Hughes Aircraft Company

Beckman Instruments, Inc.

Magnetek, Inc.

Harry A Dellamano

Michael J Little

J David Margerum

Thomas A Nussmeier

Shi-Yin Wong

Andrew Philip Kisylia

Theodore Calderone

A preferred embodiment of the present invention provides a ballast circuit, comprising three sections: an input power section that receives a line AC signal as an input and provides a DC signal as an output; a pre-regulator section that conditions the DC signal; and a lamp driver section that drives a gas discharge lamp load. The pre-regulator section includes a transformer with an input winding, an output winding, and a current sense winding. The input winding receives the DC signal provided by the input power section. The output winding is connected in a flyback configuration with a flyback blocking diode, a bulk storage capacitor, and an output terminal for the conditioned DC signal. The current sense winding generates a signal proportional to the level of the transformer current. The transformer current is controlled by a flyback switch. A resonant capacitor is connected between the flyback switch input and ground, the resonant capacitor and the transformer forming a resonant circuit. A controller actuates the flyback switch, receiving as an input the current level signal and generating as an output a pulse voltage to the gate terminal of the flyback switch. The controller actuates the flyback switch at a predetermined time after the current level signal indicates zero transformer current, coinciding with the timing of the resonant circuit such that the switching means turns on when there is zero voltage across it.

Powerfactor correcting flyback arrangement having a resonant capacitor

A method and associated means for producing simultaneous electrical representations of the electrical and acoustical (heart sound) activity of the heart, in which a pickup device and associated circuits produce a full wave rectified symmetrical heart sound signal annotated by pulses developed from the QRS wave of the electrocardiogram signal. The pickup device is designed to permit the direct (unbuffered) application of the pickup electrodes to the skin of the body and to provide a control of the associated circuits when not in contact with the body to shorten response times when the pickup device is placed in contact with the body.

Method and improved apparatus for analyzing heart activity

Method and improved apparatus for analyzing activity

Method and apparatus for measuring the magnitude of a varying analog signal and for displaying a close approximation of a final stabilized value before the signal reaches stabilization. An analog-to-digital converter converts the analog signal to corresponding digital pulse signals and the digital pulse signals are displayed to an operator. Automatic display-hold circuitry determines the pulse count difference between successive pulse count signals separated by a predetermined time interval, compares the difference to predetermined value, and, when the predetermined value is reached, generates a control signal which locks the displayed value and prevents the display from updating as the analog signal continues to vary. The difference between pulse signals is taken by storing the first signal in an up/down counter and decrementing the counter in response to the second signal. The circuitry determines the pulse count difference and the sign of the difference between the two signals by counting either (1) the number of remaining pulses in the second signal after the counter decrements to zero or (2) the number of additional pulses required to decrement the counter to zero after termination of the second signal.

Signal measuring and display control method and apparatus

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Thousand Oaks, CA, United States of America

Harry A Dellamano