WPI stimulators for electrophysiology research are constant current stimulators. These are preferred over constant voltage stimulators, because:

• Current is the quantity that stimulates most excitable tissues.
• Stimulating electrodes (and some tissues) tend to increase their resistance as stimulation progresses.

A constant current stimulator "senses" the resistance change and provides whatever voltage is needed to maintain delivery of current at the set rate.

Stimulus isolators isolate a given stimulus from ground. WPI isolators in the 300 and DLS series offer a compliance voltage (maximum output voltage) of 100V with very low noise