On Sat, Jul 24, 2010 at 5:14 AM, V G wrote: > Hi all, > > As I have mentioned previously, I am designing a temperature and > humidity control system for my university lab that I am working in. > Several dsPIC controlled remote terminal units (RTUs) will be placed > in self contained chambers. These RTUs will provide a means to log and > control temperature and humidity. Within the chambers are special > fungi that require a high relative humidity (RH) level to grow > effectively - sometimes even close to 100% RH. Hi VG, one question please: how do you will control accurately both temperature and humidity in the same time? There is an interdependence between temperature and humidity in a closed chamber, two sensors that are kept at different temperatures will show different RH values, but the same dew point can be calculated.Before taking a measurement, you always need to wait long enough for the conditions to stabilize. Not only RH levels need to stabilize but also temperature. That's clear, why it is not possible to make extremely accurate relative humidity measurements. I've did some experiments quite long time: http://adsabs.harvard.edu/abs/2009JPhCS.182a2018S but my goal was to keep the same in two different chambers. Vasile --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .