DE439705C - Ticker device for telephone private branch exchanges - Google Patents

Description

GERMAN EMPIRE

ISSUED JANUARY 25, 1927

REICH PATENT OFFICE

PATENT LETTERING

~ M 439705 CLASS 21 a 3 GROUP 5

(G 64037 VIU \ 2ia})

Johannes Eckert in Berlin-Schmargendorf and Wilhelm Graf in Berlin.

Ticker device for holiday telephone extension systems. Patented in the German Empire on April 10, 1925.

The ticker is a device that creates a slow sequence of electrical surges, e.g. B. a Self-breaker with pendulum wheel (restlessness), and has the task of indicating when that Operator of a private branch exchange (local exchange with light bulb cabinets, line telephones, etc.) overhears in a conversation. In this In the event, it should generate a rhythmic cracking (ticking) in the speech circuit.

This eavesdropping display is preferable to eavesdropping prevention for some reasons, however, the circuits known up to now have the following shortcomings:

If the ticker is permanently connected to the interrogation device, eavesdropping is indeed possible reliably displayed, but when queried there is also a ticking that for the queried participants annoying and for the ic. Cabinet operation unbearable in the long run is because it has to be pretty strong to get through while listening.

Avoid this problem by making sure that the ticker is only available for Mitis hear starts up or that its circuit is only coupled to the speech circuit when listening there is another danger. The cabinet operator can then use the ticker Bring it to a standstill unnoticed, or it can bypass the monitoring circuit in an illegal circuit - z. B. in the multiple field in the query position - listen in.

In the case of the ticker circuits which are the subject of the invention and which are described below these deficiencies are eliminated. With them is the ticker of the interrogator constantly assigned in order to avoid the possibility of bypassing mentioned and other deficiencies.

In the figures, T is a relay belonging to the ticker, which generates the ticking in the speech circuit with every response with its contacts.

F is the remote receiver / induction coil, D the direct current bridge of the interrogator. The voice connection into which the interrogator is switched on when interrogating and listening in is not shown. In Figs. 5 to 8, however, these connections are illustrated schematically.

In Fig. Ι the interrogation device is separated from the speech circuit on one side by the changeover contact of T and connected to this via a resistor W earth. This results in a change in the direct current flow of the connection and thus a click, which is barely audible in the interrogator due to the disconnection. In order to achieve this as completely as possible, the interrogation apparatus can be disconnected on both sides or, as in Fig. 2, short-circuited.

The asymmetrical influence of the voice circuit through the ticker (connection a shunt to the α line) has been chosen to also be used for single-pole Activation of the interrogator to generate ticking, e.g. B. if a plug is incompletely guided into a multiple latch so that only the tip is a latch- '; pen touches, which is usually enough to listen in The asymmetry is also provided for in all of the following ticker circuits.

By disconnecting or short-circuiting the interrogation receiver, part of the conversation in the interrogation apparatus is of course suppressed, and it is therefore important to make this deactivation as short as possible. The prerequisite for this are short ticker power surges so that the current shift in the speech circuit has been balanced out before the remote receiver is switched on again. This: prerequisite is met when using capacitor currents, as their course is very steep. Such a circuit is shown in FIG. When the ¹ contact 1 closes, the capacitor C is charged. The short burst of charging current penetrates j the speech circuit and causes j ticking. In the intermediate pauses, C discharges through the high resistance W. The discharge can also take place through a normally closed contact of T.

If you make sure that the contacts 1 and 2 do not bounce, it is possible to generate a strong ticking in the speech connection without anything being heard in the receiver F and without the switching off of the receiver interfering with speech communication.

The strength of the ticking can be regulated by the resistor W in the case of circuit ι and by the capacitor C in the case of 2.

The circuits 1 and 2 have a deficiency in that each point that starts with the Operator speaks, has the ticking in the remote receiver during the call. For the extensions This is tolerable for the switching system, because for this it is usually only a question of queries, the short one Duration is.

The situation is different in official traffic. When registering a long distance call z. B. could the officer of the remote office by the ticking, the meaning of which she does not know, Feel harassed, and it is therefore desirable for the exchange with the traffic the office and beyond to suppress the ticking on both sides. This works on the following basis:

When interrogating an exchange line (Fig. S), a holding bridge D _{000 is} switched on between the a and ib lines, through which the exchange current flows. In the exchange circuit there are only constant resistances when interrogating, and the voltage at a certain point, e.g. B. the point of application P of the ticker always has the same value. If one does not allow earth and battery to attack at this point, as in Fig. 1 and 2, but rather a voltage that corresponds to the

Voltage of the point is the same, there is no current shift and therefore no ticking. If the voltage of the point of attack changes while listening - and this can easily be achieved by correctly dimensioning the resistance values of the speech circuit - a current shift occurs and thus ticks as in the circuit ι and 2. In Figs. 5 and 7 these are \ ⁷ Obtaining illustrated, the simple case is assumed that query and listening circuit are the same. When querying (x \ bb. 5) the voltage at point P for the entered resistance values is 17 volts, when listening (Fig. 7) 14 volts. The counter voltage of the ticker circuit should therefore be 17 volts. In Fig. 3 such a circuit is shown; the counter voltage is formed here by a voltage divider ST.

For querying the extensions (Fig. 6), the suppression of the ticking is not perfectly possible in this way, because the microphone of the extension with its variable resistance is located in the circuit, and because the extension lines also have very different resistances. As already ₌ stated, this is not necessarily a necessity. It is important, however, that when listening to a conversation between two extensions at point P there is the necessary voltage difference against the equalizing voltage of the ticker circuit. In the example chosen, the difference according to Fig. 8 is 20 - 17 = 3 volts.

The same basic circuit in other single arrangement shown in Fig. 4. A voltage difference between the points P and the ticker counter voltage loads on the secondary winding of J ₁ and a resistance W, the ^r to \ ermeidung of speech current losses can be very high, the capacitor C of high capacity . Through the ticker contact 1, C is discharged via the low-resistance winding of the induction coil J ₁ , as a result of which an induction current arises in the secondary winding, which penetrates the voice connection and generates ticking. Meanwhile, the remote receiver is short-circuited by contact 2.

C ₂ is supposed to lock the trunk against earth. C ₁ and D ₁ are required for the speech circuit for reasons of symmetry.

Two exemplary embodiments are shown in FIGS. 9 to ιι of other new ticker circuits in which the interrogation receiver does not need to be switched off and there is no ticking at all when interrogating. The effective tension for generating the ticking is here taken from the c- core of the pair of cords used for the connection; a- and fr-wire of the telephone connection are not involved and are not shown.

The ticker device is placed on the c-core of the pair of cords when the SU speech switch is turned. When interrogating an exchange line (Fig. 9), the c-wire is not live, and the changeover relay U therefore remains inactive. By means of the ticker contact 1, winding I of J _{1 is} cycled to the c-core. Since the other end of I is connected to earth, there is no current and therefore no ticking. But as soon as the connection plug VS is plugged into an extension jack NK , current flows through W ", c-wire and W ₁ , and when contact 1 is closed, a branch current flows through winding I, which induces an induction current in winding III and thus ticks in the voice connection generated.

When an extension is queried (Fig. 10), U picks up, so that winding II is connected to the c-wire through the ticker contact. The voltage of this wire is with a battery voltage of 24 \ ^r olt

600

600

6oo

= 8 volts.

The same voltage is present across the voltage divider ST at the other end of II, and when 1 closes there is therefore no current flow in II and, accordingly, no ticking. When listening, on the other hand, if the VS is also in a jack NK , the c-wire leads

24.

600

600 600

= 12 volts,

and winding II has a voltage difference when contact 1 is closed of 4 volts, which creates a ticking.

Fig. 11 shows the same basic circuit with a similar click generation as in Fig. 4. The voltage difference between the c-wire and the ticker current path that occurs when listening in charges the capacitor C, which is clocked by contact 1 of T via the low-resistance primary winding I of J _{1 is} discharged, which generates ticking in a known manner.

Fig. 10 applies accordingly to queries and eavesdropping on extension traffic.

The numerical values and details of the circuit are only examples; the real one The ticker circuit can be adapted to any type of switching device circuit. If z. B. the c-core when querying If there is voltage in an exchange line, winding I in Fig. 9 and 11 is the one to give the same counter-tension.

The essence of the ticker circuits in Figures 9-11 is that using the voltage of a local circuit of the connection when inquiring about voltage equality, with every eavesdropping attempt, z. B. also one in the multiple field, voltage inequality in the generating circle of the ticker is caused, and that this Voltage imbalance that causes ticking.

In order to give the extensions the possibility of a possible decommissioning of the To notice tickers, a circuit like the one in Fig. 12 can be set up.

In the common battery feed for

the call sign is one winding of an induction coil J ₂ , one end of which is also connected to the battery, while the second end of the winding is grounded via the ticker contact 2. The resulting induction currents in the first winding flow when a call is made from an extension via the extension call sign NAR and the extension device and are noticeable as ticks in the extension receiver until the cabinet operator asks. The presence of this ticking before the query is therefore a sign of the correct course of the ticker.

This facility is also for certain old ticker circuits discussed at the beginning expedient. It also offers the extensions other advantages. Namely, if there are discussions at short intervals are led one after the other, so one can look at the occurrence or absence of the ticking Immediately recognize when a call is made whether the main unit has already disconnected or not.

The surveillance stitching can also be generated differently, e.g. B. by interruption of the call flow or by changing its strength.

Claims (7)

Patent claims: i. Ticker equipment for private branch exchanges, in which the ticker is permanently assigned to the interrogator, characterized in that the Ticking in those operational processes (queries, inquiries, etc.) where it interferes would be suppressed in part of the speech circuit or in the entire speech circuit is. 2. ticker device according to claim 1, characterized in that the interrogation device or only whose remote receiver is disconnected or short-circuited during each ticker (Fig. 1 to 4), so that no ticking can be heard in the interrogator. ' 3. ticker device according to claim 1, characterized in that the ticking is generated by a disturbance of the direct current flow in the speech circuit, which is caused by a shunt to a line core, a capacitor current or other causes arise (Fig. 1 to 4). 4. ticker device according to claim 1, characterized in that the ticking is generated indirectly by the fact that the voltage difference between the speech circuit and the ticker device charges a capacitor which is discharged through a ticker contact via an induction roller which creates an induction current in its secondary winding connected to the speech circuit (Fig. 4). 5. Ticker device according to claim 1 to 4, characterized in that the generation of the ticking for external calls is prevented by a counter voltage (Fig. 3 and 4), so that neither in the interrogator nor in the Public subscriber with whom the operator is speaking can be heard ticking. 6. ticker device according to claim 1, characterized in that the ticker flow path is connected to a local circuit of the speech circuit, the voltage of which when queried is equal to the Tension of the ticker, but unequal when listening, and that the voltage difference when listening 'Ticking generated (Fig. 9 to 11) while no ticking can be heard in any of the devices involved during the other operating processes. 7. Monitoring device for tikker facilities in telephone secondary no station systems according to claim 1, characterized in that • that the branches when you call, hear a ticking that is switched off when interrogating, which indicates the progress of the ticker and, at the same time, the input of the Recognize the call. For this purpose ι sheet of drawings.