DE1052476B - Circuit arrangement for transistors connected to a central battery via long-distance lines and operated in emitter circuit for telecommunication systems, in particular telephone systems - Google Patents

Description

GERMAN

In telecommunications, in particular telephone systems, are used to remotely control an electrical or mechanical operation given switching criteria via long-distance lines that are at a remote location from a electrical device are received and evaluated. This evaluation can consist in that the switching criterion given via the line activates a highly sensitive relay, which in turn activates the relevant process triggers, or it consists in first strengthening the switching criterion and then to give this reinforced criterion to another line or a normal relay or a To control electric motor or generator. In the latter case, this electrical device provides a line amplifier represent.

The electrical equipment connected to a trunk line is required, especially when in use As a line amplifier, special bias sources so that they also respond to weak switching criteria can address. However, the length of the trunk line is for known reasons, e.g. B. due to the asymmetry limited by leakage resistances, if the switching criteria are still the electrical equipment should control. This is particularly evident when the electrical device is over the pipeline is to be fed by a central battery. It is therefore a special feature of the establishment To give voltage source.

It is also known in private branch exchanges, which are used to record the self-dialing long-distance traffic Charges incurred for the individual extensions in the form of alternating current pulses at 16 kHz can be fed to the private branch exchange via the trunk line, through one in front of the Exchange arranged bypass amplifier on the individual counters of the extension forward more. The amplifier device formed from emitter circuit transistors nings at the subscriber stations require a bias voltage, which is usually the central battery of the exchange is removed. In an arrangement of this type it has already been proposed that The necessary bias voltage can be taken from a capacitor, which is made over a symmetrical bridge Resistors or chokes are connected to the subscriber line and constantly from the central battery being charged. Such an arrangement is independent of the line length and still has a substantially constant bias. The discharge of the capacitor is triggered by the incoming alternating current counting pulses.

The invention is now based on the object of the proposed arrangement Principle also for remote control of electrical

Long-distance lines to a central battery

connected, in emitter circuit

operated transistors for telecommunication,

in particular telephone systems

Applicant:

Standard electrical system Lorenz

Aktiengesellschaft,

Stuttgart-Zuffenhaus en,

Hellmuth-Hirth ~ Str. 42

Georg Vogel, Stuttgart-Stammheim,
and Hans-Ullrich Knauer, Korntal,
have been named as inventors

To use switching devices or to amplify further to be ₂ -leitender AC switching criteria via a long-distance line, for example in telephone systems. They give the opportunity to use the amplifier devices located in the course of a long-distance line to amplify the switching criteria z. B. to arrange counting pulses relatively far from each other without additional expenditure on switching means and only to use the normal voltage applied to the wires for this purpose. This is achieved according to the invention in that when AC switching criteria are met, the collector current of the transistors, which is dependent on the charging voltage of the capacitor, is passed through the primary side of an output transformer.

According to a further embodiment of the invention, the switching criteria are forwarded via the same long-distance line the primary side of the input transformer and the secondary side of the output transformer between

the two wires of the

Long-distance line

arranged.

A blocking element for the switching criteria is located between the two transformers. About the distances between two amplifiers To be able to make it even bigger, it is useful to have 2 transistors in push-pull connection to arrange. The secondary winding of the input transformer is between the base sides of the two transistors arranged. When the switching criteria are met, the capacitor is connected in parallel each of the two transistors and half the primary windings of the output transformer unload. It is also useful in the collector circuit

809 769/130

of the transistors to arrange a monitoring relay that, if the amplifier fails, the short circuit of the Locking element for the switching criteria and the disconnection of the two transformers from the long-distance line causes.

The line amplifier according to the invention has the advantage that it can also be used to amplify continuous tones can be used. Any frequency ranges that can be selected can be amplified.

The invention is described below with reference to the exemplary embodiments shown in the drawings explained in more detail.

Fig. 1 shows a line amplifier according to the invention, in which incoming alternating current pulses be passed on increasingly;

FIG. 2 shows an arrangement according to FIG. 1, in which alternating voltages in the course of a trunk line be reinforced.

The line amplifier shown in FIG. 1 consists of two push-pull transistors T1 and T2 . The emitter side of both transistors is grounded on the one hand and connected to the capacitor C on the other. The other side of the capacitor C is connected to the symmetrical center point of a bridge circuit made up of the two identical resistors Wl and WI . The bridge circuits from the resistors Wl and WT. are arranged between the two conductors α and b . The circuit of a central battery (not shown) connected via lines α and b runs over this bridge. The capacitor C is charged with half the voltage of the central battery. This symmetrical arrangement makes it irrelevant how far this bridge is from the central battery. The attenuation of the line itself as well as the leakage resistance between the two wires have no effect. The voltage drop is only caused by the asymmetrical leakage resistances, e.g. B. between a line core and earth, determined. It can therefore be assumed in practice that the capacitor C is fed with a constant charging voltage regardless of the line length. By the charged capacitor C, a predetermined bias voltage is continuously applied two transistors T1 and T 2. If now via line α and b is a switching criterion, z. B. an alternating current pulse, it is passed through the blocking element Dr, C 3 to the primary side of the transformer Ül . The secondary side of this transformer Ül is in series with the bases of the two transistors Tl and Γ2. When the switching criterion occurs, the two transistors become conductive, so that the capacitor C can discharge via the following circuit:

C, emitter of both transistors T1, T2, collector sides of the two transistors T1, T2, primary side of transformer Ü2, means tapping this primary winding, back to capacitor C.

The amplified current pulse is passed through the transformer Ü2 to the long-distance line a, b . In the following pulse pause, the capacitor C is charged again, so that the necessary bias voltage is applied to the transistor when the next current pulse arrives.

The arrangement shown in FIG. 1 can be used when both the incoming and the amplified switching criteria are to be given over the same line. This is e.g. B. when counting calls in telephone systems, especially telephone private branch exchanges, the case. The arrangement of FIG. 1 is expediently used when the pulse repetition time is greater than the time constant of the supply circuit W1, W2 and C. High amplifications of the incoming alternating current pulses are then achieved.

In a modification of the example according to FIG. 1, however, the forwarding of the amplified switching

criteria are given via a special line. In this case, the locking member Dr would be omitted. Such an application is possible when other operations are not taking place on the same line, e.g. B. if you only use remote controls

IS to be applied. By the arrangements according to the Invention can thus electric motors, generators or relays for connecting an electrical Circuit can be controlled by the switching criteria, practically without any dependence on the line

length.

Fig. 2 shows an expedient embodiment of the arrangement according to FIG. 1 and is advantageous for Amplification of alternating voltages used in the course of a long-distance line. This arrangement can be used in

specific distances are assigned instead of the known repeater devices of the long-distance line. In order to amplify the alternating voltages of a certain range, e.g. B. the voice frequency band, to enable a state of equilibrium between the charging of the capacitor C by the DC voltage given over the line a, b and the discharge of the same via a transistor T 3 by the alternating voltages also given over the line a, b. The push-pull circuit of two transistors T1 and T 2 shown in FIG. 1 is not to be used here, since in the push-pull circuit only very low leakage currents flow over the collector sides of the two transistors and thus no permanent modulation

Alternating voltages can take place. Such a one Switching is therefore particularly suitable for criteria with a time lag.

If only one transistor is used, as shown in FIG. 2, constant modulation via the collector side K is achieved. A monitoring relay R is expediently arranged in the collector circuit K , which with its contacts rl, r2 and r 3 short-circuits the input transformer Ül and the output transformer Ü2 on the one hand and the blocking element for the alternating voltages Dr, C 3 on the other hand if the amplifier fails. In the course of the long-distance line a, b , such amplifier devices can be arranged at certain intervals, all of which are fed by a central battery at the beginning or at the end of the line.

Claims (8)

Patent claims: 1. Circuit arrangement for emitter circuit connected to a central battery via long-distance lines operated transistors in telecommunications systems, in particular for remote control of electrical switching devices in telephone systems, where there is a bridge circuit of resistors between the two cores of the long-distance line or chokes is arranged, at the symmetrical center of which a capacitor is connected which gives the transistors a substantially constant bias voltage regardless of the Line length supplies and the to any Time of switching criteria given over the line to trigger a process is discharged, characterized in that when AC switching criteria occur, the collector current of the transistors (Tl, T2, TZ) dependent on the charging voltage of the capacitor (C) via the primary side of an output transformer ( Ü2) is performed. 2. Circuit arrangement according to claim 1, characterized in that the switching criteria are fed to the transistors (Tl to T3) via an input transformer (Ül). 3. Circuit arrangement according to claim 1 and 2, characterized in that with increased forwarding of the switching criteria via the same long-distance line, the primary side of the input transformer (Ül) and the secondary side of the output transformer (i / 2) are arranged between the two wires of the line and that between the two Transmitters a blocking element is switched on for the switching criteria in the line. 4. Circuit arrangement according to Claim 1 to 3, characterized in that the secondary winding of an input transformer (Ül) is arranged between the base sides of two push-pull transistors (T 1 and T 2) to the exception of the switching criteria and that when the switching criteria are met, the capacitor ( C) is discharged via the parallel connection of the two transistors (Tl, T 2) and half the primary windings of the output transformer (t / 2). 5. Circuit arrangement according to claim 1 to 3 for amplifying alternating voltages in the course a long-distance line, characterized in that between the charging of the capacitor (C) due to the direct voltage and the discharge of the same via a transistor (T 3) an equilibrium state exists, so that the alternating voltages experience a temporary gain in power. 6. Circuit arrangement according to claim 1 to 3 and 5, characterized in that a monitoring switching means (R) is arranged in the collector circuit (K) of the transistors (z. B. T3), which the short circuit of the blocking element (Dr, C 3) and the The transformer (Ül, Ü2) is switched off if the electrical device fails. 7. Circuit arrangement according to claim 1 to 6, characterized in that the charge and discharge of the capacitor (C) is tuned so that in a predetermined range with variable Input level, the same output level is always achieved. 8. Circuit arrangement according to claim 1 to 7, characterized in that in the course of the long-distance line several electrical devices are arranged. which are from a central battery at the beginning or at the end of the pipeline. Legacy Patents Considered:
German Patent No. 969 178. 1 sheet of drawings © 809769/130 3.59