# connecting PT100 to uController

#### eric_s88

Joined Apr 20, 2011
157
Hi everybody

I'm going to measure a surface temperature with pt100. what I got from this sensor is that, its resistance varies with the temperature. and the "100" stands for 100 $\Omega$resistance in 0 degrees. and should have a current source to transform the resistance to a voltage and feed this to uC adc. (10bit)

my problem is how to design current source ? would it be right to use current source ICs ? and how much big should be that current ?

thank you

#### MikeML

Joined Oct 2, 2009
5,444
Here is something I did years ago: (never throw anything away). Stare at it for a while, and come back if there is something you dont understand.

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#### Dodgydave

Joined Jun 22, 2012
8,292
one here for an Arduino..

#### MikeML

Joined Oct 2, 2009
5,444
one here for an Arduino..
I question why, in that circuit, they start with the bridge unbalanced?

#### Dodgydave

Joined Jun 22, 2012
8,292
I question why, in that circuit, they start with the bridge unbalanced?
Maybe starting at a different temperature than yours, alter the bridge resistors to suit your design