Hi
I am looking at making a remote soil moisture probe using a pic micro controller. The probes are read by measuring the resistance between two electrodes within the probe. The resistance can vary between approximately 0.5K and 35K. the problem is to prevent the probe from becoming polarized the measurement must be taking using an AC source, around 3Vp-p. Does anyone have any experience in doing something like this? Would I just use a shut resistor, rectify the voltage on each side and read the voltage drop with two A/D channels?