A hand held shower head with a filter replacing pre-alarm assembly includes a propeller wheel with a magnetically induced signal emitter and a correspondingly placed signal receptor, as well as a digital display connected to the signal receptor. The voltage drive circuit may include a series stack of capacitors connected between gates of the stacked PMOS and NMOS transistors. The cleaning head assembly is moveably mounted on a support beam so as to be maintained a substantially fixed distance from the caul sheet. The assembly also includes at least one bearer for locating and supporting a load, such as long products, on the tray. The phases and duty cycles of the digital switching signals are controlled by the digital control circuit.