Fda
Latest Gadget Freak… Fridage alarm! Schematics included –

A fridge that’s alert for midnight snacks…When you’ve popped in your fridge alarm, getting peckish in the middle of the night and forgetting to close the door – along with escalating electricity bills – will be a thing of the past. Italian inventor Flavio Dellepiane has designed a 3V battery-powered fridge alarm that beeps if you leave the door open for more than 20 seconds. When the fridge lamp illuminates, the alarm’s photo resistor lowers its resistance, the IC starts counting down and after a preset delay the piezoelectric buzzer beeps for 20 seconds.

Fridge alarm – Link.