U.S. Philips Corporation

Erich J Palm

Christianus H Bergmans

Johannes B Meertens

A power supply circuit for generating two direct voltages. A preload, having a tap for deriving the second voltage, is arranged between the lead conveying the first voltage and a reference potential. To prevent mutual influences between the two voltages, the preload is in the form of a series arrangement of at least one resistor and a plurality of reverse-biassed semiconductor diodes, an abrupt change of the differential resistance occurring above a given value of the current through these diodes. A controllable semiconductor element for controlling the second voltage is incorporated between the tap and the lead conveying the second voltage. The first voltage may be an E.H.T. for a final anode of a picture display tube, the second voltage is then a focussing voltage for a focussing electrode of this tube.

Power supply with two output voltages

A DC voltage to DC voltage converter where the period of a controllable switch is maintained for a period which produces current and voltage levels which will not damage any of the converter circuit elements. First and second voltage supply networks are provided, each comprising an inductor, one end of which is an input of the voltage supply network, the other end connected to first and second diodes. The second diode serially connects the inductor with a capacitor. The junction of the capacitor and second diode correspond to an output of the voltage supply network. The second voltage network receives the output of the first voltage network. The first diodes of each voltage network are connected to a transistor switch which is terminated by serially connected third and fourth diodes. A winding serially connected the junction of the third and fourth diodes with the second network output voltage junction. A tuning capacitor across the fourth diode establishes a resonant current in the winding. A signal from the winding is coupled to the transistor switch for changing the state of the transistor switch. Voltages across the transistor switch are established by the resonant tuning capacitor to a safe level. The converter is useful for providing horizontal deflection in a picture display device.

DC switching voltage converter for multiplying an input DC voltage

A circuit for converting an input d.c. voltage into a stabilized output d.c. voltage. The circuit comprises a plurality of supply networks having diodes which are arranged in series and have the same conductivity direction, and the series network of an inductor and a storage capacitor in parallel with one of the diodes. The series diodes of a supply network are arranged in parallel with the storage capacitor of a supply network located closer to the input voltage source, the diode of the first supply network being connected to said source. A winding is connected by means of one side to the junction between the inductor and the capacitor of the supply network located remote from the source and by means of its other side to a further diode and to a controllable switch, the other side of the further diode being connected to the junction between the first and the second diode of the network located remote from the source. The circuit comprises also a tuning capacitor. The output voltage is kept constant by control of the period of time during which the switch is conducting.

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Eindhoven, Netherlands

Erich J Palm