I'm building my own bator, and we were able to get everything today except the fan. we couldn't find one small enough to fit in the cooler. is it totally necessary to have a fan? we are thinking about asking a local computer guy for the large fan from one of his dead computers, but we don't know how to connect it to a power source. the light is at the top of the cooler and obviously the eggs will be at the bottom. any ideas on what to do?