Making an LED you blow out like a candle, without any additional sensors
by Cory Doctorow from on (#3X87H)
https://www.youtube.com/watch?v=TD6A_tvbKT0
LEDs are diodes (that's what the D stands for) and diodes are sensitive to voltage drops: when you blow on an LED, you make it ever so slightly cooler, and that causes an infinitesimal, but detectable voltage drop. (more")