CN2285944Y

CN2285944Y - Device of preventing fraudulent calling for telephone line

Info

Publication number: CN2285944Y
Application number: CN 97204793
Authority: CN
Inventors: 韩义和
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-02-17
Filing date: 1997-02-17
Publication date: 1998-07-08
Anticipated expiration: 2007-02-17

Abstract

The utility model discloses an anti-theft device for telephone lines, which is made of electronic integrated circuits and collects a monitoring circuit, a two-tone multi-frequency code sending circuit and a power supply circuit into integration. The utility model is composed of a circuit board, an integrated circuit, electronic elements, etc. and is arranged in a plastic small box. The front and the rear ends of the utility model are respectively provided with a pair of connecting terminals, and the rear end can be connected with one or two telephones. The anti-theft device of the utility model can disturb a line thief's code sending system, so that the thief's telephone can not send codes. The anti-theft device of the utility model has the advantages of simple circuit, convenient connection, few elements, low cost and good effect, and can thoroughly relieve users' worry about telephone being stolen.

Description

The telephone line alarm

The utility model relates to a kind of telephone line alarm that adopts electronic integrated circuit to make and be used with telephone set.

Sold multiple telephone line alarm on the domestic market at present, though a bit antitheft ability is arranged, but be still far from perfect, such as the fast XD-1328 type phone bodyguard who reaches Telecommunication Apparatus Factory's production in special zone, Shantou, Guangdong Province, the antitheft telephone set of HA-158 (II) P/TSDL/LCD type that Kangmeisi Communication Co., Ltd., Shenzhen City produces, all be to utilize the single-tone interference signal, the noise that a bit disturbs is just arranged, the small voice that warning is arranged, the appropriator number dialing telephone call that can do as usual, exchanger metering system as usual charges, and particularly this class kind alarm is also just genuine inoperative during unmanned or WorkPhone unattended in night daytime in the family.

The purpose of this utility model is for thoroughly solving the stolen difficult problem of telephone line, a kind of signaling system that can upset appropriator is provided, and makes the telephone line alarm that the phone of appropriator can't signaling.

Technical solution of the present utility model is: adopt integrated circuit to manufacture, mainly by the level monitoring circuit, multifrequency signaling circuit and power supply circuits three parts are formed, be installed in the plastics etui, front end has the sub-a of pair of terminals, b to be connected with the outside line of Local Exchange, and the rear end also has the sub-a1 of pair of terminals, b1 to be connected with user's telephone set.The level monitoring circuit is made up of triode T1, T2, resistance R 6, R7, R8, capacitor C 5, photoelectric coupling circuit GD, diode D5-11, voltage-stabiliser tube WD; Multifrequency signaling circuit is made up of IC, resistance R 1-3, capacitor C 1-4, triode T4, crystal oscillator body JZ; Power supply circuits are made up of diode D1-4, resistance R 4, R5, triode T3.

The annexation of three parts is seen circuit theory Fig. 2, power supply circuits 3 are the complete machine power supply, connected mode is as follows: the positive terminal of diode D2, D4 in the power supply circuits 3 is connected with R6, R7 in the monitoring circuit 1, the T2-C utmost point in the monitoring circuit 1 and the T3-b utmost point in the power supply circuits 3 join, and the T3-C utmost point in the power supply circuits 3 is connected with integrated circuit (IC)-10 pin of multifrequency signaling circuit 2.

The utility model circuit is simple, need not debug in the ordinary course of things, so making is not had specific (special) requirements, the staff with general radiotechnics can be by the figure assembling; Because the utility model has designed monitoring circuit and dual-tone multifrequency signaling circuit in one, so thoroughly solved the stolen technical barrier of telephone line; The utility model uses element few, with low cost in addition, so can the unit of being implemented accept, also can be popular in users.

The utility model is provided by following examples and accompanying drawing.

Fig. 1 is a contour structures schematic diagram of the present utility model.

Fig. 2 is a circuit diagram of the present utility model.

Describe specific operation process such as overall structure circuit arrangement of the present utility model and operation principle with reference to the accompanying drawings in detail:

Profile of the present utility model is made of a plastic casing, the lid and bottom of plastic casing are freely to connect, and circuit partly is installed in the box, and two are provided with binding post a, b, a1, b1, circuit part is by level monitoring circuit 1, dual-tone multifrequency signaling circuit 2 and power supply circuits 3 are formed, and level monitoring circuit 1 is by two triode T1, T2, three resistance R 6-8, a capacitor C 5, a photoelectric coupling circuit GD, seven diode D5-11, a voltage-stabiliser tube WD forms; Multifrequency signaling circuit 2 is by integrated circuit (IC), three resistance R 1-3, and four capacitor C 1-4, triode T4 and 3.58 megahertz crystal oscillator body JZ form; Power supply circuits are by 3 four diode D1-4, two resistance R 4, R5, and a triode T3 forms.Its overall structure circuit arrangement is as figure, and annexation was narrated.Below concise and to the point narration operation principle: after circuit is connected; electric current is supplied with entire circuit through the D1-4 of power supply circuits 3 rectification; arrive the triode T3-e utmost point through resistance R 4 current limlitings; for preventing the T3 misoperation; be provided with negative bias resistance R 5; supply with level monitoring circuit T1 simultaneously; bias voltage of T2; the height of this voltage will be controlled the conducting of T3 and end; there is not line idle when usurping; present high level; this moment, electric current was through resistance R 7; voltage-stabiliser tube WD; triode T1 conducting; R8 plays shunting action to monitoring voltage; triode T2; T3 ends; integrated circuit (IC)-10 pin no-voltage and quitting work; if circuit is stolen account for busy; present low level; voltage-stabiliser tube WD ends; triode T1 ends; resistance R 6 provides bias current for triode T2; T2; the T3 conducting; electric current is through R4; the e-c of T3 is to integrated circuit (IC)-10 pin; the IC-10 pin has voltage; satisfy the condition of work of IC; owing to be subjected to the control of JZ3.58 megahertz crystal oscillator body to produce and send touch-tone signal; T4 presents to loop through triode; make the receiver work of post office switch; the signaling system of extension set is usurped in upset; for preventing the excessive resistance R 1 of establishing of triode T4 electric current; R2 plays metering function; resistance R 3 starts low level for one on integrated circuit (IC)-5 pin; C5 is the buffer capacitor of protection triode T4; C1 is a high-frequency bypass capacitor; C2 is an integrated circuit (IC)-15; buffer capacitor between 18 pin; C3; C4 is the buffer capacitor of crystal oscillator body JZ; when you control oneself off-hook; the bridge circuit that another part of level monitoring circuit is made up of diode D5-8 makes the conducting of photoelectric coupling circuit GD3-4 pin; drag down the base potential of triode T2, T2; T3 ends, and the integrated circuit (IC) outage is quit work; make your phone unblocked, do not do the voltage clamp protection with diode D9-11 for photoelectric coupling circuit GD is not damaged.

Directly for model, crystal oscillator body JZ 3.58MH, triode T1, T2, T4 be with VCE 〉=160V, npn type with W91210 or other for the optimal selection integrated circuit (IC) of components and parts, and T3 is with VCE 〉=160V, positive-negative-positive, GD PC-817, resistance R 1:200, R2:2K, R3:180K, R4:13K, R5:180K, R6:20M, R7:13M, R8:470K 560K, voltage-stabiliser tube WD 16V, capacitor C1:0.33UF, C2:200P, C3:30p, C4:30P, C5:0.022UF, diode D1-11:1N4002.

Claims

1, a kind of telephone line alarm that adopts electronic integrated circuit to manufacture, mainly by the level monitoring circuit, dual-tone multifrequency signaling circuit, power supply circuits three parts are formed, be installed in the plastic casing, the end of box, freely be connected with lid, before the plastic casing, after respectively establish the sub-a of pair of terminals, b and a1, b1, connect respectively on Local Exchange's outside line and the telephone set, it is characterized in that: the level monitoring circuit is by triode T1, T2, resistance R 6-8, capacitor C 5, photoelectric coupling circuit GD, diode D5-11, voltage-stabiliser tube WD forms, multifrequency signaling circuit is by integrated circuit (IC), resistance R 1-3, capacitor C 1-4, triode T4, crystal oscillator body JZ forms, power supply circuits are by diode D1-4, resistance R 4, R5, triode T3 forms, diode D2 in the power supply circuits, the positive terminal of D4 and the R6 in the monitoring circuit, R7 is connected, T2 collector electrode in the monitoring circuit and the T3 base stage in the power supply circuits are joined, and the T3 collector electrode in the power supply circuits is connected with integrated circuit (IC)-10 pin of multifrequency signaling circuit.