Arduino online as my solar sufficiency controller
Monday, October 2 2006
It was sunny at times today and I monitored my solar collector at times to see if it was being properly controlled by the new Arduino controller. It started up just fine, and later I brought a laptop down to the basement to fix an obvious bug in the software I'd written. (I would have used USB-Over-Network software to reprogram it from my main computer, but I had to actually be there to reset the processor, something one must do immediately before reprogramming an Arduino board.)
Later as the sun set I watched to see if the sunset part of the algorithm would work. I'd set it so that solar panel heat sufficiency would be determined to no longer be present once the post-heatsink temperature of the system had risent to within ten degrees of the panel temperature. Unfortunately, though, it seemed my temperature calculation algorithm was off by ten degrees for the meat thermometer probe I'd used in the panel, so by the time the Arduino had decided the panel was too cold for useful heat, the sun had nearly set.
Hours later I realized that somehow the circulator pump for the solar loop was still running even though none of the switches that turn that pump on were actually on. It turned out that a pull-up resistor on the line telling the Arduino about the status of the pump was enough of a pull-down resistor to the 30-volt pump activation relay circuitry to keep it from turning off. Eliminating this pull-up resistor was all I had to do; the relay-itself was plenty of pull-up for that line. (I'd only needed that resistor while testing the disconnected Arduino box.)
This evening two couples came over to our house for a breaking of the Yom Kippur fast. Candles were lit and Hebrew prayers were said, though, religiously speaking, I think everyone present was either an atheist or a Buddhist. Gretchen asked me at one point if I was uncomfortable being the only non-Jew present and I said, "It's not like being the only Jew at a neo-Nazi rally."
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