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From: "Bram van de Kerkhof"
References: <3D905023.firstname.lastname@example.org> <email@example.com>
Subject: Re: ph meter using PIC??
Date: Wed, 25 Sep 2002 14:05:59 +0200
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Organization: Oce Technologies B.V.
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This story is verry nice but i don't think you can build it yourself.
I'm also looking for a PH measurement circuit and found this:
you will have to know german for the text but the circuits and pictures
for it self.
"Tauno Voipio" wrote in
> "andy" wrote in message
> > tom wrote in message
> > > I wonder if there is a good infrared spectrometer way to do
> > > this pH measurement? I was looking into that about 15 years ago
> > > and never found the perfect spectral wavelength for it. The idea
> > > here is that the aquarium liquid is sampled for its absorbtion
> > > in a narrow band of the infrared. This band would be at a
> > > wavelength of absorbtion of some indicator compound that is added
> > > to the water in a known concentration. The abosorbtion of the
> > > indicator compound would change, dependant on the pH. The
> > > absorbtion would indicate the pH. This would allow a flow-through
> > > pH meter that didn't use the old method of a semipermiable
> > > barrier.
> > >
> > > I saw some flow-through spectrometers being sold several years
> > > ago. They didn't mention the ability to do pH, they were
> > > mostly for juding organic matter content of the water.
> > >
> > I was working on a flow through system years ago that was designed to
> > measure organic matter in water. I beleive the same company was
> > concurrently developing a similar method of measuring PH. Don't know
> > if they succeeded. I honestly thought they were on to a winner but
> > they don't seem to sell either system as yet. Maybe they are still
> > working on it..
> For a different approach to pH measurement, see:
> Tauno Voipio
> tauno voipio @ iki fi
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