Abstract: To substantially reduce harmonic distortion and improve the power factor of n operating circuit for a fluorescent lamp, a smoothing circuit (G) is interposed between the outputs from a power rectifier (GL) and an inverter (WR) supplying the fluorescent lamp (L) with high-frequency energy. The smoothing circuit includes a two electrolytic capacitor (C1, C2)--three diode (D1, D2, D3) network, which is so connected, and the diodes so polarized that, during charging of the capacitors, a series circuit is established with one (D2) of the three diodes in series with the two capacitors. For discharge of the capacitors to supply the inverter when the rectified voltage is lower than the capacitor voltage, the two capacitors (C1, C2), through the other two diodes (D1, D3), are connected in parallel to supply the inverter. To substantially reduce harmonic distortion to less than about 30% and improve the power factor of the circuit to above 0.

Abstract: To improve the high-voltage flash-over characteristics of high-pressure dharge lamps (1), and especially to prevent flash-over between terminal leads emanating from the lamp bulb and extending into a lamp base (14), the lamp base which is formed with a cup-shaped opening (13) has an insert pad (18) placed therein of fibrous web, pile, fleece or mat material, made of ceramic, quartz or glass fibers. In manufacture, the fibers are compressed, thereby fitting tightly against the terminal end, typically a pinch or press seal, of the discharge lamp bulb, and thereby substantially increasing the high voltage flash-over resistance between the terminal leads and permitting hot re-ignition of the lamp, which may require pulses of between 15 to 20 kV.

Abstract: To facilitate assembly of tiny cores used in accessory circuitry for a flescent lamp, bases of two transistors (20, 20') are connected to inductive windings on a core (2) which is retained by a primary winding (3) on the printed circuit (PC) board (1). The windings connected to the bases are formed by U-shaped wires surrounding the core which--preferably--is a toroidal core. The windings may include a resistor (8, 8') located within the toroidal core to heat quickly and, also, heat the core, the resistor extending at right angles to the PC board and forming one leg of the U-shaped conductor legs forming the impedance winding around the core.