Mhm,
if you now put the temperature on the X-Axis and the ppm on the y-Axis there should be a large difference at the temperature extremes.
32 degrees -5 vs -10 ppm
21 degrees -17 vs -8 ppm
if I see it right.
The 26 degrees remain stable at +10 ppm
with best regards
Andreas
That doesn't seem right. l100.log,2 ends (~32.6°C) with
1678890905: 100.02594300000099Ohm @305.73
1678890914: 100.025840499997Ohm @305.73
1678890923: 100.02601549999899Ohm @305.73
1678890932: 100.02580287500001Ohm @305.7
1678890942: 100.025825Ohm @305.72
1678890951: 100.02595Ohm @305.73
1678890960: 100.02595749999999Ohm @305.71
1678890969: 100.025979000001Ohm @305.71
1678890978: 100.02579300000001Ohm @305.72
1678890987: 100.025840499997Ohm @305.72while l100.log starts (~32.25°C) with
1678895116: 100.026115499999Ohm @305.38
1678895139: 100.026165Ohm @305.38
1678895154: 100.02606Ohm @305.38
1678895169: 100.0260525Ohm @305.37
1678895184: 100.02602875Ohm @305.38
1678895199: 100.025965Ohm @305.38
1678895214: 100.026074000001Ohm @305.38
1678895229: 100.025937999997Ohm @305.38
1678895244: 100.026075250001Ohm @305.38
1678895259: 100.02602999999999Ohm @305.4
1678895274: 100.0260275Ohm @305.37
1678895289: 100.025902875Ohm @305.39
1678895304: 100.025984Ohm @305.42
1678895319: 100.025979000001Ohm @305.4
1678895334: 100.026002875Ohm @305.43
1678895349: 100.0259225Ohm @305.44
1678895364: 100.02600799999999Ohm @305.44
1678895379: 100.02602375Ohm @305.44
1678895394: 100.026Ohm @305.46
1678895409: 100.02589898437499Ohm @305.45
1678895424: 100.026040499997Ohm @305.46
1678895439: 100.025989625Ohm @305.46
1678895454: 100.02611175Ohm @305.46
1678895469: 100.025955Ohm @305.45
1678895484: 100.0260058125Ohm @305.43
1678895499: 100.02597649999899Ohm @305.46
1678895514: 100.026043000001Ohm @305.45
1678895529: 100.025869000001Ohm @305.47
1678895544: 100.02590196874999Ohm @305.45
1678895559: 100.025955Ohm @305.45
1678895574: 100.026040499997Ohm @305.47
1678895589: 100.025948000001Ohm @305.44
l100.log,2 starts with (~21.3°C):
1678809320: 100.026325Ohm @294.52
1678809350: 100.02639087499999Ohm @294.53
1678809380: 100.026377749999Ohm @294.52
1678809410: 100.0263815Ohm @294.52
1678809440: 100.02634800000101Ohm @294.53
1678809470: 100.026340499997Ohm @294.53
1678809499: 100.02623799999701Ohm @294.52
1678809530: 100.026298984375Ohm @294.52
1678809560: 100.026369000001Ohm @294.52
1678809589: 100.02632875Ohm @294.52
1678812920: 100.0261Ohm @294.44l100.log ends at a lower temperature, but has around 21.2°C:
1678974324: 100.02589699999999Ohm @294.32
1678974339: 100.02591749999999Ohm @294.29
1678974354: 100.02580987500001Ohm @294.35
1678974369: 100.0259979375Ohm @294.35
1678974384: 100.02589393749999Ohm @294.36
1678974399: 100.02585749999999Ohm @294.36
1678974414: 100.02600196875Ohm @294.34
1678974429: 100.02583799999701Ohm @294.36
1678974444: 100.0260009765625Ohm @294.35
1678974459: 100.0258958125Ohm @294.34
1678974474: 100.026077749999Ohm @294.35
1678974489: 100.026008625Ohm @294.35Given the spread (and the fact that the temperature is recorded by an Arduino reading a voltage divider using a NTC and a run-of-the-mill metal film resistor), I'd be hesitant to read a hysteresis into that. More importantly perhaps, while the TC of the 3457A in the comfort zone might be small, it ain't 0. I'd think if one wants to measure individual ppms, one needs a better set-up (e.g. aforementioned temperature-stabilized comparison resistor).
I use the graphs only for illustration, not in an attempt to extract data as I keep the data files around (wished hardware manufacturers would do the same). It's just easier to share the graphs, as the data files are on a different host (and the eevblog server doesn't like .log files
.