Hey Guys, First off I would like to say that if this thread is in the wrong place, could you please move it to the correct section?


Anyway, I'm a student studying and for a 'quick' project I plan on creating a fridge alarm, and I would like some advice on some certain areas, Anyway, I've outlined my plans below.

I plan on creating a fridge alarm, which will indicate when the door is left open for roughly two minutes and thirty seconds, to do this I plan on using a LDR to detect the light and have two 1uf capacitors and 1M variable resistor to charge, the let off a buzzing sound, Basically, it is the circuit below; (please change the 'xx' to 'tt', as I can't post links yet)

hxxp://i38.photobucket.com/albums/e149/Jack6194/Other/LDRCIR.png

Could you see any problems, or how to get a better time delay?