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Author Topic: Thermocouple and AD8495  (Read 2175 times)
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I'm trying to measure temperature with a thermocouple (k-type) and Analog Devices AD8495 thermocouple amplifier. The AD8495 outputs 5 mV/°C. I  have the AD8495 wired like this:

Pin 1: Thermocouple -
Pin 8: Thermocouple +
Pin 2 & 3: GND
Pin 5 & 6: Arduino input A0
Pin 7: +5v

I have a simple sketch where I read A0, print the value, wait 250ms and repeat.

The A0 input value is not very stable, they range from about 30 to 60.  This correspond temps in the 30s and 40s F.  Actual temperature is high 60F. And the temp in the room is not changing.  I don't understand why the temp in my sketch is changing so much.

Does anyone have experience with the AD8495?  Any suggestion for getting this to work better.

AD8495 info: http://www.analog.com/en/mems-sensors/analog-temperature-sensors/ad8495/products/product.html


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Did you implement the input filter and bypass capacitors as shown in Figure 33 of the datasheet?

http://www.analog.com/static/imported-files/data_sheets/AD8494_8495_8496_8497.pdf
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Did you implement the input filter and bypass capacitors as shown in Figure 33 of the datasheet?

http://www.analog.com/static/imported-files/data_sheets/AD8494_8495_8496_8497.pdf

No, not initially.  But I just did it now and it didn't improve things.  Now the ADC value is 4 and once in a while it jumps up to a bit, anywhere 15 - 22, for a second or less.
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For the resistors and capacitors on the thermocouple inputs, I used the values shown in the schematic below.  For +5V I used what is shown in the data sheet: 0.1uF and 10uF.



* AD44-10_FIG_06.jpg (35.98 KB, 408x196 - viewed 62 times.)
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