Starter for fluorescent lamps - uses cathode preheating and synchronises their ignition with the mains voltage frequency

摘要

The ignition process is started by sudden interruption of a current in a circuit containing cathode filaments and an inductance. It comprises a control unit connected to the mains, with a rectifier (8) and a flip-flop (9) with at least two transistors, set by the rectifier output voltage. Its output controls a relay (6) whose make contact (7) makes or breaks the heating current flowing through the inductance and cathode filaments. A timer (10) determines the preheating time by the flip-flop (9) resetting. A synchronisation device (11) controlled by the mains acts directly on the timer (10) and ensures that the current is interrupted at about its maximum.