A circuit intended to provide two D.C. voltages of inverted polarities based on an A.C. voltage, comprising: two capacitors having their respective electrodes connected to two terminals intended to receive said A.C. voltage and having their second respective electrodes connected to each other by two first diodes in anti-series; a controllable current source having a first terminal connected to the common anodes of said first diodes; two second diodes connected in anti-series between said terminals intended to receive said A.C. voltage and having their common cathodes connected to a second terminal of said controllable current source; a circuit for controlling said current source; and two third diodes connected in anti-series between said terminals intended to receive said A.C. voltage, said control circuit sampling its power supply between the common cathodes of the second diodes and the common anodes of the third ones.