109.3035 ohm resistor

Using Arduino General Electronics
20

PapaG:

be80be:
Where did you find that a PT100 is 109.3035 It's 109.73 at 25C could you show how you did the math for Fahrenheit

Well:

25 * 9 / 5 + 32 = 77 degrees F

(75 - 32) * 5 / 9 = 23.9 degrees C

From the chart at http://www.tnp-instruments.com/sitebuildercontent/sitebuilderfiles/pt100_385f_table.pdf :

77 degrees F = 109.735 ohms
75 degrees F = 109.304 ohms

It all looks right to me.

I think your misreading the chart. You look at the 70F row and move 6 columns (-5) right to reach 65 degrees = 109.304 ohms.

Lefty