Need a temperature sensor of 0.1*F accuracy

[Mithun_K_Das]

I need a temperature sensor. minimum tolerance have to be 0.1*F. The temperature need to be sensed and then have to show in a seven segment display.

 

[sky_123]

What temp range?
For room temp range, SE95D will provide you with a figure in fractions of a degree (approx 0.03degreeC). It is accurate to +-1 degree C which is +-0.55degree fahrenheit.
For accuracy closer to what you specify (+-0.13 degree F), consider ADT7420.

 

[Mithun_K_Das]

temp. range -30 to +155 *F. Also device package should be dip/to seried. smd have a problem.

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temp. range -30 to +155 *F. Also device package should be dip/to seried. smd have a problem.

 

[jasonc2]

Through-hole packages will limit your options.

For SMD the only one I found (on Mouser) close to your range and accuracy requirements is: https://www.mouser.com/catalog/specsheets/TSYS01_datasheet_rev0_3_20120113.pdf
It has ~0.18 °F accuracy from 23 °F to 122 °F and ~0.90 °F accuracy outside of that range from -40 °F to 257 °F.

For DIP/TO there are a few options there https://www.mouser.com/Sensors/Temp...zuzecZ1z0juplZ1z0juqsZ1z0jo0cZ1yzxrv8&FS=True but the best accuracy is ~0.90 °F.

 

[tpetar]

What you plan to measure ?

Range -34,44C to 68,33C. If you whant to measure room, you should know that temp can vary for 4C for normal rooms.
All depends where you measure and how, there is some rules for measuring temp in room.

 

[Mithun_K_Das]

basically I need to control the temperature by 0.1*F tolerance for am embroidery machine room. Thats why need a sensor of that accuracy. Can I use thermistor? will it be efficient?

 

[sky_123]

I think I mentioned a sensor accurate to +-0.13 degrees Fahrenheight in my post. It is SMD. It is of the same order of resolution as you requested.

Also as mentioned, +-0.55 degrees Fahrenheit accuracy is obtainable with SE95D. It is in a large SMD package (SO-8) which anyone can easily hand-solder. And others have mentioned alternatives too.

You could try several and find the most accurate, or you could calibrate manually periodically, since some of the sensors have very high resolution (e.g. the resolution of the SE95D is 0.03 degree C).

You could try a thermistor as long as you're confident you can design a decent analog circuit with the accuracy you need (I suspect it would be hard).

 

[jasonc2]

Why do you need that accuracy?

Local temperature variations within the room will exceed 0.1°F, especially with machinery radiating heat. Even just a person in the room will radiate enough heat to cause local variances that exceed 0.1°F.

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I think I mentioned a sensor accurate to +-0.13 degrees Fahrenheight in my post. It is SMD. It is of the same order of resolution as you requested.

Your conversions are off. The ADT7420 datasheet reports ±0.2°C = ±0.36°F accuracy.

±1°C is ±1.8°F.

In general ΔF = ΔC * 9 / 5.

 

[sky_123]

You're right. I don't use Fahrenheit, and trusted a site which had got it back-to-front.

 

[islurpundalik]

try an RTD sensor like PT100 or Pt1000 ( class A type ). it can give you the required accuracy provided you use a decent analog processing circuit as sky suggested.

and as you mentioned tat you want to control the temperature within +/- 0.1 °F does not necessarily mean it should have that accuracy. It would be sufficient to only have the resolution within that value because ultimately, as jason suggested, it would be practically very hard to check the accuracy within 0.1°F .

 

[tpetar]

Precision for each sensor is not for whole measurement range of temp. Precision can be worse in scale margin, but for better information about that you can check manufacturer datasheet about that particular sensor.

Temperature in normal house living room can vary in several degrees of celsius, all depends where you put sensor, are there open windows, doors, are there some cooling fans,.... You will measure lets say 30C and in other part of room you will have 26C.

If you need to control and monitor temperature in some particular part in your production, sensor can be installed closer to that part or production process.


My opinion is that you can try with DS18B20. Sensor have 0,5C accurency and is good for this purpose.

 

[KRIS255]

Building temperature sensors with a thermistor is very difficult. In the first place the thermistor is non-linear and the linearizing equation is only approximately correct because of device variations. Second you would have to design very accurate and stable electronics to sense the thermistor resistance (taking care, of course, to minimize self heating effects). Third how are you going to calibrate your thermistor circuit? You would have to put your thermistor and some calibration sensor in some kind of stable temperature well and where would you get that? You cannot calibrate in air because air currents have more temperature variation than your spec. To assure 0.1 F accuracy, the calibration sensor would need an accuracy of at least 0.02 F and that sounds like a pretty expensive gadget to me. I think you will discover you are spending enormous amounts of time and money trying to get 0.1 F accuracy. In my opinion I think you would be much better off buying something that is guanranteed to have the accuracy you need. By the way, I have tried this, and one problem I ran into was that some of my customers did not believe my sensor was accurate and he was unconvinced by my limited calibration data. It would have been a lot easier if I had simply used a commercial device with published spec.
Jim Christensen

 

[tpetar]

Improving The Accuracy of Temperature Measurements
https://www.picotech.com/applications/temperature.html

 

[dick_freebird]

I doubt that the accuracy of the sensor is anywhere near the
top of your list of error-budget contributors, so you are trying
too hard.

 

[Jestin_cubetech]

DS18B20 Temperature Sensor