To celebrate the five-millionth download of their Android app, the folks at OpenSignal decided to have a cake in the shape of the Android logo. However in the spirit of doing things differently, they also went with an electronic candle solution. The candles are replaced with rows of LEDs controlled by an Arduino, which also has a piezo sensor that can detect vibration (and also strong gusts of breath). Thus the LEDs are turned on, and flicker out when the vibration on the piezo is strong enough, ideal for simulating birthday cake candles - for example:
That's a fun and neat method of replacing candles, however be sure to safely insulate any electronics from parts of cake that will be eaten. For the schematic and more details, check out the OpenSignal website. And for more, we're on twitter and Google+, so follow us for news and product updates as well.
If you're interested in working with piezos for various reasons we have a neat little SOUND: sound and buzzer module:
It can be used as a noise-maker driven by your microcontroller for audible feedback of events, and it can also be used as a knock-detector input to sense events and react to them. Includes a built-in 1M resistor to allow the piezo element to detect shocks. For more information and to order, please visit the product page here.