An off the wall idea - if you have one of them there old fangled bike dynamos, use the varying voltage output to judge speed. Might not be all that accurate though due to lack of voltage range. Colin -- cdb, colin@btech-online.co.uk on 17/08/2009 Web presence: www.btech-online.co.uk Hosted by: www.1and1.co.uk/?k_id=7988359 -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist