SparkFun Forums

[normanmedi]

Hello everyone,
I have a problem with remote temperature sensing using PT100 and pic16F877A and I hope that someone can help me. The problem is that in my design, PT100 is supposed to be at a distance of over 100m from the main pic board. The board is a standard temperature meter using pic16F877A with 2*16 LCD. I have made a lot of research as to how the noise in the sensor's wires can be suppressed. In some designs, a capacitor has been installed at the input of the pic, in some designs, this has been rejected since the capacitor prevents any slight change of the voltage to be sensed at the input of the pic. Some designs have made use of and Opamp circuit to amplify the PT100s voltage but it is not clear whether the Opamp circuit is to be installed close to the PT100 or close to the PIC board. Can anyone help me on this? I want to use 3-wire PT100, and I appreciate if you can comment on that. I am not stuck to 3 wire sensor and I may change it if there is no other option. I have currently 3wire and it would be better for me if I can use it.
Regards
Norman

[skimask]

Use another '877A, do the math/conversion/etc at the sensor and send the data over a serial connection to the other '877A.