> > Those ubiquitous motion detectors for outdoor lights use capacitive dropping > to supply the > low voltage for the ICs and electronics. Cap and small R in series with the > AC input to a bridge rectifier. > Works out well in that the bridge rectifier permits current flow in both > directions, which is > necessary to get current flow through the cap (the cap has to charge and > discharge).
Over here that sort of circuit was common for the power supply for the control electronics in washing machines and the like. It may still be, I've not worked on anything that recent. -tony
