Circuit arrangement for operating a discharge lamp from a low voltage DC-voltage source

Abstract

Abstract The circuit arrangement for the radio-frequency operation of a discharge lamp (L) connected to a low-voltage DC source has a self-oscillating push-pull converter with two power transistors (T1, T2) and a drive transformer (Tr2), a series resonant circuit in parallel with the output circuit, having a resonant inductor (L1) and a resonant capacitor (C3), as well as a power transformer (Tr1) for the transmission of the radio-frequency oscillation of the push-pull converter into the series resonant circuit. The primary winding (n1) of the drive transformer (Tr2) for the push-pull converter is connected in series with the secondary winding (n3) of the power transformer (Tr1) in the series resonant circuit. The output current thus flows via the primary winding (n1) of the drive transformer (Tr2), resulting in continuous matching of the transistor control to the load conditions. In addition, a device to vary the time constants of the control circuits of the push-pull converter is provided, by means of which the lamp power is stabilised in the event of variations in the operating voltage. The device preferably consists of a transistor (T3) whose emitter-collector junction is connected in parallel with the real total resistance of the control circuits. <IMAGE>

Inventors

• 👤 Joachim Arlt

Bibliographic Details