Continue to Site

# what type of temperature sensor is this

Status
Not open for further replies.

#### Hayee

##### Member level 3
Dear All,
Can anyone tell me what type of Temperature sensor it is? and there is no model or type mentioned on it.
I want to read the temperature in microcontroller and then convert its values into real temperature values.

Thanks

Solution
Hi,

There´s no prove that it´s an NTC.
It could be a PTC, a diode, a thermocouple, or any other temperature sensor.

Klaus
Dear All,
Can anyone tell me what type of Temperature sensor it is? and there is no model or type mentioned on it.
I want to read the temperature in microcontroller and then convert its values into real temperature values.
View attachment 184198
Thanks
That is a thermistor , most probably a NTC type thermistor ,for further information google is your friend ;-)

If you don't have a datasheet, characterize the sensor by measuring the resistance at two temperatures, e.g. ambient and 100 °C (boiling water).

If you don't have a datasheet, characterize the sensor by measuring the resistance at two temperatures, e.g. ambient and 100 °C (boiling water).
That will be good if all you want to measure is ice or boiling water. Thermistors are extremely non-linear, so you need calibration curves, a look-up table, etc. to get anything useful out of them.

Yes, NTC curve is nonlinear but can be described by two parameters, R25 and B. In so far two point calibration can be sufficient. First task is to verify that it's actually a NTC.

Hi,

There´s no prove that it´s an NTC.
It could be a PTC, a diode, a thermocouple, or any other temperature sensor.

Klaus

If you don't have a datasheet, characterize the sensor by measuring the resistance at two temperatures, e.g. ambient and 100 °C (boiling water).

Yes I measured the resistance at a room temperature it was around 14Kohms and when I put soldering iron (approx 300 c )on that resistance go in ohms like 10 ohm.
Now what you guys say about it? should i go for a lookup table for a certain range like 20 to 100 degree. or use any formula.
But for this we should know the scaling factor means 1c cause how much resistance to drop or increase.

Hi,

the plastics doesn´t look like it is suitable for 300°C.

Klaus

Ok, so it's NTC. But without knowing more about the device there's no way to calibrate it with just two points. You could measure several points and then interpolate values in between those points, or infer a second-order equation. It all depends on how accurate you need to be.

For standard accuracy requirements, manufacturers specify NTC with a two parameter model. Review application notes for details.

What I usually do:
- use NTC in voltage divider circuit
- measure voltage
- calculate Rntc
- calculate Temperature from exponential NTC characteristic
T=B*Tn/(B+ln(Rt/Rn)*Tn). Rn

Empirical tables give higher accuracy, it might be however that type variation exceeds table error margin by a factor.

Status
Not open for further replies.