Many experiments in electrophysiology use a brief pulse of current as a stimulus to excite nerve or muscle fibers. It is desirable that the source of this E.M.F. should be isolated both from ground and from the timing generator used to release the stimulus. The DS2A and DS3 fulfill these requirements by using self contained batteries as the source of power and optical coupling is employed to isolate the stimulator from the trigger source. Precise timing of stimulus application can be controlled by a PC or other stimulus generating device such as the DG2 Trigger Generator. The duration of the stimulator output is adjustable over the range of 20 microseconds to two seconds by controls on the stimulators or can be the same as the applied trigger pulse.

Current is drawn from the batteries only and instruments have nonconductive enclosure. A single shot button is provided, which operates at all times irrespective of the trigger input.