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TMP36 temperature sensor with a long wire: getting noisy & unstable signal


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4 replies to this topic

#1 provat

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Posted 20 February 2014 - 05:06 PM

Hello,

My name is Provat. I am trying to use a TMP36 temperature sensor with labjack UE9. TMP36 is just a 3 wire temperature sensor (Signal, GND, VS). I have added long extension wire (about 25 ft) with the sensor. But when I have hooked up my sensor with labjack I am getting very noisy and untable signal. sometimes signal looks reasonable but sometime noisy and it's unstable. I have tried with different computer (PC, laptop..) and got same situation. I have also tried with a U6 labjack and I got same problem.

 

If anyone could give me some troubleshooting idea that would be really healpful for me.

Thanks in advance

Provat



#2 LabJack Support

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Posted 20 February 2014 - 05:38 PM

Try adding a 10k resistor from signal to ground.

 

See comments in EI-1034 and LM34 information:

 

http://labjack.com/s...erature-sensors



#3 provat

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Posted 21 February 2014 - 10:03 AM

''Try adding a 10k resistor from signal to ground.''

I tried like this..but no luck



#4 LabJack Support

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Posted 21 February 2014 - 12:43 PM

We don't have any experience with the TMP36, but see the "Capactive Loads" section in the LM34 datasheet and consider adding a series resistor.

 

http://www.ti.com/li...ymlink/lm34.pdf

 

I do see that the TMP36 datasheet has a similar section:

 

http://www.analog.co...TMP35_36_37.pdf

 

It would also be useful to look at the TMP36 signal with an oscilloscope, so you can see what exactly the signal is doing.



#5 eka

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Posted 22 February 2014 - 07:40 AM

Try using BOTH methods in the LM34 sheet.   Signal to grd (75ohm inseries with a cap) then 2K resistor to LJ on signal line. 

This should be near the LM34.  At least for the LM34, this has worked well for me.

eka




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