Make your self Thermocouple Signal Conditioning

Dear all hands,
Thermocouple i think is a most hard transducer to deal with it, but because its temperature range and aviabillity to make by ourself, termocouple still in wide use. In short list, signal conditioning for termocouple must has figure of merit like that :

1. Good CMMR at reasonable gain, usually above 90 db.

2. Has thermal compensation capability.

We can use precision op-amp for this need and use a another temperature transducer for thermal compensation. Precision op-amp like CP07 and zenner diode sometime is adequate.

Four years ago i used thermal compensation like suggested by national semiconductor , below is the circuit:

This circuit use LM335 , a themperature transducer (Kelvin), and for amplification we can use CPo7 in output terminal.