Fluorescent lamp for operating on low current

摘要

A fluorescent lamp drawing low current has the supply voltage regulated downwards after firing and therefore works in current-saving fashion. The control unit consist of an O/V voltage switch, a PWM control circuit, a window discriminator with minimum, maximum and middle-value control outputs, an electronic starter and an electronic switch like a triac. The zero voltage switch (1) releases the control at zero-crossing of the AC supply voltage in order to avoid voltage peaks and to minimise loading on the mains. The PWM circuit (3) takes over the control of the voltage after firing with reference to the control signals of the window discriminator (5). The window discriminator monitors the voltage after the firing and controls the PWM circuit. The electronic starter serves for rapid firing and release of the PWM control circuit. The choke (6) and the capacitor (7) serve to smooth the voltage.