Method and device for controlling the thread joining in rotor spinning machines

Device for controlling thread joining in a rotor-spinning machine having means for rotating the rotor of the spinning-machine, means for introducing a thread to be joined into the rotating spinning-machine rotor, means for feeding fiber into the rotating rotor so as to form a ring thereof coming into contact with the thread so as to be joined thereto, and means for withdrawing the joined thread from the rotating spinning-machine rotor, comprising means for detecting the rotary speed of the spinning machine rotor at a given instant, pulse generating means for producing pulses with a frequency proportional to the rotary speed of the rotor of the spinning machine, said pulse generating means comprising a pulse transmitter connected to a rotating member of the spinning machine, and a pulse receiver, said rotating member being a part of the spinning machine revolving at a speed proportional to the rotary speed of the rotor of the spinning machine, and means actuable by the pulses for digitally influencing a measure of the material being spun in the spinning operation.