looked on net everywere to find out if anyone built this. i seem to be the only one crazy enough to do this. i will try to explain how i did it. i first found an old antenna stand, mounted it to my roof ,put a bearing on top then ran a 1" shaft through the roof were i installed another bearing . i then mounted a cieling fan(54") on the shaft. on the top of the shaft i mounted a squirrel cage fan . the fan went really fast but spun out of control, and had no power. i then mounted an old sprocket on the shaft. the sprocket is heavy(about 10lbs), the effect was it slowed the fan down and it was much more consistent . if you have wind this works unbelievably well. this fan has been in service for 2 yrs. and has had no issues. the fan starts up at 3 mph and works well at 7 mph . i built this out of throw away parts. i believe a roof turbine will do the same thing as long as you have some type of flywheel on it. i should put some type of speed control on it because sometimes it is just to much. it blows things off my counter at high wind speeds. to keep noise and vibration to a minimum make sure shaft is true,but even if its not it will just be a little loud. because i had all of the parts this only took a little over an hour to build. everyone who sees this work is thourghaly amazed. some actualy step back because they are afraid it will come apart, but it never does.