Abstract: A photovoltaic system, method and apparatus are disclosed. In an exemplary embodiment, the system includes a photovoltaic array, a distribution system that distributes power within a premises of a demand-side energy consumer, an inverter coupled to the distribution system that is configured to convert DC power from the photovoltaic array to AC power and apply the AC power to the distribution system, a damping portion configured to damp high frequency voltages derived from the inverter, and trapping circuitry coupled to the damping portion that is configured to reduce a level of low frequency current traveling through the damping portion.

Abstract: An apparatus and method for switching between matching impedances is described. One illustrative embodiment matches a first predetermined value of a dynamically varying load impedance to a predetermined source impedance and causes a phase shift between the source and the load that permits a second predetermined value of the dynamically varying load impedance to be matched to the predetermined source impedance by the addition, between the source and the load, of a single reactive element. Determining whether the dynamically varying impedance of the load is the first predetermined value or the second predetermined value permits the single reactive element to be omitted from or included in an impedance-matching circuit as needed to match the dynamically varying impedance of the load to the predetermined source impedance.

Abstract: Disclosed herein is a modular aquarium apparatus generally comprising a watertight housing which suspends a glass thermometer safely therein. The housing includes a ballast chamber carrying a weight of predetermined characteristics sufficient to provide the housing with sufficient negative bouyancy such that the housing, without more, will float at the top of an aquarium with the lower portions of the housing submerged. With the addition of a special sinking sub-assembly carrying additional ballast the aforementioned thermometer housing may be converted into a sinkable housing for measuring temperatures at the bottom of the aquarium. Alternatively, the housing may be provided with a special cap and hanger arrangement for converting the housing into a hanging thermometer assembly adapted to be suspended from the upper wall portions of an aquarium tank.

Abstract: An aquarium thermometer is provided which may be selectively, horizontally positioned at a plurality of depths along a wall of an aquarium tank for comparing the temperatures at different levels to ascertain and to monitor temperature gradients in the tank. The thermometer assembly of the invention includes a water tight house having spaced ferrous components or magnets adjacent the opposite ends of the thermometer scale. A separate positioning handle, having similarly spaced, registerable magnets at its opposite ends, is adapted to cooperate with the thermometer housing on the wall, to cause the thermometer inside the tank to move correspondingly with the handle. The positioning handle and the thermometer housing may mount pairs of oppositely polarized magnets.

Abstract: A simplified keyboard for a terminal device, calculator, or the like, in which each key is sequentially scanned and parallel key code data is sent to an entry register. A pair of flip-flops in combination with firmware ascertain that only valid key code data is sent to the entry register for utilization by the system, providing double entry and key bounce protection. The firmware further provides N-key rollover and auto repeat with a variable repeat rate, and expands the keyboard from a single-mode to an eight-mode capability.