Update, May 2015: This calibration is unneeded for all modern controllers, as the default software values match the current controller/LM61 combination.

Why calibrate?

Following some requests, we measured and calculated the proper coefficients for adjusting the external temperature sensors. There are three factors, as seen in the software (v. 3.0 and later): C1, F, and C2.

  • C2 is mainly for offsetting the internal box's excess temperature, so it isn't used for the external sensors.
  • F is the slope of the straight line.
  • C1 is the offset: the value read at 0 ºC.

Coefficients

The Configuration options dialog, temperature sensor calibration section, with the C1, F and C2 fields circled for both the internal and external sensor rows.
The three calibration fields—C1, F and C2—one row per sensor.

For the Armadillo or Platypus controllers:

  • Using the LM61 temperature sensor: C1 = 192, F = 1.7
  • Using the LM60 temperature sensor: C1 = 94, F = 3

And for the "Classic" Seletek controller:

  • Using the LM61 temperature sensor: C1 = 190, F = 3.6
  • Using the LM60 temperature sensor, we got odd results, but we're fairly confident the same values as the internal sensor will work (there's no isolation in this model): C1 = 133.5, F = 4.88