Abstract: A method for manufacturing a PMUT device including a piezoelectric element located at a membrane element is provided. The method includes receiving a silicon on insulator substrate having a first silicon layer, an oxide layer, and a second silicon layer. Portions of a first surface of the second silicon layer are exposed by removing exposed side portions of the first silicon layer and corresponding portions of the oxide layer, and a central portion including the remaining portions of the first silicon layer and of the oxide layer is defined. Anchor portions for the membrane element are formed at the exposed portions of the first surface of the second silicon layer. The piezoelectric element is formed above the central portion, and the membrane element is defined by selectively removing the second layer and removing the remaining portion of the oxide from under the remaining portion of the first silicon layer.

Abstract: A monitoring circuit for an electrical generator for recharging a motor vehicle battery. The monitoring circuit includes a driver transistor, a field coil current sensor, and driver circuit. The collector-emitter path of the driver transistor is connected in series to the field coil of the generator and a direct current voltage source. The field coil current sensor provides a signal indicative of the current flowing in the field coil. The driver circuit drives the transistor as a function of the voltage produced by the generator and the signal provided by the field coil current sensor. The driver circuit includes a detector circuit and a processing and comparison circuit. The detector circuit is connected to a phase of the generator and provides a signal indicative of the generator's rotation speed.

Abstract: The system includes a current generator including an alternator and an associated rectifier whose output is connected by a cable to a terminal of a battery. A switch is connected to that terminal of the battery and an indicator lamp connected in series with the switch is switched on when no current is supplied by the generator. A voltage regulator is connected to the field winding of the generator and has first and second inputs connected to the output of the generator and to the lamp respectively. The voltage regulator includes a control circuit for monitoring the potential difference between the first and second inputs of the voltage regulator and for switching on the lamp if that potential difference is greater than a pre-established reference value when the generator is operating. This enables any interruption of the connection between the generator and the battery to be indicated to the user.

Abstract: A system for recharging a battery includes a current generator, a switch operable by a key and connected to the battery, an indicator lamp connected in series with the switch, and a voltage regulator with first and second inputs connected to the output of the generator and to the lamp, respectively. The regulator includes a circuit for regulating the current supplied to the field winding of the alternator in dependence on the voltage supplied by the generator, a supply circuit for supplying the voltage regulator circuit, and control circuit for enabling the supply circuit to operate when a current is flowing in the lamp and when the generator is in operation. The control circuit includes a comparator connected to the second input of the regulator, and hence to the lamp, and adapted to supply an enabling signal to the supply circuit when the voltage at the second terminal exceeds a predetermined threshold.