I no longer use light bulbs as a heat source. Lost several good hatching eggs in my homemade incubater when the light bulb burned out, switched to using 2 bulbs, but now opt for ceramic heat "bulbs" like they use for reptiles, they don't tend to burn out and they emit no light, and they fit into a regular light socket. I have a digital controller I bought off ebay that allows me to switch from cooling to heating mode by changing settings and it was only about 13 bux shipped, from china of course
John.