Abstract: Protection against damage caused by excessively high input energies, e.g., from ocean storms, is provided in energy converting systems by, in response to the detection of excessively high input energies, changing the electrical impedance of the electrical load to which power from an electrical generator is being delivered for increasing the generator output current for reducing the power converting efficiency of the generator. This increases the mechanical impedance presented by the generator to the source of input energy for reducing the motion producing effect of the input energy.

Abstract: An input device for computers or electronic games using piezoelectric elements. Four piezoelectric devices are mounted on a base in positions ninety degrees apart. A user actuation element, such as a directional control pad and or a joystick is pivotally disposed on the base above the piezoelectric sensors. A biasing element such as a spring, foam or rubber element is positioned between the actuation element and the base to support the actuation device in a neutral position when no face is being applied by a user to also return the activation element to its neutral position after a user's force is removed. Opposing sensors are connected to a bridge circuit such that in the neutral position of the actuation element the output voltage of the bridge is one half of the input voltage.