Hi there Doug

Well this may be a list for electronics, but I did just such
a project last year as part of a project for my BE degree
in electronics. I built a conductivity sensor and did some
interfacing for a pH sensor which is very tricky as the
output impedance is in the giga-ohm range. But if you
would like any further information please do not hesitate
to contact me and I'll do my best to help you.
You may also want to have a look at http://www.autogrow.com
By the way, the conductivity was measured using a 16C84
Regards


Gavin
Auckland, New Zealand

-----Original Message-----
From:   Douglas Gourlay [SMTP:dlg@WORLDCHAT.COM]
Sent:   Monday, July 19, 1999 10:38 AM
To:     PICLIST@MITVMA.MIT.EDU
Subject:        Gardening/Greenhouse automation project

Hello there,

I am just starting to design a simple home greenhouse/hydroponic automated
irrigation system but thought someone on here may already have done this or
knows where to find such a project on the net.  I have little experience
with the electronics but am an avid kit builder and have good mechanical
skills.

In particular, I would like to sense waterlevel, temperature and ideally,
conductivity, and add water, cooling (mist) or heat (electric) and
nutrients based on observed results.

I think that even alerting the need for replenishment of nutrients (ie just
detecting falling conductivity) might be sufficient.

Thanks for any suggestions?

Doug




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