Hi If you send light (from a LED to a mirror at a 45 degree angel, you can = "see" the light at "the other 45 degrees" witrh a photodetector. = However, if yu cool the mirror, (with a pelzier element), the humidity = in the air will condensate and blurr the light, which you detect. = Measure the temperature on the mirror surface, and look up in a Molliere = diagram (in you PIC program table...). what rel. humidity corresponds to = that temperature. This should be air pressure (altitude) compensated Piece of cake ! (BUY a sensor for 100 bux, if you really need to measure accurately. I = gathered you would like to do this as a hobby experiment; right ?) Sven in Sweden -----Ursprungligt meddelande----- Fr=E5n: G. Cadman Till: PICLIST@MITVMA.MIT.EDU Datum: den 15 maj 2001 18:43 =C4mne: Humidity Sensors >Anyone had any dealings with humidity sensors and how to make then out >of discrete components? >Thank you for your help in advance. > >Regards > >G > >-- > > >Information in this communication and any attachments are confidential, >and may not be copied or used by anyone other than the addressee, nor >disclosed to any third party without our permission. If you have >received >this communication in error, please notify the sender immediately and >then >destroy any copies of it. There is no intention to create any legally >binding contract or other commitment through the use of this email. > >-- >http://www.piclist.com#nomail Going offline? Don't AutoReply us! >email listserv@mitvma.mit.edu with SET PICList DIGEST in the body > > -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu