surface 6 of said storage drum in order to form an intermediate yarn store or yarn supply said yarn then is withdrawn by said textile machine overhead of said storage drum 3 depending on consumption in housing 1 a drive motor 7 for said winding element 4 is received which is controlled by a control device 8 said control device 8 is receiving control signals from a device s yarn sensor provided in housing bracket 2 drive motor 7 for example is controlled such that the yarn y is wound onto the storage drum 3 until the first winding 10 in withdrawal direction is reaching a detection zone 11 then the drive motor 7 is stopped or decelerated and will only then be accelerated again as soon as said detection zone has been cleared by said yarn again said device s contains at least one light source l and at least one signal generating receiver r light diode or photo transistor both of which are integrated into a switching circuit 12 a reflector b is provided countersunk below the surface 6 of said storage drum 3 which reflects light emitted by said light source l towards receiver r advantageously said reflector is situated at a light permeable plate p inserted into the surface 6 of said storage drum.