A yarn feeder (10) provided with a drum (12) which supports, wound thereon, a yarn (Y) which can be unwound upon request of a downstream machine, an annular braking body (16) is coaxially pushed against an output end (12a) of the drum (12) by actuation means (18) which act axially; an articulated joint (24) is functionally interposed between the actuation means (18) and the braking body (16); the weight of the braking body (16) generates a torque about at least one articulation axis (X, Z) of the joint (24), against which elastic means (34) act which are functionally associated with the joint (24).