Abstract: A lighting system composed of: an AC ballast for delivering AC power from an AC power source to a lamp; an emergency power supply for delivering AC power to the lamp when the AC power source fails; and a switch for disconnecting the AC ballast from the AC power source when the AC power source fails.

Abstract: A table tennis game is provided that can be used with an automatic table tennis ball serving device, the game including a plurality of sensors which can be arranged on the surface of the table to serve as targets, the sensors having means for detecting the impact of a table tennis ball. The game contains a programmable microcomputer connected to the sensors which converts the impact into a score, calculates the automatic server's score, times the game, and displays the respective scores and elapsed time of play.

Abstract: A liquid level sensing device for determining the level of a liquid in a liquid confining unit, methods of making and operating the device and a laundry machine using the device are provided, the device comprising a pair of electrode plates disposed in spaced apart relation so as to be adapted to be in a certain position relative to the confining unit and having opposed ends, an electrical circuit connected to the electrode plates for creating a voltage signal therefrom that varies in relation to the level of the liquid in the confining unit relative to the electrode plates, a control for determining the actual level of the liquid from the signal, and a third electrode plate disposed in spaced apart relation to the pair of electrode plates and being adapted to cooperate with one of the pair of electrode plates to provide a reference voltage signal to determine the electrolytic base of the liquid.

Abstract: A liquid level sensing device for determining the level of a liquid in a liquid confining unit, methods of making and operating the device and a laundry machine using the device are provided, the device comprising a pair of electrode plates disposed in spaced apart relation so as to be adapted to be in a certain position relative to the confining unit and having opposed ends, an electrical circuit connected to the electrode plates for creating a voltage signal therefrom that varies in relation to the level of the liquid in the confining unit relative to the electrode plates, a control for determining the actual level of the liquid from the signal, and a third electrode plate disposed in spaced apart relation to the pair of electrode plates and being adapted to cooperate with one of the pair of electrode plates to provide a reference voltage signal to determine the electrolytic base of the liquid.

Abstract: A method and circuit for operating a fluorescent lamp having a starter with power supplied by a battery by generating an alternating current from energy supplied by the battery; supplying the alternating current as a starting current to the lamp for a selected period of time; and, at the end of the selected period of time, generating a direct current from the alternating current and supplying the direct current to the lamp in place of the alternating current.

Abstract: A closed-loop control for sensing the completion of popcorn popping in a microwave oven and automatically shutting down the oven. A microphone type sensor is acoustically coupled to the microwave oven cavity and provides an electrical signal to an amplifier and filter. The amplified and filtered signal is processed by a pop detector which includes an integrator and shut-down command generator responsive to a decreasing rate of popping to shut the oven off. The integrator provides a pre-pop timer function to maintain the oven on until popping commences. In an alternative sensor embodiment, a piezolelectric type sensor is used. In an alternative pop detector embodiment an adaptive threshold comparator which automatically adjusts pop detector operation to discriminate the popping signal from ambient noise present in the oven.

Abstract: A closed-loop control for sensing the completion of popcorn popping in a microwave oven and automatically shutting down the oven. A sensor is acoustically coupled to the microwave oven cavity and provides an electrical signal to an amplifier and filter. The amplified and filtered signal is processed by a pop detector which includes an integrator and shut-down command generator responsive to a decreasing rate of popping to shut the oven off. The integrator provides a pre-pop timer function to maintain the oven on until popping commences. In an alternative embodiment, the peak rate of popping is detected and held and the oven is shut off when the popping rate falls to a predetermined ratio of the peak rate or a predetermined time elapses after the peak rate is detected, whichever first occurs.