Systems and methods are provided for determining an orientation of one or more client devices relative to a computing device. The system diaphragm is seated in the image-side belly at a spacing in front of the image plane. The shaft extends generally downward from the cente of the bottom side of the handle, The pad is connected generally at the center of its top side to the bottom end of the shaft. The amplifier and clamp circuits may further include a clamp voltage generator circuit.