Solenoid engines are nothing new, though they still seem to be a fairly common project among the curious. Using a hard drive makes such a project much more simple and straight forward, that is if you want to keep it that way.
This solenoid engine uses a software control loop (code below) running on a 16MHz Adafruit Trinket to adjust its speed. The program specifically alternates between a modest 180RPM to a smashing 3000RPM every five or ten seconds! Watch the video below!
After winning the Adafruit/Hack a Day Trinket contest I had to decide what to do with my new Trinket microcontroller. A few weeks went by before I came across this universal foot switch. With plenty of space inside it was just begging to be part of a new Trinket project. One thing led to another and then I realized that I am terrible when it comes to over-thinking the headings and greetings to my emails and other messages .
Thus came the Trinket Auto Greeter, or TAG for short; it types out a random greeting from a list at the push of a button. The code has been made available on the project page for anyone to use or edit.