DE1762597A1 - Hybrid circuit - Google Patents

Description

Dipl.-Phys. Leo Thul

Patent attorney
7 Stuttgart-Feuerbach
Short street 8

. ISE / Reg. 5930
G. Beszedics - 21

INTERNATIONALSTANDARDELECTRIC CORPORATIONvNEWYORK

Hybrid circuit

The priority of registration in Austria from i8. July 1967 No. A 6679/67 is in Availed

The invention is concerned with a hybrid circuit for two-wire four-wire circuits in transmission systems, in particular Speech circles with electronic line simulation that adjusts itself to the required value.

Hybrid circuits with not on an average of the one in question coming line impedances set simulation circuit have a changeable replica, which is made up of, for example, guide ladders to achieve a low return flow, a bridge circuit decoupled by isolating transformers.

Other embodiments use non-linear resistors or With the help of control voltages changeable impedances of non-linear resistors, for which, depending on the in use standing line, the appropriate replica resistance with the help line-specific selector contacts, i.e. included in the switching program, can be set.

July 16, 1968

Krü / Wl ./.

009840/0418

ISE / Reg. 3930 - 2 -

There are also hybrid circuits with pilot tone control on various occasions proposed for continuous replica adjustment; this is used to control the replica impedance Get used to the necessary DC control current from the impedance measuring device connected to the line to be simulated. A A major disadvantage of a simulation circuit with variable resistors is that the phase angle fluctuates. This fact always means that the simulation is not effective for the entire frequency band, or the adjustment is insufficient will. Furthermore, the control speed of the simulation is not sufficient in the case of fluctuating line attenuation.

So while the one solution has little regard for what is required Phase angle, the second solution has a strong amplitude dependence of the simulated current through the characteristics of the used directional guide and therefore results in distortion, especially at low level values.

The object of the invention is to provide a hybrid circuit with electronic line simulation while avoiding the disadvantages mentioned above specify where the current is simulated as faithfully as possible in terms of amplitude and phase. According to the invention, this is thereby achieved achieves that a current transformer is arranged in the outgoing line of the hybrid circuit and in the line simulation branch one controlled by a fork converter and reproducing the amount and phase of the current flowing through the primary winding of the current converter Transistor circuit is provided, in such a way that the current flowing in the simulation branch according to amount and phase im is essentially equal to the current going into the line.

The transistor circuit provided in the simulation branch can consist of one or more counter-coupled amplifier stages.

The decrease in a current-proportional control signal can according to the invention can also be done via any network behind a measuring shunt instead of a current transformer.

0098A0 / 0418 /

ISE / Reg. 3930 - 3 -

A further development of the hybrid circuit according to the invention is that for the flow of energy via the line to Hybrid circuit the simulation circuit on the source impedance of the generator is tuned, whereby either no or even negative damping can be achieved in this energy direction is. It is therefore possible to use the simulation circuit as an amplifier for the incoming energy flow.

Furthermore, the supply voltage required for the transistor circuit can be produced from its own loop current.

The invention will now be explained with reference to the drawing, which shows a hybrid circuit according to the invention with electronic line simulation represents.

The ones on generator G, which also represent the output of an amplifier voltage generated should be strong at terminals PP ' occur less. The current Jl and Jn must therefore be in the two primary winding parts gwl and gw2 of the fork converter GW be the same in amount and phase. Above the. Current transformer W becomes a current Jn proportional to the line current Jl in the simulation branch arranged transistor circuit N supplied. The transformation ratio ü of the current transformer W and the current gain the negative feedback transistor circuit N in the simulation branch are now designed so that the current in the primary side of the current transformer with the output current of the transistor circuit largely coincides in amount and phase.

In the present example, for the sake of clarity, the transistor circuit is only a single-stage emitter counter-coupled "Amplifier stage executed. The following equations apply:

0 0 9 8 AO / 0418 B ^AD OHiQSNAt *

ISE / Reg. 5930 - 4 -

jT * άτι ->

U = ÜJ1 · Rb

U is the operating voltage of the transistor stage and Rb is the resistance of the parallel connection of the resistors R1, R2 and RJ , neglecting the input resistance of the transistor T, which is justified given a sufficiently large current gain.

The following equation also applies:

■ Jn '* Jl- £ _ de

Where de the voltage gain of the transistor T in the collector base e and Re mean the emitter resistance.

So is is

Jn = ti Jl Rb g _e 1

or 1 = ü · Rb · | _e

The current Jn through the simulation N is therefore of the voltage amplification of the transistor stage operated in the basic collector circuit, the transformation ratio of the current transformer and the Dimensioning of the resistors Rl, R2, Rj5 and Re depends.

For the decrease of the current proportional control signal can be Place of the converter also a measuring shunt arranged in the line are ^ due to the voltage drop in the transistor circuit in the Sewing branch is controlled.

There is also the option of using suitable switching means the supply voltage of the transformer from its own Establish loop current, which is particularly advantageous in hybrid circuits to simulate back hearing loss in microphone units is used.

7 claims 009840/0418 '././■■

1 BIr drawing, 1 Pig. '"

Claims (7)

ISE / Reg. 3930 - 5 - Claims Hybrid connection 'for two-wire four-wire circuits in transmission systems, especially for speech circuits with electronic line simulation, characterized in that a current transformer (W) is located in the outgoing line (1) of the hybrid circuit is arranged and in the line simulation branch one of fork transducers (¥) controlled and the one through the primary winding (wl) of the current transformer (W) flowing current (Jl) according to the amount and Phase reproducing transistor circuit (N) is provided, in such a way that the flowing in the replication branch Current (Jb) in magnitude and phase essentially equal to that outgoing current (D2) in the line. 2. Hybrid circuit according to claim 1, characterized in that the transistor circuit (N) provided in the replication branch consists of only one negative feedback amplifier stage. 3 · hybrid circuit according to claim 1, characterized in that the transistor circuit (N) provided in the replication branch consists of several counter-coupled amplifier stages. 4. Hybrid circuit according to claim 2 or 3 »characterized in that that for the acceptance of a control signal proportional to the current any equivalent network instead of a current transformer is arranged behind a measuring shunt. 5 hybrid circuit according to claims 1 to 4, characterized in that that for the flow of energy via the line to the fork switch the transistor circuit is matched to the source impedance of the generator, which in this energy direction either no damping or even negative damping can be achieved. I6.7.I968
Krü / Wl 009840/0418 IS ^ / Reg. 3930 - 6 - 6. Hybrid circuit according to claims 1 to 5, characterized in that « that for the transistor circuit, e.g. the arrangement in a call station for the simulation of feedback attenuation necessary supply voltage can be produced from its own loop current is. 7. Hybrid circuit according to claims 1 to 6, characterized in that that the replication arrangement is additionally supplied with voltage-proportional control signals in the correct phase. 009840/0418