Subject: From: Date:

Light and Pool water sensors Frank Herron Charlotte NC Sun, 19 Jul 98 10:38:26 EDT

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For a Light Sensor you can buy an X10 Sundowner.  It looks like a mini console
and has a photocell built in.  Transmits an X10 command.  To not use an Analog
input you could built your own using a photocell and a pot to adjust.  You
need some hysterious, and a time delay, so a momentary cloud won't make your
system think it is night.  I built one with 741 opamp and relay.  Also could
use a 339 comparitor.
For pool temp I constructed an LM34 sensor inside a piece of plastic tube
about four inches long.  Sealed it up with Aquarium Sealant.  Drilled small
hole in   top of filter housing and sensor assembly is immerssed in filter
water.  The    sensor must be immersed.  This is second summer, doing good.
This feeds an     Analog board.  (Alpha Card)

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