Abstract: A circuit arrangement is provided for testing a passive bus network system which comprises stations which are connectible to a coaxial cable segment via media adapter units, the stations realizing the data packet exchange via the coaxial cable segment with carrier sense multiple access with collision detection access method. In conjunction with a status receiving device which monitors the transmitted data packets, the passive bus network system is monitored by the data transmitter and the data receiver in view of the presence of the line terminating impedances, the proper connection of the media adapter units to the transmission medium, as well as the transmitting and receiving functions and the collision recognition and state of the collision recognition circuit.

Abstract: A receiver for optical digital signals has a transimpedance amplifier, the input of which is connected to an operating voltage via an active photodiode, and the output of which is connected to an input of a comparator. An operational amplifier is provided, the one input of which is connected to the input of the transimpedance amplifier, and the other input of which is connected to the operating voltage via a further, unilluminated photodiode. A reference voltage at the other input of the comparator is generated from the output voltage of the operational amplifier via a voltage divider.

Abstract: In a data network distributor adapted to connect a plurality of data stations with each other directly, and with remote stations over a network bus, a selective voltage supply system allows units shared in common with the local data stations to be powered only as needed, and to draw power from the individual data stations requiring service. Individual power sources in each data station are connected to a common line through decoupling diodes and current limiting resistors, and the common line supplies a plurality of voltage supply units which are operative to supply power to commonly used units as needed, including transmitting and receiving units for the network bus, a data diversion device for diverting local communications from the network bus, and a common control circuit for data collision recognition.

Abstract: An optical receiver comprises a plurality of sequentially-connected, symmetrically-constructed operational amplifiers having two complementary outputs. For the determination of the operating points and for suppressing the offset voltages, one output of each amplifier is connected by way of a negative feedback path to the second input of the first amplifier, whereas the useful signal is supplied to the first input of the first amplifier.

Abstract: With the aid of a delay element and an EXCLUSIVE OR gate, from a binary input signal, upon the occurrence of a level change, an inhibit signal is obtained which blocks a freely-oscillating renewal pulse generator at its output, upon occurrence of level changes in the binary signal, so that the pulse transmission can proceed undisturbed by the renewal pulses through data pulse generators which are activated by the level changes of the binary signal occurring at a tap of the delay element, this is for the purpose of emitting a data pulse which is chronologically offset relative to a level change. The renewal pulses can follow a data pulse, however, at random times within a maximum time interval which is determined by the repetition frequency of the renewal pulses, since no chronological synchronization of the renewal pulses to a preceding data pulse is provided.

Abstract: 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.

Abstract: 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.