temperature sensor AD592 calibrate and map degrees

hello , i,m experimenting with some temperature sensors and i was wondering what is the best or easiest way to calibrate this sensor ?

and also how could i get the degrees in celsius . i was making this simple map if the values from 5v are 0 1023 and in the datasheet http://www.analog.com/static/imported-files/data_sheets/AD592.pdf it says it goes from Wide Operating Temperature Range: –258C to +1058C

so map (0 _ 1023) to (-25 _ 105 ) but i,m not sure that will be the real map to do ?

What value resistance are you using? -25 C is 248K, so your output current at -25C is 248uA (I think), and at 105C (378K) it will be 378uA.

hello I,m not using any resistance i was connecting directly to ground 5v and analog pin , what resistance should i use or what will be the way to connect it then ?

The device you linked to delivers 1uA / K, so connecting it directly to an analogue pin measuring voltage won't work. You need to convert the current to a voltage using a resistor, like it shows in the datasheet. You then connect the analogue pin to the junction of the resistor and the sensor, and measure the voltage across the resistor. A 10K ohm resistor should give you 10mV/K, so -25C will give 2.48V, and 105C will give 3.78V

ok so if i understood well is 5v to 5v ground to ground and a resistor of 10k between the sensor data pin and the analog arduino pin ?

also if the range of voltage is between 2.48V and 3.78V which will be values from the analog pin from 507.4080 to 773.3880 then if i map this from (min 507 max 773 ) to degrees ( min -25 max 105 ) i should get the right temperature right ?

hi , i tried with the 10k resistor and all i get is a sort of ramdom number i tried it in diferent ways between the sensor data and the arduino pin between the 5v and the sensor 5 between the ground and the sensor ground but nothing all ramdom data , if i heat the sensor this ramdom data goes up so in some how it does slightly something but very wrong .

could you give me a few more details how to connect it ?

in this site http://lafa06c.blogspot.com/ they are using one AD592 in the circuit it looks like they are using one 100[ch937] resitor and a 0.22 capacitor http://photos1.blogger.com/blogger/7657/3120/1600/Electrical%20Diagram%20copy.1.jpg i have those here but i,m not to sure how they connect them ?

cheers

Hi,

I'm also trying with an AD592, and i've got some data out of it. The way to connect it, using a 10k resistor:

Connect +5v to ad592 Connect analog 0 to ad592 Connect 10k resistor to ad592 Connect resistor to ground.

(see examples for piazo or light-resistor, same principle) (also see Tutorial/Calibration)

You mentioned the example in java, but I figured they use a different technique. First of all they don't use arduino, and they don't measure resistance directly. Instead they measure the time it takes to reach 2,5v (hence the capacitor? (again not very sure) ). Then they convert this time to temp, (because it will take longer as the temp goes down ( again not very sure :)) ) i I tried to mimic this with arduino, but I figured I need to set "HIGH" to 2.5V instead of 5V to be able to use the same "technique"

Returning to the "old" way I did get some "sensible" readings, 567 low, 633 high (using ice and hot-water) but this posses a small problem: Only a 66 (points) diff, which is not enough. If the real temp-diff is about 80, I will still only be able to measure with more than 1 degree steps.

Does anyone have a idea how to fix this? I would like 0.5 as a minimum step-size

Does anyone have a idea how to fix this?

Use a lower reference voltage, or a bigger (more ohms) resistor?

hi Michiel , are you getting steady values ? i get jumps of 100 values connecting the data pin of the sensor to the arduino analog pin then the + pin on the sensor to 5v and the - pin to one part of the resistor the other part of the resostor to ground .

also are you mapping the outputing values to (567 low, 633 high ) , (-25ºlow, 105º high ) ?

cheers

also are you mapping the outputing values to (567 low, 633 high ) , (-25ºlow, 105º high )

567 low, 633 high (using ice and hot-water)

Thanks for the quick replies.

are you getting steady values ? i get jumps of 100 values

Yes, they are steady. Are you sure the connections are ok? I got jumping values when i removed the ground....

Use a lower reference voltage, or a bigger (more ohms) resistor?

I just started to play with this, and i have just a few resistors, of which 10k is the biggest. So i can't try than one yet.

A lower voltage (3.3v) gives me lower numbers: 311 seems 18c, 370 is about 85c So still a 59 when i would like about 130..., maybe a bigger resistor will do the trick...

just started to play with this, and i have just a few resistors, of which 10k is the biggest

You could put them in series…

Been fiddling: Tried adding more resistors in series, got it up to 13,3 kh (really need to get more ;))

Which did make a difference but not enough: low: 331, high 364 (cold and hot water, can't keep it boiling all the time :))

I've also tried upping the voltage to 10v, which gives me around 4.8 volt with hot water, but the difference seems same/smaller.

I'll order a set of resistors....

Just as remark: I bought this: http://www.parallax.com/Store/Sensors/AllSensors/tabid/760/CategoryID/46/List/0/Level/a/ProductID/86/Default.aspx?SortField=ProductName%2CProductName

Which is a ad592, but the documentation found on the net could be different of course...

And i'll order a capacitor as well, maybe i can mimic the "example" ...

hi again thanks for the answers , there might be something i,m doing wrong when connecting it , i still get not stedy values big jumps .

you said that :

Connect +5v (pin 1 in the sensor ad592)
Connect analog 0 to (pin 2 in the sensor ad592 )
Connect 10k resistor to ad592 which pin in the sensor ? ???
Connect resistor to ground( pin 3 in the sensor )

i think i tried all posible combinations can you rechecked for me the above connections procedure ?

all this have only 2 pins :
(see examples for piazo or light-resistor, same principle)

sorry i just dont know why is not working my exact model is the AD 592 anz #0826

Here's my setup:

http://in-orde.nl/projects/arduino_temp.jpg

(bit out of fucus ...)

thanks for the photo yes we are using complety diferent things here is the one i,m using http://www.analog.com/static/imported-files/data_sheets/AD592.pdf it is got 3 pins and this is how it looks http://shop.conrad.nl/elektronica-meetapparatuur/componenten/sensoren/temperatuursensoren/174912.html how could i connect mine ?

I’m a newbe at this, but what i distill from the sheet:

Connect +5v to pin 1
Connect analog 0 to pin 3
Connect resistor to pin 3
Connect ground to resistor

I suspect we have a similar sensor, only mine has a neat jacket …
(but i’m not sure…)

pin 2 isn’t connected…

yes you are right michiel , ingnoring pin 2 data pin and connecting it like an ldr i get a stedy value but the range i get is only of 20 values i put some frozen botte and got the value 491 and aproaching fire i got 470 , so this still does not look as they way to go , also if my sensor it is got this data pin it must because it is more advance way to to do well i dont know , is there any other way to connect it using the 3 pins any of you guys ?

NC Probably means "Not Connected" And i see no reverences to pin 2 in the data.

I'm guessing you don't need it ....

About the measurements: it seems you have the same issue as i do. If you have a couple of resistors left, you could try the suggestion by "Groove".

Guessing that 20k - 30k might work ...