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### Topic: Temperature Probe (Read 3393 times)previous topic - next topic

#### Drew Davis

##### Jan 20, 2013, 09:57 pm
Hello,

I just bought a temperature probe and I need some help. Does anybody know if it is a 5v or 3.3v sensor and which wire is positive and which wire do I attach into my analog port on the Arduino. Both of the wires are black, but one as a grey stripe on it.

Thanks,
Drew

http://media.digikey.com/pdf/Data%20Sheets/U.S.Sensors/USP10979.pdf

#### Krodal

#1
##### Jan 20, 2013, 10:10 pm
One of the wires is perhaps shielded against electric noise.
But I don't know which one.

It is a NTC resistor of 10k at 25 degrees Celsius, maximum 105 degrees Celsius.

You have to find some examples how to connect it, and how to calculate the temperature.

#### Drew Davis

#2
##### Jan 20, 2013, 10:16 pmLast Edit: Jan 20, 2013, 10:32 pm by Drew Davis Reason: 1
I have looked all over for examples and I can't find any. I can calculate the temperature by using a thermometer and comparing what the probe values are vs the temperature, but I don't know how to connect the probe to the Arduino.

Any ideas?

Thanks,
Drew

#### LarryD

#3
##### Jan 20, 2013, 10:55 pm
You can try this schematic.
The R5 resistor can be adjusted to get the voltage you want at the temperature you want.
No technical PMs.
The last thing you did is where you should start looking.

#### Krodal

#4
##### Jan 20, 2013, 10:58 pm
Some add a capacitor to eliminate noise.

Simple example:
http://playground.arduino.cc//Main/Kty81-110

Extended library:
http://playground.arduino.cc//ComponentLib/Thermistor4

#### Drew Davis

#5
##### Jan 20, 2013, 11:11 pm
Wow! This is a lot more complicated then I thought.

LarryD: On your schematic what is "Arduino 0v" and "RT1"? (I'v never really used a schematic before)

Krodal: Where would I put the capacitor in LarryD's schematic?

Also I don't have an R5 resistor and I would like to get this working ASAP. Could I use a 10K Ohm resistor for now?

Thanks!!!

#### LarryD

#6
##### Jan 20, 2013, 11:37 pm
Quote
LarryD: On your schematic what is "Arduino 0v" and "RT1"? (I'v never really used a schematic before)

This is the GND pin, found on the Power header on your Arduino board
Put a .1uF capacitor Across the Thermistor (RT1, your temperature sensor)
Quote
Also I don't have an R5 resistor and I would like to get this working ASAP. Could I use a 10K Ohm resistor for now?

R5 is 10K
No technical PMs.
The last thing you did is where you should start looking.

#### Drew Davis

#7
##### Jan 21, 2013, 12:06 am
Thanks!!! I will try it out and post the results.

#### Drew Davis

#8
##### Jan 21, 2013, 12:14 am
It works perfect! I did not need to use the capacitor.

Thanks for all the help!!!

#### LarryD

#9
##### Jan 21, 2013, 01:05 am
The capacitor is used to protect the analog input from transient noisy problems.
This may result from long cables in a electrical noisy environment.
If you are just doing a test you don't need the capacitor.
No technical PMs.
The last thing you did is where you should start looking.

#### Drew Davis

#10
##### Jan 21, 2013, 04:48 pmLast Edit: Jan 21, 2013, 06:01 pm by Drew Davis Reason: 1
Thanks! I will put a capacitor in when I put the probe into my project.

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