DEP0041908DA - Circuit arrangement for triggering switching processes in telephone systems with dialer operation - Google Patents

Description

The invention relates to a circuit arrangement for triggering switching operations in telephone systems with dialer operation. It is not always possible to trigger a switching process with the current that can be transmitted via a line. The invention nevertheless enables the desired switching process to be controlled in that a memory switching means is charged by a large number of current impulses of any rhythm or frequency and, after charging, is discharged via switching means, thereby causing them to respond. Thus, the sum of a large number of small current surges, which in themselves are insufficient for control, is used by the invention to initiate the desired switching process.

In telephone systems with dialer operation there is sometimes the task of initiating a switching process from office to office via a connection line, whereby the switching means on the connection line should have a high impedance for language reasons and must be galvanically isolated from the connection line for circuit-related reasons ( e.g. by interposing capacitors or glow lamps). The blocking capacitors must be kept as small as possible in order to avoid influencing other switching processes (e.g. the pulse generation).

It is now not possible to use very small capacitors to transmit an alternating current of low frequencies (e.g. 25 or 50 Hz) with sufficient strength to operate a normal telephone relay. Other sources of alternating current with a higher frequency (e.g. 450 Hz) available in telephony technology, which are only intended for the transmission of audio signals, do not have the power to operate normal telephone relays across the connecting lines. The measure according to the invention enables the desired switching process to be triggered even in such a case.

In an advantageous embodiment of the invention, an alternating current of any frequency charges a larger capacitor over a longer period of time via one or more wires of a connection line and via blocking capacitors of small capacitance by means of one or more rectifiers, and this larger capacitor is charged via an intermittently switched relay in briefly discharged again and the relay energized by the brief (but strong) discharge surge; that triggers the desired switching process.

Some embodiments of the invention are shown in the drawing. Show it:

1: the two transmissions located at the ends of a 2-wire connecting line;

Fig. 2 and 3: further circuits for charging capacitors, which serve as a memory.

The circuits are used to trigger a connection running over a 2-wire connection line. In the same way, the arrangement could of course also be used for other purposes (e.g. for the transmission of counting characters in the case of multiple counting during a call, for network group calls, etc.).

The transfer converting from 3 wires to 2 wires is, for example, in a telephone exchange at the output of a first group dialer. The connecting line continuing from this transmission leads to the incoming transmission in another telephone exchange. The incoming transmission is permanently connected to a second group selector via the further wires a, b, c. If an I. group selector checks the outgoing transmission, the following current path is established:

Earth and test relay in the first group selector, c input of the outgoing transmission, d4, b wire of the connection line, b1, B, c output of the incoming transmission, occupancy relay in the second group selector, voltage.

The test relay in the first group selector responds and sets keep the voter silent. Relay B responds in the incoming transmission and binds itself via contact b2. At the same time, the second group selector enters the occupied state by closing contact b2. Then the high-resistance relay C responds in the outgoing transmission:

Earth, d2, C, a-wire, b6, a-wire to the II. Group selector, A-relay in the II. Group selector, voltage.

The C relay connects to the first group selector via contact c4 and via the c wire. The contact c2 brings the D-relay, which causes the connection or activation of the speech wires.

For the purpose of triggering the connection established, the c-wire is disconnected from the first group selector in a known manner. The C relay drops out in the outgoing transmission, which closes the following alternating current circuit:

Earth, AC source Q, d6, C1 (C2), c1 (c5), a-wire, (b-wire), b6 (b1), C3 (C4), DRI (DR II), Gl1 and C5 (Gl2), Earth.

This alternating current remains about 3 '' on the a-line, namely as long as the D-relay has picked up in the outgoing transmission. The D-relay is separated from the voltage itself by the contact c2, but remains under the influence of the electrolytic capacitor C6, which gives it a drop-out delay of about 3 ". Only a very small alternating current flows through the resistance of the very small capacitors C3 and C4 (0.1 uF each) and the inductor windings DRIi and the connecting line. However, it is enough to charge the electrolytic capacitor C5 (from 50 uF) in the course of a second.

In the incoming transmission, relay X is briefly connected to capacitor C5 via the contact lu of a slow interrupter about every second. The energy stored on the capacitor C5 in a period of one second is discharged in a very short time via the relay X when the X relay is switched on, with relay X responding and binding via contact x4. The quiet side of the cycle x4 opens the c-wire to the II. group selector, which triggers the II. group selector and the relay B drops out in the incoming transmission. When contact b4 opens, relay X drops out again and the tripping process is ended.

According to FIG. 2, the capacitor C5 can be charged via the rectifiers Gl1-Gl4 arranged in a Graetz circuit.

In FIG. 3 it is indicated that instead of the rectifier Gl2 of FIG. 1, a resistor W which is not too low (of the order of magnitude of 10-20,000 ohms) can also be used, the charging time of the capacitor C5 being somewhat longer, however. In this sketch it is shown that the switching process can also be carried out via only one wire, with a symmetry compensation being applied to the other wire.

Claims (8)

1) Circuit arrangement for triggering switching operations in telephone systems with dialer operation, characterized in that a memory switching means (electrolytic capacitor C5) is charged by a large number of current impulses of any rhythm or frequency and, after charging, is discharged via switching means (X) and thereby makes it respond. 2) Circuit arrangement according to claim 1, characterized in that an alternating current of any frequency over one or more wires of a connecting line and over blocking capacitors of smaller capacitance by means of one or more rectifiers charges a larger capacitor in a longer period of time. 3) Circuit arrangement according to claim 1 and 2, characterized in that a larger capacitor is discharged again in a short time via an intermittently switched relay and thereby excited by the brief discharge surge of the relay, which triggers the desired switching process. 4) Circuit arrangement according to claim 1 to 3, characterized in that the transmission of alternating currents of any frequency takes place via a wire and earth. 5) Circuit arrangement according to claim 1 to 4, characterized in that the transmission of the alternating currents of any frequency takes place over both lines simultaneously and earth. 6) Circuit arrangement according to claim 1 to 5, characterized in that when both lines are connected simultaneously, two rectifiers or four rectifiers are used in a Graetz circuit. 7) Circuit arrangement according to claim 1 to 6, characterized in that the alternating current is applied for a certain time (3 "). 8) Circuit arrangement according to claim 1 to 7, characterized in that the intermittent connection of the relay triggering the switching process takes place several times (every seconds) within the time for which the alternating current is applied.