A SIMPLE ELECTRONIC TIMER TO REGULATE PULSE TRAIN FROM ORDINARY STIMULATOR FOR EXPERIMENTS IN NEUROPHYSIOLOGY

A simple electronic timer for regulating pulse train from an ordinary simple stimulator is described. The timer has been constructed using N E555V, a monolithic integrated circuit used in an astable timing opera tion mode. It can be connected to any ordinary stimulator to provide t rains of pulses of variable duration and frequency. Trains of four pul ses in 2s at 30s intervals were generated by the timer from an ordinar y Grass SD9 stimulator and were comparable to the pulses from the Gras s S88.