 # How to use an "NTC-like" Thermal sensor

I bought an thermal sensor for a shool projekt but i have no idea how it works and i cant find anythin about it.
I you speek german look here: https://www.voelkner.de/products/938169/Iduino-Temperatursensor-Modul-ST1147-55-bis-125C.html
It just wont work like in the Tutorial from Funduino. I think its because its a different type of sensor, but i realy have no idea. Pls help!

but i have no idea how it works and i cant find anythin about it.

Google "iduino temperature sensor st1477" has this as the first lisitng. Gives NTC type and code.

Thx so much. I did google the same thing but didnt find anything. Maybe because im from germany.

Is the following one your NTC sensor? (Collected from the Site you referred.) Figure-1: Pictorial view

1. The R1-S network should be the following (please check): Figure-2: S-R1 network

2. The response of the sensor module (Signal Vs Temp) is not found; so, we have to calibrate it against known two points before we use it.

3. Calibration Procedure
(a) Apply +5V between Pin-1 and Pin-3; Pin-3 is the GND potential.
(b) Connect DVM between Pin-2 and Pin-3.
(c) Record room temperature in 0C with a thermometer; record DVM reading in Volt. This is your one known point A(VDT1, T1).

(d) Change room temperature by controlling the A/C. Record room temperature in 0C with a thermometer; record DVM reading in Volt. This is your second known point B(VDT2, T2).

(e) The 3rd unknown point is C(VDT, T).
([f) Find equation for T in terms of VDT. T = k*VDT + c; where, k and c are known constatnts.

(g) If using Arduino UNO, set the VREF for the ADC at DEFAULT (5V).
(h) By simple algebraic manipulation, we will find – T = k*(5/1024)*analogRead(A3) + c.
(i) Make the following declaration/definition.

``````float roomTemp;
``````

DerAlteMalte:
Thx so much. I did google the same thing but didnt find anything. Maybe because im from germany.

In my experience, if you change the Google language to English, first, and then do the search. Then later change back to German, you may discover much information.

Paul

GolamMostafa:
([f) Find equation for T in terms of VDT. T = k*VDT + c; where, k and c are known constatnts.

The normal approximations are not that accurate for an NTC but a linear approximation is useless for a range greater than 1-2 °C. These things are totally non-linear in temperature response!

The normal approximations are not that accurate for an NTC but a linear approximation is useless for a range greater than 1-2 °C. These things are totally non-linear in temperature response!

Any suggestion on how to bring reasonable linearity in the response of the NTC using hardware/software. After linearity correction, do we still need to apply the two-point calibration scheme on the NTC in order to read the unknown temperature?

Use the Steinhart & Hart equation, beta function or even a lookup table for your NTC (a list of resistances per temperature, if you have 1°C steps a linear interpolation over that one step is still quite OK).

Remember to use a precision resistor for pull-up (no more than 1% tolerance, preferably very low temperature coefficient) as otherwise that's just another major error.