CN2265640Y

CN2265640Y - Lock for preventing telephone line from fraudulent use

Info

Publication number: CN2265640Y
Application number: CN 96202330
Authority: CN
Inventors: 王忍柱
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-01-17
Filing date: 1996-01-17
Publication date: 1997-10-22
Anticipated expiration: 2006-01-17

Abstract

The utility model relates to an anti-theft lock for telephone lines, composed of a correcting circuit for voltage polarities, a sampling circuit and an erasing circuit for dialing information. The anti-theft lock can automatically work when a user's telephone line is stolen by someone, and prevent all dialing information and sound on the telephone lines being sent out. The utility model does not make any difference on original functions of a telephone after installation, and is suitable for theft protection of pulse telephones and dual-audio telephone lines.

Description

The telephone line anti-theft lock

A kind of telephone line anti-theft lock is eliminated circuit by polarity of voltage correcting circuit, sample circuit, dialing information and is formed.It relates to the burglar alarm technical field.Being used for Pulse Electric phone and dual tone phone machine circuit prevents usurping.

In the prior art, anti-theft device for telephone circuit has various ways, is exactly wherein a kind of as patent 91218199.0 " antitheft acoustic-optic alarm on the communication line bar " at present.Conclude anti-theft device and mainly contain three kinds: the one, encrypted code lock on program-controlled telephone; The 2nd, adopt electronic circuit to pin subsets; The 3rd, on telephone line, put interference signal and stolen with light indication telephone line.As electronics 94 years bound volumes (descending) of newspaper 122 pages of " can be contained in the telephone lock in the terminal box ", 98 pages " phone is usurped annunciator ", 184 pages " phone mouse activity indicator ".The subject matter that above-mentioned several burglar alarm exists is: 1. " antitheft audible-visual annunciator on the communication line bar " is made up of trigger, signal generator, sound and light alarm and target indicator light, complex structure, and single telephone subscriber can not use.2. the coded lock of program-controlled telephone belongs to paid service, and is uneconomical.3. " can be contained in the telephone lock in the terminal box ", can only prevent that telephone set is stolen, and can not prevent that telephone line is stolen.4. " phone is usurped annunciator " and " phone mouse activity indicator " is simple in structure, but needs independent current source, can only send interference signal and light hint, can not stop appropriator to continue to use phone.

The purpose of this utility model provides a kind of independent current source, simple in structure, cost is low, easy to use, antitheft reliability is high telephone line anti-theft lock of not needing.

To achieve these goals, this telephone line anti-theft lock is eliminated circuit by polarity of voltage correcting circuit, sample circuit, dialing information and is formed.Form the polarity of voltage correcting circuit by diode D1-D4, Light-Emitting Diode D9, resistance R 4.Form the resistance sampling circuit by resistance R 1, R2, R3, capacitor C1, C2, voltage-stabiliser tube WD1, NAND gate 1,2,3.Form the photoelectricity sample circuit by diode D7, light-emitting diode D8, optoelectronic semiconductor pipe IC2, NAND gate 4.Form dialing information by relay J, diode D5, D6, triode BG, capacitor C3 (or voltage-stabiliser tube WD2), K switch and eliminate circuit.

Be described in further detail below in conjunction with drawings and Examples.

Fig. 1 is the utility model telephone line anti-theft lock block diagram.Wherein A is the polarity of voltage correcting circuit; B is a sample circuit; C is that dialing information is eliminated circuit.

Fig. 2 is the detailed circuit diagram of the utility model telephone line anti-theft lock.

Diode D1-D4 forms bridge circuit, input is connected between the telephone wire L1L2, output is connected between the contact and ground wire of resistance R 1, R3, relay J, correction voltage polarity, output voltage is supplied with resistance R 1, R2 potential-divider network, resistance R 3, capacitor C2 charging circuit, relay J and triode BG.4 series connection (by the relay J contact) of Light-Emitting Diode D9 and resistance R are connected between telephone wire L2 and the ground wire, and (by the relay J contact) is connected on the anode of capacitor C3 to be used to whether judge telephone line L2, and the bright expression wiring of D9 is correct.Light-Emitting Diode D9 also can be used as light warning and shows that resistance R 4 is a current-limiting resistance.

Resistance R 3, capacitor C2 series connection between supply voltage and ground wire and voltage-stabiliser tube WD1 form charging circuit, to capacitor C2 charging, the charging voltage on the C2 is as the power supply of integrated circuit (IC) 1 by R3 for supply voltage.Voltage-stabiliser tube WD1 prevents that capacitor C2 goes up overtension and burns out integrated circuit (IC) 1 in the sample circuit transfer process.Integrated circuit (IC) 1 is a cmos nand gate, and NAND gate 1,3,4 is connected into inverter, and 2 are connected into NAND gate, and the IC1 power positive end is connected on resistance R 3 and the capacitor C2 contact, the negativing ending grounding line.Resistance R 1, R2 series connection between supply voltage and ground wire and capacitor C1 form the partial pressure type sample resistance.When the telephone set on-hook resistance R 1, R2 contact voltage greater than , during off-hook less than This voltage control NAND gate 1,2,3 is output as high level or low level, makes triode BG conducting or ends.Capacitor C1 filtering ringing voltage disturbs.Be serially connected on the telephone wire L2 after light-emitting diode D8 and the diode D7 parallel connected in reverse phase, optoelectronic semiconductor pipe IC2 is connected between NAND gate 1 output and NAND gate 4 inputs, and diode D7 prevents the anti-phase puncture of light-emitting diode D8.The photoelectricity sample circuit course of work: when the subsets on-hook, the telephone line no current flows through, and light-emitting diode D8 does not work, and optoelectronic semiconductor pipe IC2 is in high-impedance state, and the voltage of NAND gate 4 inputs is lower than

, output is a high level, this moment, the output of NAND gate 2 was controlled by the resistance sampling circuit only.When the subsets off-hook, this moment, NAND gate 1 was output as high level, had electric current to flow through in the telephone line, and light-emitting diode D8 is bright, and optoelectronic semiconductor pipe IC2 becomes low-resistance by high resistant, the input terminal voltage that makes NAND gate 4 greater than

, output is a low level, NAND gate 3 outputs are low level still, and triode BG is ended.

Capacitor C3 (or voltage-stabiliser tube WD2) is connected in parallel on the telephone wire L1L2, controls break-make with relay J.After relay J and the diode D5 parallel connection and triode BG series connection between supply voltage and ground wire, triode BG base stage is connected on the output of NAND gate 3, by NAND gate 3 its conductings of control or end.When NAND gate 3 is output as high level, make triode BG conducting, relay J work, the closing of contact, capacitor C3 this moment (or voltage-stabiliser tube WD2) just is connected in parallel between the telephone wire L1L2, the dial impulse or the double-audio signal of appropriator telephone set output fallen in filtering (or amplitude limit), dialing information sent out do not gone out, and blocked telephone line.When NAND gate 3 was output as low level, triode BG ended, and relay J is not worked, and the contact disconnects, and capacitor C3 (or voltage-stabiliser tube WD2) does not strobe, and makes telephone line unimpeded.

K switch is connected in parallel on diode D7 two ends.When K switch disconnected, subsets did not play antitheft effect, when K switch is connected, short circuit light-emitting diode D8, the photoelectricity sample circuit is not worked, and pins subsets, prevent that others from usurping, K switch also can be used to check the quality of telephone line anti-theft lock simultaneously.The effect of diode D6 is after the relay J closing of contact, the supply voltage on the telephone wire through D6 to capacitor C2 charging with supply with integrated circuit (IC) 1 supply voltage, make the relay J self-insurance.

L1L2 answers the call line, and A, the B machine of answering the call substitutes original call machine terminal box with the telephone line anti-theft lock.L2 is a telephone wire power supply main track, and L1 is a telephone wire power supply negative wire.

The utility model course of work is as follows: when the telephone line anti-theft lock is connected to telephone line, supply voltage charges to capacitor C2 through resistance R 3, when capacitor C2 voltage rose to integrated circuit (IC) 1 rated operational voltage, this anti-theft lock promptly was in the operating state of awaiting orders.1. behind people's phreaking off-hook, telephone line voltage is by high step-down, the resistance sampling circuit working, output pulse-triggered dialing information is eliminated circuit working, capacitor C3 just is parallel between the telephone wire L1L2, filter out the dial impulse or the double-audio signal that send on the appropriator telephone set, dialing information is sent do not go out, pinned telephone line.2. when the user used telephone set, the photoelectricity sample circuit was worked, and the controlling resistance sample circuit is inoperative, did not trigger dialing information and eliminated circuit working.Capacitor C3 also just can not be parallel between the telephone wire L1L2, does not strobe, and telephone line is unimpeded.3. when other people made a phone call to dial to the user, telephone line voltage did not reduce, and the resistance sampling circuit is not worked, bell signal can arrive subsets by telephone line, behind user's off-hook, and the work of photoelectricity sample circuit, the controlling resistance sample circuit is inoperative, and telephone line is unimpeded.

When the user need pin telephone set, connect K switch and get final product.When customer inspection anti-theft lock quality and capacitor C3 polarity whether connect to the time, the connection K switch, light-emitting diode D9 Ying Liang behind the off-hook, capacitor C3 polarity is correct, it is obstructed outwards to make a phone call, the telephone line anti-theft lock is working properly.K switch disconnects, and subsets do not play antitheft effect.

As embodiment of the present utility model, the ratio of resistance R 1, R2 is 5: 1, like this when telephone set on-hook supply voltage raises, NAND gate 1 input terminal voltage greater than , supply voltage reduces during off-hook, and NAND gate 1 input terminal voltage is lower than

The utility model has the advantages that: 1. do not need independent current source, can be directly installed on the telephone line.During the telephone set on-hook, have only integrated circuit (IC) 1 work, IC1 is a cmos circuit, resistance R 1, the desirable big resistance resistance of R2, R3, embodiment of the present utility model when awaiting orders operating state current sinking below 20 microamperes.2. reliability height.Owing to adopted dialing information to eliminate circuit, can all filter dial impulse on the telephone wire and double-audio signal.3. the user uses telephone set need not increase any new procedures, and anti-theft lock can be worked automatically, need not Artificial Control.4. simple in structure, cost is low, and is easy for installation.Usefulness telephone line anti-theft lock substitutes telephone connect wire box during installation, the input and output that terminal box is imported, the output line correspondence is connected on the telephone line anti-theft lock is connect on the post get final product.

Claims

1. a telephone line anti-theft lock is eliminated circuit by polarity of voltage correcting circuit, sample circuit, dialing information and is formed.Its major technique is characterised in that:

The polarity of voltage correcting circuit is made up of diode D1-D4, light-emitting diode D9 and resistance R 4.Diode D1-D4 forms bridge circuit, and input is connected between the telephone wire L1L2, and output is connected between the contact and ground wire of resistance R 1, R3, relay J.Light-emitting diode D9 and resistance R 4 series connection (passing through relay contact) are connected between telephone wire L2 and the ground wire.

Sample circuit is formed the resistance sampling circuit by resistance R 1, R2, R3, capacitor C1, C2, voltage-stabiliser tube WD1, NAND gate 1,2,3.Form the photoelectricity sample circuit by diode D7, light-emitting diode D8, optoelectronic semiconductor pipe IC2, NAND gate 4.Resistance R 1, R2 series connection between supply voltage and ground wire and capacitor C1 form the partial pressure type sample resistance.Resistance R 3, capacitor C2 also series connection between supply voltage and ground wire and voltage-stabiliser tube WD1 form charging circuit, the charging voltage on the capacitor C2 is as the power supply of integrated circuit (IC) 1.Integrated circuit (IC) 1 is a cmos nand gate, and NAND gate 1,3,4 is connected into inverter, and 2 are connected into NAND gate, and the IC1 power positive end is connected on resistance R 3 and the capacitor C2 contact, the negativing ending grounding line.Be connected on the telephone wire L2 after diode D7, the light-emitting diode D8 parallel connected in reverse phase, optoelectronic semiconductor pipe IC2 is connected between NAND gate 1 output and NAND gate 4 inputs.

Dialing information is eliminated circuit, is made up of relay J, diode D5, D6, triode BG, capacitor C3 (or voltage-stabiliser tube WD2).Capacitor C3 (or voltage-stabiliser tube WD2) is connected in parallel on the telephone wire L1L2, controls break-make with relay J.After relay J and the diode D5 parallel connection and triode BG series connection between supply voltage and ground wire, triode BG base stage is connected on the output of NAND gate 3, by NAND gate 3 its conductings of control or end.Diode D6 (by the relay J contact) is connected between telephone wire L2 and resistance R 3, the capacitor C2 contact.

2. device according to claim 1, its said polarity of voltage correcting circuit is characterized in that: light-emitting diode D9 shows as light warning simultaneously.

3. device according to claim 1, its said sample circuit is characterized in that: the ratio of resistance R 1, R2 is 5: 1.

4. device according to claim 1, its said dialing information is eliminated circuit, and it is characterized in that: K switch is connected in parallel on diode D7 two ends.K switch can be regular hand tap or cipher switch.