LED Gumball Machine
Do you need an LED? The answer is always yes. But what if you need one right now? Build yourself an LED gumball machine and never run out again!
This machine was created for the BTU Lab at CU Boulder because students constantly needed LEDs but filling parts bins always seemed to fall to the tragedy of the commons. We’d put 1,000 LEDs into the bin and they’d be gone in less than 2 weeks.
With the LED Gumball dispenser the LEDs last for more than a semester. It’s amazing how much a 15 second pause will cause people to think twice.
Pulse Width Modulation
Hobby Servo Tutorial
And if you really want to get geeky, have a look at this posting on state machines. State machines are a good way to change between the states 'wait for user to press button' to 'ignore buttons and don't dispense right now'.