DE1055606B - Circuit arrangement for a call connection in telephone switching systems - Google Patents

Description

The invention relates to a circuit arrangement for a call connection in telephone switching systems. In known arrangements for the call connection the ringing voltage source is connected to the feed relay via a sequential changeover contact and thus placed over the voice line of the busy connection set to the subscriber line of the called party. Of the Changeover contact must be designed as a sequence changeover switch in order to connect the feed relay with not to temporarily interrupt the supply voltage source when the call is switched off, if the Feed relay receives no delay. However, this leads to the ringing voltage source during the duration the changeover time of the sequential switch is short-circuited. A protective resistor has therefore been introduced by which the current intensity is limited. But if there are several such protective resistances at the same time parallel to the ringing voltage source, then it is heavily loaded again, even if the contacts remain protected from overload. This disadvantage could be caused by ringing parallel to a partial winding of the feed relay can be reduced, but not eliminated, because the partial winding represents an additional, not insignificant load for the ringing voltage source.

The object of the invention is to avoid the known disadvantages. It is characterized by that the ringing voltage lock off the supply voltage from the ringing voltage source via a Capacitor lying parallel to one or both of the line branches in the connecting device Windings of the relay serving as a feed relay for the called subscriber via a switch-off contact of the call disconnection relay is applied to one or both wires in the connection device and that in the connection of the partial winding of the feed relay connected to the DC feed voltage the one wire of the voice line in the connecting device is looped a diode, which as Blocking resistance for the ringing current in the shunt circuit acts.

The arithmetic treatment of the problem at hand shows that the diode follows the bypass circuit Charging of the capacitors so completely blocks that only a negligibly small current in the shunt circuit occurs.

When the ringing voltage source is connected to an occupied connection device, the feed relay then, if it is very sensitive and can respond quickly, even before the upstream one is charged The capacitor is attracted by its charging current through the diode. To avoid this with certainty, will the state of charge of the capacitor in a further embodiment of the circuit S according to the invention circuit arrangement.

for a call connection

in telephone. Switching systems

Applicant:

Standard electrical system Lorenz

Corporation,

Stuttgart-Zuffenhausen,

Hellmuth-Hirth-Str. 42

Dipl.-Ing. Wolfgang Weisser, Stuttgart,

and Günter Lehmann, Korntal (Kr.Leonberg),

have been named as inventors

arrangement via a high-resistance resistor before the ringing voltage source is connected to a occupied connection device established.

The drawing shows an exemplary embodiment of the circuit arrangement according to the invention in FIG. 1 which the ringing voltage source parallel to the one winding of the feed relay of the called subscriber is, in Fig. 2 a second embodiment, in which the ringing voltage source parallel to both The windings of the feed relay are applied to the two wires of the subscriber line.

The ringing voltage source R _1, the internal resistance of which is represented by Ri , is on the one hand on the positive battery terminal, on the other hand via the capacitor C 1 and a call disconnection contact k of a call disconnection relay, not shown, on one wire a of the connection set. The inference of the response circuit for the call relay is given via the capacitor C2, signal generator Wk, & -Ader, FII, R. The diode D in the feed circuit, which contains the winding FI of the feed relay Y , blocks the shunt via the voltage source U against the ringing current.

Another embodiment of the circuit arrangement according to the invention is shown in FIG. 2; the feeding of the ringing voltage takes place parallel to the windings FI and FII of the feed relay to the wires α and b of the speech line. The call circuit is closed via R, kl, b-Aäer, WK, C 2, α-wire, k 2, C, Ri, R. The internal resistance of the ringing voltage source is indicated above by the resistance Ri. As stated above, the diode blocks the

909 507/118

Secondary circuit against ringing current; the high- value resistors R1 and R2 block the ringing current from passing through the supply voltage source U.

The mode of operation of the circuit arrangement according to the invention is based on the arrangement described above the switching elements clearly emerge.

Claims (2)

Patent claims: 1. Circuit arrangement for a call connection in connection devices in telephone switching systems, characterized in that the call voltage via a capacitor (Cl) blocking the supply voltage (U) from the call voltage source in parallel to one (FI) or both of the line branches (a, V ) in the connecting device adjacent windings (FI, FII) of the feed relay (F) for the called subscriber via a switch-off contact (k, kl, k2) of the Rufabschaltelais on one (a) or on both wires (a, V) in the connecting device and that in the connection of the DC supply voltage (U) lying partial winding (FI) of the supply relay (F) to one wire (a) of the speech line (a, V) in the connection device a diode (D) is looped, which acts as a blocking resistance for the ringing current in the shunt circuit (D, Yl, U) acts. 2. Circuit arrangement according to claim 1, characterized in that the DC supply voltage (U) from the Rufsgannungsquelle (R) blocking capacitor (C 1) via high-resistance resistors (RI ₁ R2) is applied to the DC supply voltage source (U) . 1 sheet of drawings © 909'507 / 118 4.59