Coil Winders help wind bobbins with Copper wire and these bobbins are used in various applications such as in reed relay coils, microphone, speakers, motors and generators. Coil winders, or coil winding machines, as they are also know, wind bobbins with the enameled Copper wire at very high speeds. For the winding to be consistent as well as to ensure cable cuts are minimized, closed loop tension control systems are used. The wire, which is to be wound, is usually taken through a spring, which gives cushioning when winding on bobbins, which are not circular. The purpose of this arm is to also act a a buffer for feeding wire to the bobbin, during high speed winding. A reed sensor mounted on this arm, with a magnet mounted on the lower limit stop ensures that the optimum tension level of the wire is always maintained during winding and this provides a closed loop system. Reed Sensors can also accurately count the number of turns on a bobbin, as it is being rotated.