temperature sensor distance LM34 vs 10k

temp F LM34 69.82 thermistor = 70.33 temp F LM34 68.36 thermistor = 70.49 temp F LM34 68.85 thermistor = 70.33 temp F LM34 69.34 thermistor = 70.33 temp F LM34 68.85 thermistor = 70.33 temp F LM34 69.34 thermistor = 70.33 temp F LM34 68.85 thermistor = 70.33 temp F LM34 69.82 thermistor = 70.33 temp F LM34 68.36 thermistor = 70.49 temp F LM34 68.36 thermistor = 70.49 temp F LM34 70.31 thermistor = 70.33 temp F LM34 68.85 thermistor = 70.33

A man with one watch knows what time it is. a man with two is never sure.

this is all raw. simple analog in. have not incorporated the Aref as yet.

Something ain't right. When the LM34 goes down in temp, the thermistor goes up?

And despite the various ranges, accuracy still suffers at 5F and less or 3F with no load. That's both the "A" and "CA" Probably not important, though, at temperatures that low, as I mentioned earlier.

since I am just staring all this, the thought goes to successive Analog reads
typically you read once, toss the results, then read a second time and keep those.

float lm34 = (5.0 * analogRead(2) * 100.0) / 1024;

that worked.

I dipped the 10k into ice water and the LM34 readings changed.

cup of hot tap water and cup of ice water

using only the 10k readings at 5 seconds.

temp F LM34 69.82 - 142 thermistor = 74.45 - 496 temp F LM34 69.34 - 142 thermistor = 90.38 - 593 temp F LM34 69.34 - 142 thermistor = 94.92 - 619 temp F LM34 69.34 - 142 thermistor = 97.07 - 631 temp F LM34 69.34 - 142 thermistor = 97.98 - 636 temp F LM34 69.82 - 143 thermistor = 98.34 - 638 temp F LM34 69.82 - 142 thermistor = 98.70 - 640 temp F LM34 69.34 - 142 thermistor = 98.89 - 641 temp F LM34 69.82 - 143 thermistor = 98.89 - 641 // repeat value, switched to cold temp F LM34 69.82 - 143 thermistor = 81.53 - 540 temp F LM34 69.34 - 143 thermistor = 56.41 - 382 temp F LM34 69.82 - 142 thermistor = 49.60 - 340 temp F LM34 69.82 - 143 thermistor = 47.27 - 326 temp F LM34 69.82 - 143 thermistor = 46.27 - 320 temp F LM34 69.82 - 143 thermistor = 46.10 - 319 temp F LM34 69.34 - 142 thermistor = 45.76 - 317 temp F LM34 69.82 - 142 thermistor = 45.59 - 316 temp F LM34 69.82 - 143 thermistor = 45.42 - 315 temp F LM34 69.34 - 142 thermistor = 45.76 - 317 // did not drip, ended test

repeated with the LM34 in the dunk tanks

temp F LM34 83.50 - 171 thermistor = 68.59 - 459 temp F LM34 90.33 - 186 thermistor = 68.43 - 458 temp F LM34 93.75 - 192 thermistor = 68.28 - 457 temp F LM34 94.73 - 194 thermistor = 68.12 - 456 temp F LM34 96.19 - 197 thermistor = 68.28 - 457 temp F LM34 97.17 - 198 thermistor = 68.12 - 456 temp F LM34 97.17 - 199 thermistor = 67.96 - 455 temp F LM34 97.66 - 200 thermistor = 67.80 - 454 temp F LM34 97.66 - 200 thermistor = 67.80 - 454

temp F LM34 97.66 - 199 thermistor = 67.65 - 453 temp F LM34 94.73 - 194 thermistor = 67.65 - 453 temp F LM34 72.75 - 149 thermistor = 67.80 - 454 temp F LM34 57.13 - 117 thermistor = 67.80 - 454 temp F LM34 52.25 - 107 thermistor = 67.80 - 454 temp F LM34 49.80 - 102 thermistor = 67.96 - 455 temp F LM34 48.34 - 99 thermistor = 67.96 - 455 temp F LM34 47.85 - 98 thermistor = 67.96 - 455 temp F LM34 47.85 - 97 thermistor = 67.65 - 453 temp F LM34 46.88 - 95 thermistor = 67.80 - 454 temp F LM34 46.39 - 95 thermistor = 67.96 - 455 temp F LM34 46.39 - 95 thermistor = 67.80 - 454 temp F LM34 45.90 - 94 thermistor = 67.96 - 455 temp F LM34 45.41 - 93 thermistor = 67.80 - 454 temp F LM34 45.41 - 93 thermistor = 67.80 - 454

The LM34 family can work below 5F with a simple trick. One or two diodes in the ground line of the LM34, and a resistor from output to ground. That enables the output to become negative in respect to the LM34 ground. Figure#17, page 14 in the Ti datasheet. Two A/D inputs of the Arduino are needed. Leo..