Abstract: The invention concerns an acoustic alarm safety device comprising a case (2), a vibrating element (20) associated to a membrane (22) so as to make it vibrate, electrical means for providing a control signal to said vibrating element, and means (18) for actuating the electrical means.This device is characterized in that it further comprises a pierced backcover (28) attached to said case (2) and arranged so as to protect it, and so as to allow a vibration of the set of the vibrating element-membrane (20, 22), said backcover being attached to said case in a manually removable manner, and a fitted ring (26) to which is attached said membrane (22), said ring (26) and said membrane (22) being associated to the case in such a way that the set ring-membrane (26, 22) ensures the waterproofness of the case (2).

Abstract: The control circuit of the piezoelectric vibrator comprises two branches, each comprising switching means (T1, T2) arranged to go into a blocking state and a conducting state following the reception of a control signal, and a series connection of a coil (2,2') with a diode (3,3'), a first terminal (A,A') of said series connection being connected to a voltage supply source (1) and a second terminal (B,B') of said connection being connected to said switching means (T1,T2).The vibrator (4) is connected between said second terminals (B,B') so as to be excited in alternance in a first direction, when said first switching means are in the blocking state and at the same time the second switching means are in the conducting state, and in a second direction, when said second switching means are in the blocking state while at the same time the first switching means are in the conducting state.