A power supply circuit, comprising: an AC to DC voltage converter (3, 5, 6, 8), having AC input terminals and DC output terminals, wherein said AC to DC voltage converter (3, 5, 6, 8) is configured to receive an AC mains voltage on said AC input terminals to generate a corresponding rectified DC voltage on said DC output terminals, wherein said AC to DC voltage converter (3, 5, 6, 8) comprises a full-wave diode bridge rectifier connected between said AC input and said DC output terminals to generate said rectified DC voltage as a rectified replica of said AC mains voltage and said AC to DC voltage converter (3, 5, 6, 8) comprises a tank capacitor connected between said DC output terminals to hold said rectified DC voltage and an input capacitor connected between the full-wave diode bridge rectifier and an AC input terminal of said AC input terminals in order to limit an AC current absorbed by said full-wave diode bridge rectifier and a resistor connected electrically in parallel with the tank capacitor to discharge the tank capacitor when the load cannot be supplied because it is out of order or its electrical connection is damaged; at least an input switch configured to connect/disconnect at least one AC input terminal of said AC input terminals to AC mains; at least one driving unit directly connected between a first DC output terminal of said DC output terminals and at least one respective intermediate terminal of the power supply circuit, said at least one driving unit being configured to generate a control signal which is logically active when said at least one respective intermediate terminal is not disconnected from a second DC output terminal of said DC output terminals; at least one output switch configured to be turned on when said control signal is logically active, and configured to connect a respective at least one load to be supplied by said DC output terminals allowing electric charge stored in the tank capacitor to flow throughout the load; a switching relay having an excitation coil connected between said AC input terminals and configured to be powered every time an AC voltage is applied to said AC input terminals, and having at least one internal switch controlled by said excitation coil and configured to connect said at least one respective intermediate terminal to said second DC output terminal of said DC output terminals when said excitation coil is not powered; wherein said at least one driving unit is a resistive voltage divider directly connected between said first DC output terminal and said at least one respective intermediate terminal, wherein said control signal is made available at a middle terminal of the resistive voltage divider. an AC to DC voltage converter (3, 5, 6, 8), having AC input terminals and DC output terminals, wherein said AC to DC voltage converter (3, 5, 6, 8) is configured to receive an AC mains voltage on said AC input terminals to generate a corresponding rectified DC voltage on said DC output terminals, wherein said AC to DC voltage converter (3, 5, 6, 8) comprises a full-wave diode bridge rectifier connected between said AC input and said DC output terminals to generate said rectified DC voltage as a rectified replica of said AC mains voltage and said AC to DC voltage converter (3, 5, 6, 8) comprises a tank capacitor connected between said DC output terminals to hold said rectified DC voltage and an input capacitor connected between the full-wave diode bridge rectifier and an AC input terminal of said AC input terminals in order to limit an AC current absorbed by said full-wave diode bridge rectifier and a resistor connected electrically in parallel with the tank capacitor to discharge the tank capacitor when the load cannot be supplied because it is out of order or its electrical connection is damaged; at least an input switch configured to connect/disconnect at least one AC input terminal of said AC input terminals to AC mains; at least one driving unit directly connected between a first DC output terminal of said DC output terminals and at least one respective intermediate terminal of the power supply circuit, said at least one driving unit being configured to generate a control signal which is logically active when said at least one respective intermediate terminal is not disconnected from a second DC output terminal of said DC output terminals; at least one output switch configured to be turned on when said control signal is logically active, and configured to connect a respective at least one load to be supplied by said DC output terminals allowing electric charge stored in the tank capacitor to flow throughout the load; a switching relay having an excitation coil connected between said AC input terminals and configured to be powered every time an AC voltage is applied to said AC input terminals, and having at least one internal switch controlled by said excitation coil and configured to connect said at least one respective intermediate terminal to said second DC output terminal of said DC output terminals when said excitation coil is not powered; wherein said at least one driving unit is a resistive voltage divider directly connected between said first DC output terminal and said at least one respective intermediate terminal, wherein said control signal is made available at a middle terminal of the resistive voltage divider.