Field Trips: Atmel Headquarters


Super Awesome Sylvia and I were invited to attend Bring Your Kids to Work Day at Atmel recently. (Atmel, of course, is the company that makes the microcontrollers found inside Arduino products and in many of our own projects and kits.) We were there to help provide tangible, interesting, and playful examples of how Atmel chips can be used. And of course, we weren’t going to miss an opportunity to visit Atmel headquarters!

Photo courtesy of Atmel

The biggest hit with the kids were the Octolively interactive LED modules (sporting the Atmel ATmega164P). When the kids waved their hands over them, the LEDs would light up and ripple. Some of the kids would start out by poking and grabbing at the LEDs until they lit up, but as soon as I told them it would work “even without touching it” their eyes would get big, and they’d wave their hands over the top, enthralled.

Some of the other things we brought were our handheld game, the Meggy Jr RGB (with the ATmega328P); a Bulbdial Clock (Atmega328P again), which points rings of LEDs at different heights down at a central point to create shadow hands of different lengths; our giant Alpha Clock Five (ATMega644A); and the Larson Scanner (ATtiny2313A), which lights up nine red LEDs to make a scanning robot eye.

Photo courtesy of Atmel

Another project that captured the kids’ attention was a Keepon by BeatBots. Other demonstrations included a quadcopter and a hacked hexabot.

Photo courtesy of Atmel

We got to have lunch in the bright sun in the courtyard with Avary Kent, who was demonstrating the PuzzleBox, a brain-controlled helicopter.

Photo courtesy of Atmel

Sylvia got to give the PuzzleBox a try, triggering it to fly as soon as she concentrated hard enough.


After lunch, we got to tour of a couple of labs. This workbench was well stocked with a Metcal soldering iron (our favorite) and lots of tools and supplies.


Apparently the poor Pleo on this bench needed some repair.

Chip testing machine

This machine is for inspecting and testing chips after they have been removed from their housing.

We got to go into the RF anechoic chamber, and watch as our cell phones stopped receiving any signals.

Horsing around

We also had some time to hang out and horse around with friends new and old. Our friend Paul Rako seemed to be having as much fun as the kids.

Photo courtesy of Atmel

Thanks to Paul and Atmel for inviting us to visit!

How Printed Circuit Boards are Designed (1960 Edition)

We found this gem in A Manual of Engineering Drawing for Students and Draftsmen, 9th Ed., by French & Vierck,1960, p. 487.

Printed Circuits allow miniaturization and the elimination of circuit errors—advantages that cannot be obtained by other methods. Once a pattern or suitable design is established, preparation of a black and white drawing can start. Scales for reduction, for example, 4 to 1, 3 to 1, or 2 to 1, are used. To insure sufficient bonding area of the metal laminate during soldering operations, lines should not be less than 1/32 inch in width when reduced. Line separation should never be closer than 1/32 inch on the final circuit. Figure 19.24 illustrates the drawing of printed circuits.

From the Mailbag: On the Digi-Comp II

Peter wrote in about his experience with the Digi-Comp II:

I just wanted you and the entire Evil Mad Scientist team to know that the Digi-Comp II was a big success.  I used it to explain digital computers to a group of second graders and fifth graders. In an age of iPads and smartphones, it’s surprisingly hard to demonstrate the beauty and magic of digital computer.  The Digi-Comp II was perfect, looked great, and worked flawlessly. Thanks!

PCBmodE: Make your PCB a work of art

The folks at BoldPort have created PCBmodE, free open source software for designing printed circuit boards, but with an artistic perspective. Traditional EDA tools are designed from an engineering perspective, whereas PCBmodE treats the PCB as a creative palette. They aim to give you freedom to express your design with all the tools of the medium.

We wanted to create circuit boards that have curvey traces, meandering paths, and multiple soldermask layers, so we developed PCBmodE (say “PCB mode”), an open source Python software that unshackle us from the constraints imposed by traditional PCB design tools. We use the power of Inkscape — the leading open source vector graphics editor — to achieve any shape imaginable. Together with our powerful back-end tools, we can manufacturable beautifully functional boards.

They’ve posted about several of their example boards including pieceof (pictured above), a Raspberry Pi daughterboard called shimmy, and a tribute board dedicated to Bob Pease. This is a really neat approach to building circuit boards, and it looks like it has a lot of potential.

Play with your food: How to Make Sconic Sections

Sconic Sections

The conic sections are the four classic geometric curves that can occur at the intersection between a cone and a plane: the circleellipseparabola, and hyperbola.

The scone is a classic single-serving quick bread that is often served with breakfast or tea.

And, at the intersection of the two, we present something entirely new, delightfully educational, and remarkably tasty: Sconic Sections.

Sconic Sections: Circle Sconic Sections: Ellipse
Sconic Sections: Parabola Sconic Sections: Hyperbola

In what follows, we’ll show you how to bake cone-shaped scones, to slice them into plane geometric curves, and to highlight those curves by selective application of toppings.  We’ll also discuss some of the methods that didn’t work so well, as we refined our methods for making these.

Onwards, towards parabolic preserves and hyperbolic Nutella!

Continue reading Play with your food: How to Make Sconic Sections

Open Discussion: Does Solder Expire?

Solder 4

When we recently wrote about looking at solder paste up close, we happened to mention that it has a shelf life— something that you might expect to be uncontroversial considering that there is an expiration date, printed right there on the jar.

But, our reader Trav commented

Very nice pics. What happens to solder paste when it expires? does it taste funny? Do the balls go flat?

I assume the paste rather gets runny and doesn’t hold the solder in place or it gets thick and won’t spread evenly.

I’ve heard of it expiring, but never knew how. I’ve had a tube of flux for 20 years now. When it gets too thick, I put in a couple drops of alcohol and it seems to work good as new.

We like the “balls go flat” theory!  But seriously, we presume that they wouldn’t label paste with a short shelf life— typically 4-12 months, when kept refrigerated, depending on the type of paste —unless there were a reason (and hopefully, a good reason) to do so.

A blog post on the Indium Corporation web site offers a little insight.  It turns out that the “activator” chemicals within the flux, which serve to clean oxides off of the surfaces that will be soldered, also interact with the microscopic solder balls, gradually scouring off their surface oxides.  When the solder particles are clean enough, they can actually cold-weld together, resulting in increased effective grain size and viscosity.  As Trav notes, adding a little alcohol can reduce the viscosity of flux, but we can see how increased grain size and other factors (such as having used up some of the activators) could affect performance in other ways.

But in any case, it sounds like there are a range of experiences out there, and we would like to open the question for discussion: What has your experience been with out-of-date solder paste? Has it worked just fine? And if not, what was the failure mode?


Solder 2
Separately, what about (flux-cored) solder wire?

Kester has this to say, in their policy about shelf life:

Flux cored solder wire has a limited shelf life determined by the alloy used in the wire. For alloys containing more than 70% lead, the shelf life is two years from date of manufacture. Other alloys have a shelf life of three years from date of manufacture.

So, our spool of lead-free solder pictured above, with date of manufacture 3/16/05 expired five years ago in 2008.  Presumably one reason for a stated expiration date is that the flux becomes less active over time as it interacts with the solder metal.

But in our personal experience, this kind of solder seems to generally work just fine, even many years past its nominal shelf life.

Solder 3

Many others seem to have had a similar experience with solder wire.

When we wrote about assembling a vintage Heathkit, we mentioned that it came with solder.  It actually came with two little packets of solder, specifically 60/40 rosin-core, cheerfully labeled “Made Expressly For Heathkit by Alpha Metals, Inc.”

Seeing as (1) the kit and solder date back nearly 40 years, (2) Alpha Metals also uses the three-year figure for shelf life, and (3) we already had a fresh, open spool of Alpha Metals 60/40 rosin-core solder in the lab, we opted to use the fresh spool and save the vintage solder packets for a rainy day.  Were we wrong to do so?   Certainly, some of our readers thought so:

Solder shelf life? Are you sure about that? Solder paste has a shelf life but I’ve never heard of a shelf life for a real coil of 60/40 rosin core solder. I’ve used some pretty old stuff myself, a quick Google search for solder shelf life found me a discussion where a guy is talking about using solder from the 60s with no problem on the first click!

So what has your experience been? Have you used “old” solder, and if so, how well did it work?

Bay Bridge Progress Photos

The SAS tower comes into focus.
The self anchored suspension span tower comes into focus, after crews dismantled the scaffolding that supported the 525-foot tower.
Courtesy of Caltrans.

Here in the San Francisco Bay area, we’ve been watching the progress of the replacement of the east span of the Bay Bridge, which connects San Francisco to Oakland via Yerba Buena Island.

Inside the East Span’s Splay Saddle
A look inside the East Span’s Splay Saddle, where the main cable wraps around the west end of the bridge.
Courtesy of Caltrans

The California Department of Transportation has been doing an incredible job of sharing the progress with the public since construction began in 2002. The latest set of drool-worthy engineering photos is up on the Bay Bridge Info site, giving a peek deep inside the project.

workers cut into the shear keys at Pier E2 repairing broken rods on the eastern span
Sparks fly as workers cut into the shear keys at Pier E2. Bay Bridge crews have been hard at work repairing broken rods on the eastern span.
Courtesy of Caltrans

The media archive chronicles the project since its start in video and pictures, so you can delve even deeper. You can also follow @BayBridgeInfo on twitter for updates. The new bridge is nearing completion, and is scheduled to open Labor Day weekend this year.

The 2013 Open Hardware Summit: Call for Papers Extended

OHS 2012

Good news if you’re still working on— or haven’t yet started —your proposal for this year’s Open Hardware Summit: The call for papers has been extended, so you’ve got another week to fine tune your talk, poster, or demo proposal.

Submissions are now due by JUNE 28, 2013.

The Open Hardware Summit is the world’s first comprehensive conference on open hardware; a venue to discuss and draw attention to the rapidly growing Open Source Hardware movement.  This year’s summit takes place on September 6 at MIT.


Previously: The 2013 Open Hardware Summit: Call for Papers,
The 2013 Open Hardware Summit: Tickets Now Available

Photo credit: Open Hardware Summit on Flickr.