Discharge lamp light intensity control - comprises switch for selection between two choke coil tapping terminals

摘要

The light intensity control is used for a discharge lamp with a ballast circuit including a choke coil (2) and capacitors. It comprises a switch connected in the supply circuit for the lamp and used to select one of two tap-off terminals for the choke coil (2). A resistor (24) is connected between the working contact (11) of the switch and one of the choke coil terminals connected to the fixed switch contacts (13, 14). This resistor (24) may have a resistance such that the current through the lamp is 0.1 amperes when the switch working contact (11) lies between the two fixed contacts (13, 14).