Fluorescent starter circuit with half wave diode heating - has supplementary electrode with reverse bias voltage on diode which causes heating current flow for boosting starter action

摘要

The glow-start circuit for fluorescent tubes uses half wave diode heating current to supplement that supplied to the bimetal contacts in the starter from the NTC (negative temp. coefficient) resistor circuit. The circuit ensures correct operating temp. for the starter so reducing the incidence of repeat starts. The circuit comprises the glow-starter with bimetal contacts (1,2) and a supplementary electrode (5). The diode (3) and the NTC resistor (4) are in parallel and a limiting resistor (7) is included to prevent the diode current becoming excessive. The diode (3) and resistor (4) are in parallel with the supplementary electrode (5) and one contact (2) of the bimetal ones. At switch on the bimetal contacts (1,2) are closed and current heats them. Additional heating is provided by current through the supplementary electrode (5) to the bimetal due to the high potential drop across these electrodes due to reverse biasing the diode (3) and the high value NTC resistor (4). This enhances the heating effect, and with the NTC resistor action delays the bimetal contact opening.