Thursday, April 7, 2016

To see the King, to sell the cow, to make the potion to lift the curse...

I've had to push the Wraith Stone back a little.

Did a little more reading up. There is a piece of development art that shows, together, "Excalibur" in a form much like it appears in the game, something that is almost certainly an early version of the Galali Key, and a thing that simply has to be the Wraith Stone, although the in-game version is quite different. And there are a lot of interesting fan theories about all these resemblances! (Me, I see a certain Atlantean influence in the Galali Key, and that fits in oh-so-well with some of the revelations in Tomb Raider: Underworld).

Well, I'm not building the in-game version. It is boring and ugly (although the really ugly one I've seen references on turns out to be the one worn by an otherwise excellent Tonner doll of Amanda.)

I've more-or-less decided to sculpt the thing then either mold it, or 3d scan it (using the NextEngine scanner at TechShop), print that, then probably make a mold off the print after cleaning it up. I still have no idea how to control translucency to get the weird look of glowing inclusions within a matrix of darker stone. But all that takes a back seat to the real problem; the electronics layer has simply become too complex.

Found a cute little chip, the WS2803, which can drive 18 channels at 30ma constant-current PWM from a mere two channels of serial input. (There's also the TLC5940, which takes several more pins to control but hits a whopping 120ma per channel). As another option, SeeedStudio now does PCB assembly at a very, very reasonable rate -- making an ATmega (with the speed to software-PWM those 16 GPIO pins) an even more attractive alternative.

Aka, I could do the whole thing in surface mount. But that, plus the need to build in LiPO charge management, means the engineering on this thing might be too big for a single step. Better to work out some of the kinks on the Holocron fork of the DuckLight circuit.

So I'm back to the Holocron.

I'm to the point where I need to stop designing and start bending metal (which I'm told is aerospace jargon, but I'm unable to find a cite). There are all sorts of wonderful creative ways I could realize a Holocron, but I need to put that exploration aside and complete what I have; a perfectly functional way to realize one that takes the form of an inexpensive kit.

My intended price point is under $50 for a full kit, electronics included. Said electronics being an animated lighting effect, internal power with USB re-charge, and a slot for including a user-provided USB thumb drive inside.

I still haven't traced down why my first circuit (otherwise quite functional) would reset the chip when I went for a full zero-to-full on two channels (aka a Police Car flasher lighting animation). The next PCB is mostly to correct that and some other errors I found (such as one of the programming pins being wrong, and some traces run too close to the edge of the board), and to add on a LiPO charge circuit and the connectors to support the USB and LiPo components.

Otherwise, here's the current gordian knot cutting:

Shell design on the "Stolen Holocron" model as much as possible, with only one USB slot instead of that being incorporated into the design. Giving up on ideas like mirrored acrylic sheet or thin metal or some really clever geometry and go back to using the fact that you need to paint the shell as the way that the seams all get hidden.

Diffusor design sticking with pale transparent color and drafting up a abstract geometrical design of vaguely astronomical/clockwork shapes.

Circuitry layer maintained, using a darker transparent color as before, but designed at the full size of a cube side so that the pieces can be layered together and snapped together as a unit, thus placing any glue (and the seams) at the edges where it gets hidden by the shell anyhow. The only cleverness I'll have here is integrating the "spider" so it fits into tabs on these other layers and requires no glue or other support.

And also (after looking at purchasing Illustrator) going to stick with Inkscape, but draft everything on graph paper first to work out the design elements there instead of wrestling with them within Inkscape.

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