A temperature-activated valve for a conventional fire sprinkler utilizing a hyperelastic single-crystal shape memory alloy is described. The element retrieval device is configured to retrieve and transport a movable element in response to control data. The group code may be determined based on the link or linkset from which a message is received or from the message itself. The active transient response circuit is coupled between the output stage and the multiphase pulse width modulator and configured to detect the voltage level at the output stage and provide a signal to the multiphase pulse width modulator that is a function of the amplitude of the deviation of the detected voltage level from a target voltage. Selecting or rejecting electrode locations involves selecting locations suitable for implantation of subcutaneous cardiac electrodes and implanting at the selected locations. The movement signal is evaluated to identify a periodic signal component thereof, and the frequency of this periodic signal component is identified.