On Fri, May 27, 2011 at 11:55 AM, Pedro Côrte-Real <[email protected]> wrote: > The way the system works is it reads temperatures in the panel > (outside) and on the top and bottom of the water tank. So for those I > would need to use the built in sensors as it would be hard to access > the spots to install new sensors. I could however use what you suggest > to measure the temperatures of the tubes bringing water to and from > the panel.
I've done some more experimentation and this seems to actually be pretty easy. The control board has all three sensors continuously connected to the same GND and V+. Reading the tension between those points with a multimeter gives me a very nicely linear relation between the tension I measure and the temperature the control board itself shows. All I need now is a 1wire voltage meter. The only snag is that within the useful range (I've measured 25ºC ~ 68ªC) the voltage only moves from 1.052V to 1.176V. Does any of the onewire sensors have +-0.001V actual precision and not just output? If not I'll have to design a PCB with some op amps to expand the range for better measurement. Pedro ------------------------------------------------------------------------------ AppSumo Presents a FREE Video for the SourceForge Community by Eric Ries, the creator of the Lean Startup Methodology on "Lean Startup Secrets Revealed." This video shows you how to validate your ideas, optimize your ideas and identify your business strategy. http://p.sf.net/sfu/appsumosfdev2dev _______________________________________________ Owfs-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/owfs-developers
