> Where does the 150 msec come from ? Did I miss something ? That's just how fast I was turning it, to give you some idea of scale The picture is a screenshot of the analyser You'll recall that slow speed was the most troublesome. It seems fine up to 60Hz, which is faster than expected for this application -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist