Abstract: A device for measuring and indicating changes in the resistance of a living body including a single battery source, a means for setting a reference voltage level provided across the battery, a unity gain high input impedance and low output impedance buffer amplifier having as its input the reference voltage level, a balanceable resistance bridge having the output of the buffer amplifier applied thereto and having the living body coupled thereto as a part of the bridge, a meter amplifier for amplifying any imbalances in the bridge caused by changes in the resistance of the living body and a meter coupled to the output of the meter amplifier for indicating the changes in resistance of the living body.