Abstract: A system and method for providing a constant current source driver for a light emitting diode string. The converter includes a current sensor that derives feedback signal corresponding to a peak current through the light emitting diode string. The feedback signal is used by a controller to vary a duty cycle of the controller to regulate the average current. The controller is operable to regulate the average current as the number of light emitting diodes is increased and/or decreased.

Abstract: A system and method for providing a constant current source driver for a light emitting diode string. The converter includes a current sensor that derives feedback signal corresponding to a peak current through the light emitting diode string. The feedback signal is used by a controller to vary a duty cycle of the controller to regulate the average current. The controller is operable to regulate the average current as the number of light emitting diodes is increased and/or decreased.

Abstract: A receiver for demodulating differential phase shift keying data, the data having bit values dependent upon whether the phase of a carrier is inverted or not inverted during a bit interval, the receiver having a phase locked loop oscillator for locking up with the phase of the carrier, a phase detector for sensing differences in phases between the oscillator signal and the incoming data, an oscillator controller for controlling the output phase of the oscillator in response to the phase detector, a phase sense detector which detects whether or not the carrier has been inverted, a data clock responsive to the oscillator and to the phase sense detector for providing a data clock signal defining a bit interval, and a bit detector responsive to the phase sense detector, the data clock and the oscillator for integrating the incoming data.

Abstract: A remotely controlled dimming solid state ballast system for gas discharge lamps adapted to respond to external control signals is disclosed which includes the ballast itself along with integral controls for interfacing with an external addressing control system, which may be a powerline carrier system. The external control system includes a signal receiver for receiving, and recognizing remotely transmitted control signals addressed to said ballast. An output device is provided for generating an output control signal modulated in response to the control signals to provide the desired control setpoint of the lamps controlled by the ballast or to turn the lamps on or off.

Abstract: A transducer for providing an output signal having a value determined by an input pressure differential includes a capacitance manometer having a first input for receiving a first input pressure and a second input for receiving a second input pressure, the capacitance manometer having a capacitance determined by the difference between the first and second input pressures, and an output circuit connected to the capacitance manometer for providing an output signal having a value dependent upon the capacitance.

Abstract: An access control card for use in an access control system. A battery, a wireless signal sensor such as an antenna for receiving coded wireless signals such as coded radio frequency signals generated by a card reader, a clock connected to the battery and including a receiver are connected to the antenna for supplying a received signal based upon the coded radio frequency signal. A memory for stores first and second stored codes, and a transmit circuit connected to the antenna, to the clock and to the memory compares the first stored code to the received signal and transmits the second stored code when there is a match between the received signal and the first stored code.