Abstract: A water purification apparatus is provided. The apparatus includes a casing and an electrode array. The casing has an outer surface, a substantially annular inner surface, and a water flow passage chamber surrounded by the substantially annular inner surface, the water flow passage chamber providing an outer annulus region and an inner central region. The electrode array features at least four electrodes in adjacent relationship to one another and circumferentially spaced apart from another about the outer annulus region, each electrode having a respective first planar surface and a respective second planar surface facing and substantially parallel to the respective second planar surface and the respective first planar surface of the adjacent electrodes on opposite sides thereof.

Abstract: A water purification apparatus is provided. The apparatus includes a casing and an electrode array. The casing has an outer surface, a substantially annular inner surface, and a water flow passage chamber surrounded by the substantially annular inner surface, the water flow passage chamber providing an outer annulus region and an inner central region. The electrode array features at least four electrodes in adjacent relationship to one another and circumferentially spaced apart from another about the outer annulus region, each electrode having a respective first planar surface and a respective second planar surface facing and substantially parallel to the respective second planar surface and the respective first planar surface of the adjacent electrodes on opposite sides thereof.

Abstract: A swimming pool alarm system is provided for actuating an alarm in response to the movement of a person in a swimming pool. The system includes a transmitter mounted below the surface of a swimming pool to continuously transmit ultrasonic sound waves through the body of water, and a similarly positioned receiver detects sound waves in the water and generates an electrical signal in response thereto. The electrical signal is continuously monitored, and the movement of a person in the pool alters the received ultrasonic sound waves and the corresponding electrical signal to produce an alarm signal for actuating an alarm indicator.

Abstract: The invention comprises a self-adjusting ballast system for a high intensity discharge lamp. The ballast has a current limiter which modifies the lamp's present duty cycle to prevent damage if bulb rectification or another overcurrent condition occurs. It also has a current integration feedback loop for controlling lamp current during start-up.

Abstract: A self-adjusting ballast system for a high intensity discharge lamp. A lightweight, inexpensive and efficient ballast controls the strike and warmup stages of the high intensity discharge lamp, in particular high wattage lamps, through direct sensing of the radiant energy or heat output of the lamp itself. A current controller corrects for current imbalance in the alternating current lamp circuit due to bulb rectification or magnetic imbalance in the inverter transformer system.

Abstract: An analog read-only memory system is provided for converting an input signal to an output signal functionally related to the antilog of the input signal. A resistor-capacitor network conveniently provides an analog memory circuit, converting a linear time base to an output voltage antilogarithmically related to the charging time. Solid state switching devices are actuated in response to control signals to initiate a memory sweep, or capacitor charging cycle, after a time interval determined by the input signal to form the desired antilog conversion; and transferring the output signal to a holding circuit until a subsequent output is provided. The memory sweep is periodically repeated to maintain an output in antilogarithmic relationship with the input.