| 摘要 |
Circuit with a switch-off device for the operation of light sources The invention relates to a circuit with a switch-off device for the operation of light sources (Lp), have the following features: a self-commutated half-bridge inverter having a series circuit of an upper electronic switch and a lower electronic switch (T 1 , T 2 ), which are joined at a half-bridge midpoint (M) and are connected between a supply voltage (+) and a ground potential, a start capacitor (C 3 ) which is joined via a trigger element (DIAC) to a control electrode of the lower electronic switch (T 2 ), and a switch-off device having an input (E) and an output, which are configured and connected so that they discharge the start capacitor (C 3 ) if a switch-off signal is applied to the input (E). The switch-off device contains a time delay. In order to be able to keep the components in the time delay small, it is proposed that the switch-off device should comprise two successively connected transistor stages (T 3 , T 4 ) with bipolar transistors, a first stage (T 3 ) being configured as a collector circuit and a second stage (T 4 ) being configured as an emitter circuit. The second stage (T 4 ) may perferable be used to suppress start pulses.
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