DE1128475B - Electronic subscriber circuit - Google Patents

Description

Electronic subscriber circuit The invention relates to a with two electronic switches equipped subscriber circuit for electronically controlled telephone systems.

Analogous to electromechanical solutions, it is necessary that the classic Functions of such subscriber circuits, such as idle status, incentive and identification status, Occupied status and shutdown status, as minimum requirements must be met, if interference affects the exchange facilities via the subscriber lines should be avoided.

A circuit arrangement for a subscriber line is known, where one wire is grounded through a resistor and connected to the base of a transistor connected is. Three different voltage sources are used to control the transistor Tension. When the subscriber loop is closed, the transistor is used the calling line is marked, but the deactivation state is marked not ensured with this arrangement.

A circuit arrangement is also known.:. at the one separately assigned subscriber wire connected to a test wire via a decoupling resistor is. Apart from the additional test wire, this arrangement is also not in the Able to ensure the shutdown state. Furthermore, the circuit remains subordinate Facilities occupied for an unnecessarily long time.

With the invention, an electronic subscriber circuit is created, which meets the aforementioned requirements with optimal effort.

Two electronic, monostable switches; z. B. Transistors.

According to the invention, the object is achieved in such a way that when closing the subscriber loop at a low-resistance resistor that is over the one switch connected to the tip and / or ring is effective, the voltage potential can be tapped for identification and that the second switch is occupied is so effective that both switches have a bistable character in common, which is maintained until the one to the a- and / or b-wire connected resistance is maintained subscriber loop is interrupted.

In the event of incorrect occupancy (shutdown status) beyond the occupancy status become the occupancy potential and that of the second electronic monostable switch the potential that occurs via diodes at a third resistor is evaluated in such a way that that a potential reduction occurring at the resistor as a criterion for the incorrect assignment serves.

The invention is explained in more detail using two exemplary embodiments.

Fig. 1 shows a subscriber circuit in an electronically controlled Government office. A monostable electronic switch T 1 is connected to the b-wire, which acts on a low resistance R 2.

The second electronic monostable is via a voltage divider R 4, R 5 Switch T 2 connected to the former.

Both switches are transistors and are z. B. via the Zener diode Z1 at a fixed emitter potential.

The a-wire serves as the collector resistance for switch T1 connected resistor R 1. The collector resistance for switch T 2 is R 3.

The second switch is connected to the b-wire via the voltage divider R 6, R 7 turned on.

The individual resistors and voltage divider ratios are dimensioned so that when the subscriber loop is interrupted, switch T 1 is closed, ie the transistor is conductive. If the subscriber loop is closed, a voltage drop occurs across resistor R 2, which can be evaluated for identification via diodes D 1, D 2, D 3.

This potential is at the resistor R 2 until the switch T 1 is opened, d. i.e. the transistor is blocked. This happens through outside influence via the c-wire and represents the occupancy case. The switch T2 is closed, d. i.e. the transistor is blocked.

The connection is made via the c-wire and the limiting resistor RS triggered and the subscriber loop is still closed, then remains over the Voltage divider R6, R 7 of switch T 2 closed because switch T1 is open is.

This bistable state exists until the subscriber loop is interrupted.

Both switches then return to their monostable state. at an incorrect assignment reduces the previously fixed potential at resistor R 10, which comes about as a result of potential comparison across diodes D 4 and D 5 with resistor R 9 comes. This reduction serves as a criterion for incorrect occupancy and is evaluated.

The diode D 6 serves as a decoupling diode for central signaling of incorrect assignments, in Fig. 2 the potential for the identification is also tapped at resistor R 2. Here, however, the switch T1 is immediately over the c-core is open. Such a change in potential occurs on the b-wire on that the switch T 2 is closed via the voltage divider R 6, R 7.

If the connection is triggered via the c-wire and the subscriber loop is still closed, then switch T 2 remains closed via voltage divider R 6, R 7, since switch T 1 is still open.

This bistable state exists until the subscriber loop is interrupted.

If an assignment via the c-core is directly against the voltage carried out on the zener diode Z 1, a faulty assignment occurs at the resistor R 10 evaluable voltage drop.

Claims (2)

PATENT CLAIMS: 1. Electronic subscriber circuit for electronic Controlled telephone systems with two transistors working as monostable switches are connected to the a- and / or b-wire of the subscriber line and the identification potential can be tapped off at the emitter resistor of one transistor, characterized in that that the one transistor (T1), at its emitter resistor (R2) the identification potential can be tapped, with its collector on one of the wires (b) of the subscriber line is turned on and that the second transistor (T2) with the base to the same Wire (b) of the subscriber line is switched on, so that when the test wire is occupied (c) both switches have a bistable character in common, such that in dependence from the occupancy potential of the second transistor (T2) in the on state and the first transistor (T1) goes into the blocking state, and that the bistable character is maintained beyond the occupancy state until one over a resistor (R 1) connected to one of the wires (a) and via the base resistor (R 7) of the second transistor (T2) maintained loop is interrupted. 2. Electronic switch according to claim 1, characterized in that in the event of incorrect assignment beyond the occupancy status, the occupancy potential and that at the second switch (T2) occurring potential can be evaluated at a resistor (R 10), that a potential change occurring at the resistor (R10) as a criterion for the incorrect assignment is used. Publications considered: German patent specification No. 954,799; German interpretative document No. 1029 044.