Abstract: The hand-held induction air-cooled induction heater used for heating of metallic mechanical or decorative objects to facilitate their removal or installation contains a high frequency inverter operating in voltage or current resonant mode, including power semiconductor switching device(s) having turn-on or turn-off delay time, circuitry to control the timing of on and off periods of said switching device(s), the circuitry having delay time, wherein the threshold voltage or current reference to initiate commutation or timing is not zero, and is dynamically varied in response to the instantaneous input inverter supply voltage and/or inverter frequency to achieve switching device(s) heating or dissipation reduction resulting from improved commutation timing of said power switching devices.

Abstract: The present invention concerns a projection system for providing a distributed manifestation within an environment. The projection system includes a data generator for generating a plurality of data sets of associated state data and spatial coordinate data. The projection system also includes a projector in communication with the data generator for receiving the data sets. The projector is provided with a signal generating module for generating a plurality of electromagnetic signals, and a projecting module for projecting each of the electromagnetic signals towards a target location within the environment. The projection system also includes a plurality of receiving units distributed within the environment, each receiving unit having a receiver for receiving one of the electromagnetic signals when the receiving unit is positioned in the corresponding target location, each receiving unit being adapted to perform a change of state in response to the state data.

Abstract: Disclosed is a high voltage inverter for converting DC power to AC power with one or more AC output phases. The inverter has for each AC output phase an AC input phase circuit comprising first and second cold cathode field emission controllable electron tubes of triode, tetrode or pentode structure. Each electron tube has a first input node for connection to a high voltage DC potential in excess of 20 KV and a second input node for connection to ground. First electron tube is serially connected between a first end of a primary winding and ground, and second electron tube is serially connected between a second end of the primary winding and ground. Control circuitry controls the electron tubes so that the first and second electron tubes alternatively conduct so as to alternately bring the first and then second end of the primary winding approximately to the potential of ground.

Abstract: A circuit and method are provided for supplying a DC output signal having a magnitude that is proportional to the mathematical product of a variable frequency AC signal and a variable magnitude DC signal. The method implemented by the circuit includes converting the variable frequency AC signal to a first intermediate AC signal that is a fixed pulse-width, variable period signal having a duty cycle representative of the frequency of the AC signal, and having an amplitude that varies between a first voltage magnitude and a second voltage magnitude. The first intermediate AC signal is converted to a second intermediate AC signal by setting the first intermediate AC signal amplitude equal to a third voltage magnitude when the intermediate signal amplitude is equal to the first voltage magnitude, and equal to a fourth voltage magnitude when the intermediate signal amplitude is equal to the second voltage magnitude. The second intermediate AC signal is filtered to thereby convert it to the DC voltage signal.

Abstract: An electrical invertor circuit comprising a first common electrode and at least two secondary electrodes and means permitting an electric discharge to be established between said first electrode and any one of said second electrodes. A magnetic field is applied through the gaps between said first electrode and said secondary electrodes so as to switch the discharge from one to another of the secondary electrodes. In one arrangement there are two secondary electrodes in the form of two secondary substantially semi-annular electrodes disposed around a circular central electrode so that a rotating spoke discharge is formed. The two semi-annular electrodes are then connected to the terminals of the primary winding of an output transformer whereas a center tap of said winding is connectable to the central electrode through a D.C. power supply.