On Wed, Apr 28, 2010 at 09:23:47PM -0400, Paul Alfille wrote:
> You inspired me to hook up my moisture meter.
>
> As Mathias points out, the properties offered reflect different
> possible setups for the DS2760.
> Unfortunately, we don't have the definitive formula for offering a
> moisture variable.
>
> The DS2760 has 16 pins and a bunch of measured variables. See
> http://datasheets.maxim-ic.com/en/ds/DS2760.pdf
>
> This includes memory, current, voltage, temperature and a PIO.
>
> In my case a dry sensor at 21.65C measure a current of -0.129375
> The supply voltage is measured at 4.8V
Short version:
Paul, do you think you could talk to Eric on producing a "moisture"
variable that is based on the current value and temperature corrected?
Here is what I found out:
There was something wrong with my hub or connection it seems and now
it's working and I'm getting varying values for current.
However, the current value becomes bigger if the temperature goes up.
In other words, one can't use the "current" value as an accurate
moisture meter because it is not temperature corrected.
I ran a test where I had a fully wet sensor, I took it out of the glass
of water, put it in a warmer place (5C warmer at most) and the current
value went from -1.38687 all the way to -1.45187 just because of the
temperature rise.
Eventually things stabilized and the humidity went down again as the
sensor started drying up further.
Marc
--
"A mouse is a device used to point at the xterm you want to type in" - A.S.R.
Microsoft is to operating systems & security ....
.... what McDonalds is to gourmet cooking
Home page: http://marc.merlins.org/
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