there is an awesome article out there about the science behind annealing brass. unfortunately i am too new to post the link to the web site here.. so: bisonballistics.com/articles/the-science-of-cartridge-brass-annealing is the url.
many youtube videos out there as well, both diy and buy my machine now. most are good ideas and pretty easy to fabricate. The one I liked best was annealeez.