The present invention describes a method for tracking a solar generator having a plurality of solar modules to the sun, wherein at least one electric output quantity of part of the solar module of the solar generator is detected and a tracker, on which the solar generator is mounted, is controlled such that the detected electric output quantity has a predetermined value. As a result, an undercut of a fixation hole is reduced or eliminated, and hence it becomes easier to process a die. The system comprising a feed back system comprising the input, the adaptive filter, at least an ear microphone, at least one sound reproduction means and a comparison means for comparing an input signal to a signal received by the microphone upon during reproduction of said input signal, said comparison means providing a comparison signal for regulating the adaptive filter. The first processing unit receives status on the second device from the first device indicating whether the second device is available or unavailable. Among other things, the outlet box may also be provided with external cable clamps, fold-out depth tangs, device connection flanges, and pre-attached ground leads. The packaged compounds and agents also include instructions for using the agent to promote axonal growth in a subject.