Irving,

"presumably you'd be rotating the suction head which would have a vacuum tube attached"

Correct. And you are also correct that I am thinking in terms of designing my own driver board - mostly from sheer habit, but also because that way I end up with exactly what I want (or alternatively, have only myself to blame if I don't). I'm planning to spend time thinking through this project over Christmas (although I have the wife in bed with 'flu at the moment, and I'm therefore having to do all the running around town that she normally does) and because of family commitments little will actually happen in terms of either hardware or software until Q2 of 2010; but by then I expect to have thought through all the details and be ready to move quickly once I start in the Spring. I'm looking forward to it greatly now, because almost everything I do has a processor and a PCB in it somewhere, and to be able to knock those out quickly and easily will be really useful. I'll post pictures and circuits when I get there.

Ian