Yet More TMP36 Wierdness

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chip overclock
 
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Yet More TMP36 Wierdness

Post by chip overclock »

Disclaimer: I'm fundamentally a SW guy. But this seems like it ought to be pretty simple. I know I'm doing something really boneheaded.

After trying all the advice in the forums here I've given up trying to get good results from the TMP36 temperature sensor over the Arduino ADC.
Now I'm just trying to get the test in the TMP36 tutorial to work.

L-R: Power, Multimeter Positive, Power Ground & Multimeter Ground

Image

C/W: Thermometer reading 75F which feels about right, multimeter reading 490mV or about -1C/30F, 2xAA battery back, TMP36.

Image

It moves around from the high 300s to as high as 640 but is pretty stable in the high 400s.
It does increase when I put a finger on it. It has never indicated the actual room temperature.
I've tried three different TMP36s from two different suppliers, so I'm pretty sure it's me. I even tried another multimeter.

Any ideas? advTHANKSance!

-- Chip

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philba
 
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Re: Yet More TMP36 Wierdness

Post by philba »

That's about what I'd expect for 25C from a TMP37

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chip overclock
 
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Re: Yet More TMP36 Wierdness

Post by chip overclock »

Yes, that occurred to me too. It's about 25C or 76F. But all three sensors (from two suppliers) I've tested are labelled TMP 36GZ on their faces.

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philba
 
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Re: Yet More TMP36 Wierdness

Post by philba »

It's possible that they are mislabeled. That's known to happen though it's pretty rare. To test properly, you need a second data point - 50 or 100C. Any way you could put it in boiling water?

The good news - if mislabeled, it's a trivial change in your code.

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