Conductance of water versus frequency

In 1973, I designed the house to run on minimum heating in the upper foothills of the (fairly cold) Sierra. 1800 square, with a wood stove as the primary heater on the bottom floor with pretty large fans pushing the hot air down. The stovepipe of the stove runs 22 feet from the stove to the roof jackbox. THere is a "magic heat" (fan) on the stovepipe about three feet above the stove to take the "waste" heat and circulate it around the house. THe remaining 20 feet or so simply radiate as much heat as it can around the house. I've never made a temperature measurement as to how much temperature drop I have between stove and roof jack, but I'm willing to guess that it is significant.

So far this year I've used half a cord and may wind up using another half cord by the end of the winter/spring. Right now on the top floor, I'm at a cozy 70°F, while the downstairs is a couple of degrees cooler.

"rather slow" is not well defined, but if the diode case (surrounded by shrink sleeving) is allowed direct contact with the "water", the response time ought to be measured in single seconds, if not milliseconds.

Jim

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That was our first approach way back. It failed because of slow response time and since the water is not clean all sort of foreign material will attach to that diode and in time fail to respond.

Regards

Klaus

I rather think that the concept is Theta(ja) is a lot higher than Theta(jw) modulate the power and you always can tell if water is present.

But then the circuitry starts to become involved and I'd opt for the de-tuned oscillator thing. Much simpler sensor, just a clean plate.

Well go to a local library and look up the well measured values for conductivity and permittivity for various concentrations of salinity and versus frequency for selected salinities. Then measure permittivity (by its effect on capacitance).

That assumes a nearly perfect sensor. However, after a few years (months in our area) crud starts to build up on it. Out here mostly whitish mineral deposits. I medical speak a water sensor can develop quite an impressive callus. That's when the usual conductivity measurement can fall apart.

I have lived in areas where such build-ups were harder to get off than the clinkers in a pellet stove. Ideally you'd want a system where you don't have to worry about such things for a decade or so.