>FWIW - a raindrop has a terminal velocity of a few tens of >kilometres per second So I should abandon my opto attempt and try a microwave radar gun= instead perhaps :) ? colin -- cdb, bodgy1@optusnet.com.au on 05/11/2002 -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.