Thermocouple multiplexing

[alcuemar]

thermocouple multiplexing

Hello,

I would like to know if anyone has experience in thermocouple circuits??

I would like to know if It is possible to multiplex thermocouple input signals (mV) in one ADC.

Thanks in advance!

Alcuemar

 

[Kral]

multiplexing thermocouples

alcuemar,
It can be done, but it's not easy. There are two problems you need to deal with:
.
The voltage amplitude is low, so you need to amplify the signal to get decent resolution and accuracy from your A/D converter.
.
You must provide cold junction compensation. This is required because the connection from the thermocouple and the copper of a printed wiring board form a thermocouple.
.
The Analog Devices AD595 performs the cold junction compensation and gain functions in one chip. However, you need one for each channel.
Regards,
Kral