CA2083205A1 - Remote-controlled master switch facility - Google Patents
Remote-controlled master switch facilityInfo
- Publication number
- CA2083205A1 CA2083205A1 CA002083205A CA2083205A CA2083205A1 CA 2083205 A1 CA2083205 A1 CA 2083205A1 CA 002083205 A CA002083205 A CA 002083205A CA 2083205 A CA2083205 A CA 2083205A CA 2083205 A1 CA2083205 A1 CA 2083205A1
- Authority
- CA
- Canada
- Prior art keywords
- remote
- mos
- master switch
- controlled master
- facility according
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 21
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 21
- 239000010703 silicon Substances 0.000 claims abstract description 21
- 230000008878 coupling Effects 0.000 claims abstract description 20
- 238000010168 coupling process Methods 0.000 claims abstract description 20
- 238000005859 coupling reaction Methods 0.000 claims abstract description 20
- 239000003990 capacitor Substances 0.000 claims description 21
- 239000000758 substrate Substances 0.000 claims description 6
- 238000005259 measurement Methods 0.000 abstract description 16
- 238000000034 method Methods 0.000 abstract description 7
- 230000001419 dependent effect Effects 0.000 abstract description 2
- 238000000926 separation method Methods 0.000 abstract 1
- 230000005540 biological transmission Effects 0.000 description 6
- 238000012360 testing method Methods 0.000 description 5
- 241000689109 Corella <basidiomycete fungus> Species 0.000 description 3
- 230000000295 complement effect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 101150054451 Rtel1 gene Proteins 0.000 description 2
- 230000003111 delayed effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000005669 field effect Effects 0.000 description 2
- 238000013461 design Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 230000004807 localization Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 241000894007 species Species 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/30—Modifications for providing a predetermined threshold before switching
- H03K17/305—Modifications for providing a predetermined threshold before switching in thyristor switches
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M3/00—Automatic or semi-automatic exchanges
- H04M3/22—Arrangements for supervision, monitoring or testing
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/06—Modifications for ensuring a fully conducting state
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/51—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used
- H03K17/56—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices
- H03K17/687—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices the devices being field-effect transistors
- H03K17/6871—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices the devices being field-effect transistors the output circuit comprising more than one controlled field-effect transistor
- H03K17/6872—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices the devices being field-effect transistors the output circuit comprising more than one controlled field-effect transistor using complementary field-effect transistors
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/51—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used
- H03K17/56—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices
- H03K17/687—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices the devices being field-effect transistors
- H03K17/6871—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices the devices being field-effect transistors the output circuit comprising more than one controlled field-effect transistor
- H03K17/6874—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices the devices being field-effect transistors the output circuit comprising more than one controlled field-effect transistor in a symmetrical configuration
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M3/00—Automatic or semi-automatic exchanges
- H04M3/22—Arrangements for supervision, monitoring or testing
- H04M3/26—Arrangements for supervision, monitoring or testing with means for applying test signals or for measuring
- H04M3/28—Automatic routine testing ; Fault testing; Installation testing; Test methods, test equipment or test arrangements therefor
- H04M3/30—Automatic routine testing ; Fault testing; Installation testing; Test methods, test equipment or test arrangements therefor for subscriber's lines, for the local loop
- H04M3/301—Circuit arrangements at the subscriber's side of the line
Landscapes
- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Monitoring And Testing Of Exchanges (AREA)
- Interface Circuits In Exchanges (AREA)
- Remote Monitoring And Control Of Power-Distribution Networks (AREA)
- Monitoring And Testing Of Transmission In General (AREA)
- Telephone Function (AREA)
- Selective Calling Equipment (AREA)
- Electronic Switches (AREA)
- Dc-Dc Converters (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Remote-controlled master switch facilities are required so that, at the interchange point between the telecommunication network of one operating company to the network of another company, it is possible to determine in which part of the coupled networks an error has occurred, i.e. to facilitate the DC-separation of the networks from each other for measurement purposes. Remote-controlled master switch facilities based on TRIACs and MOS-FETs are known, whereby a common switching threshold is used. When controlled silicon rectifiers are used as electronic switches, the switches are connected to each other via a coupling device so that dial pulses can be transferred from the telephone to the exchange and switches with insensitive control terminals can be used. According to the invention, the application of normally-off MOS-FETs of the enhancement type facilitates a high turn-on threshold and a low turn-off threshold so that the usual measurement process of voltage lowering can be applied. It is also possible to make the turn-on threshold dependent on the polarity of the voltage.
Remote-controlled master switch facilities are required so that, at the interchange point between the telecommunication network of one operating company to the network of another company, it is possible to determine in which part of the coupled networks an error has occurred, i.e. to facilitate the DC-separation of the networks from each other for measurement purposes. Remote-controlled master switch facilities based on TRIACs and MOS-FETs are known, whereby a common switching threshold is used. When controlled silicon rectifiers are used as electronic switches, the switches are connected to each other via a coupling device so that dial pulses can be transferred from the telephone to the exchange and switches with insensitive control terminals can be used. According to the invention, the application of normally-off MOS-FETs of the enhancement type facilitates a high turn-on threshold and a low turn-off threshold so that the usual measurement process of voltage lowering can be applied. It is also possible to make the turn-on threshold dependent on the polarity of the voltage.
Description
The invention relates to a remote-controlled master switch facility of a telecommunications network.
In the course of the privatization of telecommunication connections, from a certain point onwards, the so-called interchange point, subscribers can freely install and use their own private telephone or telephone system. The maintenance of such private telephone systems lies in the hands of the private operator, and is not the responsibility of the network provider. In the case of a disturbance or fault, it is thus particularly useful to the network provider to be able to as easily as possible determine whether the fault has occurred within his network or within the private telephone system, since the network provider is only responsible for eliminating faults up to the interchange point. Faults which occur behind the interchange point must be eliminated by the subscriber himself. Localization of faults from a central test site is facilitated by remote-controlled master switch facilities which are inserted into the line at the interchange point. Such remote-controlled master switch facilities essentially consist of electronic switches which facilitate cutting off the subscriber for the purpose of carrying out measurements. During normal telephone operation these switches are closed. When a fault occurs, the measurement is made from the telecommunications maintenance center using a test facility, whereby an electronic signal or a voltage is used to open the switch so that the subscriber line can be tested without the subscriber being connected. Usually these measurements involve pure DC measurements which serve to determine resistances.
There are various different known circuits for remote-controlled master switch facilities which differ from each other in their circuit concept. One type of circuit arrangement uses MOS field effect transistors ~MOS~
In the course of the privatization of telecommunication connections, from a certain point onwards, the so-called interchange point, subscribers can freely install and use their own private telephone or telephone system. The maintenance of such private telephone systems lies in the hands of the private operator, and is not the responsibility of the network provider. In the case of a disturbance or fault, it is thus particularly useful to the network provider to be able to as easily as possible determine whether the fault has occurred within his network or within the private telephone system, since the network provider is only responsible for eliminating faults up to the interchange point. Faults which occur behind the interchange point must be eliminated by the subscriber himself. Localization of faults from a central test site is facilitated by remote-controlled master switch facilities which are inserted into the line at the interchange point. Such remote-controlled master switch facilities essentially consist of electronic switches which facilitate cutting off the subscriber for the purpose of carrying out measurements. During normal telephone operation these switches are closed. When a fault occurs, the measurement is made from the telecommunications maintenance center using a test facility, whereby an electronic signal or a voltage is used to open the switch so that the subscriber line can be tested without the subscriber being connected. Usually these measurements involve pure DC measurements which serve to determine resistances.
There are various different known circuits for remote-controlled master switch facilities which differ from each other in their circuit concept. One type of circuit arrangement uses MOS field effect transistors ~MOS~
2 1~ ~ 3 ~ ~ ~
FET) as switching devices, while the other type of circuits work with silicon rectifiers as switching elements.
Remote-controlled master switch facilities which work with silicon rectifiers are described in DE-39 23 981 and EP-016~840. The controlled silicon rectifiers used are thyristors and triacs which incorporate two main connections and one gate connection. With the help of a trigger pulse which is fed to the gate, these components can be brought into a low-resistance co~dition. This condition is maintained until the current flowing via the switch drops below a certain value referred to as the retaining current. The control circuit usually consists of a resistor and one or two zener diodes, whereby the zener diodes can be used to set the breaking voltage.
Furthermore, an AC bridging path is placed across the switches which facilitates the transfer of the AC ringing voltage. The bridging path incorporates a capacitor with a relatively high capacitance of 10-20 microfarads. This capacitance causes prohlems in conjunction with the pulse dialling method used in many countries, because a quick switch response, which in conjunction with the pulse dialling method is usually in the 50-60 millisecond clock range, is prevented. In currently existing remote-controlled master switch facilities it is thus necessary to keep the capacitance in the bridging path as low as possible. Furthermore, switches with sensitive gate terminals have to be used. Now, in order to prevent unintentional closure of the switches with their sensitive gate terminals, additional cixcuit technology is required.
For example, to short brief voltage pulses, capacitors are inserted between the gate terminals and the main connections of a switch.
Instead of controlled silicon rectifiers it is also possible to use MOS field effect transistors as switches in a remote-controlled mast~r switch facility.
The main advantages of MOS-FETs are their low ohmic 2~832~3 resistance ln the switched-on condition and their high impedance gate terminal. The low ohmic resistance results in better transmission characteristics than with silicon rectifiers. With suitable control of the gate terminal, the AC ringing current can be transferred via the MOS
transistor so that the AC bridging path necessary in conjunction with a remote-controlled master switch facility with controlled silicon rectifiers is not required.
U.S. 4,635,084 and the Si7iconix publication "Low Power Discretes Data Book, 1989, p. 9-152f" describe remote-controlled master switch facilitias which use depletion-typa normally-on MOS-FETs as switches. The disadvantage of this arrangement is that these remote-controlled master switch facilities are activated by a voltage pulse which is higher than the supply voltage. The telephone line is thus briefly opened at the interchange point, during which time the measurement can be made. The interval is determined by a time constant, i.e. it is a ixed given time. The standard measurement process whereby the voltage is lowered can thus not be carried out.
A main objective of the present invention is the provision of a remote-controlled master switch facility for subscriber lines of the aforementioned species which does not evidence any problems during the transmission of dial pulses, and which allows the application of the usual measurement processes.
According to an aspect of the present invention, there is provided a remote-controlled master switch facility consisting of two electronic switches connected into the respective subscriber line, whereby each switch incorporates a controlled silicon rectifier, the control input of which is driven by a parallel connected zener diode with resistor and incorporates a parallel bridging of the silicon rectifier, which consists of a capacitor and a resistor wherein the control inputs of the silicon rectifier are connected by a coupling device.
According to another aspect of the present invention, there is provided a remote-controlled master switch facility consisting of two electronic switches connected into the respective subscriber line, whereby each switch incorporates at least one MOS-FET, wherein normally-off MOS-FETs of the enhancement type are used.
If the remote-controlled master switch facilities operate with controlled silicon rectifiers, then, according to the invention, the two control branches (which each consist of a zener diode and a resistor) are connected to the coupling device. The coupling device consists of a capacitance and a resistor connected in series. The connection according to the invention between the two control branches by the coupling device ensure a quick response time for the silicon rectifiers. It is thus possible to apply high capacities in the AC bridging path without any disturbances occurring during the transmission of dial pulses. Additionally, the high capacity in the bridging path in conjunction with the line resistances and the terminating resistances create a high-pass filter which allows the transmission of digital signals. Furthermore, the control circuit embodiment of the invention allows the use of switches having less sensitive gate inputs so that additional components for preventing unintentional closing of the switches are not required.
If thyristors are used as switches, diodes have to be connected parallel to the thyristors to carry the current flowing awav from the subscriber. Since the remote-controlled master switch facility must operate independent of polarity, one thyristor and one diode are ~rovided for each line route. Corresponding to the polarity of the remote-controlled master switch facility, the thyristor takes over current flow in one line while the diode takes over currsnt flow in the other. If triacs are to be used as switches, the diodes can be left out since the triacs conduct current in both directions.
~ 3 If MOS-FETs are used as switches in remote-controlled master switch facilities, then, accordiny to the invention, enhancement-typ~ usually off MOS-FETs are used.
Each MOS-FET switch is selected by a voltage divider which defines the turn-on threshold. The low turn-off threshold of the remote-controlled master switch facility is achieved by additional MOS-FETs which, in conjunction with a serial low-value resistor, partially bridge the voltage divider of the turn-on threshold. This produces an hysteresis effect for the control circuit. A MOS-FET switch consists o~ at least one, and at most two MOS-FET branches which, in turn, incorporate one or two MOS-FETs. If a MOS-FET switch consists of two branchesl one branch will have n-channel and the other will have p-channel MOS-FETs, and the branches are connected in parallel. A voltage divider is provided for each branch, whereby the bridging necassary for the hysteresis effect only involves one branch of the respective switch. The turn-on voltage may be a few volts below the supply voltage of the telecommunications network, while the turn-off voltage may be below 10 volts. The application of capacitors effects a delayed turn-off of the MOS-FETs and thus facilitates the transmission of AC
ringing currents. Of particular advantage is the fact that, due to the application of enhancement type MOS-FETs, the same measurement method, by way of lowering the control voltage, can be used as with remote-controlled master switch facilities with controlled silicon rectifiers. By using DC/DC converters, it is possible to render the n-channel branches redundant. Thereby complementary circuits are included.
If there is only one measurement voltage available for test purposes, it is of advantage if the remote-controlled master switch facility can also be controlled by a voltage. This is achieved hy reversing the polarity of an electronic switch in a core. The switching function of the remote-controlled master switch facility ,3~0~
can then be achieved by reversing the polarity of the measurement voltage, if the latter is below the breaking voltage of the switch. This can be implemented for both types of remote-controlled master switch facilities, i.e.
such facilities with silicon rectifiers or MOS-FETs as switches.
Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which:
Figure 1 is a schematic diagram of a subscriber line;
Figure 2 illustrates a remote-controlled master switch facility with controlled silicon rectifiers;
Figure 3 illustrates the behaviour of a remote-controlled master switch facility with controlled silicon rectifiers, with and without a coupling device in conjunction with pulse dialling;
Figure ~ illustrates a remote-controlled master switch facility with M~S-FET switches;
Figure 5 shows a simplified circuit section of the circuit according to Figure 4;
Figure 6 schematically illus~rates a second embodiment of a remote-controlled master switch facility with MOS-FET switches;
Figure 7 illustrates a third embodiment of a remote-controlled master switch facility wi.th MOS-FETs and DC/DC converters;
Figure 8 illustrates a remote-controlled master switch facility with controlled silicon rectifiers and reversed-polarity electronic switches; and Figure 9 illustrates a remote-controlled master switch facility with MOS-FET switches, the switches of which are mutually polarity reversed.
Figure 1 shows a subscriber line, where the subscriber's line 11 (consisting of two lines lla and llb) leads from the exchange 10, which for matters of ~ ~ ~ .3~
simplification also lncorporates the maintenance center, to the intercha~e point where there is a remote-controlled master switch facility 12. sehind the interchange point 12 there is a private network 13 with its terminal equipment 14. The remote-controlled master switch facility 12 essentially consists o~ two electronic circuits 12a, 12b which facilitate cutting off the subscriber. These switches are voltage-dependently controlled by a suitable control voltage. The brea~ing voltage is lower than the supply voltage for the subscriber's line 11, so that during normal telephone operation the switches are closed. In a fault situation, a measurement is made from the exchange 10 usin~ a suitable test device which works with two voltages.
One of these voltages is above the breaking voltage, the other is below it. Lowering the voltage benaath the switching threshold causes the switch to open, and the subscriber's line can be tested without the subscriber being connected.
Figure 2 shows a preferred embodiment of a remote-controlled master switch facility in which thyristors S1, S2, which are connected into lines ~~A~ (Ila) and ~-B~ (llb) are being used as switches. In order to provide polarity independence for the remote-controlled master switch facility, diodes D3 and D4 are connected parallel to thyristors Sl and S2, whereby the forward direction of the diodes D3, D4 is opposed to the forward direction of the thyristors. In correspondence with the polarity of the remote-controlled master switch facility, in one line branch the thyristor takes over current flow while in the other line the diode does this. If, for example, core lla of the telecommunication circuit is positive compared with core llb, during operation the supply current will flow via thyristor S1 and Diode D4.
~nother possible embodiment o~ the invention is a remote-controlled master switch facility with triacs. In thiscase diodes D3, D4 are redundant since a triac conducts ~3S~
current in hoth directions. The bridying paths 20, 21 are connected parallel to the switches. The voltage-dependent turn-on characteristics of thyristors S1, S2 is achieved through the implementation of the control branches 30, 31.
To achieve rapid response for the thyristors S1, S2 during pulse dialling, both control branches are connected via a coupling device 40.
In the pulse dialling method, dial pulses are generated in the telephone 14 by way of a dial pulse switch within the telephone which opens and closes in the frequency of the pulses. When the dial pulse switch is closed, current must flow so that the dial pulses can be recognized by the exchange 10. Consequently, the corresponding thyristor of the remote-controlled mastar switch facility 12 must be closed during a dial pulse to allow the current to flow. When the dial pulse switch within the telephone opens, the thyristor will also open since the retaining current is underflowed. The thyristor must close approximately every 100 milliseconds. When there is no coupling device 40, this rapid closing of the thyristor is prevented by the capacitor in the bridging path, because, during the previous pulse, the capacitor was discharged via the conducting thyristor and can not recharge to the breaking voltage during the 30-40 milliseconds that the dial pulse switch is open. Due to the high-impedance telephone, the time constant for charging the capacitors C1, C2 in the bridging path 20, ~1 is somewhere in the range between 20 and 100 milliseconds.
The time constant for thP coupling device 40 is smaller than 10 milliseconds so that the capacitor C3 of the coupling device 40 can supply the trigger pulse for the thyristor S1, S2 when the dial pulse switch in the telephone closes. The coupling device 40 thus utilizes the charging current of the capacitors Cl, C2 which arises after the dial pulse switch opens, whereby part of this current is stored in the capacitor C3 of the coupling 2 1~ ~3 r3 ~
device ~0 and is thus available as trigger energy for the thyristors when the dial pulse switch closes again.
Figure 3 illustrates the behaviour of the remote-controlled master switch facility, both with the coupling device 40 (broken line) and without the coupling device 40 (solid line), for pulse dialling. In ihis example, the potential of core lla is positive with respect to the potential of core llb. Figure 3(I) shows the conditions for the dial pulse switch within the telephone 14, Figure
FET) as switching devices, while the other type of circuits work with silicon rectifiers as switching elements.
Remote-controlled master switch facilities which work with silicon rectifiers are described in DE-39 23 981 and EP-016~840. The controlled silicon rectifiers used are thyristors and triacs which incorporate two main connections and one gate connection. With the help of a trigger pulse which is fed to the gate, these components can be brought into a low-resistance co~dition. This condition is maintained until the current flowing via the switch drops below a certain value referred to as the retaining current. The control circuit usually consists of a resistor and one or two zener diodes, whereby the zener diodes can be used to set the breaking voltage.
Furthermore, an AC bridging path is placed across the switches which facilitates the transfer of the AC ringing voltage. The bridging path incorporates a capacitor with a relatively high capacitance of 10-20 microfarads. This capacitance causes prohlems in conjunction with the pulse dialling method used in many countries, because a quick switch response, which in conjunction with the pulse dialling method is usually in the 50-60 millisecond clock range, is prevented. In currently existing remote-controlled master switch facilities it is thus necessary to keep the capacitance in the bridging path as low as possible. Furthermore, switches with sensitive gate terminals have to be used. Now, in order to prevent unintentional closure of the switches with their sensitive gate terminals, additional cixcuit technology is required.
For example, to short brief voltage pulses, capacitors are inserted between the gate terminals and the main connections of a switch.
Instead of controlled silicon rectifiers it is also possible to use MOS field effect transistors as switches in a remote-controlled mast~r switch facility.
The main advantages of MOS-FETs are their low ohmic 2~832~3 resistance ln the switched-on condition and their high impedance gate terminal. The low ohmic resistance results in better transmission characteristics than with silicon rectifiers. With suitable control of the gate terminal, the AC ringing current can be transferred via the MOS
transistor so that the AC bridging path necessary in conjunction with a remote-controlled master switch facility with controlled silicon rectifiers is not required.
U.S. 4,635,084 and the Si7iconix publication "Low Power Discretes Data Book, 1989, p. 9-152f" describe remote-controlled master switch facilitias which use depletion-typa normally-on MOS-FETs as switches. The disadvantage of this arrangement is that these remote-controlled master switch facilities are activated by a voltage pulse which is higher than the supply voltage. The telephone line is thus briefly opened at the interchange point, during which time the measurement can be made. The interval is determined by a time constant, i.e. it is a ixed given time. The standard measurement process whereby the voltage is lowered can thus not be carried out.
A main objective of the present invention is the provision of a remote-controlled master switch facility for subscriber lines of the aforementioned species which does not evidence any problems during the transmission of dial pulses, and which allows the application of the usual measurement processes.
According to an aspect of the present invention, there is provided a remote-controlled master switch facility consisting of two electronic switches connected into the respective subscriber line, whereby each switch incorporates a controlled silicon rectifier, the control input of which is driven by a parallel connected zener diode with resistor and incorporates a parallel bridging of the silicon rectifier, which consists of a capacitor and a resistor wherein the control inputs of the silicon rectifier are connected by a coupling device.
According to another aspect of the present invention, there is provided a remote-controlled master switch facility consisting of two electronic switches connected into the respective subscriber line, whereby each switch incorporates at least one MOS-FET, wherein normally-off MOS-FETs of the enhancement type are used.
If the remote-controlled master switch facilities operate with controlled silicon rectifiers, then, according to the invention, the two control branches (which each consist of a zener diode and a resistor) are connected to the coupling device. The coupling device consists of a capacitance and a resistor connected in series. The connection according to the invention between the two control branches by the coupling device ensure a quick response time for the silicon rectifiers. It is thus possible to apply high capacities in the AC bridging path without any disturbances occurring during the transmission of dial pulses. Additionally, the high capacity in the bridging path in conjunction with the line resistances and the terminating resistances create a high-pass filter which allows the transmission of digital signals. Furthermore, the control circuit embodiment of the invention allows the use of switches having less sensitive gate inputs so that additional components for preventing unintentional closing of the switches are not required.
If thyristors are used as switches, diodes have to be connected parallel to the thyristors to carry the current flowing awav from the subscriber. Since the remote-controlled master switch facility must operate independent of polarity, one thyristor and one diode are ~rovided for each line route. Corresponding to the polarity of the remote-controlled master switch facility, the thyristor takes over current flow in one line while the diode takes over currsnt flow in the other. If triacs are to be used as switches, the diodes can be left out since the triacs conduct current in both directions.
~ 3 If MOS-FETs are used as switches in remote-controlled master switch facilities, then, accordiny to the invention, enhancement-typ~ usually off MOS-FETs are used.
Each MOS-FET switch is selected by a voltage divider which defines the turn-on threshold. The low turn-off threshold of the remote-controlled master switch facility is achieved by additional MOS-FETs which, in conjunction with a serial low-value resistor, partially bridge the voltage divider of the turn-on threshold. This produces an hysteresis effect for the control circuit. A MOS-FET switch consists o~ at least one, and at most two MOS-FET branches which, in turn, incorporate one or two MOS-FETs. If a MOS-FET switch consists of two branchesl one branch will have n-channel and the other will have p-channel MOS-FETs, and the branches are connected in parallel. A voltage divider is provided for each branch, whereby the bridging necassary for the hysteresis effect only involves one branch of the respective switch. The turn-on voltage may be a few volts below the supply voltage of the telecommunications network, while the turn-off voltage may be below 10 volts. The application of capacitors effects a delayed turn-off of the MOS-FETs and thus facilitates the transmission of AC
ringing currents. Of particular advantage is the fact that, due to the application of enhancement type MOS-FETs, the same measurement method, by way of lowering the control voltage, can be used as with remote-controlled master switch facilities with controlled silicon rectifiers. By using DC/DC converters, it is possible to render the n-channel branches redundant. Thereby complementary circuits are included.
If there is only one measurement voltage available for test purposes, it is of advantage if the remote-controlled master switch facility can also be controlled by a voltage. This is achieved hy reversing the polarity of an electronic switch in a core. The switching function of the remote-controlled master switch facility ,3~0~
can then be achieved by reversing the polarity of the measurement voltage, if the latter is below the breaking voltage of the switch. This can be implemented for both types of remote-controlled master switch facilities, i.e.
such facilities with silicon rectifiers or MOS-FETs as switches.
Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which:
Figure 1 is a schematic diagram of a subscriber line;
Figure 2 illustrates a remote-controlled master switch facility with controlled silicon rectifiers;
Figure 3 illustrates the behaviour of a remote-controlled master switch facility with controlled silicon rectifiers, with and without a coupling device in conjunction with pulse dialling;
Figure ~ illustrates a remote-controlled master switch facility with M~S-FET switches;
Figure 5 shows a simplified circuit section of the circuit according to Figure 4;
Figure 6 schematically illus~rates a second embodiment of a remote-controlled master switch facility with MOS-FET switches;
Figure 7 illustrates a third embodiment of a remote-controlled master switch facility wi.th MOS-FETs and DC/DC converters;
Figure 8 illustrates a remote-controlled master switch facility with controlled silicon rectifiers and reversed-polarity electronic switches; and Figure 9 illustrates a remote-controlled master switch facility with MOS-FET switches, the switches of which are mutually polarity reversed.
Figure 1 shows a subscriber line, where the subscriber's line 11 (consisting of two lines lla and llb) leads from the exchange 10, which for matters of ~ ~ ~ .3~
simplification also lncorporates the maintenance center, to the intercha~e point where there is a remote-controlled master switch facility 12. sehind the interchange point 12 there is a private network 13 with its terminal equipment 14. The remote-controlled master switch facility 12 essentially consists o~ two electronic circuits 12a, 12b which facilitate cutting off the subscriber. These switches are voltage-dependently controlled by a suitable control voltage. The brea~ing voltage is lower than the supply voltage for the subscriber's line 11, so that during normal telephone operation the switches are closed. In a fault situation, a measurement is made from the exchange 10 usin~ a suitable test device which works with two voltages.
One of these voltages is above the breaking voltage, the other is below it. Lowering the voltage benaath the switching threshold causes the switch to open, and the subscriber's line can be tested without the subscriber being connected.
Figure 2 shows a preferred embodiment of a remote-controlled master switch facility in which thyristors S1, S2, which are connected into lines ~~A~ (Ila) and ~-B~ (llb) are being used as switches. In order to provide polarity independence for the remote-controlled master switch facility, diodes D3 and D4 are connected parallel to thyristors Sl and S2, whereby the forward direction of the diodes D3, D4 is opposed to the forward direction of the thyristors. In correspondence with the polarity of the remote-controlled master switch facility, in one line branch the thyristor takes over current flow while in the other line the diode does this. If, for example, core lla of the telecommunication circuit is positive compared with core llb, during operation the supply current will flow via thyristor S1 and Diode D4.
~nother possible embodiment o~ the invention is a remote-controlled master switch facility with triacs. In thiscase diodes D3, D4 are redundant since a triac conducts ~3S~
current in hoth directions. The bridying paths 20, 21 are connected parallel to the switches. The voltage-dependent turn-on characteristics of thyristors S1, S2 is achieved through the implementation of the control branches 30, 31.
To achieve rapid response for the thyristors S1, S2 during pulse dialling, both control branches are connected via a coupling device 40.
In the pulse dialling method, dial pulses are generated in the telephone 14 by way of a dial pulse switch within the telephone which opens and closes in the frequency of the pulses. When the dial pulse switch is closed, current must flow so that the dial pulses can be recognized by the exchange 10. Consequently, the corresponding thyristor of the remote-controlled mastar switch facility 12 must be closed during a dial pulse to allow the current to flow. When the dial pulse switch within the telephone opens, the thyristor will also open since the retaining current is underflowed. The thyristor must close approximately every 100 milliseconds. When there is no coupling device 40, this rapid closing of the thyristor is prevented by the capacitor in the bridging path, because, during the previous pulse, the capacitor was discharged via the conducting thyristor and can not recharge to the breaking voltage during the 30-40 milliseconds that the dial pulse switch is open. Due to the high-impedance telephone, the time constant for charging the capacitors C1, C2 in the bridging path 20, ~1 is somewhere in the range between 20 and 100 milliseconds.
The time constant for thP coupling device 40 is smaller than 10 milliseconds so that the capacitor C3 of the coupling device 40 can supply the trigger pulse for the thyristor S1, S2 when the dial pulse switch in the telephone closes. The coupling device 40 thus utilizes the charging current of the capacitors Cl, C2 which arises after the dial pulse switch opens, whereby part of this current is stored in the capacitor C3 of the coupling 2 1~ ~3 r3 ~
device ~0 and is thus available as trigger energy for the thyristors when the dial pulse switch closes again.
Figure 3 illustrates the behaviour of the remote-controlled master switch facility, both with the coupling device 40 (broken line) and without the coupling device 40 (solid line), for pulse dialling. In ihis example, the potential of core lla is positive with respect to the potential of core llb. Figure 3(I) shows the conditions for the dial pulse switch within the telephone 14, Figure
3(II~ shows the charge voltage at capacitor Cl of the bridging path 20 as a function of time, Figure 3(III) represents the loop current as a function of time and Figure 3(IV) shows the current in the coupling device.
If the circuit is operated without the coupling device, then prior to the first dial pulse 50, capacitor Cl is charged up to the breaking voltage determined by diode Dl. The thyristor Sl can then fire and a constant loop current 70 then flows for the duration of the pulse.
Following the dial pulse 50, the capacitor Cl slowly recharges. However, the time constant is very high because the impedance of the telephone between pulses can range between 100 K-Qhms and several M-Ohms. Thus, at the beginning of the next dial pulse 51, the capacitor voltage 61 will not as yet have reached the breaking voltage level and the thyristor Sl can not be fired. During the pulse 51, an increased charging current 71 flows because during the period of a dial pulse the telephone becomes low-impedient (typically around 300 Ohms). Due to the increased charging current, the voltage on the capacitor Cl, ~2 increases correspondingly rapid. At the beginning of the third pulse 52~ the voltage will not as yet have reached the breaking voltage, sc that the thyristor Sl does not fire at the beginning of the pulse but at some later point 72. Due to the discharge of the capacitor C1, the condition for the fourth pulse corresponds to the condition during the second pulse 51.
; ' ,-2 ~
The behaviour of the circuit with a coupling devic~ 40 is shown in Figure 3 (I) through (IV) with the broken line. For the first pulse 50, the thyristor Sl will fire because of the charge voltage of the capacitor Cl .
For the second pulse 51, the charge voltage is not sufficient for the thyristor to fire. The trigger pulse 80 is thus supplied by the coupling device 40 which charged up between pulses.
Figure 4 shows a preferred embodiment of the invention in which the switches 12a, 12b are implemented with MOS~FETs. The MOS-FET switch 12a includes the two MOS-FET branches 100, 101 while the MOS-FET switch 12b is formed by the MOS-FET branches 102, 103. In this embodiment, the MOS-FET branches 100, 103 incorporate p-channel MOS-FETs and branches 101, 102 incorporate n-channel MOS-FET. Each MOS-FET branch consists of a MOS FET
pair (Ql, Q2), (Q3, Q4), (Q6, Q7) and (Q8, Q9) whereby in each case the gate and source terminals of a MOS-FET pair are connectad. The channel substrate diodes are connected in opposition to each other so that the current can only flow between the subscriber and the exchange via the MQS
transistor channels. It is also conceivable to connect the drain terminals with each other instead of the source terminals, to prevent the current from flowing via the substrate diodes. The p-channal branches 100, 103 respectively take the current which flows to the subscriber, while the n-channel branches 101, 102 take over the current flowing from the subscriber to the exchange.
Since each switch 12a, 12b has both an n-channel as well as a p-channel, the circuit operates independent of polarity.
Control for the MOS-FET branches 100, 101, 102 and 103 i5 implemented via one voltage divider each (Rtl, Rt8~, (Rt2, Rt7), (Rt3, Rt6~, (Rt4, Rt5). The resistance Rt8 of the voltage divider for branch 100 can be bridged by a MOS FET Q5 with a serial resistor Rsl and a diode Dsl.
The gate of the controlling MOS-FET Q5 is driven by the 2 ~ ~ ~3 ~
voltage divider ~s2, ~s3. The same applies for branch 103;
here a controlling MOS-FET Ql0 with a serial re~istor Rs4 and a diode Ds2 bridge resistor Rt5 in the through-connected state of the MOS-FET. The gate of Q10 is wired up with a voltage divider comprising resistors Rs5 and Rs6.
For voltage limitation purposes, æener diode pairs Zl, z2, Z3 and Z4 are wired up between the source and base lines of the respective hranches 100, 101, 102 and 103. The same applies for MO~-FETs Q5 and Ql0, where zener diode pairs Z6 and Z3 are used. The wiring and the voltage divider are dimensioned such that a high turn-on voltage and a low turn-off voltage are obtained. The turn-on voltage may be a few volts below the supply voltage of the telecommunication network while the turn-off voltage may be l~ below 10 volts. This circuit arrangement takes into account that when low-impedance terminal equipment is put into operation, the voltage drops well below the turn-on threshold of the remote-controlled master switch facility.
The controlling MOS-FETs Q5 and Q10 produces hysteretic behaviour in the switching threshold for the n-channel branches 101 and 102. The capacitors CGl through C~4, which are wired between the source and gate lines of branches 100, 101, 102 and 103, cause a delayed turn-off of the MOS-FETs and thus facilitate the transmission of AC
ringing currents.
Figure 5 shows a simplified circuit section of the circuit illustrated in Figure 4, and the accompanying wiring to the exchange side and the subscriber side.
Figure 5 is used to explain the mode of operation o~ the circuit shown in Figure 4 Put simply, the exchange is represented as a DC voltage source Vamt and two resistors Ra and Rb which represent the supply resistances and line resistances for each core lla and llb. In this simplified description, the telephone on the subscriber side is represented as a cradle switch GU and a resistor Rtel.
When the cradle switch is open, i.e. the receiver is hung 320~
up, the full supply voltage Vamt is available to the subscriber ~nd thus also to the input of the remote-controlled master switch facility, since resistors Ra and Rb are small comparsd with the insulation resistance of the telephone. When the cradle switch G~ is closed, the telephone 14 is low impedient and resistors Ra, Rb and Rtel form a voltage divider, whereby, depending on the line length, only 15 to 30% of the exchange voltage Vamt reaches the telephone 14. The switching threshold of the remote-controlled master switch facility must thus be not higherthan this limit, and, for an exchange voltage Vamt of 60V, would be 9V. However, in test situations it is desirable to be able to perform measurements with voltages between 10 and 20 V, without the subscriber being connected. This is not possible in conjunction with a simple switching limit of 9V. ~ control circuit is thus required which provides a high turn-on threshold and a low turn-off threshold, i.e.
one which exhibits hysteretic behaviour. The two MOS-FETs Ql and Q2 which are serially wired into the subscriber line lla, (with their respective source and gate terminals connected with each other) lead the current to the telephone 14 in the switched-on condition. The control for branch 100 (comprising Ql and Q2), is implemented through voltage divider Rtl and Rt8. These two resistances determine the turn-on threshold of the circuit and can be placed, for example, at 50% of the exchange voltage (supply voltage). Thus the turn-on voltage is considerably higher than the voltage which would by available at the input of the remote-controlled master switch facility while the cradle switch GU is closed. If the turn-on threshold is exceeded, the MOS-FETs Ql and Q2 are rendered conductive and the same voltage that is present at the input of the remote-controlled master switch facility is also present at the output of the same, i.e. at voltage divider Rs2, Rs3.
The voltage divider Rs2, Rs3 is dimensioned in such a way that, for small voltages of approximately 15 to 20% of the exchanga voltage, the n-channel MOS~FET Q5 is conductive.
In this condition, the high-impedance resistor Rt8 is bridged by thP low-impedance resistor Rsl. The consequence of this is that, even if the cradle switch GU is closed, the MOS-FETs Ql and Q2 remain conductive even for small voltages. Since the MOS-FETs can be practically powerlessly controlled, the voltage divider resistances can be kept very high, i.e. in the ~-Ohm range, so that the power consumption of the circuit is very small.
Figure 6 shows a simplified schematic diagram of an embodiment of the invention in which a single MOS-FET is used in each of the branches 100, 101, 102 and 103 instead of a MOS-FET pair, respectively. Switches 12a and 12b consist o~ one n-channel (Ql, Q~) and one p channel (Q3, Q6) MOS-FET, which are connected in parallel in such a way that the anodes of the substrate diodes are wired towards the subscriber. In this case the substrate diodes of the MOS-FETs can only conduct current from the subscriber to the exchange. That is why the switching threshold for the return flow branch is not greater than 0.6V. Otherwise the circuit design corresponds to the embodiment according to Figure 4.
Figure 7 shows a further preferred embodiment of the invention, wherein the control circuits for the branches are diagrammatically represented as blocks 160 and 161, and correspond to that shown in Figure 4. The n-channel MOS-FET branches 101 and 102 of the circuit shown in Figure 4 can be left out if the p-channel branches 100 and 103 are each controlled by a DC/DC converter 150, 151 in addition to the above described control circuits 160, 161 which cause tha hysteretic behaviour. The converters 150, 151 generate a negative voltage when the correspondiny p-channel pair 100, 103 is in the negative branch of the telecommunications line and conducts current from the terminal equipment to the exchange. A complementary circuit with n-channel switches and DC/DC converters, which 1~
generate a positive potential for the n-channel switch which is in the positive branch, is also conceivable.
Figure 8 shows a remote-controlled master switch facility with controlled silicon rectifiers, and represents a modified version of the circuit shown in Figure 2. The electrollic switch 12b in core b is reverse poled to switch 12a. Thus the forward direction of diodes D2 and D4 and thyristor S2 is antiparallel to that of diodes D1 and D3, and thyristor Sl in core a. When core a has a positive voltage with respect to core b, thyristors Sl and S2 ars inhibited if the measurement voltage is below the switching voltage. When the measurement voltage is neg~tive, diodes D3 and D4 become conductive and the subscriber side is included in the measurement process, i.e. switches 12a and 12b are switched back on again.
Figure 9 shows a correspondingly modified ~OS-FET
circuit from Figure 6. In this case the MOS-FET
transistors in core b are interchanged. Transistor Q6 is now an n-channel type and transistor Q8 is a p~channel type. On the other hand, in the circuit according to Figure 6, the switches are symmetrical. Furthermore, the respective Schmitt trigger transistor Q10 of the corresponding control has been replaced with the complementary p-channel type.
If the circuit is operated without the coupling device, then prior to the first dial pulse 50, capacitor Cl is charged up to the breaking voltage determined by diode Dl. The thyristor Sl can then fire and a constant loop current 70 then flows for the duration of the pulse.
Following the dial pulse 50, the capacitor Cl slowly recharges. However, the time constant is very high because the impedance of the telephone between pulses can range between 100 K-Qhms and several M-Ohms. Thus, at the beginning of the next dial pulse 51, the capacitor voltage 61 will not as yet have reached the breaking voltage level and the thyristor Sl can not be fired. During the pulse 51, an increased charging current 71 flows because during the period of a dial pulse the telephone becomes low-impedient (typically around 300 Ohms). Due to the increased charging current, the voltage on the capacitor Cl, ~2 increases correspondingly rapid. At the beginning of the third pulse 52~ the voltage will not as yet have reached the breaking voltage, sc that the thyristor Sl does not fire at the beginning of the pulse but at some later point 72. Due to the discharge of the capacitor C1, the condition for the fourth pulse corresponds to the condition during the second pulse 51.
; ' ,-2 ~
The behaviour of the circuit with a coupling devic~ 40 is shown in Figure 3 (I) through (IV) with the broken line. For the first pulse 50, the thyristor Sl will fire because of the charge voltage of the capacitor Cl .
For the second pulse 51, the charge voltage is not sufficient for the thyristor to fire. The trigger pulse 80 is thus supplied by the coupling device 40 which charged up between pulses.
Figure 4 shows a preferred embodiment of the invention in which the switches 12a, 12b are implemented with MOS~FETs. The MOS-FET switch 12a includes the two MOS-FET branches 100, 101 while the MOS-FET switch 12b is formed by the MOS-FET branches 102, 103. In this embodiment, the MOS-FET branches 100, 103 incorporate p-channel MOS-FETs and branches 101, 102 incorporate n-channel MOS-FET. Each MOS-FET branch consists of a MOS FET
pair (Ql, Q2), (Q3, Q4), (Q6, Q7) and (Q8, Q9) whereby in each case the gate and source terminals of a MOS-FET pair are connectad. The channel substrate diodes are connected in opposition to each other so that the current can only flow between the subscriber and the exchange via the MQS
transistor channels. It is also conceivable to connect the drain terminals with each other instead of the source terminals, to prevent the current from flowing via the substrate diodes. The p-channal branches 100, 103 respectively take the current which flows to the subscriber, while the n-channel branches 101, 102 take over the current flowing from the subscriber to the exchange.
Since each switch 12a, 12b has both an n-channel as well as a p-channel, the circuit operates independent of polarity.
Control for the MOS-FET branches 100, 101, 102 and 103 i5 implemented via one voltage divider each (Rtl, Rt8~, (Rt2, Rt7), (Rt3, Rt6~, (Rt4, Rt5). The resistance Rt8 of the voltage divider for branch 100 can be bridged by a MOS FET Q5 with a serial resistor Rsl and a diode Dsl.
The gate of the controlling MOS-FET Q5 is driven by the 2 ~ ~ ~3 ~
voltage divider ~s2, ~s3. The same applies for branch 103;
here a controlling MOS-FET Ql0 with a serial re~istor Rs4 and a diode Ds2 bridge resistor Rt5 in the through-connected state of the MOS-FET. The gate of Q10 is wired up with a voltage divider comprising resistors Rs5 and Rs6.
For voltage limitation purposes, æener diode pairs Zl, z2, Z3 and Z4 are wired up between the source and base lines of the respective hranches 100, 101, 102 and 103. The same applies for MO~-FETs Q5 and Ql0, where zener diode pairs Z6 and Z3 are used. The wiring and the voltage divider are dimensioned such that a high turn-on voltage and a low turn-off voltage are obtained. The turn-on voltage may be a few volts below the supply voltage of the telecommunication network while the turn-off voltage may be l~ below 10 volts. This circuit arrangement takes into account that when low-impedance terminal equipment is put into operation, the voltage drops well below the turn-on threshold of the remote-controlled master switch facility.
The controlling MOS-FETs Q5 and Q10 produces hysteretic behaviour in the switching threshold for the n-channel branches 101 and 102. The capacitors CGl through C~4, which are wired between the source and gate lines of branches 100, 101, 102 and 103, cause a delayed turn-off of the MOS-FETs and thus facilitate the transmission of AC
ringing currents.
Figure 5 shows a simplified circuit section of the circuit illustrated in Figure 4, and the accompanying wiring to the exchange side and the subscriber side.
Figure 5 is used to explain the mode of operation o~ the circuit shown in Figure 4 Put simply, the exchange is represented as a DC voltage source Vamt and two resistors Ra and Rb which represent the supply resistances and line resistances for each core lla and llb. In this simplified description, the telephone on the subscriber side is represented as a cradle switch GU and a resistor Rtel.
When the cradle switch is open, i.e. the receiver is hung 320~
up, the full supply voltage Vamt is available to the subscriber ~nd thus also to the input of the remote-controlled master switch facility, since resistors Ra and Rb are small comparsd with the insulation resistance of the telephone. When the cradle switch G~ is closed, the telephone 14 is low impedient and resistors Ra, Rb and Rtel form a voltage divider, whereby, depending on the line length, only 15 to 30% of the exchange voltage Vamt reaches the telephone 14. The switching threshold of the remote-controlled master switch facility must thus be not higherthan this limit, and, for an exchange voltage Vamt of 60V, would be 9V. However, in test situations it is desirable to be able to perform measurements with voltages between 10 and 20 V, without the subscriber being connected. This is not possible in conjunction with a simple switching limit of 9V. ~ control circuit is thus required which provides a high turn-on threshold and a low turn-off threshold, i.e.
one which exhibits hysteretic behaviour. The two MOS-FETs Ql and Q2 which are serially wired into the subscriber line lla, (with their respective source and gate terminals connected with each other) lead the current to the telephone 14 in the switched-on condition. The control for branch 100 (comprising Ql and Q2), is implemented through voltage divider Rtl and Rt8. These two resistances determine the turn-on threshold of the circuit and can be placed, for example, at 50% of the exchange voltage (supply voltage). Thus the turn-on voltage is considerably higher than the voltage which would by available at the input of the remote-controlled master switch facility while the cradle switch GU is closed. If the turn-on threshold is exceeded, the MOS-FETs Ql and Q2 are rendered conductive and the same voltage that is present at the input of the remote-controlled master switch facility is also present at the output of the same, i.e. at voltage divider Rs2, Rs3.
The voltage divider Rs2, Rs3 is dimensioned in such a way that, for small voltages of approximately 15 to 20% of the exchanga voltage, the n-channel MOS~FET Q5 is conductive.
In this condition, the high-impedance resistor Rt8 is bridged by thP low-impedance resistor Rsl. The consequence of this is that, even if the cradle switch GU is closed, the MOS-FETs Ql and Q2 remain conductive even for small voltages. Since the MOS-FETs can be practically powerlessly controlled, the voltage divider resistances can be kept very high, i.e. in the ~-Ohm range, so that the power consumption of the circuit is very small.
Figure 6 shows a simplified schematic diagram of an embodiment of the invention in which a single MOS-FET is used in each of the branches 100, 101, 102 and 103 instead of a MOS-FET pair, respectively. Switches 12a and 12b consist o~ one n-channel (Ql, Q~) and one p channel (Q3, Q6) MOS-FET, which are connected in parallel in such a way that the anodes of the substrate diodes are wired towards the subscriber. In this case the substrate diodes of the MOS-FETs can only conduct current from the subscriber to the exchange. That is why the switching threshold for the return flow branch is not greater than 0.6V. Otherwise the circuit design corresponds to the embodiment according to Figure 4.
Figure 7 shows a further preferred embodiment of the invention, wherein the control circuits for the branches are diagrammatically represented as blocks 160 and 161, and correspond to that shown in Figure 4. The n-channel MOS-FET branches 101 and 102 of the circuit shown in Figure 4 can be left out if the p-channel branches 100 and 103 are each controlled by a DC/DC converter 150, 151 in addition to the above described control circuits 160, 161 which cause tha hysteretic behaviour. The converters 150, 151 generate a negative voltage when the correspondiny p-channel pair 100, 103 is in the negative branch of the telecommunications line and conducts current from the terminal equipment to the exchange. A complementary circuit with n-channel switches and DC/DC converters, which 1~
generate a positive potential for the n-channel switch which is in the positive branch, is also conceivable.
Figure 8 shows a remote-controlled master switch facility with controlled silicon rectifiers, and represents a modified version of the circuit shown in Figure 2. The electrollic switch 12b in core b is reverse poled to switch 12a. Thus the forward direction of diodes D2 and D4 and thyristor S2 is antiparallel to that of diodes D1 and D3, and thyristor Sl in core a. When core a has a positive voltage with respect to core b, thyristors Sl and S2 ars inhibited if the measurement voltage is below the switching voltage. When the measurement voltage is neg~tive, diodes D3 and D4 become conductive and the subscriber side is included in the measurement process, i.e. switches 12a and 12b are switched back on again.
Figure 9 shows a correspondingly modified ~OS-FET
circuit from Figure 6. In this case the MOS-FET
transistors in core b are interchanged. Transistor Q6 is now an n-channel type and transistor Q8 is a p~channel type. On the other hand, in the circuit according to Figure 6, the switches are symmetrical. Furthermore, the respective Schmitt trigger transistor Q10 of the corresponding control has been replaced with the complementary p-channel type.
Claims (22)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A remote-controlled master switch facility consisting of two electronic switches connected into the respective subscriber line, whereby each switch incorporates a controlled silicon rectifier, the control input of which is driven by a parallel connected zener diode with resistor and incorporates a parallel bridging of the silicon rectifier, which consists of a capacitor and a resistor wherein the control inputs of the silicon rectifier are connected by a coupling device.
2. A remote-controlled master switch facility according to claim 1, wherein the coupling device consists of a series connection of a capacitor and a resistor.
3. A remote-controlled master switch facility according to claim 2, wherein the electronic switches are inserted into the lines with opposed polarity.
4. A remote-controlled master switch facility consisting of two electronic switches connected into the respective subscriber line, whereby each switch incorporates at least one MOS-FET, wherein normally-off MOS-FETs of the enhancement type are used.
5. A remote-controlled master switch facility according to claim 4, wherein the MOS-FET switches are controlled in such a way that they exhibit a high turn-on threshold and a low turn-off threshold.
6. A remote-controlled master switch facility according to claim 5, wherein the control for a MOS-FET
switch consists of at least one voltage divider and one controlling MOS-FET.
switch consists of at least one voltage divider and one controlling MOS-FET.
7. A remote-controlled master switch facility according to claim 6, wherein both controlling MOS-FETs are of the same type.
8. A remote-controlled master switch facility according to claim 7, wherein both controlling MOS-FETs are of the n-channel type.
9. A remote-controlled master switch facility according to claim 6, wherein the turn-on voltage is in the order of magnitude of the supply voltage for the telecommunications network.
lo. A remote-controlled master switch facility according to claim 9, wherein the turn-off voltage is approximately 15% of the supply voltage of the telecommunications network.
11. A remote-controlled master switch facility according to claim 5, wherein one MOS-FET switch consists of an n channel and a p-channel MOS-FET branch connected in parallel to it.
12. A remote-controlled master switch facility according to claim 11, wherein there is a capacitor connected between the common source line and the gate line of a MOS-FET branch.
13. A remote-controlled master switch facility according to claim 12, wherein a MOS-FET branch consists of one MOS-FET.
14. A remote-controlled master switch facility according to claim 13, wherein the anodes of the substrate diodes are wired towards the subscriber.
15. A remote-controlled master switch facility according to claim 11 or 12, wherein one MOS-FET branch contains a pair of MOS-FETs.
16. A remote-controlled master switch facility according to claim 15, wherein the channel substrate diodes of a MOS-FET pair are connected in opposition to each other.
17. A remote-controlled master switch facility according to claim 16, wherein the respective gate and source terminals of a MOS-FET pair are connected with each other.
18. A remote-controlled master switch facility according to one or several of claims 5 through 10, wherein a MOS-FET switch consists of a p-channel branch, whereby the branch contains a pair of MOS-FETs whose respective gate and source terminals are connected with each other.
19. A remote-controlled master switch facility according to claim 18, wherein the gate line of each branch is additionally controlled by a DC/DC converter.
20. A remote-controlled master switch facility according to claim 5, wherein the turn-on threshold for negative voltages differs from that for positive voltages.
21. A remote-controlled master switch facility according to any one of claims 6, 9, 10, 12-14, 15-17 or claim 20, wherein one of the two controlling MOS-FETs is a p-channel type while the other is an n-channel type, and the MOS-FET transistors in a core are interchanged.
22. A remote-controlled master switch facility according to claim 1 or 4, wherein the circuit is structured complementarily.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP4200775.5 | 1992-01-11 | ||
| DE4200775A DE4200775C1 (en) | 1992-01-11 | 1992-01-11 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2083205A1 true CA2083205A1 (en) | 1993-07-12 |
Family
ID=6449496
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002083205A Abandoned CA2083205A1 (en) | 1992-01-11 | 1992-11-18 | Remote-controlled master switch facility |
Country Status (17)
| Country | Link |
|---|---|
| EP (1) | EP0551565A3 (en) |
| JP (1) | JPH05336234A (en) |
| KR (1) | KR930017380A (en) |
| CN (1) | CN1075239A (en) |
| AU (1) | AU2837892A (en) |
| BR (1) | BR9300036A (en) |
| CA (1) | CA2083205A1 (en) |
| DE (1) | DE4200775C1 (en) |
| FI (1) | FI925107A (en) |
| HU (1) | HUT63530A (en) |
| IL (1) | IL103734A0 (en) |
| MX (1) | MX9300052A (en) |
| NO (1) | NO924717L (en) |
| PL (1) | PL297217A1 (en) |
| TW (1) | TW214022B (en) |
| YU (1) | YU693A (en) |
| ZA (1) | ZA928760B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1052260C (en) * | 1995-06-23 | 2000-05-10 | 葛军 | Beer made from black rice |
| DE69533619D1 (en) * | 1995-07-31 | 2004-11-11 | St Microelectronics Srl | Electrically operated switch, integrated circuit and electronic circuit using the same |
| FR2802366B1 (en) * | 1999-12-14 | 2002-05-31 | St Microelectronics Sa | PULSE-CONTROLLED ANALOG SOCKET |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4438299A (en) * | 1982-02-26 | 1984-03-20 | Tomim William L | On-line telephone troubleshooting apparatus |
| GB2149274A (en) * | 1983-10-31 | 1985-06-05 | Teradyne Inc | Testing subscriber lines |
| US4635084A (en) * | 1984-06-08 | 1987-01-06 | Eaton Corporation | Split row power JFET |
| GB2162711A (en) * | 1984-07-18 | 1986-02-05 | Siliconix Ltd | Solid state switch |
| US4653084A (en) * | 1984-07-20 | 1987-03-24 | Om Ahuja | Remote actuated switch |
| US4852145A (en) * | 1988-07-22 | 1989-07-25 | Teradyne, Inc. | Telephone subscriber loop test system |
-
1992
- 1992-01-11 DE DE4200775A patent/DE4200775C1/de not_active Expired - Fee Related
- 1992-09-09 EP EP19920115376 patent/EP0551565A3/en not_active Withdrawn
- 1992-11-10 FI FI925107A patent/FI925107A/en unknown
- 1992-11-11 CN CN92113145A patent/CN1075239A/en active Pending
- 1992-11-12 IL IL103734A patent/IL103734A0/en unknown
- 1992-11-13 ZA ZA928760A patent/ZA928760B/en unknown
- 1992-11-13 AU AU28378/92A patent/AU2837892A/en not_active Abandoned
- 1992-11-18 CA CA002083205A patent/CA2083205A1/en not_active Abandoned
- 1992-11-27 TW TW081109534A patent/TW214022B/zh active
- 1992-12-07 NO NO92924717A patent/NO924717L/en unknown
- 1992-12-23 KR KR1019920025175A patent/KR930017380A/en not_active Application Discontinuation
- 1992-12-29 PL PL29721792A patent/PL297217A1/en unknown
-
1993
- 1993-01-06 YU YU693A patent/YU693A/en unknown
- 1993-01-07 MX MX9300052A patent/MX9300052A/en unknown
- 1993-01-08 BR BR9300036A patent/BR9300036A/en not_active IP Right Cessation
- 1993-01-11 HU HU9300047A patent/HUT63530A/en unknown
- 1993-01-11 JP JP5002652A patent/JPH05336234A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| BR9300036A (en) | 1993-07-13 |
| KR930017380A (en) | 1993-08-30 |
| NO924717D0 (en) | 1992-12-07 |
| MX9300052A (en) | 1993-11-01 |
| AU2837892A (en) | 1993-07-15 |
| YU693A (en) | 1994-06-10 |
| NO924717L (en) | 1993-07-12 |
| TW214022B (en) | 1993-10-01 |
| JPH05336234A (en) | 1993-12-17 |
| EP0551565A2 (en) | 1993-07-21 |
| CN1075239A (en) | 1993-08-11 |
| HU9300047D0 (en) | 1993-04-28 |
| HUT63530A (en) | 1993-08-30 |
| FI925107A (en) | 1993-07-12 |
| FI925107A0 (en) | 1992-11-10 |
| EP0551565A3 (en) | 1994-05-25 |
| ZA928760B (en) | 1993-06-09 |
| IL103734A0 (en) | 1993-04-04 |
| DE4200775C1 (en) | 1993-05-19 |
| PL297217A1 (en) | 1993-07-12 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR950704856A (en) | COMMUNICATIONS CHANNEL TESTING ARRANGEMENT | |
| US5818923A (en) | System and method for supressing pulse dialing feedback occurring particularly with auxiliary acoustic ringers in socket telephone systems | |
| US4479122A (en) | Remotely controlled switched access to the console port of an electronic computer | |
| US4306119A (en) | Telephone outpulsing circuit | |
| US4489222A (en) | Telephone line interface | |
| CA2083205A1 (en) | Remote-controlled master switch facility | |
| US3808381A (en) | Continuity testing circuit for testing transmission paths | |
| HUT71765A (en) | Communication channel switching arrangement having a pair of lines | |
| US3725614A (en) | Communication arrangement allowing network path testing | |
| US5517565A (en) | Integrated ringer relay circuit and method | |
| US4071879A (en) | Reversible current apparatus | |
| US5461670A (en) | Telephone subscriber system incorporating a drive interface for a telephone line switch at a different reference potential | |
| US5019730A (en) | Information separation device | |
| US5103473A (en) | Telephone system communication mechanism employing central office sleeve lead | |
| SU1130982A1 (en) | Device for checking conditions of rectifiers of m-phase adjustable converter | |
| SU1061289A2 (en) | Party device of low-capacitive quasi-electronic automatic telephone exchange | |
| JP2581790B2 (en) | Switching device for off-talk communication service demonstration | |
| SU1525938A1 (en) | Device for monitoring switching systems | |
| SU1409425A2 (en) | Multioperator power supply system for d.c. welding | |
| KR870001638B1 (en) | Hook flash circuit of telephone | |
| SU1651301A1 (en) | Impulse noise simulator | |
| GB2154394A (en) | Telephone subset apparatus | |
| IL43517A (en) | Direct current supply arrangement for subscriber telephone terminal | |
| JPS6161557A (en) | Metering pulse sending circuit | |
| JPS6194490A (en) | Subscriber circuit |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |