Jinx clear.net.nz> writes: > I believe it's current control using semis. The same way that extremely > short flashes of a known length are made for high speed photography Current control cannot be used with a plasma arc tube, the rise time is on the order of a few nanoseconds, it is slowed down by wire inductance and capacitor internal impedance alone. However short pulses appear dimmer than they really are. To fire the lamp 20 times per second one needs a trigger circuit without a charge capacitor, i.e. a direct dc/dc converter basically using the normal trigger coil driven by a mosfet. Peter -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist