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MAX31865 - is this PT100 or PT1000?
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MAX31865 - is this PT100 or PT1000?

by PThompson509 on Tue Jul 27, 2021 10:17 pm

Hi Folks,

I bought 3 MAX31865 temperature sensor amplifiers for the RTD - PT100 temperature sensor.
Just because I was feeling paranoid, I checked the resistor on the board, and it reads 4301, which should be used for the PT1000 sensor, not the PT100 sensor.
Am I reading this correctly?

Picture of the resistor attached.
IMG_4163.jpeg
IMG_4163.jpeg (932.68 KiB) Viewed 45 times


Thanks in advance, Peter
PThompson509
 
Posts: 4
Joined: Mon Jun 10, 2013 8:49 pm

Re: MAX31865 - is this PT100 or PT1000?

by adafruit_support_bill on Wed Jul 28, 2021 5:58 am

There are 2 different marking systems for SMT resistors - 3 digits and 4 digits. They are similar enough to be confusing.
The resistor on your board uses a 3-digit code. The first two digits are the significant digits, the third is the multiplier (i.e. how many zeros to add)

So "431" is 430 Ω which is correct for a PT100.

https://learn.adafruit.com/adafruit-max ... aq-3012913
If marking is 4300 or 431 its PT100
If marking is 4301 or 432 its PT1000

adafruit_support_bill
 
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Re: MAX31865 - is this PT100 or PT1000?

by PThompson509 on Wed Jul 28, 2021 12:18 pm

Thank you. As always, it helps to read ALL of the descriptive text, doesn't it?

Cheers!
PThompson509
 
Posts: 4
Joined: Mon Jun 10, 2013 8:49 pm

Please be positive and constructive with your questions and comments.