Hello Peter, I don't think this kind of meter will work in this application. Just the temperature changes from night to day will change conductivity of your water as it comes into your house. Two technologies come to mind for water protection, heat and carbon filtration. If you already have a filtration system, a carbon cannister would take care of most organic molecules. But you have to change it regularly, and you will have to have a way to determine when it is used up. And smelling funky is not a scientific way to do this. Those of us in the big leagues send samples to a lab for analysis at $150 or more a pop to test our carbon. THis is not practical for homes. Boiling water before drinking, and making it into tea, is a simple means of removing many pathogens and volatile substances, plus you get tea. Probably the easiest and most sensible approach. alice sorry it doesnt have a pic in it. > Hello Alice, > > Thanks for replying. This is a home project to monitor the quality of my > house drinking water. I am a little bit worrying about terrorists, who can > inject some toxic materials into the water line. Although the city is > monitoring it 24/7, but I want to monitor it myseft also. > > I currently use a reverse osmosis system in my house to produce the drinking > water from the tap water. I plan to monitor the input and output water from > this system continously using two conductivity sensors and a PIC-based > microcontroller, which can alert me if the water quality is changed. In the > market, it is caled TDS meter, which is availale from $100 to several > thousand dollars. It's so expensive so I plan to build it myself. I think it > quite simple because the output of the conductivity sensor is usually > resistivity based, that I can use IC555 to generate and count the frequency. > So the only thing I need now is some good-quality-but-inexpensive > conductivity sensors. Please let me know if you know where I can buy them. > Thanks for your help. > > Peter > > ----- Original Message ----- > From: "alice campbell" > To: > Sent: Tuesday, October 16, 2001 12:40 PM > Subject: Re: [PIC]: TDS or conductivity sensor > > > > Hello Peter, > > > > Before we can help you, we need a little more information. Is this for a > commercial product, a science project, or a hobbyst project? Is it > lab-grade or field-grade? What exactly are you trying to monitor in > groundwater? Are you trying to detect a change in quality, or trying to > precisely determine the conductivity of water? Is it surface or ground > water? Is it in-place, or from stored samples? > > > > Natural water generally contains about 12-50 separate dissolved > constituents, all of which contribute something to the conductivity of > water. Some of these substances, like carbonation, can fizz in and fizz out, > while others are pretty inert. Exposure of groundwater to air can change > the conductivity of the water without really affecting the concentrations of > other dissolved salts. > > > > So you see, we need to have some idea what you are trying to do, and how > you are going about it, before we can suggest conductivity probes > > > > Alice > > > > > > > > > > > Repost, please response if you know where I can buy some inexpensive > > > conductivity sensors used to monitor the quality of drinking water. > Thanks. > > > > > > Peter > > > > > > ----- Original Message ----- > > > From: "Peter Tran" > > > To: > > > Sent: Monday, October 15, 2001 10:40 AM > > > Subject: [PIC]: TDS or conductivity sensor > > > > > > > > > > I'd like to build a TDS meter using a PIC. Could someone please tell > me > > > > where I can find out some inexpensive conductivity sensors for this > > > project? > > > > Thanks for your help. > > > > > > > > Peter > > > > > > > > -- > > > > http://www.piclist.com hint: The list server can filter out subtopics > > > > (like ads or off topics) for you. See http://www.piclist.com/#topics > > > > > > > > > > > > > > > > > > -- > > > http://www.piclist.com hint: The PICList is archived three different > > > ways. See http://www.piclist.com/#archives for details. > > > > > > > > > > > > > -- > > > > _______________________________________________ > > Sign-up for your own FREE Personalized E-mail at Mail.com > > http://www.mail.com/?sr=signup > > > > > > Have you downloaded the latest calling software from Net2Phone? Click here > to get it now! > > > > http://www.net2phone.com/cgi-bin/link.cgi?157 > > > > > > > > -- > > http://www.piclist.com hint: The PICList is archived three different > > ways. See http://www.piclist.com/#archives for details. > > > > > > > > -- > http://www.piclist.com hint: The PICList is archived three different > ways. See http://www.piclist.com/#archives for details. > > > -- _______________________________________________ Sign-up for your own FREE Personalized E-mail at Mail.com http://www.mail.com/?sr=signup Have you downloaded the latest calling software from Net2Phone? Click here to get it now! http://www.net2phone.com/cgi-bin/link.cgi?157 -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.