Abstract: A circuit uses a single control input to an oscillator of an electronic ballast to program the parameters of soft-start frequency, pre-heat frequency, ignition ramp time, and ballast run frequency. The output frequency of the oscillator is based on an electrical parameter at the control input node. A resistor-capacitor network may be used to program the soft-start ramp time and ignition ramp time. The resistive element of the restive-capacitance network may be used to program the pre-heat frequency. A switchable impedance may be used to program the ballast run frequency. A look-up table circuit may also be used in the alternative to implement a single control input for the oscillator of an electronic ballast.
Abstract: The median frequency in the emission from a microwave generator (14), which operates in a pulsed manner, is shifted when the generator (14) operates between passive reflectors (23) whose axes are parallel thereto. In the axial direction, the reflectors (23) are approximately the same length (L) as the generator (14), with length matching through telescopic rods being preferable. However, the frequency is governed primarily by the distance (D) between the reflectors (23-23) between which the generator (14) is operated. Once desired resonance conditions have been found, for example for injection of microwave radiation into the mechanical structure of an external arrangement, this frequency relationship can be fixed by the magnitude of the length of the preferably telescopic coupling piece (16) between the resonator (13) and the antenna (18).
Abstract: An oscillator for a power converter control outputs a pulse train based on a charging time of a capacitor linked to a variable current source. A digital to analog converter (DAC) controls the variable current source in conjunction with a switch to determine the charging time of the capacitor. By varying the digital DAC input, the charging time of the capacitor is modified, thereby modifying the frequency of the pulse train. A comparator compares the capacitor voltage to a toggled threshold, which switches depending on whether the capacitor is charging or discharging. The comparator output supplies the pulse train that can be used in a half bridge switching arrangement for the power converter, which can also serve as an electronic ballast for a lamp.
March 2, 2004
Date of Patent:
March 6, 2007
International Rectifier Corporation
Thomas J. Ribarich, Peter Green, Muthu Subaramanian
Abstract: A plurality of battery/voltage polarity switching circuits are constrained to operate in switching synchronism by a timing circuit associated with each polarity switching circuit that are interrelated to one another such that only the fastest response timing circuit is operative to supply a common synchronizing signal to all the polarity switching circuits.
Abstract: A high-frequency, high-power generator of the type in which energy is stored in the capacitance of a transmission line and then discharged into a load by the action of a spark discharge device. The load is connected between one end of a transmission line conductor and ground and the other end of the same conductor is grounded. The line is folded and both ends of the other transmission line conductor are connected to the spark discharge device. A charging circuit applies a voltage to the latter conductor and when it reaches the discharge potential of the spark discharge device, the latter discharges to connect both ends of that conductor to ground. This provides relatively well-defined positive and negative pulses to the load.