CN2222414Y

CN2222414Y - Telephone arrangement for preventing eavesdropping

Info

Publication number: CN2222414Y
Application number: CN 95206055
Authority: CN
Inventors: 李敏
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-03-28
Filing date: 1995-03-28
Publication date: 1996-03-13
Anticipated expiration: 2005-03-28

Abstract

The utility model relates to a device for preventing telephone theft, which belongs to the field of telephone communication in an electric communication technique. The device for preventing telephone theft is composed of a housing, an input and an output terminal, a circuit board, an isolating circuit, a switch circuit, a memory and energy saving circuit and a protective circuit. The device for preventing telephone theft has the advantages of no power consumption, few components and low cost. The device for preventing telephone theft is a device for preventing telephone theft allowed to access to a network in the department of post telephone and telegraph.

Description

The phone antitheft device

The utility model relates to a kind of phone anti-theft arrangement, belongs to the field of telephone communication of electrical communication technology.

Phone antitheft device in the market is to adopt power voltage supply of telephone wire own or employing to provide two kinds of forms of DC power supply for oneself, with the anti-theft arrangement of the power voltage supply of telephone wire own owing to need steal electric energy from circuit, the infringement electric network performance, postal and telecommunication entities do not allow network access; And adopt the anti-theft arrangement of providing DC power supply for oneself not only to consume energy, and component number is many, volume is big, cost is too high.

The purpose of this utility model is to provide a kind of employing memory accumulator and switching circuit, not from phone network steal electric energy, component number is few, cost is low, postal and telecommunication entities allow the phone antitheft device of network access.

Technical solution of the present utility model is as follows: a kind of phone antitheft device; by shell; the input and output terminals; circuit board is formed; the input and output terminals are positioned on the circuit board; buffer circuit is installed on the circuit board; switching circuit; memory accumulator and protective circuit; its special character is that buffer circuit is serially connected with between anodal A+ of input terminal and the anodal a+ of outlet terminal; the memory accumulator is connected to output connection and rectifies; negative pole a+; between the a-; be connected in series between input terminal negative pole A-and the outlet terminal negative pole a-; protective circuit is connected to output connection and rectifies; negative pole a+; between the a-; its trigger end is drawn by switching circuit, and switching circuit is parallel to the buffer circuit two ends.

Buffer circuit adopts resistor R 2 to isolate, and the memory accumulator adopts capacitor C1 to form, and protective circuit adopts LED and controllable silicon 3TC sequential circuit or adopts the transistor circuit, and switching circuit adopts the transistor switching circuit to form.

The transistor switching circuit is made up of transistor BG1 and BG2; the BG1 base stage with link the anodal A+ of input terminal after resistance R 1 is connected in series on; the BG1 collector electrode is connected on the anodal a+ of outlet terminal; the BG1 emitter is connected to the BG2 base stage; the BG2 emitter is connected on the anodal a+ of outlet terminal; the BG2 collector electrode with link on the outlet terminal negative pole a-after resistance R 3 is connected in series, the BG2 collector electrode is also received the trigger end of protective circuit.

When protective circuit adopts LED and controllable silicon 3TC sequential circuit, must be in the reset button Q of normally off in the anodal a+ of circuit input terminal place serial connection one.

Protective circuit also can adopt transistor BG3 circuit; this moment, the BG3 base stage was introduced by the BG2 collector electrode of switching circuit; the BG3 collector electrode is connected by the anodal a+ of resistance R 4 and outlet terminal; the BG3 emitter is connected with outlet terminal negative pole a-, and the BG3 collector electrode also is connected with the BG2 base stage by resistance R 5.

The utility model can not only reduce product cost, and can cut down the consumption of energy, and reduces telephone network is disturbed, and obtains postal and telecommunication entities' network-entry license.

Description of drawings:

Fig. 1-the utility model functional-block diagram;

Fig. 2-the utility model embodiment 1 schematic diagram;

Fig. 3-the utility model embodiment 2 schematic diagrams.

Drawing explanation: R1, R2, R3, R4, R5-resistance, C1-electric capacity, BG1, BG2, BG3-transistor, 3TC-controllable silicon, LED-indicator light, A+, A--input terminal, a+, a--outlet terminal, Q-reset button.

Further specify the utility model below in conjunction with embodiment.

Embodiment 1; with reference to figure 2; a kind of phone antitheft device; by shell; the input and output terminals; circuit board; buffer circuit R2; switching circuit; memory accumulator C1 and protective circuit are formed; the input and output terminals are installed on the circuit board; buffer circuit R2 is serially connected with between the anodal A+ and a+ of input and output terminals; memory accumulator C1 is connected to output connection and rectifies; negative pole a+; between the a-; protective circuit by indicating device LED be parallel to outlet terminal both positive and negative polarity a+ after controllable silicon 3TC is connected in series; between the a-; controllable silicon 3TC trigger end is drawn from switching circuit; switching circuit is the transistor switching circuit; form by transistor BG1 (NPN pipe) and BG2 (PNP pipe); the BG1 base stage with link the anodal A+ of input terminal after resistance R 1 is connected in series on; the BG1 collector electrode is connected on the anodal a+ of outlet terminal; the BG1 emitter is connected to the BG2 base stage; the BG2 emitter is connected on the anodal a+ of outlet terminal; the BG2 collector electrode with link on the outlet terminal negative pole a-after resistance R 3 is connected in series, the BG2 collector electrode is also received the trigger end of the controllable silicon 3TC of protective circuit.

Just often, this phone antitheft device adds in the circuit, and to capacitor C 1 charging, input, output both end voltage equate that switching circuit and protective circuit all are in cut-off state to electric current through resistance R 2, and whole phone antitheft device does not have any power consumption.When phone uses, because the memory energy storage function of capacitor C 1, can judge that machine side (user side) electricity consumption of living is lived or circuit side (steal side) uses phone, as phone side's phone, output cathode end a+ voltage descends rapidly, capacitor C 1 is discharged rapidly, and whole device cuts little ice, and phone normally uses; If circuit side's steal phone, input positive terminal A+ voltage descends rapidly, capacitor C 1 both end voltage makes resistance R 2 two ends produce higher differential pressure, this pressure reduction adds on two emitter junctions of the transistor BG1 of switching circuit and BG2, the BG1 emitter inverse is punctured play 7 volts of pressure stabilization functions, the BG2 conducting, the electric current that produces on the BG2 collector electrode produces voltage drop on R3, make controllable silicon 3TC conducting, the luminous indication phone of indicating device is stolen, and keep, at this moment because the line load increase can't be made a phone call steal phone person always.

The person recovers circuit just often when the steal phone, because protective circuit still is in clamped state, so phone side still can't use phone also can't be talked about, must clicks the reset button Q that is in normally off and reset, and makes the phone antitheft device return to normal monitor state.

Embodiment 2; with reference to figure 3; the difference of this embodiment and embodiment 1 is that protective circuit adopts transistor BG3 (NPN pipe) circuit; the BG3 base stage is introduced by the BG2 collector electrode of switching circuit; the BG3 collector electrode is connected by the anodal a+ of resistance R 4 and outlet terminal; the BG3 emitter is connected with outlet terminal negative pole a-, and the BG3 collector electrode also is connected with the BG2 base stage by resistance R 5.

During circuit side steal phone, switching circuit BG2 collector resistance R3 goes up and produces a pressure drop, makes the BG3 conducting, and the BG3 collector potential descends, and BG2 keeps conducting, and BG3 keeps clamped state, and protective circuit is clamped to be made the steal person can't make a phone call.When the steal person put down phone, the conducting of BG1 emitter junction raise the BG2 base potential, and BG2 ends, and BG3 ends, and it is normal that circuit recovers.

Claims

1; a kind of phone antitheft device; by shell; the input and output terminals; circuit board is formed; the input and output terminals are positioned on the circuit board; buffer circuit is installed on the circuit board; switching circuit; memory accumulator and protective circuit; it is characterized in that described buffer circuit is serially connected with between input terminal positive pole (A+) and the outlet terminal positive pole (a+); the memory accumulator is connected to output connection and rectifies; negative pole (a+); (a-) between; be connected in series between input terminal negative pole (A-) and the outlet terminal negative pole (a-); protective circuit is connected to output connection and rectifies; negative pole (a+); (a-) between; its trigger end is drawn by switching circuit, and switching circuit is parallel to the buffer circuit two ends.

2, according to the described phone antitheft device of claim 1; it is characterized in that described buffer circuit adopts resistance (R2) to isolate; the memory accumulator adopts capacitor (C1), and protective circuit adopts clamped protective circuit, and switching circuit adopts the transistor switching circuit.

3; according to the described phone antitheft device of claim 2; it is characterized in that described transistor switching circuit forms by transistor (BG1) with (BG2); (BG1) base stage with link on the input terminal positive pole (A+) after resistance (R1) is connected in series; (BG1) collector electrode is connected on the outlet terminal positive pole (a+); (BG1) emitter is connected to (BG2) base stage; (BG2) emitter is connected on the outlet terminal positive pole (a+); (BG2) collector electrode with link on the outlet terminal negative pole (a-) after resistance (R3) is connected in series, (BG2) collector electrode is also received the trigger end of protective circuit.

4,, it is characterized in that described protective circuit adopts light-emitting diode (LED) and controllable silicon (3TC) to compose in series according to claim 1,2,3 described phone antitheft devices.

5, according to claim 1,2,3 described phone antitheft devices; it is characterized in that described protective circuit adopts the clamped protection of transistor (BG3) circuit; (BG3) base stage is triggered by switching circuit (BG2) collector electrode; (BG3) be connected in series a resistance (R5) between collector electrode and (BG2) base stage; (BG3) emitter is connected to outlet terminal negative pole (a-), (BG3) collector electrode be connected to outlet terminal positive pole (a+) after resistance (R4) is connected in series.

6, according to the described phone antitheft device of claim 4, it is characterized in that on shell, also being equipped with a reset button (Q) that is in normally off, this reset button (Q) input terminal positive pole (a+) of connecting is in the line located.