I wrote : > I think inductors/chokes come into it somewhere too. Not as the > primary switch (if I can invent such a term) but to limit current Poorly written. What I meant was that for a full flash the capacitor is allowed to discharge directly into the tube, but a lesser flash may use a choke to either impede current or as component to measure current through and stop the discharge -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist