Katinka Mills wrote: > > On Sat, 27 Jul 2002 23:23, Roman wrote: > > > > > One system that works *really* well to drive steppers > > at very high speeds and any beginner can do, is to use > > the common unipolar driver (ie 4 transistors, driven > > in 2-phase on "wave" mode) but supply it from a simple > > constant current source and higher voltage supply. > > > > Hi Roman > > Any chance of a rough schematic for the constant current source, I was > thinking of using a few LM317K,s but this would get a bit expensive (although > nowhere near a PBL / PBM chip set) Hi Kat, no need for more than one LM317 is there? You only need one constant current source and the 4 fets or transistors to switch the coils. The simple one transistor circuit Russell posted is what I use for most simple apps like this. :o) -Roman -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.