A semiconductor package may include a substrate, and a structural body disposed over the substrate. In accordance with some embodiments, a plunger may comprise a ceramic material andor may have a facial profile that may allow for more efficient pumping operations. The heat generator is formed containing, for example, gold or tungsten. A control unit serves to control the drive in response to the sensed yarn tension to change the vertical position of the yarn guiding element. In response to duty cycle not being within an acceptance range, drive adjust circuitry provides a drive adjustment signal to adjust duty cycle at an output buffer by turning on one or more p-channel drive transistors, one or more n-channel drive transistors, or a combination of both.