texas instruments makes a chip for this, it's an 8 pin device. i know that
it is being used in dishwaters to sense how dirty the water is. check out
their site.

michael


-----Original Message-----
From: PHXSYS <PHXSYS@AOL.COM>
To: PICLIST@MITVMA.MIT.EDU <PICLIST@MITVMA.MIT.EDU>
Date: Saturday, April 11, 1998 8:44 PM
Subject: opacity meter


>Hello everyone!
>
>I want to build an opacity meter to check discoloration in a liquid
solution.
>New fluid is relatively clear, but as it degrades over time it turns darker
in
>varying stages. I thought of using an infrared sender and receiver, but
I've
>never used one and need some help getting started. Any help ideas, sample
code
>or a "point in the right direction" would be greately appreciated..
>
>Thanks in advance
>
>Jon
>