Hi All

I am thinking of getting involved in a local drive to
conserve some of our indigenous fish. A big problem
with our river systems is that is is controlled without
much thought on the biological implications. For
instance dumping a huge amount of water into a river
during the breeding season is bad for the procreation.
(Think how *you* would feel if someone emptied
a bucket of cold water on you and your partner!)

To get to the point, we need some way of collecting
data of the water conditions. These would include
water level, temperature, visibility, air temperature,
ambient light and barometric pressure.

Temperature and visibility and ambient light would
be easy to measure. How does one measure a river's
water level (2.5m change) without little contacts that
will corrode?

My idea is to put a vertical pipe with a hole in the
bottom into the water. A speaker (with a plastic
cone) is placed at the top of the pipe and the
frequency sweeped from the low resonant frequency
to the high resonant frequency. I could detect the
peak amplitude with an electret microphone.
What do you think?

BTW what sort of a sensor would be able to measure
barometric pressure? I am going to pay for this, so it
had better be cheap!

--
Friendly Regards

Tjaart van der Walt
mailto:tjaart@wasp.co.za

Add your voice !!
Vote at the Great G Com Public Vote. Go to :
http://www.wasp.co.za/~tjaart/gcomvote.html

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