Electromechanical generator for converting mechanical vibrational energy into electrical energy, comprising: a central mast, an electrically conductive coil assembly 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, a biasing device mounted between the mast and the core assembly and comprising a pair of first and second plate springs, each having an inner edge respectively fitted to first and second opposite ends of the mast and an outer edge fitted to the magnetic core assembly, each of the plate springs comprising a spring member comprising an inner portion substantially orthogonal to the axis and including the respective inner edge, and a cylindrical outer portion substantially parallel to the axis and including the respective outer edge, the spring member being a folded sheet spring and the inner and outer portions are connected by a fold.