Dimmable electronic transformer circuit

US4862041A · kind A · utility

Assignee

• Patent-Treuhand-Gesellschaft fur elektrische Gluhlampen mbH · DE

Inventor

• Walter Hirschmann · Munich, DE

Key dates

• Filing date: Oct 13, 1987
• Grant date: Aug 29, 1989
• Expiry date: Oct 13, 2007

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S315/05
• WIPO field: Electrical machinery, apparatus, energy
• WIPO sector: Electrical engineering

Abstract

To permit dimming of a halogen incandescant lamp, or set of lamps connected to an electronic transformer circuit which receives operating voltage from a power network, rectifies the current supply and chops the rectified power to provide high-frequency alternating voltage for transformation to low voltage of the incandesent lamp, a non-current compensated choke having an inductance of at least 50 mH is connected in series between the rectifier output terminals and the rectifier system terminals, an oscillation start acceleration circuit including a CR circuit is connected in parallel with the starting circuit for the alternately operating transistors and a pair of symmetry resistors (R6,R7) are connected in parallel to symmetry defining capacitors (C6,C7), connected across the rectifier output terminals and a mid-point (M) of the oscillation transistors. The arrangement permits soft starting of the transistors, even if a serially connected phase controlled dimmer circuit suddenly connects line voltage at peak value across the rectifier, while providing for continuous energy release, even if the dimmer control is turned beyond the 90.degree. phase angle position and, for example, to…