Diana Aragon with her magnetic stirrer.

When IEEE Spectrum and MAKE magazine put out a call for clever do-it-yourself electronics projects, they didn’t expect that one of the 30 contestants would be an 11-year-old girl. Diana Aragon designed and built a magnetic stirrer that impressed the judges so much she received an honorable mention. She did get a little help from her father, IEEE Member Dave Aragon.

Building things is nothing new for the seventh grader from Berkeley, Calif. She’s been taking things apart since she was a youngster. She used a solder gun for the first time at age seven and, with a friend, built a tiny robotic mouse that raced around the floor. When she was nine, she got a Furby (a robotic toy) and disassembled it. Furby parts are still showing up in her projects.

She has been raised in a tech-savvy home. Her father works on wireless networking software at Trapeze Networks in Pleasanton, Calif., and her mother, Cecilia, is a staff scientist at the Lawrence Berkeley National Laboratory.

MOVED BY NECESSITY Diana wasn’t looking for an electronics project when she came up with the idea for the stirrer. Rather, she was immersed in the study of crystals but was getting tired of all the stirring needed to saturate solutions prior to crystal growth. So she asked her parents if they could buy her a device that would stir the solutions. Her father said such tools existed but were too expensive. But, he added, there was a less-expensive option: magnetic stirring bars that could be dropped into a beaker and turned by an external magnet. He suggested that maybe they could buy the stirring bars and build their own device.

The young Aragon didn’t know that commercial magnetic stirrers typically use a magnet turned by a motor. She proposed a stirrer with no moving parts that instead used crossed electromagnets. By turning the current to these magnets on and off and changing its direction, such a device could spin a magnetic stirring bar.

Her father ordered parts to build two boards: a logic generator and a motor driver. He built the logic generator on a Radio Shack breadboard while explaining the process to Diana. Although building the logic generator was straightforward, building the motor driver board was a different story. Dave bought a kit intended to control two DC motors forward and in reverse. It was ideal for the function, but the tiny board was densely packed with parts. Certain that he’d ruin the parts during soldering, he ordered an extra set.

He planned to build the motor driver himself, but Diana begged to do it. “At first I was nervous,” Diana says, “because I hadn’t soldered anything in a long time.”

“She wouldn’t have been nervous if I hadn’t told her that she was going to break it,” her father says.

Although she started out afraid she would “connect things that shouldn’t be connected,” Diana completed the board perfectly. Finally, after winding wire for the electromagnets with her brother during a long car trip, Diana’s project was ready. She and her father connected the boards and clipped the leads to a battery. But the stirring bar didn’t spin. “It just kind of twitched,” Diana says.

There were two problems: a loose control wire was preventing one of the magnets from operating, and a too-short stirring bar wouldn’t stay centered. After fixing both problems, the device worked flawlessly, and Diana began a new set of crystal experiments.

By this time, the Aragons had realized that Diana’s stirrer design, because it lacked moving parts, differed significantly from commercial stirrers. They considered patenting it but discovered that a similar device had been patented in the 1800s as a drink mixer for bartenders. That’s where the do-it-yourself contest came in. The Aragons submitted their project to IEEE Spectrum. While her father is considering encasing the magnetic stirrer in resin to make it waterproof so it can be used in a temperature-controlled bath, Diana has already moved on to a new project. She has built a robot by following instructions on Carnegie Mellon University’s Robotics Institute’s Web site (http://www.terk.ri.cmu.edu/recipes/index.php) and now plans to learn Java to program it.