CN2188264Y

CN2188264Y - Subscriber telephone protector

Info

Publication number: CN2188264Y
Application number: CN 94227209
Authority: CN
Inventors: 高荫川
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-02-23
Filing date: 1994-02-23
Publication date: 1995-01-25
Anticipated expiration: 2004-02-23

Abstract

The utility model relates to a subscriber telephone protector, which is provided with connecting ends AB and AB' which are respectively connected with a telephone line and a telephone. The back of the circuit connecting end AB is arranged in a bridge connection mode with a set of voltage detecting circuits DV of divider resistors which are connected in series, and a leading-out end is led between a pair of close resistors and connected with the input end of a checking logic circuit IC 1 with a quadruple double input or negator-circuit structure. One output end is connected with a pulse dynamic absorption circuit IC 3 composed of a four-layer diode and a transistor, and the other output end is connected with a dual-tone code generating circuit IC 2 by a single supply dual comparator. On the basis, a current detection circuit DA and a bridge sample circuit IC 5 composed of two side branches whose voltage dividing values are unequal are connected in parallel between both ends of BB'.

Description

Subscriber telephone protector

The utility model relates to a kind of have can prevent that user telephone line is stolen, eavesdropped and the protective device of function such as line fault warning.

Along with the development of telephonic communication cause, it is also increasing to utilize the telephonic communication circuit to invade the malfeasance of telephone subscriber's legitimate rights and interests, and wherein illegal on-hook is usurped the subscriber's line conversation and the eavesdropping dialog context is the most normal event on route of user.The measure that can effectively take precautions against this is few at present.In addition, for various reasons, after phone routes opened circuit or accident such as short takes place, how in time to be found as early as possible also was a problem anxious to be solved.

The purpose of this utility model is to provide a kind of subscriber phone protective device for addressing the above problem, and can in time find when making fault such as its telephone line is illegally usurped, eavesdropped and opens circuit, short circuit, reports to the police, and can stop the generation of relevant illegal act.

Subscriber phone protective device of the present utility model uses for being connected between telephone line and the phone, therefore should have respectively with telephone line and with joining union end AB in phone input port and AB '.Cross-over connection has the voltage detecting circuit (DV) that the branch pressure drag by the series connection form constitutes after the circuit union end AB of this device, arbitraryly in this series resistance draw an exit between to adjacent resistor, link with the input of the detection logical circuit (IC1) in charged source with quadruple two input OR-NOT circuit structures, an output of this logical circuit connects with the input that the pulse that is made of four-layer diode and triode dynamically absorbs circuit (IC3), and another output of this detection logical circuit (IC1) is through the input connection end of a single supply dual comparator (IC4) with the diphthong coding generation circuit (IC2) with DTMF pulsing device function.This structure can prevent effectively that telephone line from being usurped by other people illegal on-hook.

Based on this structure, but between the BB ' two ends in above-mentioned two union end AB and AB ' also cross-over connection by the current detection circuit of forming by resistance and voltage-stabiliser tube (DA), the cross-over connection bridge sampling circuit (IC5) that has the both sides of not waiting to prop up resistance to constitute also with it by partial pressure value with being in parallel, wherein the partial pressure value smaller side prop up and B end between be parallel with electric capacity (C2), both sides are propped up respectively and are connected with the different inputs of above-mentioned single supply dual comparator (IC4).Can increase the anti-eavesdrop function after increasing this part-structure.

For strengthening prompting to abnormal state, to arouse attention, in said structure, also can add the warning structure that sound equipment and/or light can take place, as outside or internal alarm device and light-emitting diode visual alarms such as (LED) devices etc. such as buzzer, music integrated circuit.

In said structure, detect the self-powered battery that can charge repeatedly automatically that preferably adopts of logical circuit (IC1), to save the inconvenience of changing battery.In addition, the power supply of other each operating circuit all detects logical circuit thus provides.

During use, when substation when off-hook does not remain static, the ends A B of voltage detecting circuit in the foregoing circuit (DV) is a high level.When having illegal on-hook to usurp in the circuit, its level reduces, the partial pressure value of each divider resistance that promptly is in series reduces, become low level, and the detection logical circuit (IC1) that can be connected with it detects, and starts the operating circuit that links with it and sound, optical alarm circuit by different outputs then.For the phone of pulsed, what be activated is that pulse dynamically absorbs circuit (IC3), and the pulse signal that illegal on-hook is taken place sponges, and can't send; For the phone of audio frequency formula, what be activated then is the diphthong coding generation circuit (IC2) that has preset some spacings, sends the spacing that is preset, and illegal on-hook can't be used.So just prevented that user telephone line from illegally being usurped effectively.Also can send alarm signal when meanwhile, sound, light warning structure being set in the device.When subscriber's line opens circuit or during short circuit, the dividing potential drop on the voltage detecting circuit (DV) reduces to zero, this device then with the same manner work, sends alarm signal.

When user's off-hook was conversed, there was voltage at current detection circuit under the normal condition (DA) two ends, are in high level, and control detection logical circuit (IC1) blocks other operating circuit and remains static.Simultaneously, the comparator (IC4) by bridge sampling circuit (IC5) control also is in normal rest state.If illegal on-hook eavesdropping is arranged on the circuit this moment, then the voltage drop examined on the circuit (DA) then of electric current reduces.Because the partial pressure value smaller side props up and is parallel with electric capacity in this bridge sampling circuit, its partial pressure value can't be suddenlyd change, the dividing potential drop that former partial pressure value larger side props up then reduces suddenly, cause both sides to prop up the height upset of partial pressure value, cause comparator (IC4) to overturn thereupon, make warning structure generation alarm signal, the user of announcement has eavesdropping to exist.

This shows that this protective device has the kinds of protect function to subscriber phone.

Below structure of the present utility model is described, but this example should be interpreted as it is qualification the utility model scope with example shown in the drawings.

Fig. 1 block diagram of the present utility model

Fig. 2 electrical schematic diagram of the present utility model

As shown in the figure, this routine protective device has three external terminal A, B and B ', and wherein AB is and outer phone circuit union end, and AB ' is the union end with the phone input interface.The cross-over connection of AB end back has the voltage detecting circuit DV that is made of series resistance R1 and R2, by wherein drawing on line between resistance R 1 and the R2, with the inspection that has the self-charging battery of quadruple two input OR-NOT circuit structures then the input of logical circuit IC1 connect.This logical circuit for example can be selected 74HC02 type integrated circuit for use, and its output pin 13 is connected with the outer voice guard IC6 of a buzzer form.Another output pin 4 of this IC1 dynamically absorbs electric IC3 with the pulse of a four-layer diode and audion and connects; The output pin 10 again of IC1 for example can be selected the LM393 integrated circuit for use with a single supply dual comparator IC4----and power supply input pin 8 connects.The output pin 1 of IC4 connects with the diphthong coding generation IC circuit 2 of the DTMF pulsing device integrated circuit type that presets some spacings, and another output pin 7 of IC4 connects with the interior alarm IC7 of a function of music sheet type.At between BB ' of union end of device except that being connected with the LED that shows the phone operating state, cross-over connection also in parallel simultaneously has the current detection circuit DA that is made of the resistance R 3 of series connection and voltage-stabiliser tube ZD1, with constitute a side by R4 and R5 and prop up, R6 and R7 constitute the bridge sampling circuit IC5 that opposite side props up, the latter's partial pressure value should be less than the former during propped up these both sides, and the latter also is parallel with capacitor C 2 between holding with B.Two input pins 5 and 6 that prop up respectively with comparator IC4 the both sides of IC5 link.

In addition, damage components and parts, in above-mentioned voltage detecting circuit DV, also be in series with the diode D1 of a protection usefulness for avoiding the repercussion ringing-current.

Claims

1; a kind of subscriber phone protective device; have with the joining union end AB of outer phone circuit and with the joining union end AB ' of phone input interface; it is characterized in that the voltage detecting circuit (DV) that after union end AB cross-over connection has the divider resistance by the series connection form to constitute; by drawing an exit between a pair of adjacent resistor wherein; link with the input of the detection logical circuit (IC1) in charged source with quadruple two input OR-NOT circuit structures; this output that detects logical circuit connects with the input that the pulse with four-layer diode and audion dynamically absorbs circuit (IC3), and another output of this detection logical circuit (IC1) connects through the input of single supply dual comparator (IC4) with the diphthong coding generation circuit (IC2) with DTMF pulsing device function.

2, device as claimed in claim 1, it is characterized in that being connected to by the resistance (R3) of series connection and the current detection circuit (DA) of voltage-stabiliser tube (ZD1) formation at the BB ' two ends of said union end AB and AB ' span, with its cross-over connection bridge sampling circuit (IC5) of having the both sides of not waiting to prop up resistance to constitute also explicitly by partial pressure value, wherein the less side of partial pressure value is propped up between (R6 and R7) and B end and also is parallel with electric capacity (C2), and both sides are propped up respectively and connected with the different inputs of single supply dual comparator (IC4).

3, device as claimed in claim 1 or 2 is characterized in that being connected with between an output of said detection logical circuit (IC1) and its power supply the sound generator (IC6) of warning usefulness.

4, device as claimed in claim 1 or 2 is characterized in that an output of said single supply dual comparator (IC4) is connected with the sound generator (IC7) of warning usefulness.