now the shop will heat itself up during the day and cool back down at night – it should already be warm for the first person who arrives. Also I got a dozen more little plastic bins for the big wooden cabinet: two of its eight shelves are now devoted to little containers. We’ll put all the sewing and crafting tools in there, and some of the sewing notions too.

November 22, 2011

I ordered supplies for another project: I’m going to build a set of microcontroller-driven Christmas-tree lights. Each light will incorporate a miniaturized version of the controller I used on the Shame Project, which will drive a standard (low-power) LED. It will run the same evolving rhythm pattern generator algorithm, but I’m going to tweak the color selector: the colors will be fully saturated and limited to the range from red to green. That is, the lights will use reds, oranges, yellows, and greens in varying brightness, but no blue, white, pink, or purple.

November 21, 2011

New idea for a very old problem: buffer-centric IO is a nifty zero-copy input abstraction.

Last winter I made a custom ski jacket out of gore-tex and ballistic nylon. It’s getting up near winter again, and I am thinking about designing a matching pair of trousers. I’ve been wearing a cheap pair of waterproof overalls for the last five or six years, and while they do the job they are neither flattering nor especially comfortable. The cuffs are also pretty well slashed up by errant ski edges.

My concept is a slim, bell-bottom style pant with a contrasting quarter-panel on the front outside thigh, plus articulated ballistic nylon knee inserts and wide cuff covers. A double waistband with integrated poly-webbing belt would keep snow out. Contrasting, top-stitched patch pockets with hidden zippers would provide a safe place to stash keys or a cell phone, and a thin line of retroreflective piping would add a hint of flash to the side seams.

Ava and I went out to La Push this weekend to celebrate her birthday. It was dark by the time we rolled in on Friday, but Saturday was clear and bright. We got up late and spent the day rambling around on the beach. It was cold but there was very little wind so it was easy to bundle up and stay comfortable.

The River’s Edge Restaurant has a disappointingly thin seafood menu for a place next door to the fishing marina. It was expensive and not very good – we’ll bring our own food next time.

Sunday we drove out to Neah Bay, bought some smoked steelhead, and hiked out the short trail to the end of Cape Flattery. I love that place, standing out on what feels like the edge of the world, nothing but Tatoosh Island with its little lighthouse, then half a planet’s worth of ocean.

We found some bullwhip kelp washed up on the beach the day before, and it was fun to see the floating forest of live specimens swaying in the low tide around the sea stacks.

November 15, 2011

Full-spectrum LED array, installed

It lights up the room really well – the light is focused directly down on Ava’s desk, but it’s enough light for the whole room, and it brightens up the walkway outside too.

I don’t have equipment to measure the power spectrum, but subjectively the light appears a little too warm. The new power supply runs the white LEDs at a lower current level than I’d originally planned; I would guess they are putting out about 75% of the planned lumens. It’s not bad – it’s very comfortable, easily the warmest light I’ve ever seen out of a non-incandescent light. If I were going to build another light using the same driver, I’d use a different ratio, but this device will do its job nicely.

November 13, 2011

Finished full-spectrum LED array


I spent a quiet afternoon today soldering up an array of LM317 current regulators, attaching them to the LEDs, and running up a pair of power rails. It sounds simple but there were many little pieces of wire to cut, strip, and tin, and the whole thing took about five hours. Ava came along and helped out, which was fun.

ALTSpace was really hopping – there were people in and out all day. Cassie was doing some paper cutting work, Jason and a friend of his spent a couple hours building computers out of all the spare parts he has on his workbench, Mel was working away on jewelry, Brian did some beer brewing, and a couple from Austin stopped by just because they happened to be in town. It was great. One of my big goals for ALTSpace was to create a social hub and it’s great to see that happening.

November 11, 2011

I saw the intertubes

The Millwheel and Flume teams took a tour of Google’s datacenter in The Dalles yesterday. I can’t say much about what I saw, but there’s rather a lot that I would say if I could. It was an eyeball-widening sort of place.

I still don’t like the fact that the computer industry has decided on massive centralized datacenters as the way we’re going to do things. It’s great that Google is committed to not being evil, but no organization maintains its original values forever, and we’d all be better off in the long run if we built evil-tolerant distributed systems.

November 7, 2011

Review of active projects

Of the dozen projects I listed a month ago, I’ve completed #2 (ALT&S expansion), #3 (living room couch), #4 (mysterious music project), #6 (dimmer for Hunter’s geode sculpture), #8 (repackage Shame Project lights for use in my living room), and #9 (serger workbench for ALT&S).

I haven’t touched the electric skateboard; it’s too cold and rainy out to ride such a contraption anyway. The high-output full-spectrum light has had a couple of setbacks, but once that next Digikey package arrives I should be able to finish it up in a night or two. The City Light thing – well, they weren’t actually looking for a proposal, just some kind of artist resume. It was frustrating and nothing is going to come of it.

The rhythm synthesizer algorithm is still kicking around in the back of my brain, but I may divert that mental energy toward learning to use Ableton Live. It’s been a long time since I did any studio production work, and the Mysterious Music Project reminded me how much I enjoy composition. I haven’t lined up any live-PA gigs lately; I think maybe I will spend some of this winter “in the studio”, making dance music.

Last on last month’s list was my motorcycle: it’s been in the shop for the last two and a half weeks. I’m not sure what’s going on with the mechanic but I’m getting worried. He had to order in a new front tire and some special tool to replace the clutch, but still, it shouldn’t be taking this long. Meanwhile I have been driving the car to work, or having Ava drop me off. It’s not so much fun.

The new active project list:
0) Finish assembling the full-spectrum LED array
1) Radian: clean up after introducing a new allocator and a new X64 backend
2) Recruit new members for ALTSpace – lots of room now
3) Acquire and learn to use Ableton Live

That’s a really short list. No wonder those boxes of fabric at the shop have been catching my eye every time I walk by…

I do have a few things on the home improvement list too:
– install AirPort base station for better internet access in the office
– figure out why one of the Shame Project lights doesn’t light up and fix it
– weed old stuff out of wardrobe
– help Ava hang up her wall-sized mirror
– introduce a more rational organization to the file box

November 6, 2011

Latest home improvement work

Our kitchen has one big light, on the ceiling in the center of the room. It is adequate but not bright; you want something a bit more intense when actually cooking. I added a strip of under-counter LEDs months ago, which helped a lot on the preparation side of things, but it’s still pretty dim over on the range itself.

While rummaging around looking for a camera cable this afternoon, I happened to find an Edison-based LED bulb I bought three or four years back. It was one of the very first generation of LED-based home lighting products, and I never used it for anything as its light beam was too narrowly focused: but aha, I thought, this would make an excellent spotlight for the range.

A cheap screw-on base and some not-at-all-up-to-code wiring later, it works perfectly: bright white light pointing straight down at the stove top.

Of course I found out why the main light is so dim: it has two sockets, but only one is populated. Ha. Still, this LED device solves the problem, and only burns 3 watts. It’d take at least 10 or 15 watts in the ceiling fixture to yield the same effect.


November 4, 2011

A photo of my halloween costume

I’m sexy and I know it, yeah!

November 3, 2011

Progress on the full-spectrum LED array

I did some more work on the light module for Ava’s desk last night. The goal is to construct a full-spectrum array comparable to a 500W halogen work light, to illuminate her work surface and help stave off the Seattle grey-sky winter blues. I estimate that it should be possible to produce a comparable level of light using only 150W. Of course LED-based lights are available at all brightness levels now, but I am not aware of any commercial full-spectrum units yet – and after designing this project it is pretty easy to see why. Give it another year or two and I think this sort of light will be available off-the-shelf, but right now it is still a challenging hobbyist project. Perfect for me to play with!

As per usual, I have gotten myself in a little deeper than I expected. Every LED project I’ve done previously starts with a fixed-voltage DC power supply, then I add appropriate current regulation for each LED circuit. This time I knew I was going to be drawing a great deal of current, so I thought it would make more sense to run all the LEDs off 120VAC. This is not as crazy as it sounds: it’s the same thing all those LED christmas light strings do, only I’m using much more powerful emitters. Instead of running all the lights in parallel, regulating each one independently, I decided to run all the LEDs in series with a single regulator: dividing a single power loss across all the lights, instead of multiplying it by the number of lights.

I started with a bridge rectifier and a large capacitor; the output, I expected, would be roughly 120VDC. Each of the Bridgelux emitters drops 8.9V, so I wired up a dozen of them in series. Then I threw in an LM317HVT linear regulator, rated for 40V / 1.5A, and configured it as a 1-amp current regulator.

This did not work. The lights came on briefly, then something went “pop”, and the lights went out. In the second or two before I managed to disconnect the power, two of the LEDs flared on and went “pop”, leaving a black smudge across the lens. Uh oh.

Further testing revealed that the output from the rectifier was nothing like 120V – instead I was getting something close to 170V! Now of course the whole point of alternating current is that the voltage alternates, swinging back and forth constantly. When we say that wall outlets supply “120 volts” or “110 volts”, that’s the RMS average – at any given instant, the outlet voltage may be anywhere between -170V and +170V. I expected that my little rectifier/capacitor setup would smooth out the peaks and valleys, giving me a nice steady 120V, but it appears that I’m drawing so little current that the voltage just stays high all the time. This is just a guess, really – it would all be so much easier if I had an oscilloscope.

I think the first “pop” was the LM317HVT, which is designed to handle a maximum of 40V difference between input and output. On encountering a 60V difference, it must have fried itself closed; with no remaining current regulation, the LEDs started overloading, and thus the bright flash and the pop as the magic smoke escaped.

I ordered a bunch of replacement emitters, replaced the two damaged ones, and added six more to the chain. Now I have eighteen of the Bridgelux units wired up in series, for a total drop of 160.2 volts. I also threw in a 10-watt, 68-ohm resistor to help out with current regulation. This seems to work, and it is almost hilariously bright. I should be able to replace the LM317HVT now and keep the current set where I want it.

If I can get this to work, the next step is to augment the “neutral white” spectrum with three other frequencies. “White” LEDs have a big spike in the blue range and a softer, broader lump in the yellow/green; this setup stimulates all three of our color receptors more or less equally, so the light looks white, but it doesn’t actually illuminate colored surfaces evenly. The reds are very weak, and there’s a noticeable gap in the cyan as well. My solution is to interleave colored LEDs with the white ones, adding 660nm (deep red), 627 nm (red), and 505 nm (cyan). I’m sure somebody, somewhere, has tried something like this before, but I haven’t been able to find any trace of it on the web, so I don’t really know how it’s going to come out. I expect that I will have to tweak the color balance somewhat, but in the end I hope to have a very bright light with all visible frequencies reasonably well represented.