Conductivity

Cenlasoft

Hello,
I have been playing around with the applied sensors and doing the conductivity test in one of the experiments. I want to use two small wires inserted into a plant stem and measure conductivity while treating the soil wit salt water. I want to log this data via a serial connection with some software I developed. The question I have is that. what is the best way to measure conductivity? Would a AD chip be best? I want to test this on a BSII and then port to an SX28 project.
Thanks,
Curtis
·

Jim Richey

I would think that the conductivity value you are looking for would be read by the resistance value,in ohms,between the two wires.The resistance,combined with a capacitance,will generate an RC reading easily interpreted by your BS2 into a meaningful figure.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Thanks, Parallax!

Dave Paton

You'll need to use an AC signal to do that, otherwise the plant's PH will eat one of your electrodes. I'd suggest something like a switched capactior core to generate a bipolar squarewave, and then an RMS converter to give you a real voltage. Read it with an 8 bit ADC and it should work nicely. I did something similar waaaay back when to read a chemically based soil moisture sensor from a company whose name I've forgotten. The design of the AC drive was the hardest part...any polarization would kill the cell. In your case, any polarization will eat your electrodes (especially if they're just copper) and contaminate the plant.

My $0.02 as a former precision ag researcher.

-dave

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
This is not a sig. This is a duck. Quack.