adeguntoro
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i'm looking for DS18B20 calibration result.

Sun Dec 31, 2017 2:40 pm

Hai,

i'm looking for DS18B20 calibration result, maybe you have it. The reason why i ask, because i dont have termometer with high accuracy to calibrate the sensor. I just want to calibrate my sensor from 18 celsius - 30 celsius.

Thanks for your help.

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DougieLawson
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Re: i'm looking for DS18B20 calibration result.

Sun Dec 31, 2017 3:58 pm

They're reasonably accurate with no calibration needed. My DS18B20 compares well to a MXP31855 thermocouple amplifier.
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gordon77
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Re: i'm looking for DS18B20 calibration result.

Sun Dec 31, 2017 4:05 pm

https://www.maximintegrated.com/en/supp ... 0-faq.html

Take a look at... You specify ±0.5°C performance in the 0°C to +85°C range, but the typical curve in the data sheet only extends from 0°C to +70°C. What is the typical error curve of the DS18B20 beyond that range?

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bensimmo
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Re: i'm looking for DS18B20 calibration result.

Sun Dec 31, 2017 4:26 pm

No one can calibrate but you with yours.
That's part of calibration.


My 5 ds18's all the same batch read within 0.5C of each other at the correct temp as expected.

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bensimmo
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Re: i'm looking for DS18B20 calibration result.

Sun Dec 31, 2017 4:28 pm

gordon77 wrote:
Sun Dec 31, 2017 4:05 pm
https://www.maximintegrated.com/en/supp ... 0-faq.html

Take a look at... You specify ±0.5°C performance in the 0°C to +85°C range, but the typical curve in the data sheet only extends from 0°C to +70°C. What is the typical error curve of the DS18B20 beyond that range?
He's only looking for 18C to 30C

B.Goode
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Re: i'm looking for DS18B20 calibration result.

Sun Dec 31, 2017 5:22 pm

DougieLawson wrote:
Sun Dec 31, 2017 3:58 pm
They're reasonably accurate with no calibration needed. My DS18B20 compares well to a MXP31855 thermocouple amplifier.
Doesn't matter....

It's for a University project, and the tutor/supervisor says it must be calibrated,.

Doing it without a temperature measurement device of greater accuracy/resolution as a comparison or reference seems to be challenging!

I could do it for 0degC to 100degC if that helps...

gordon77
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Re: i'm looking for DS18B20 calibration result.

Sun Dec 31, 2017 5:24 pm

bensimmo wrote:
Sun Dec 31, 2017 4:28 pm
gordon77 wrote:
Sun Dec 31, 2017 4:05 pm
https://www.maximintegrated.com/en/supp ... 0-faq.html

Take a look at... You specify ±0.5°C performance in the 0°C to +85°C range, but the typical curve in the data sheet only extends from 0°C to +70°C. What is the typical error curve of the DS18B20 beyond that range?
He's only looking for 18C to 30C
The Graph linked to shows that as well. But as others say they need calibrating individually.

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DougieLawson
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Re: i'm looking for DS18B20 calibration result.

Sun Dec 31, 2017 5:55 pm

B.Goode wrote:
Sun Dec 31, 2017 5:22 pm
I could do it for 0degC to 100degC if that helps...
Don't you mean at 0°C and at 100°C and assume the temps in-between will be a true reflection of ambient.

I've used brownian motion generators to test waterproof temp sensors.
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davidcoton
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Re: i'm looking for DS18B20 calibration result.

Sun Dec 31, 2017 6:06 pm

Don't double post viewtopic.php?f=29&t=201067#p1251900

If you don't understand calibration, you need to talk to your teacher and find out what it is and what the teacher requires.
You CANNOT use another result from another device.
You CANNOT calibrate without using another measuring device with known accuracy, and which gives the accuracy you need.
You CANNOT write a correction routine without knowing the device response.
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bensimmo
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Re: i'm looking for DS18B20 calibration result.

Sun Dec 31, 2017 9:49 pm

gordon77 wrote:
Sun Dec 31, 2017 5:24 pm
bensimmo wrote:
Sun Dec 31, 2017 4:28 pm
gordon77 wrote:
Sun Dec 31, 2017 4:05 pm
https://www.maximintegrated.com/en/supp ... 0-faq.html

Take a look at... You specify ±0.5°C performance in the 0°C to +85°C range, but the typical curve in the data sheet only extends from 0°C to +70°C. What is the typical error curve of the DS18B20 beyond that range?
He's only looking for 18C to 30C
The Graph linked to shows that as well. But as others say they need calibrating individually.
Ah sorry I realise you are quoting a section for him/her to read from the link, my bad.
Not actually asking for him/her.

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bensimmo
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Re: i'm looking for DS18B20 calibration result.

Sun Dec 31, 2017 9:52 pm

davidcoton wrote:
Sun Dec 31, 2017 6:06 pm
Don't double post viewtopic.php?f=29&t=201067#p1251900

If you don't understand calibration, you need to talk to your teacher and find out what it is and what the teacher requires.
You CANNOT use another result from another device.
You CANNOT calibrate without using another measuring device with known accuracy, and which gives the accuracy you need.
You CANNOT write a correction routine without knowing the device response.
He could quote it is factory calibrated at manufacturing and reference the links given above.

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davidcoton
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Re: i'm looking for DS18B20 calibration result.

Mon Jan 01, 2018 9:41 pm

bensimmo wrote:
Sun Dec 31, 2017 9:52 pm
He could quote it is factory calibrated at manufacturing and reference the links given above.
Indeed, if the factory calibration meets the (unknown here) specification.
And if the teacher will allow that, rather than expected the OP to demonstrate an understanding of calibration procedures.
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gordon77
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Re: i'm looking for DS18B20 calibration result.

Tue Jan 02, 2018 12:24 pm

davidcoton wrote:
Mon Jan 01, 2018 9:41 pm
bensimmo wrote:
Sun Dec 31, 2017 9:52 pm
He could quote it is factory calibrated at manufacturing and reference the links given above.
Indeed, if the factory calibration meets the (unknown here) specification.
And if the teacher will allow that, rather than expected the OP to demonstrate an understanding of calibration procedures.
From the link l posted...


The DS18B20 reads with an accuracy of ±0.5°C from -10°C to +85°C and ±2°C accuracy from -55°C to +125°C.

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davidcoton
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Re: i'm looking for DS18B20 calibration result.

Tue Jan 02, 2018 9:16 pm

gordon77 wrote:
Tue Jan 02, 2018 12:24 pm
davidcoton wrote:
Mon Jan 01, 2018 9:41 pm
bensimmo wrote:
Sun Dec 31, 2017 9:52 pm
He could quote it is factory calibrated at manufacturing and reference the links given above.
Indeed, if the factory calibration meets the (unknown here) specification.
And if the teacher will allow that, rather than expected the OP to demonstrate an understanding of calibration procedures.
From the link l posted...


The DS18B20 reads with an accuracy of ±0.5°C from -10°C to +85°C and ±2°C accuracy from -55°C to +125°C.
But we don't know the project requirements -- are they tighter than that, or not so onerous? In one case, calibration is required, in the other it is not. Unless it is a project requirement to demonstrate an understanding of calibration procedures.
"If it ain't broke, fix it until it is."
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bensimmo
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Re: i'm looking for DS18B20 calibration result.

Wed Jan 03, 2018 7:55 am

But that's not for is, but for adeguntoro to decide with his teachers/lecturers advice.

He has the specs presented to him, he has the calibration and errors charts presented to him, time for Teacher to earn the money and do the Teaching/Pupil thing ;-)

of course one thing is lag on response and stabilization time, a not should be these are also for the modules Dallas sell, not the repackaged metal casing and and wires version (which is mention in the docs and told to ask the manufacturer of them).

I hope adeguntoro comes back with what he found out and how he did it :-) it even if this device is suitable.

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davidcoton
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Re: i'm looking for DS18B20 calibration result.

Wed Jan 03, 2018 12:26 pm

bensimmo wrote:
Wed Jan 03, 2018 7:55 am
But that's not for is, but for adeguntoro to decide with his teachers/lecturers advice.
Precisely. Only he knows the spec for his project (or maybe he doesn't, which is part of the problem).
bensimmo wrote:
Wed Jan 03, 2018 7:55 am
I hope adeguntoro comes back with what he found out and how he did it :-) it even if this device is suitable.
+1
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adeguntoro
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Re: i'm looking for DS18B20 calibration result.

Fri Jan 05, 2018 5:37 am

Sorry for slow respond.

last week i ask to my examiner about calibration, i use simple math sensor_result - xx number = temperature_result. But, he said what i'm doing is wrong. So, i ask again "how to calibrate correctly ?", and he said "use math equation like polynomial". And now i'm confuse how to do it.

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davidcoton
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Re: i'm looking for DS18B20 calibration result.

Sat Jan 06, 2018 11:25 am

See my response in your other thread.
You need to use calibration data from multiple points (temperatures) to generate a polynomial equation that will convert the actual reading to a calibrated temperature.
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