Current control circuit for discharge lamps used in display sign - uses controller switch to reduced supply potential or series inductors in order to limit current drawn

摘要

The current controller reduces the current drawn by discharge tubes (2,3,5) used in an illuminated sign by automatically reducing the supply voltage to the discharge tubes (2,3,5) once the discharge is established, or by switching in series connected inductors. The discharge tubes (2,3,5) may be connected singly or in groups to high voltage transformers (4,6) connected in parallel across a supply line (7, 8). The electric supply is derived from the AC mains (9,11), which are connected across the full winding of an auto-transformer (14). A full voltage and a reduced voltage connection (13) are made to the auto-transformer and a changeover switch (10) provided to switch the lamp supply (7,8) between the two potentials. A controller (12) operates the changeover switch as required.