DE1280978B - Circuit arrangement for limiting the current flowing on the occupancy wire of the three-wire connecting lines between partial and full-time employees in telephone systems - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

H04m

German class: 21 a3- 28/01

Number: 1280978

File number: P 12 80 978.8-31 (T 33844)

Filing date: May 11, 1967

Opening day: October 24, 1968

The main patent application relates to a circuit arrangement for limiting the current flowing on the occupancy wire of the three-wire connecting lines between the switching offices in telephone systems, in which the traffic between the offices is handled between successive election levels and in which a resistor is connected in series between the incoming occupancy wire of the line and the office battery and the emitter-collector path of a transistor is connected, the base electrode of which is connected to a device which regulates the conductivity of the transistor as a function of the voltage drop across the resistor to different values in accordance with the occupancy states of the line.

The invention relates to a further development of the subject matter of the main patent application.

The current limiting transistor described there, its emitter-collector path in the incoming Occupancy wire c is switched on, has the advantage of overload protection in addition to its current-regulating effect. If a ground fault occurs near a group selector or a connection set on, it takes up the resulting short-circuit power. A power transistor with this capacity but also in its blocked state has a volume resistance that is compared to the usual Transistors of smaller load capacity is relatively low.

If the connection set VSC of an exchange does not work with a rotary selector of a sub-exchange, but with an incoming alternating current transmission WUe-k (see R. Führer, "Landesfernwahl II", Gerätechnik, 1962, p. 217), the emitter collector is located - Route this transistor over the practically resistance-free occupancy wire c directly to the sensitive blocking relay R of the alternating current transmission housed in its own exchange. The response current value of the blocking relay R is so low that very high demands must be placed on the blocking capacity of the power transistor mentioned. There is therefore the risk that, in particular at relatively high ambient temperatures and when the transistor is blocked, a blocking current occurs which causes the blocking relay R of the alternating current transmission to respond.

The arrangement according to the invention overcomes this disadvantage. It is made by a proportionate Little expensive additional device the response of the locking relay in the present locked state of the Transistor avoided with certainty.

Circuit arrangement for limiting
des on the assignment core of the three-core
Connection lines between part and
Full offices in telephone systems flowing
Current

Addition to registration: T 29613 VIII a / 21 a3
Interpretation document 1 233 023

Applicant:

Telefunken

Patentverwertungsgesellschaft mb H.,
7900 Ulm, Elisabethenstr. 3

Named as inventor:

Herbert Heymann, 7150 Backnang

The invention is characterized in that in series with the emitter-collector path as a function of from the voltage drop and from the occupancy states controllable transistor the emitter-collector path of a further transistor is connected, which is fed through a of its base electrode Potential in the state of occupancy and / or occupancy of the following exchange facilities into its conductive state, but can be transferred into its blocked state if it cannot be assigned is.

The invention is described using the circuit diagram. In the occupancy wire c of the incoming line from the switching devices of a preceding switching center or from the alternating current transmission WUe-k arranged in the same switching center, there is a series connection of the resistor Rl and the emitter-collector path of the current-regulating transistor TsI die known from the main patent application Emitter-collector path of the switching transistor Ts 6, the base electrode of which via the resistor R 11 to the collector electrode of the transistor Ts S and via

809 628/1191

the resistance !? 12 is connected to the collector electrode of the transistor Ts 3.

When the transistor TsS is conductive , both the control transistor TsI and the switching transistor Ts 6 are controlled to be conductive and the occupancy wire c is thereby connected to the office battery (-60). The regulating transistor TsI , controlled by the regulating device Ts2, Ts3, TsA, TsS, exerts its current regulating effect, while the switching transistor Ts 6 works in its saturation state and does not cause any appreciable voltage drop due to its emitter-collector path. Its power loss is therefore low in contrast to the control transistor TsI. A small switching transistor, which naturally has a good switching ratio, that is to say a large ratio of its blocking resistance to the forward resistance, can therefore be used for him.

Are the VSC to the Link Set associated coupling fields KF and / or register is busy or can not be assigned, so are locked by the open contacts and the locked transistors Ts2 and Ts3 also in the assignment Wire c lying transistors TsI and Ts6. The possibly low blocking resistance of the power transistor TsI cannot have any effect, since the current through the winding of the relay R of the AC transmission WUe-k is determined by the blocking resistance of the transistor Ts 6 .

In the embodiment shown in the circuit diagram, the switching transistor Ts 6 is connected between the collector electrode of the regulating transistor TsI and the c-wire. But it can also be placed directly between the office battery (-60) and the resistor A1. In the event of a ground fault in the c wire, this type of circuit can have the advantage of a constant base current of the switching transistor Tsß .

Claims (2)

Patent claims: 1.Circuit arrangement to limit the current flowing on the occupancy wire of the three-wire connecting lines between the switching offices in telephone systems, in which the traffic between the offices is handled between successive election levels and in which the series connection of a resistor and the between the incoming occupancy wire of the line and the office battery Emitter-collector path of a transistor is connected, the base electrode of which is connected to a device that regulates the conductivity of the transistor depending on the voltage drop across the resistor to different values according to the occupancy states of the line, according to patent application T 29613 VIII a / 21 a ³ ( German Auslegeschrift 1233 023), characterized in that in series with the emitter-collector path of the transistor (TsI), which can be regulated as a function of the voltage drop and the occupancy states, the emitter-collector path of another Transistor (Ts 6) is connected, which is switched to its conductive state by a potential supplied to its base electrode in the state of occupancy or the occupancy of the subsequent exchange facilities (VSC) , but can be converted into its blocking state when it cannot be occupied. 2. Circuit arrangement according to claim 1, characterized in that the base electrode of the further transistor (Js 6) via separate resistors ^ 11, Ä12) are connected to the collector electrodes of the transistors (Ts3, TsS) of the regulating device which are blocked when the office facilities cannot be occupied. 1 sheet of drawings 809 628/1191 10.68 © Bundesdruckerei Berlin