Abstract: A method for setting the trigger power of transmitter diodes that transmit data via optical paths allows the transmission power to be adjusted and adapted to the communication distance. The trigger power is determined for the present communication distance on the basis of a test signal before data transmission begins. A circuit arrangement implementing the method includes a driver circuit with a switching device that switches a circuit junction point selectively to a supply voltage or to a constant reference voltage, a voltage-controlled resistor which delivers the driver current and is controlled from the circuit junction point, and a voltage-controlled measuring resistor which delivers a measured current with a fixed relationship to the driver current and is controlled from the circuit junction point. Since the set trigger power can be reduced, the power consumption for data transmission can be reduced considerably.

Abstract: The invention constitutes a supplement to patent application No. P 31 34 883 and to patent application No. P 32 08 088. It relates to the electronic switching-off of the correction circuitry in the event of a large dwell angle and simultaneously maximum correction value. This object is attained by comparing the speed-dependent output voltage of an induction sensor at a comparator to a reference voltage which is chosen so as to be exceeded by the output voltage of the induction sensor from a certain rotor speed on with an output pulse being released at the comparator. The capacitor at which the sawtooth-shaped signal is generated is discharged by means of this output pulse such that there will not be any further correction of the control signal.

Abstract: A microphone amplifier in a telephone station furnished with current from the telephone network. When a capacitive degenerative feedback is used in the amplifier a certain time has to pass after applying the supply voltage before the operating point of the amplifier is reached because of the charging time of the capacitor. The switching of the supply voltage occurs at the dialing operation at each digit of a dial number since during the transmission period of a digit the handset including the microphone is switched off the subscriber line which carries the current usd for supplying the amplifier with energy. By the use of a special circuit the charging time of the capacitor is shortened drastically.