I would like to design measuring human skin conduction(like GSR; It is small impedace as i know).
So, Add circuits for measure small impedance like AD5933 Datasheet.
But I confused about Figure 35 (additional external amp circuit) and Figure 39(EVAL-AD5933EBZ USB Schematic) on AD5933 Data Sheet.
Which is add circuits? Figure 35? Figure 39?
Please, let me guide some ways, ASAP.