A detector of an event includes an electrical energy generator formed by a flexible piezoelectric element with a weight fastened to the flexible piezoelectric element that is biased with the weight in a position with the piezoelectric element flexed. In response to detection of the event, a trigger releases the weight so as to cause a vibration of the piezoelectric element. This vibration is converted by the flexible piezoelectric element into electrical energy. An electronic system is power by the electrical energy and is operable to generate an electrical signal indicative of the detected event.