Sunday, January 11, 2009


I recently found myself killing time in NYC, which means a visit to the good folks over at Adafruit Industries. Cue dramatic voice over, "This time, it's not social." Limor had wrapped up the prototype for her Vacuum Florescent Display (VFD) clock, but was still in need of an enclosure. I was in need of something to do. Thus - over the weekend - I had a Makeation.

It began, as all things must, with an engineers' pad, some graphite, an eraser and some high-precision calipers.

After I was thoroughly sure of the dimensions (on paper), I started sketching up the pieces to cut on the laser cutter in Illustrator. No, it's not the right tool for CAD, but you can monkey around and get center-to-center drills if you sufficiently abuse some of the alignment and grouping features. And it worked well enough to yield a first-time-right design (although one that required exactly 0.125" acrylic).

Here's the front:

The back:

And the bottom:

The final kit won't be called 'iceb0x,' but I couldn't resist. It's only a prototype run so far, but the layout of Limor's board is clean and very compact. The VFD itself is also nice. You can see from the photos that the color is a cool aqua, that's a nice contrast to the warmer tones of the highly-fetishized Nixie tubes. The other upside(s) to using a VFD over a Nixie is that it's multi-digit, not nearly so rare, and it runs at a significantly lower voltage. A VFD takes less than 40V as compared to Nixie tubes, which need 80V to 100V. I know that voltage is cool (it's current that kills) but why use a BEEFY transformer when a cute SMT core will do?

Another nice detail of the clock is that Limor has the VFD mounted on a daughter board via a right-angle header so that the tube "floats" above the PCB. That made for the trickiest part of the enclosure design -- placing the "nipple" drill in the North face that keeps the tube in place. It worked on the first pass, but I admit to tweaking it so that the tube was perfectly parallel to the PCB. There's less than 1/16" of wiggle room in the long dimension in this version of the case. I'm especially proud of the fact that it's fully-interlocking on 5 of 6 faces (the top being held on by compression from two nuts) and assembled using 6 x 4-40 screws.

If you're psyched about the VFD clock design, and can't wait for the Adafruit Industries kit to come out - it's the sort of project that's been multi-sourced by
rsw and Make Blog, among others.

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