If you wish to measure the AMOUNT of rain, they normally capture it in a
decanter which you can then read optically or capacitively.

If you simply wish to detect ANY rain, an optical transmitter / receiver
spaced 3' apart would be blocked once rain actually started.

Interesting application.

--Bob Axtell
EDTec LLC
1-888-801-1416

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads