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Thermocouples, microvolt signals and filtering

1342 Views - Created 15/06/2016

15/06/2016

Posted by:
minnytonkas

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I'm playing around with theromocoupls and your ADC board. It is working fairly well but it looks like it could use more input filtering. Something like what is discribed in this article would be probably help a lot: http://www.ti.com/lit/ug/slau509/slau509.pdf to provide both common and differential noise rejection. It would also be generally useful for measuring small signals.

Any chance of you developing a board specifically for small signals/thermocouples? If you do decide to create such a board it would be nice if it had pads for your TMP36 Temperature Sensor as well for the cold junction correction.

15/06/2016

Posted by:
andrew

Last edited: 05/06/2019

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Location:
United Kingdom

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We are currently looking at developing a dedicated thermocouple interface board around the Maxim MAX31856 which is a precision thermocouple to digital converter that would connect to the Raspberry Pi through the SPI bus.  It supports K, J, N, R, S, T, E, and B type thermocouples and has internal cold-junction compensation which should increase the accuracy.  We could add a single or dual channel ADC which would work with the TMP36 sensors.

The new board is still in the early prototyping stage at the moment.  Some MAX31856 chips arrived from Maxim this morning so I need to build a test circuit and see if they will do what we need but if they do work then hopefully we can have a working board on sale within a couple of months.

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