Siemens Aktiengesellschaft

Wilfried Traulsen

Jan Goerne

A series connection consisting of a diode and one of two transistors of a transistor push-pull circuit is connected in parallel to the feed current path for a light-emitting diode and a capacitor is interconnected between the junction of the push-pull transistors and the junction between the light-emitting diode and an additional diode which is present in the feed current path. When the transistor in the series connection is in a blocking state, the light-emitting diode receives feed current and is thus switched to a light-emitting state. The capacitor causes a current pulse to be superimposed on the feed current during switchover for rapidly driving the light-emitting diode by decreasing the time span required by the light-emitting diode to reach a condition of maximum light emission.

Drive circuit for at least one light-emitting diode

A circuit for evaluating signals has an operational amplifier and a comparator, both of which are supplied by a voltage source connected to ground at one side. The reference inputs of the amplifier and comparator are respectively connected to different taps of a voltage divider also connected across the voltage source, the taps being separated by a low-resistance resistor, thus attaining a stable zero signal level at the signal input of the comparator in the quiescent state through the non-inverting input of the operational amplifier and the output thereof, the stable zero signal level exhibiting a constant voltage difference in comparison to the reference potential at the reference input of the comparator.

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Munich, Germany

Wilfried Traulsen