The Secret Knock Gumball Machine is a project I built from the plans and instructions from Steve Hoefer’s article in Make magazine (volume 25).  Gumballs are dispensed only to those who use the secret knock on the front of the machine.  The machines uses an Arduino as the controller and a piezo sensor to detect the knock.  The machine can also learn new knocks with a single button press.  I used Oak plywoood for my [...]

I was intrigued by Mikal’s article on his Reverse Geocache Puzzle Box from Make issue 25.  This is a box which will open only in a very specific place (as determined by its internal GPS system).  The LCD display shows how far the place the box will open is from the current location.  You can find Mikal’s story about his puzzle box in the article and on the web.  In Mikal’s example, there was one [...]

The Tweet-a-Watt was one of the first projects I built from an article in Make magazine. I’ve since built many more.  It also introduced me to Limor Fried and her company Adafruit.  It turns out I already had the very Kill-a-Watt unit in use which was to be modified for the project.  So mostly I needed the XBees and some other parts.  The full Adafruit tutorial is here. The XBee was a tight fit in [...]