A two-switch (14a, 14b) flyback power supply including: - a transformer having a primary winding and a secondary winding to feed a load, - a diode and a further diode, - a pair of electronic switches (14a, 14b) alternatively switcheable on and off to connect the primary winding of said transformer to an input line to feed said primary winding of said transformer, wherein one of said electronic switches (14a, 14b) is interposed between said input line and the cathode of said further diode, wherein the anode of said further diode is coupled to the ground of the power supply, wherein the other of said electronic switches (14a, 14b) is interposed between the ground of the power supply and the anode of said diode, the cathode of said diode being connected to said input line, and wherein both ends of said primary winding of said transformer are respectively connected to the intermediate point between said one of said electronic switches (14a, 14b) and said further diode and to the intermediate point between said diode and said other of said electronic switches (14a, 14b), whereby said one of said electronic switches (14a, 14b) is an electronic switch having a control electrode floating with respect to ground, characterized in that the power supply includes: - a capacitive voltage divider (C1, C2) arranged between said input line and the ground of the device, with the dividing point of said capacitive voltage divider (C1, C2) connected to an intermediate point of said primary winding of said transformer, and - an auxiliary secondary winding (T 2AUX) in said transformer, one of the ends of said auxiliary secondary winding being connected to the control electrode of said one of said electronic switches (14a, 14b) and the opposite end of said auxiliary secondary winding being connected to the cathode of said further diode. - a transformer having a primary winding and a secondary winding to feed a load, - a diode and a further diode, - a pair of electronic switches (14a, 14b) alternatively switcheable on and off to connect the primary winding of said transformer to an input line to feed said primary winding of said transformer, wherein one of said electronic switches (14a, 14b) is interposed between said input line and the cathode of said further diode, wherein the anode of said further diode is coupled to the ground of the power supply, wherein the other of said electronic switches (14a, 14b) is interposed between the ground of the power supply and the anode of said diode, the cathode of said diode being connected to said input line, and wherein both ends of said primary winding of said transformer are respectively connected to the intermediate point between said one of said electronic switches (14a, 14b) and said further diode and to the intermediate point between said diode and said other of said electronic switches (14a, 14b), whereby said one of said electronic switches (14a, 14b) is an electronic switch having a control electrode floating with respect to ground, characterized in that the power supply includes: - a capacitive voltage divider (C1, C2) arranged between said input line and the ground of the device, with the dividing point of said capacitive voltage divider (C1, C2) connected to an intermediate point of said primary winding of said transformer, and - an auxiliary secondary winding (T 2AUX) in said transformer, one of the ends of said auxiliary secondary winding being connected to the control electrode of said one of said electronic switches (14a, 14b) and the opposite end of said auxiliary secondary winding being connected to the cathode of said further diode.