Saturday, February 19, 2011

TwinklePIC, part 6

Parts 1, 2, 3, 4, and 5

I now had a board, and I had a display. So it was a simple matter to just plug the board in and some USB power.

And lickety-split, it all came together.

Brynna is intrigued by it. I look forward to explaining this all to her (in about 10 years) in as much agonizing detail as she can tolerate. Unfortunately, as far as the original goal of the project goes - to create a twinkling nightlight - I'm afraid that it may not quite come to pass. There are a few reasons:

  1. Although LEDs are efficient, you have to remember that, on average, I'm converting less than 1 watt of electrical power into light. You'd get as much, or more, from an LED headlamp. The display is quite bright to look at, but it doesn't illuminate a room very much.

  2. These particular LEDs emit light in a fairly narrow cone. So in the dark they throw a very directed light across the room, but not much to light to the rest of the room. A different display construction, with more diffusers and scatter, could ameliorate this, but my appetite for that kind of tinkering is pretty limited.

  3. Brynna has gotten very used to the steady, soft-soft-white glow of the low-wattage CFL in the lamp in her room. She's been sleeping to that for over 18 months. She's pretty unwilling to let these LEDs replace that, although she may consent to let them augment. Recall that I'd first conceived of this project nearly three freakin years ago, before Brynna was even born. If I'd somehow managed to finish it before she could formulate opinions on her sleepytime lighting, I might have had a shot

This is not to say that it's all a failure. I learned some things and kept some of my electrical engineering skills from atrophying too much. Even if it doesn't work well as a night light, it is still an interesting curio in a lit room. The core design allows for some interesting possibilities. For instance, the LEDs needn't be all white. With a red, a blue, and a green LED, one can reproduce most any color. RGB LED clusters can be had, and I could use three channels from the TwinklePIC to drive em, and get a light element with a randomly-changing color. (As a matter of fact, I read about such a project in the latest issue of Make: magazine a few nights ago). I can use the TwinklePIC as a logic-level signal input to a much beefier LED driver, permitting arbitrarily large light output. The design is modular, so I can have two boards driving 16 channels, 3 boards for 24, etc. I have seen set ups where small plastic or glass fibers have been embedded in ceiling plaster, than sanded and exposed, with a remote light source to light them up, By bundling the fibers in random arrangements back to some number of TwinklePIC boards, we could give the B an entire twinkling night sky!

How very typical of me: to think up a dozen potential projects that I'll never have time for just as I reach the finish line for one.

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