At the elementary school my children attend, students exchange Valentine's Day cards with one another, and they compete to decorate or build the most interesting mailboxes. My 11-year-old daughter came home one afternoon with an idea for her mailbox. She asked me to help her design one so that a sensor would open the box automatically when someone walked by.

I started with a servo motor (and some mechanical linkages) taken from a broken remote controlled car, connected it to an Arduino UNO microcontroller development board, and connected a light sensor to one of the microcontroller's analog inputs. We wrote the code to monitor the sensor and track the average light level. The box would open only when the light level changed suddenly. Then the box would close slowly over a period of time.

We actually built two mailboxes, so my 8-year-old daughter could have one, too. My wife helped the girls decorate the boxes to look like their favorite animals. I used the Arduino software tools to create the firmware, and the Arduino board served as my MCU chip programmer. But I assembled the components, including the MCU chip, on a piece of perforated breadboard material, rather than using the Arduino UNO development board in the final project.

Jeremy Willden created small mailboxes for his daughters' Valentine's Day cards. The boxes use a sensor to open automatically when someone walks by.

Willden started with a servo motor and some mechanical linkages, which he connected to an Arduino UNO microcontroller development board. He then connected a light sensor to one of the microcontroller's analog inputs.

Do you have a Gadget Freak project you would like the world to see? Send a brief description of your gadget and a photo to Senior Editor Rob Spiegel.

{table 1}{table 2}{videoembed|260140}

The editors of Design News have handpicked your favorite Gadget Freak cases from over the years, bringing them together in a dynamic digital edition, complete with videos, which you can view here.