I am looking for anyone who knows how to create an inexpensive pH meter. It does not need to be hugely accurate. I was thinking like the cheap analog pH meter you can get at a garden center. I believe they are a simple bi-metal sensor that creates a potential voltage as acidity changes. This could be read by an A/D converter and create a simple digital pH meter. But, I have not been able to find any information about what metals to use.
Anyone have an idea? Or a different way to do this?
Thanks in advanced.
-Chris