Background Commercial transcranial magnetic stimulators are massive and may be difficult to transport for lecture and teaching purposes Objective To design and construct a portable, battery-powered magnetic stimulator of the lowest possible mass for use in demonstrations and simple measurements Results The functioning battery-powered single-pulse system is relatively inexpensive, weighs less than 7 pounds, including coil, incorporates external sync capability, and functions well for the intended purposes Conclusions The device may useful for teachers, researchers, and clinicians