A variety of swing training devices that are arranged to support a ball to be struck are described. A drive circuit includes a shift register circuit, and the shift register circuit includes n pieces of basic circuits which are connected vertically in multiple stages. The second shaft can be connected by a third gear-shifting element to the first power path and by a fourth gear-shifting element to the second power path. The spectral characterization is then modified to produce a modified spectral characterization. In another embodiment, a conductive line can be electrically connected to one or more rows or columns of memory cells, and another conductive line can be more rows or more columns of memory cells.