about using several thermocouple with a multiplexer

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mikelo
 
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about using several thermocouple with a multiplexer

Post by mikelo »

hi guys:
I am trying to connect several thermocouple sensors to one MAX31855 Module through multiplexer. I don't know how it could possible work. I see the thermocouple has + and - side to connect. Does anyone know how to do it?

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adafruit_support_mike
 
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Re: about using several thermocouple with a multiplexer

Post by adafruit_support_mike »

That's kind of tricky..

A normal multiplexer wouldn't work. Those are generally digital and thermocouples produce low-voltage analog signals. To select one of several thermocouples, you'd need analog switches.

The 74HC4066 is a traditional 4-channel analog switch, but its on-resistance is about 50 ohms. I'm not sure what that would do to a thermocouple's calibration. You can get analog switches whose on-resistance is less than an ohm (http://www.mouser.com/ProductDetail/Tex ... 2fp0bFw%3d) but they tend to come in really tiny packages.

Reed switches/relays would probably be your best choice.

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