I made something similar that works on the same principle, from 4" PVCThis is my take on a automatic feeder. The two hold close to 20 pounds of feed and cost about $20. They just shy of six feet tall
The only real problem I have is refilling. I use a standard sized feed scoop, which will spill feed on the ground if I'm not careful. I tried using a funnel, but the spout just backed up with my pelleted feed, so I put up with the aggravation.