On Topic: power control

On Tue, Jun 26, 2001 at 06:25:23PM -0400, Vance Dereksen wrote: I'm building an automatic door too. It would be easier to use a screw drive but I thought the "whoosh" would be completely natural if it were driven by an air cylinder instead. The main problem is I need to find electric air valves to control which end of the cylinder gets the air. Any ideas where to look? I plan to use a barn door slide that I had extra to hang the door (rectangular track about 2 x 3 inches cross-section, with wheeled "trucks" that ride in the track from which you hang the door), but it will make some noise too. With a motor screw drive, it might end up sounding more like the "cargo bay" doors. That might be OK, and the air cylinder thing is kindof complicated anyway. I'm not sure how to build one so that you hear only the "whoosh" and no other sliding/rolling noises. Maybe if the door was light enough, it could use an air suspension (blow air through holes in the bottom and sides of the door, against tracks, thus no wheels needed); but mine is heavy steel, well over 100 pounds I think. There's a picture here http://ecloud.org/~ecloud/journal/photos/door.jpg but I've done a bit more cleanup since then. I also want to run a laser beam along the edge of the door and stop it if the beam is broken. (This is also easier to do with a screw drive.) -- _______ Shawn T. Rutledge / KB7PWD ecloud(a)bigfoot.com (_ | |_) http://www.bigfoot.com/~ecloud kb7pwd(a)kb7pwd.ampr.org __) | | \________________________________________________________________