Abstract: Disclosed herein are drug delivery devices and methods for component positioning of a pump, such as a linear shuttle pump. In some approaches, a system may include first and second terminals movable with respect to one another, and a sensor device operable to detect a change in capacitance between the first and second terminals as the first and second terminals move with respect to one another. The sensor device may include a two-stage charger connected with a controller and a voltage source, the two-stage charger having a first capacitor connected with a first switch and a second capacitor connected with a second switch, the controller being operable to close the first switch to connect the first capacitor with the voltage source to charge the first capacitor, and open the first switch and close the second switch to connect the second capacitor with the voltage source to charge the second capacitor.