battery box supplying 4 different voltages?

Joe Strout · 2007-04-20T21:47:46+00:00

I'd like to make one battery box for the bot I'm working on, that will simultaneously supply 3V, 6V, 9V, and 12V. The first version of this box will get its juice from eight D cells.What I don't understand is: how can I wire this up so that it has terminals at those four different voltages, but no matter how loads are applied to them in any combination, the eight batteries drain evenly? (I want to avoid the situation where I need to change different batteries at different times, just because that would be a nuisance.)My guess is that to do this, I need to wire all eight D-cells in series, and then from this 12V supply, hang three DC-DC voltage converters in parallel for the 3V, 6V, and 9V outputs. (And the 12V output goes directly out.) Does this make you experienced roboticists recoil in horror for some reason? Is there a more elegant solution?Thanks,- Joe