DE881808C - Circuit arrangement for telephone systems, especially private branch exchanges - Google Patents

Description

Circuit arrangement for telephone systems, in particular private branch exchanges For telephone systems with automatic calling it is sometimes necessary to call through to cancel the periodic call when the connection is made for some reason, e.g. B. by not reporting the called subscriber, not can be accomplished. Such a task occurs, for example, in private branch exchanges on, with those by the .Rufstrom sent by the office in the sub-exchange a call state is caused that must be canceled again when the Exchange connection in the sub-exchange not queried for a certain period of time and the subscriber has then hung up his receiver again.

In a known arrangement, this object is achieved in that a timer consisting of thermal relays through the periodic call is switched on and comes into effect if no more ringing current arrives for a longer period of time. The arrangement is designed so that during a short ringer pause timer device that was left on but not activated under the influence of the following ringer surge is first brought back to the rest position before it is put into action again during the subsequent ringer pause.

There are also circuits known in which a periodic by the incoming ringing current switched on, the call status characterizing relay is held in the pause via a capacitor.

The invention relates to a circuit arrangement of the latter type, in particular for ancillary station systems, and is characterized in that a filter capacitor of the smoothing element of the power supply unit consisting of filter chokes and filter capacitors is used as the capacitor. The additional electrolytic capacitor otherwise required for long drop-off times of the relay is thus omitted, which means that small systems, for example, can be made even more economical: The invention is explained using the exemplary embodiment shown in the drawing, which has a switching arrangement for a small branch system with a Main and a branch, which in practice - is referred to as an intermediate switch, represents. Power is supplied by the mains. The mode of operation of the system is as follows: a) Internal connection When lifting the receiver at the main station Hst, the relay S i in the supply circuit responds, while the differential relay X i in the same circuit is not energized. When relay Si responds, relay Vi in the circuit +, si I, hi (5, 6), W4 - is switched on. To call the extension extension, the subscriber pulls the main station. his dial on and let it run down. The relay S i is therefore switched off and on again in pulses. When: first switching off the relay S i speaks in the circuit -I-, v I II, TV2 (i, 2), s 1 1, z III, s 2 I, W4, -, the relay le to which just like the relay V i holds during the entire sequence of the dial. When the relay V2 responds, the relay R i is switched on via -f-, v2III, s 1 111, RI (3, 4), uII, W2, -f-, v2111, r I VI, PW (I, 2), pw; 2tII, W2, - the pole changer relay PW switches on in self-interrupting mode. The following circuit to the call station Nst is closed by further contacts of the relay R i: (-), PW (3., 4), u V, r I IV, X 2 (5, 6), xVI; NU I, subscriber station, NUII, r i V, X 2 (I, 2), -I-. An alternating current is superimposed on this circuit, which is inductive to the. Winding 14 of the pole changer relay PW is transmitted. The alarm clock of the extension extension therefore responds. If the extension answers by lifting the receiver, the feed relay S2 of this intercom station responds. Relay S2 causes 2I via contacts s; z III, si I a short circuit. of relay T12, so that it drops out and disconnects the pole changer and the circuit for relay R i. Both microphone units are. connected over part of the trunk and can talk to each other. During the call, the relays S i, S2 and Vi are energized. The connection is triggered by hanging the receiver on both speech stations, as a result of which the feed relays come to waste - and the relay Vi also returns to its rest position.

- b) Outgoing exchange connection To establish an outgoing connection. Exchange connection, For example, from the main office, after lifting the handset, the Earthing button T pressed briefly, which in a known manner in the supply circuit This intercom station lying differential relay X i comes to response. Consequently speak in the circuit @ -, x I III, x I I, R I (I, 2), u l, C (I, 2), - the relays R i and C on.

After releasing the button, relay X i drops out, so that now the relay U in the circuit -I-, viII, v2II, U (I, 2), riIII, Ri (i, 2), uI, C (i, 2), - comes to the address. The relays `C and R i - continue to be held. Contact ci creates a loop to the office via the secondary windings of the transformer 1.fe, zvodurcli the connection devices. this office will be animated. If it is assumed that it is a matter of a voter office, the main office establishes the connection by dialing the desired number. The impulses are transmitted through the contact si II in the a-wire of the exchange line. During a series of pulses, the relay V? Responds for the duration of this series of pulses, which short-circuits the secondary windings of the transformer Ue via the contacts v21 and u IV in order to avoid pulse distortions in a known manner. After the desired voice connection has been established, the relays S i, TV i, C, - R i, U are energized in the private branch exchange.

It is assumed that the main station wants to hold an inquiry with the extension N.ct. For this purpose, the grounding button T is temporarily actuated at the main unit, so that the relay X i responds again. As a result, the relay R i is short-circuited to drop out, while the relays L 'and C in the circuit -I-, x I ZII, 2t I, U (3a 4), C (I, .2), continue to hold . After releasing the key, relay X i drops out, so that now relay L 'is also de-energized. Relay C, on the other hand , remains in the circuit +, v I II, c II, C (3, 4), -more. The extension is called in the same way as for the internal connection described above. During the consultation call, the exchange call is held via the loop closed by contacts c I and s 1 11. The primary side of the transmitter t'e is separated by contact uVI, so that the two intercom stations connected via part of the exchange line can conduct the inquiry call without the subscriber being able to overhear this call.

If the main office wants to switch back to the office again, press they turn temporarily, pushing the grounding button T, which initially relays R i and after releasing the button, relay t% also responds. The main office is in turn connected to the subscriber.

If, on the other hand, the outside call is to be taken over by the extension called in the inquiry, the latter temporarily actuates its Erdu.ngstaste so that the relay X 2 assigned to it is activated and relay R2 switches on. After releasing the button and releasing relay X2, relay tT will respond. The circuits for these switching processes correspond to those already described.

The exchange connection is released by hanging up the intercom connected to the exchange line. Relays S i or S2 and Vi come one after the other and, after relay b'i has dropped out, relays LT, R i (R2), C drop.

c) Incoming exchange connection In the case of an exchange call, the call relay AR, which is arranged in a bridge to the speech wires, is triggered by the periodically incoming call current, which closes the following circuit with its contact arIII: -I-, v2111, arIII, Z (i, 2 ),. @ Z 11I. R2 (14), u11 Pf 6, rI VI, PW (I, 2), PW In this circuit, the relays Z and R2 and the pole changer relay PTV respond. As a result, the alternating current generated by the pole changer is conducted to the main unit's speech set via contacts r2IV and r2II. Since the ringing current surge is only given briefly over the exchange line, relay AR drops out again, so that the circuit for relays Z, R 2 and for the pole changer is interrupted again. Relay 2 "is held according to the invention over the charged electrolytic capacitor C i, which is provided for the screening of the rectified alternating current, in the circuit +, Z (5,6), zI, Ci, -for the date of a pause nexti ringing current surge from the office, the electrolytic capacitor C i is recharged in a circuit running through the contact 4r i , so that the relay Z can continue to hold after the termination of the ringing current surge. Each incoming call Main point and on the other hand the charging de: Elelctrolythoiidensators, so that the relay Z_ remains attracted for the date of the periodic call When the relay Z was triggered in the circuit -, f'4, s 2 I, z II, RZ II, h I, T h, -I-the thermal relay Tdf switched on, which is initially without effect.

If the main unit Hst answers during the call pause, then the feed relay S i responds at this point. As a result, the Contact s i I switched on the relay VI, which is in the circuit +, viII, zIV, Ri (I, 2) "uI, C (i, 2), - the Relays R i and C to respond. After the relay Z_ drops, the circuit i- ', v I II, v2II, U (I, 2), r I III, R I (I, 2), Zf I, C (1, 2), relay LT energized. The response of the relay R i "C, U is the main body with the exchange line connected without the need to press the earthing button on the main unit. The function of the relay X i, which is triggered by the earthing button for outgoing exchange is actuated and causes the connection of the intercom to the exchange line, is thus taken over by the relay Z for incoming official traffic.

However, if the main unit does not answer after a certain time, then the Tliermo relay Th responds, which switches on the relay H by means of its contact tla. With each incoming ringing current surge, the relay R i in the circuit -1-, v2III, arIII, zV, hII ,, siIII, RI (3,.), U II, W2, - is switched on in addition to the relays Z_, R2, PW so that both microphone units are called. When one of the intercom stations report, the relays R i or R2, C and L 'respond, as described above, whereby the off-hook intercom station is connected to the exchange line.

The following cases are still to be considered: It is assumed that the extension Nst picks up the handset to establish a connection Time at which the main office is called from the office. Because in this Phase the relay Z is energized, is in the connecting line of the extension of the Resistor W6, which is dimensioned so that the feed relay S2 cannot respond. This prevents a connection from being made from the extension.

If an exchange call is made at a time when there is a connection between the main and the extension, the relay Z is prevented from responding by the relocated contact s2111. The call relay and the pole changer relay cannot respond either. The participants in a conversation perceive the incoming office call by the fact that a part of the filter DR is short-circuited through each ringer surge by means of the contact Ur i via contact z I, whereby a no longer full, screened feed current to the connection älldi lines of the two intercom stations is placed. The microphone units therefore receive a humming sound in the rhythm of the periodic call.

The holder NU looped into the connection lines of the intercom is intended for night traffic. When the switch is flipped, an incoming exchange call goes directly to the extension extension: The relay NK. Serves to control the mains current. As long as there is mains power, it is constantly energized. If the mains voltage is switched off, the relay drops out and connects the exchange line directly with the connection line of the main office, so that incoming exchange calls can be accepted even in the event of a power failure.

Claims (2)

PATENT CLAIMS: i. Circuit arrangement for mains-powered private branch exchanges, in which a relay which is switched on by the periodically incoming ringing current and which characterizes the call status is held by a charged capacitor in the call pause, characterized in that a filter capacitor is used as the capacitor (electrolytic capacitor C i). Siebdrossefn and filter capacitors existing smoothing element of the power supply is used. 2. Circuit arrangement according to claim i, characterized in that the relay (Z) characterizing the call status responds to an office call. Only when the microphone units are free and when occupied: ll the effect of the filter throttle (DR) z. B. by short-circuiting part of the, filter throttle by means of a contact (z I) of the then non-responding relay (Z) is canceled, so that the subscribers in an internal connection receive a hum in the rhythm of the periodic ringing current. 3. Circuit arrangement according to claim 2, characterized in that .that a changeover contact (z1) - of the relay (Z) in its rest position the short circuit of a part -the filter throttle (DR) prepared and in its working position a filter capacitor (C i) running holding circuit for the relay (Z) closes. 4. Circuit arrangement according to claim i, characterized in that the relay (Z) when reporting the call station (I-Ist or Nst) to connect it to the exchange line, the same switching means (R i or R. 2, C, U) affects the outgoing Office traffic for connecting the intercom via the one in the supply circuit, : Differential relays (Xi, X2) excited by pressing the earth button come into effect. Ä. Circuit arrangement according to claim i, characterized in; d.ass the relay (Z) when responding the ohmic resistance of the connection line which is only in the second line for receipt of an exchange call into consideration (call forwarding to the intercom Ext). Is increased so that the feed relay (S2) of this intercom station is raised when it is picked up of the listener cannot respond. Referred publications: German patent specification No. 721,907; Arthur F 1 a d and Josef K i r ch, "Railway telephony technology, self-connection systems", Berlin 1948, p. 2 @ 5, picture i9.