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NTC graph generation

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ruijc

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Hi all,

i have a NTC with just the following caracteristics:

# nom. resistance: 1 kohm
# B-constant (±7%): 3700°K
# max. permissible current: 80mA
# thermal dissipation constant: 6mW/°C
# thermal time constant: 17sec.

I have no graphs so i dont know how resistance changes with temp.

How can i obtain a graph ( temp/resistance ) with these specifications ?

Thanks
 
Hi Nigel,

That make's sense !

I was really hopping to obtain some kind of formula :D

Maybe it's not possible
 
Hi all,

i have a NTC with just the following caracteristics:

# nom. resistance: 1 kohm
# B-constant (±7%): 3700°K
# max. permissible current: 80mA
# thermal dissipation constant: 6mW/°C
# thermal time constant: 17sec.

I have no graphs so i dont know how resistance changes with temp.

How can i obtain a graph ( temp/resistance ) with these specifications ?

Thanks

Take a look at the Steinhart Hart equation:

https://www.ametherm.com/Aplications/ntc_thermistor_Steinhart_Hart.htm

https://www.daycounter.com/Calculators/Steinhart-Hart-Thermistor-Calculator.phtml

**broken link removed**

https://en.wikipedia.org/wiki/Steinhart-Hart_equation

https://www.electro-tech-online.com...efficients20for20Steinhart-Hart20Equation.pdf

https://www.electro-tech-online.com..._constant_conversions_beta_steinhart-hart.pdf


B parameter equation

NTC thermistors can also be characterised with the B parameter equation, which is essentially the Steinhart Hart equation with c=0. Using the expansion only to the first order yields:

or

or

where
R0 is the resistance at temperature T0 (usually 25 °C=298.15 K)

above is from:

https://encyclopedia.stateuniversity.com/pages/21970/thermistor.html

Hope this gets you going!
 
Hi Nigel,

That make's sense !

I was really hopping to obtain some kind of formula :D

Maybe it's not possible

Different thermistors have different curves, and they are a LONG way from linear :D

A lookup table is probably the best way, but you need to create and calibrate it - why not use something like an LM35 instead?.
 
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