A program-controlled laundry drier equipped with a rotary drum in which the material to be dried is inserted and moved during the drying process. The dryer comprising a heater for heating the drying air and a blower which guides the drying air stream into the interior of the drum. The axis of a current generator is mechanically coupled to the rotary drum and the output voltage of the current generator is applied to the excitation winding of a relay whose switching contacts switch the heating current circuit for the drying air.