Dear Steve:
It's 1 Degree centigrade.


yes:-) ,at beginning I was thinking about high sampling rate 50 Hz and using pwm, I was worry about the computational overload and I was looking for ultra simple but effective formulas for PID( thoes that big companies use to control for example an oven), I thought using dError/dOut to modify gain can be very effective and I explained to raghu and mehmet earlier why. but after a while I thought wait a minute do I really need 50 Hz sampling rate ? If I use low power heater the answer is obvious : NO, because a low power heater isn't capable to change temp quickly!

thank you