SCHALTUNG ZUR UEBERTRAGUNG EINES BINAERSIGNALES

1. A circuit arrangement for transmitting a binary signal via a wired four-terminal network, to which pulsed voltage is applied at its input and which presents at its output a d.c. voltage when the pulsed voltage is applied to its input, wherein the four-terminal network (5) comprises an optoelectronic coupler (9), the active element of which on the output side is a phototransistor (13), the base (14) of which is connected to a capacitor (17) and is connected by a resistor (18) to a first output terminal (4) of the four-terminal network (5), which first output terminal corresponds to a supply voltage terminal, or to the emitter (22) of the phototransistor (13), characterized in that end of the capacitor (17) which is remote from the base (14) of the phototransistor is connected to the collector (28) of the phototransistor (13) or to the first output terminal (4), the emitter and collector (28) of the phototransistor are connected by at least tow series-connected inverting amplifier stages (25, 26), the second output terminal (3) of the four-terminal network constitutes the output of one of the amplifier stages (25, 26) and at least one of the amplifier stages has properties which limit the output voltage.