Temperature Control
- To: pumpkins
- Subject: Temperature Control
- From: G* S*
- Date: Fri, 16 Apr 1999 22:01:12 -0500
Rick and Others,
For what it is worth, here is the run down on my scheme for tempering
the hot summer sun. Please understand that I have a very small area to
work with and I am not sure this method will scale to larger growing
areas (actually I'm not sure it will work at all). I have taken an
ADR2010 analog/digital interface and connected it to my PC. I've built 3
temperature sensors using National Semiconductor LM335az sensors, and
connected them to three of the eight analog inputs. One sensor is to
monitor soil temperature, one for plant canopy temperatures and one
ambient air. Two photo voltaic cells mounted back to back (one facing
north, one south) is used to track sun light conditions and cloudiness.
I've written some code (using visual basic) to poll the sensors once per
second and then act on the info using a rules based system. The ADR2010
has eight digital I/O lines that easily drive solid state relays I will
use to power the on/off valve(s) on my sprinkler system. The idea being
that when high temperatures are present the computer will start the
sprinkler for one minute and if the plant canopy temp falls to
acceptable levels fine, otherwise repeat. The computer will keep track
of normal watering schedules and alter some based on the amount of
additional water used for cooling.
This will be the first year for this, so I am open to all comments,
criticism, questions.
Greg
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