A simple IC pulse-pair stimulator

The present paper describes a simple and relatively inexpensive brain stimulator circuit for generating trains of conditioning (C) and test (T) pulse pairs for refractory period and excitability cycle analyses. G and T outputs are constant-current monophasic cathodal pulses of adjustable frequency, duration, amplitude, and delay. C and T pulses can be controlled manually or through logic programming and can be fed out the same or separate channels. The stimulator can be operated on either ac or dc supplies and, when battery operated, features a high degree of stimulus isolation.