space of the refrigerating equipment in order to obtain a predetermined temperature and a variable level of humidity by a sequence of operations which will be described later it is also made up of at least one conventional compressor 8 electrically startable and stoppable by ordinary means setting devices 6 and 7 each consist of a continuously adjustable potentiometer or other similar device linked to a graduated manually operated knob placed in a predetermined control position in this way by placing the knob of each potentiometer in its relative control position corresponding output voltages v a and v b of proportional size are obtained the output voltage v a is then applied to input 9 of a conventional controlled voltage generator 10 which then furnishes an output voltage v c to input 11 of a first comparator 12 this condition occurring when no voltage is applied to the other input 13 of generator 10 this control device also includes a conventional temperature sensor element 14 placed in contact with the external surface of the evaporator in the refrigerated space so as to register the temperature of the surface this sensor generates an output voltage v d which corresponds to the temperature level measured on the evaporator surface and applies that output voltage to an input 15 of comparator 12 comparator 12 also has an output 16 connected to compressor 8 and to a conventional counter 17.