Semitec 104NT-4R025H42G (SOLVED)

paboman

Is anyone using semitec 104NT-4R025H42G thermistor ?
I am converting a machine electronics from Smoothie to Duet and want to maintain that hotend thermistor but dont know how to configure the config to have a reasonable temperature readings.
I found this steinhart values from the smoothie wiki, How to input this curve into Duet config ?

0.000797110609710217F 0.000213433144381270F 6.5338987554e-08F

source:Smoothie Wiki

thx!

dc42

Ignore the first value, that's the A value and RRF uses the resistance at 25C instead. Take the reciprocal of the second value and use that as B in the M305 command. Use the third value as C.

paboman

I have changed the line to:

M305 P1 T100000 B0.000213433144381270F C6.5338987554e-08F R4700

but now I am getting 2000°C

bot

@paboman the reciprocal would be a fraction of 1/0.000213433144381270 which equates to roughly 4685.

paboman

thank you guys, learned something new today

Deltasquare

Sorry for bumping this up, but I do not get a reasonable solution.

So far, for the Semitec 104NT-4-R025H42G thermistor as it is used in the Deltaprintr Hotend (which I want to integrate) I followed along the
So for adjusting the thermistor settings I got this:

M305 P1 T100000 B4658 C6.5338987554e-08F R4700

Is this correct?

We have got the resistance at 25C (R), the calculated B Value of 4658 nd a C value of C6.5338987554e-08F (Including the F? Is this Fahrenheit or Farad or even necessary? Apparently it does not make a difference for the thermistor.)

Do I interpret this right?

It gives me appr. 680C while fluctuating within a window of about 20C.

So I checked whether I can find other values and found the thermistor on mouser:

https://www.mouser.at/datasheet/2/362/P18-NT-Thermistor-1535133.pdf

It has a B value of 4267. With this other B value I get readings in between 882C and 908C. Thats even worse.

Can anyone point me in the right direction? What am I missing? Or maybe is the thermistor broken?

dc42

@Deltasquare said in Semitec 104NT-4R025H42G (SOLVED):

We have got the resistance at 25C (R), the calculated B Value of 4658 nd a C value of C6.5338987554e-08F (Including the F? Is this Fahrenheit or Farad or even necessary? Apparently it does not make a difference for the thermistor.)

Delete the F, it's a Smoothieware thing. Also delete the R4700 - it's not needed and depending on what Duet you are using, it may be the wrong value.

However, with readings that high, I suspect a short in your wiring.

Deltasquare

Problem solved.
However it was due to the coloring of the wiring. Someone switched the colors and apparently the Heater has a pretty high resistance.
Sorry for bothering and thank you for clearing that up!

So the solution is:

M305 P1 T100000 B4658 C6.5338987554e-08