CN2240214Y

CN2240214Y - Theft-proof device for telephone

Info

Publication number: CN2240214Y
Application number: CN 95237119
Authority: CN
Inventors: 李乐华
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-07-03
Filing date: 1995-07-03
Publication date: 1996-11-13
Anticipated expiration: 2005-07-03

Abstract

The utility model relates to a theft-proof device for telephones, which comprises a telephone signal recognition circuit and an input direction regulating circuit which is matched with a user telephone. The utility model is characterized in that the utility model is provided with a telephone code sending circuit which only sends out # key signals; the telephone signal recognition circuit is a four-terminal network which is composed of a photoelectric coupler, a switching triode, a base resistor thereof and a voltage stabilizing diode. The utility model has the advantages of simple circuit, reliable performance and low cost. Due to the adoption of the # key signals, the theft-proof device for telephones can be matched with both a double-audio system telephone and a pulse system telephone, and the utility model can also cancel a calling function of picking up an auxiliary telephone by setting the output of the code sending circuit.

Description

The anti-device of usurping of phone

The utility model includes the telephone communication parts of the caller function that prevents without permission, relates in particular to the anti-device of usurping of a kind of phone.

Existing phone is anti-usurps device, of a great variety, cuts both ways." the anti-alarm of usurping of multi-function telephones " as Chinese utility model patent CN2163491Y bulletin is exactly one of them.

The purpose of this utility model provides the anti-device of usurping of another phone.

The purpose of this utility model is achieved by the following technical programs.

The anti-device of usurping of this phone, comprise telephone signal identification circuit and whole to circuit with the input of householder's telephone set adapted, it is characterized in that being provided with by the electronic switch that output started of telephone signal identification circuit and be subjected to its Control work only to send out the telephone set signaling circuit of # keyboard signal, and the telephone signal identification circuit is by a photoelectrical coupler, the four-terminal network that one switch triode and base resistance thereof and a voltage stabilizing didoe are formed, four terminals of photoelectrical coupler are four terminals of this network, the positive terminal of optical diode is a terminal 1, be connected to the whole cathode output end of input to circuit, also be connected to the transistor collector of electronic switch as power end, the negative pole end of optical diode is a terminal 2, be connected to an end of householder's phone, the collector terminal of coupling triode is a terminal 3, be connected to the transistor base of electronic switch, and the dropping resistor in electronic switch is connected to terminal 1, the emitter terminal of coupling triode is the terminal 4 as public ground, be connected to the other end of householder's telephone set, the collector electrode of switch triode and emitter also are connected to terminal 3 and 4 respectively, and the series arm that base stage is formed via base resistance and voltage stabilizing didoe is connected to terminal 1.

When the utility model is usurped receiver off-book when outside line, its telephone signal identification circuit starts electronic switch control signaling circuit immediately and sends # keyboard signal, make telephone exchange send number unobtainable tone, and then make and usurp phone and can not converse, and the use of householder's telephone set is not had any harmful effect.It is simple to have circuit, dependable performance, characteristics with low cost.Owing to adopt # keyboard signal, but be double-tone standard or pulse standard telephone set anti-device of usurping of this phone of adapted all frequently.By setting the output of signaling circuit, can also cancel the caller function that articulates secondary machine.

Accompanying drawing is an electrical schematic diagram of the present utility model.

Below in conjunction with embodiment and contrast accompanying drawing the utility model is made an explanation.

Embodiment: the anti-device of usurping of this phone, comprise telephone signal identification circuit and whole to circuit with the input of householder's telephone set adapted, it is characterized in that being provided with by compound electronic switch of forming of switch triode VT2, VT3 and the telephone set signaling circuit of only sending out # keyboard signal formed by integrated circuit (IC), and the four-terminal network that the circuit signal identification circuit is made up of photoelectrical coupler GD, switch triode VT1 and base resistance R1 thereof and voltage stabilizing didoe VD.

When being connected to householder's telephone set off-hook of terminal 2,4, in the optical diode of photoelectrical coupler GD electric current is arranged, the conducting of coupling triode, terminal 3,4 is equivalent to short circuit, triode VT2, the VT3 of electronic switch end, because the buffer action of photoelectrical coupler GD, this prevents that usurping device can not influence householder's telephone set normal talking, when nothing is usurped receiver off-book, the voltage of outer circuit can not descend, switch triode VT1 conducting, and terminal 3,4 also is equivalent to short circuit, triode VT2, the VT3 of electronic switch end, and are in normal condition.When in case receiver off-book is usurped in outside line, outer circuit voltage will drop to about 6 volts by 60 volts, be lower than the breakdown voltage value of voltage stabilizing didoe VD, make switch triode VT1 not have base current and end, switch triode VT2, VT3 provide base current and conducting by resistance R 2, and signaling IC circuit energized is sent # keyboard signal, make telephone exchange send number unobtainable tone, and then make and usurp phone and can not converse.After usurping the phone on-hook, outer circuit voltage gos up to 60 volts, and switch triode VT2, VT3 end again, recovers normal condition.

Claims

1, the anti-device of usurping of a kind of phone, comprise telephone signal identification circuit and whole to circuit with the input of householder's telephone set adapted, it is characterized in that being provided with by the electronic switch that output started of telephone signal identification circuit and be subjected to its Control work only to send out the telephone set signaling circuit of # keyboard signal, and the telephone signal identification circuit is by a photoelectrical coupler, the four-terminal network that one switch triode and base resistance thereof and a voltage stabilizing didoe are formed, four terminals of photoelectrical coupler are four terminals of this network, the positive terminal of optical diode is a terminal 1, be connected to the whole cathode output end of input to circuit, also be connected to the transistor collector of electronic switch as power end, the negative pole end of optical diode is a terminal 2, be connected to an end of householder's phone, the collector terminal of coupling triode is a terminal 3, be connected to the transistor base of electronic switch, and the dropping resistor in electronic switch is connected to terminal 1, the emitter terminal of coupling triode is the terminal 4 as public ground, be connected to the other end of householder's telephone set, the collector electrode of switch triode and emitter also are connected to terminal 3 and 4 respectively, and the series arm that base stage is formed via base resistance and voltage stabilizing didoe is connected to terminal 1.