A magnetic stimulator consisting of a capacitor discharge and associated control circuits was designed and constructed for use in research and practice. This stimulator is capable of delivering an output voltage of 1000 V and output peak current of 8 kA to a coil. Depending on the coil used, the rise time of the current pulse can be varied in steps of 30 µs or less. After each discharge, the stimulator measures the output current amplitude to within 0.2 kA and rise time to within 10 µs, and

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... lays their values on a liquid crystal panel. The stimulator can operate in pulsed or in repetitive discharge mode (1 pulse per 5 seconds). With minor modifications, the stimulator can operate up to 1600 V and provide up to 16 kA. The rise time can be changed in steps of 10 µs or less. The capability to provide output current of variable rise time makes this stimulator is a versatile instrument for both research and clinical use of magnetic stimulation. This feature, which is found in no other stimulating instrument, is important for studying the effect of current rise time on magnetically induced stimulation. With this device we can determine the optimum current pulse shape for effective stimulation with the minimum energy.