The invention relates to a grinding machine for the edges of spectacles lenses, comprising at least one grindstone and one driven shaft for holding the spectacles lenses, said shaft being able to move radially and axially relatively to the grindstone. For a single-radio device, a control interval, in place of an open interval should be scheduled at least once every maximum service scheduling period. A diode has its anode connected to one of the power supply lines and has its cathode connected to an end of a resistor, the other end of the resistor is connected to an end of a capacitor, the other end of the capacitor is connected to the other of the power supply lines.