Is your idee something like this?

http://www.hydro-gardens.com/newitems.htm#GROW-MACS

Leo
-----Oorspronkelijk bericht-----
Van: Gavin Jackson <vulcan@IHUG.CO.NZ>
Aan: PICLIST@MITVMA.MIT.EDU <PICLIST@MITVMA.MIT.EDU>
Datum: zaterdag 14 februari 1998 0:25
Onderwerp: Conductivity measurement


>Hi there
>
>I have a supervised project that involves
>converting a conventional greenhouse
>into one for hydroponics. I have to
>automate the entire thing and will
>be using a 16C74 for the job.
>
>Being hydroponics, I have to monitor
>the solution for pH and conductivity.
>I have been looking around for
>any info on measuring these two
>variables, but I have not found much.
>
>I was wondering if there is anyone that
>has ever had any experience with measuring
>either of these two. The conductivity
>is measured using two probes in the solution.
>An AC signal is passed between the two
>to prevent any build-up on one of the electrodes.
>I presume the volt drop is then measured to
>determine the conductivity which is measured
>in micro-Siemens/cm.
>
>pH is usually measured with a glass probe, but
>I'm not sure what to expect at the other end of
>the probe, as I have not come across any data
>sheets on them.
>
>Any help would be most appreciated.
>
>Gavin
>--------------------------
>vulcan@ihug.co.nz
>--------------------------
>
>