An electromechanical generator for converting mechanical vibrational energy into electrical energy, the electromechanical generator comprising: a central mast, an electrically conductive coil assembly fixedly mounted to the mast, a mount for the coil assembly, a magnetic core assembly movably mounted to the mast for vibrational motion along an axis, wherein the magnetic core assembly comprises: an outer core, comprising a one-piece tubular body, which encloses the electrically conductive coil assembly side, first and second end cores magnetically coupled to the outer core at respective first and second ends of the outer core, the first and second end cores extending radially inwardly and enclosing respective first and second opposite edges of the coil assembly, and first and second magnets spaced along the axis, contacting and being magnetically coupled to the respective first and second end cores, and defining therebetween a gap in the magnetic core assembly through which the mount extends.