A refrigerating machine comprising: - a refrigerating circuit comprising a compressor, - an asynchronous electrical motor connected to said compressor to operate it; - at least one fan (14a, 14b) coupled to a heat exchanger of said refrigerating circuit; - an operating device connected to said electric motor and to said at least one fan (14a, 14b) to supply to them a constant voltage (Vo) output having a constant frequency; said refrigerating machine being characterized in that said operating device comprises an AC/AC converter having: - an input connector apt to be connected to a single-phase power supply grid; - an output connector directly connected to said electric motor and at least one fan (14a, 14b); said AC/AC converter being configured to be, in use, supplied at the input connector with an input voltage (V-mains) having an input frequency, and to supply an accordingly an output voltage (Vo), to the output connector, having an output frequency substantially equal to the input frequency; said AC/AC converter being configured such that, in use, said output voltage (Vo) has a value equal to a predetermined value which is independent of the value of said input voltage (V-mains); said output frequency being constant and having the same value to that of said power supply grid and wherein said operating device comprises: - a control device; - a fly-back type power supply, connected to said input connector to be electrically powered; - two switches (26, 27) of which a first switch is connected to the phase of said input connector and a second switch being connected to a bridge between phase and the Neutral of said input connector; said switches (26, 27) each comprising two IGBT elements and two diode elements; said IGBT elements each having one of said diode elements connected in parallel; said IGBT elements being connected reciprocally in series and with inverted polarity; said IGBT elements being also connected to said control device and to said flyback type power supply to be controlled by said controlling device. - a refrigerating circuit comprising a compressor, - an asynchronous electrical motor connected to said compressor to operate it; - at least one fan (14a, 14b) coupled to a heat exchanger of said refrigerating circuit; - an operating device connected to said electric motor and to said at least one fan (14a, 14b) to supply to them a constant voltage (Vo) output having a constant frequency; said refrigerating machine being characterized in that said operating device comprises an AC/AC converter having: - an input connector apt to be connected to a single-phase power supply grid; - an output connector directly connected to said electric motor and at least one fan (14a, 14b); - an input connector apt to be connected to a single-phase power supply grid; - an output connector directly connected to said electric motor and at least one fan (14a, 14b); said AC/AC converter being configured to be, in use, supplied at the input connector with an input voltage (V-mains) having an input frequency, and to supply an accordingly an output voltage (Vo), to the output connector, having an output frequency substantially equal to the input frequency; said AC/AC converter being configured such that, in use, said output voltage (Vo) has a value equal to a predetermined value which is independent of the value of said input voltage (V-mains); said output frequency being constant and having the same value to that of said power supply grid and wherein said operating device comprises: - a control device; - a fly-back type power supply, connected to said input connector to be electrically powered; - two switches (26, 27) of which a first switch is connected to the phase of said input connector and a second switch being connected to a bridge between phase and the Neutral of said input connector; - a control device; - a fly-back type power supply, connected to said input connector to be electrically powered; - two switches (26, 27) of which a first switch is connected to the phase of said input connector and a second switch being connected to a bridge between phase and the Neutral of said input connector; said switches (26, 27) each comprising two IGBT elements and two diode elements; said IGBT elements each having one of said diode elements connected in parallel; said IGBT elements being connected reciprocally in series and with inverted polarity; said IGBT elements being also connected to said control device and to said flyback type power supply to be controlled by said controlling device.