The Larson Scanner Kit

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Today we’re releasing a new open-source project and kit, which is an updated approach to the “Larson Scanner.” The Larson scanner is named in honor of Glen A. Larson, the man responsible for producing both the original Battlestar Galactica and Knight Rider television shows, and consists of a set of red LEDs that scan back and forth.

Three years ago, we showed how to make a Cylon Jack-O-Lantern, in what has become one of our all-time most popular tutorials. The circuit for that project was based on a 555 timer, driving a 4017 decade counter, and has 6 pixels of resolution. To create the incandescent fading effect, we added low-pass transistor drivers. We also wrote up a version of that article for the 2007 Make Magazine Halloween special, which included a slightly nicer version of that same circuit.

And while it’s been popular, we’ve always had some nagging reservations about it, and in particular its battery life. This year, we decided to do something about it and made a much betterversion of the Larson Scanner, and so here it is:

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Bookends for physics geeks

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Books falling over? Here’s a simple bookend project. Total cost under a buck, and you can make them in just a few minutes.

The symbols on these particular bookends are in bra-ket notation, which is very common in many fields of physics related to quantum mechanics. Obviously, you can use other symbols as well– we put /* and */ around our programming books.

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linkdump: September 2009

Some thoughts on throwies

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We’re big fans of LED throwies and derivative projects where you light an LED simply by connecting it across the terminal of a small lithium coin cell.

You’ll find this trick used in a lot of our projects that call for simply lighting up an LED in a tiny space, like the temporary LED lanterns, LED Ghosties, Robogames awards,
LED origami circuitry, light-up Lego minifigures, and edge-lit holiday cards. You’ll also find them in those little keychain flashlights– open one up and there’s just a battery and an LED.

So the throwie (and I use the term loosely, referring to devices with or without magnets) is a darned useful thing. But the first time that I was introduced to the concept, I asked what a lot of other electronics-oriented people do: “where’s the resistor?”

Turns out that it’s a fair question. LEDs aren’t normally driven directly from a battery. And yet (1) people were making throwies with every imaginable color of LED and (2) they apparently weren’t exploding. So what’s the deal?

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Malleability versus Ductility

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From the Cartoon Laws of Physics comes the following wisdom:


Cartoon Law VIII: Any violent rearrangement of feline matter is impermanent.


Cartoon cats possess even more deaths than the traditional nine lives might
comfortably afford. They can be decimated, spliced, splayed,
accordion-pleated, spindled, or disassembled, but they cannot be destroyed.
After a few moments of blinking self pity, they reinflate, elongate, snap
back, or solidify.


Corollary: A cat will assume the shape of its container.

Digi-Key sends cat toys

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The other day I got a box of swag from Digi-Key.

Each week, @digikey holds “Twrivia Thursdays” on Twitter, and a few weeks back they asked “What is the name of the recycled product we use for packaging?” I didn’t realize this was a contest, but I had to answer immediately, because we know it as one of the best cat toys ever!

Anyway, I’m thrilled to have gotten my box of misc (and it says “misc” on the invoice) because it came packed with– surprise– that same packing material, Geämi, which the cats are playing with even as I type.

We posted the picture below, of JellyBean tangled in the stuff, a couple of years ago. But it deserves another viewing:


JellyBean versus the Digi-Key packaging materials

Peggy goes wild

The Peggy 2 board is not small by PCB standards, but it was just not big enough for a couple of folks.

MonsieurBon built a Giant LED Board based on the Peggy 2 circuit with a 30 x 30 display area. Here’s his photoset and video on YouTube.


Dave took his Peggy 2 and mounted his LEDs off board for his u:moon project. Here’s the project page and video and photos.


You can read about more Peggy 2 projects in our earlier story, The Peggy Strikes Back.