Thermocouple ICs have more than calibrated amplifier, among other things they got some absolute temperature reference built-in. Some kind of temperature sensor to which readings are compared and adjusted, for high accuracy. AD8495 is replacement to AD595, can read both datasheets and look for "ice point reference" / "cold junction compensation". I cant find in that link anything about where that reference would be. And probably there is more in case of thermocouples, e.g. errors, accuracy, etc, that wont be attainable in such a diy strip-down fashion.
Scale of mV voltages, sensitive reference point, high degree of accuracy required, etc, all these are not a good mix to have on a plate. And if somebody does this good with individual / discrete parts, then probably will cost much more than the IC itself.
Scale of mV voltages, sensitive reference point, high degree of accuracy required, etc, all these are not a good mix to have on a plate. And if somebody does this good with individual / discrete parts, then probably will cost much more than the IC itself.