Abstract: A series resonant converter is interposed between an unregulated voltage source and an output circuit. The converter employs a pair of power switches each, when on, completing a series resonant circuit from the source to a resonant tank circuit including the primary winding of a transformer coupled to the output circuit. The power switches are alternately turned on and off so that sinusoidal current pulses alternately flow in opposite directions in the primary winding at a frequency dependent on input and output conditions. The current flowing in the resonant circuit is monitored and the power switches are additionally controlled to prevent turn on of one switch and turn off of the other when current is still flowing in the resonant circuit.

Abstract: A power supply is provided for supplying regulated power to an output from an unregulated DC voltage source. The supply includes low and high power series resonant converters, each including a pair of power switches which are alternately turned on and off for completing a series resonant circuit with the source and with a primary winding of a transformer coupled to the output. A switch control responds to loading of the output and drives the switches on and off at an operating frequency that varies with the loading. A converter control monitors the operating frequency and controls operation of the converters such that one or both converters operate in dependence upon loading to avoid operation within a particular frequency range.

Abstract: A data terminal is disclosed and which is particularly applicable for use in data capture and data readout in a data communication system. The terminal includes means for providing a data output presentation of indicia representative of various information data characters. The presentation of indicia may, for example, include a printing function. The terminal employs a memory which stores information data characters representative of different indicia to be presented. The data characters may be entered into the memory from a data source, such as a keyboard or a central data processor. Circuitry is provided for controlling the presentation of indicia so that the indicia is presented in an orientation determined by the sequence in which the data characters are read from the memory.