Ballast circuit for fluorescent discharge lamp - uses frequency unit to generate HF for ignition and lower frequency for running of lamp

摘要

The ballast for a discharge lamp with a glow device to ignite its gas uses a DC voltage supply, a transistor unit and a transformer stage controlled by the transistor. A four-component frequency unit delivers signals to control the transistor. One component generates a h.f. signal during the ignition phase of the lamp. A second component generates a lower frequency signal corresponding to the operative state of the lamp (illuminated). A third component changes over from one regime (current flow to the glow device) to another (no current flow to the glow device) after a certain time period, the regimes being defined by the fourth component. ADVANTAGE - Simple construction with high efficiency.