The generator for a piezoelectric motor is also suitable for powering a high power LED for a dental polymerisation lamp via a rectifier, and comprises two transformers each including a primary winding and a secondary winding and four switches controlled by an ultrasonic reference oscillator, two switches being arranged to alternately connect the secondary windings of the two transformers to the piezoelectric load, and the other two switches being arranged to alternately connect the two primary windings to a voltage supply so that during the positive alternation, the primary winding of one of the transformers is charged with energy whereas the secondary winding of the other transformer is discharged into the piezoelectric load, and so that during the negative alternation, the secondary winding of the first transformer discharges the energy thereof whereas the primary winding of the first transformer is charged.