Thermocouple amplifier and level shifter

[jc256]

Hi there,

I have wired up a type t thermocouple to an LTK001 (amplifier/compensator) using the diagram given on the data sheet shown to give 10mv/deg C.
Since this runs from a +5v / -5v supply i then step down this voltage from 10v pp to 3.3v using a level shift which has a reference voltage of 1.65 volts ( level shift circuit - https://www.daycounter.com/Circuits/OpAmp-Level-Shifter/OpAmp-Level-Shifter.phtml)

So my circuit is wired ... thermocouple --> compensator --> amplifier --> level shifter.

Now, I have tested all these parts alone (minus the compensator) and I get the correct voltages but when I connect together the voltage seems to be stuck at one point

Any ideas ?

 

[barry]

I have an idea: You wired it up wrong.

Just go down the chain and see that the outputs are as expected along the way. Do you see 10mv/Deg after the LTK001? Does the output of the level shifter agree with its input?