A simple battery-operated a.c. impedance meter

WrIEN skin electrodes are used for monitoring small biological signals, e.g. an e.e.g., it is important to produce a low-impedance contact. General-purpose multimeters which provide resistance ranges use a relatively large d.c. current (50/zA) giving a polarising effect and they are sensitive to battery voltage. An a.c. impedance meter has been developed… CONTINUE READING