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Topic: 109.3035 ohm resistor (Read 3 times) previous topic - next topic

Papa G




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


I see what you are saying but it looks to me like the minus numbers just apply to the minus temperatures at the top of the chart. Look 8 rows up from the 70 degree row.

retrolefty

Your right, I was too quick to see the structure correctly that changes between negative and positive values.

Lefty

Papa G


Your right, I was too quick to see the structure correctly that changes between negative and positive values.

Lefty


Easy mistake, Master Po.  :)

Osgeld

We had a good two hour talk with our vishay rep about these precision resistors, and got a sample card of different styles they make, its interesting stuff.

Like the ones we are using for production testing to act like shunts for current measurements (like single mA with 7 points of precision after that) are in a nutshell an array of resistors in series on a die which they fuse off to make different values.

those are the cheaper ones, like 20 bucks a pop (we ordered 100 of them, that was fun explaining to the purchasing dept "you spend 2 grand on 100 resistors!")

be80be

Yep it looks like a match i just don't see a $100 for a resistor to set that.But who no's Thanks for the math PapaG
I would use hot and cold. And thanks for posting this It sure been fun racking my brain. But maybe we should ask the suppler. LOL just to see whats what.

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