Isolated Thermocouple Transducer Circuit

The AD202 are general purpose, two-port,transformer-coupled isolation amplifiers In applications where the output ofthermocouples must be isolated, a low drift input amplifier can be used with an AD204,as shown in Picture.

A three-pole active filter is included in the design toget normal-mode rejection of frequencies above a few Hz and to provide enhanced common-mode rejection at 60 Hz.

If offset adjustment is needed, it is best done at the trim pins of the OP07 itself; gain adjustment can be done at the feedback resistor. Note that the isolated supply current is large enough to Mandate the use of 1 mF supply bypass capacitors.