CN2192990Y

CN2192990Y - Siren for telephone line stealed

Info

Publication number: CN2192990Y
Application number: CN 94237025
Authority: CN
Inventors: 吴天宇
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-04-04
Filing date: 1994-04-04
Publication date: 1995-03-22
Anticipated expiration: 2004-04-04

Abstract

The utility model relates to an alarm for embezzled telephone lines, relating to an electronic alarm circuit. One piece of CMOS integrated circuit 4069 is used as a main element for forming a voltage monitoring circuit, an electric current monitoring circuit, a logical judgement circuit and an executive circuit. When a telephone line is embezzled, the logical judgement circuit performs an embezzling judge according to the signals sent by the voltage monitoring circuit and the current monitoring circuit, and the executive circuit immediately sends an alarm and starts a recorder for recording or disturbing the call of the embezzler. The utility model has the advantages of simple circuit, low cost and tiny electricity consumption of watch, and the utility model can differentiate a normal off-hook and an embezzled off-hook, needs not to be watched by people and can implement various countermeasures, etc. The utility model can be used for alarming for embezzled telephone lines and broken telephone lines and other alarm devices.

Description

Siren for telephone line stealed

The utility model relates to a kind of electronic alarm circuit.

Along with popularizing of phone, the stolen phenomenon of telephone wire increases gradually.Usually adopt the method for Monitoring Line voltage or monitoring phone to find the stolen of telephone wire, but generally be difficult in time find, just perceive in the time of often will arriving the alternating current telephone expenses.The purpose of this utility model is to improve above-mentioned the deficiencies in the prior art, and provides a kind of telephone wire stolen alarm.

The utility model is achieved by the following scheme: the stolen alarm of telephone wire is made up of electric voltage observation circuit, current monitoring circuit, logic judging circuit, executive circuit and power supply.Telephone line voltage marquis's voltage when phone does not have off-hook is 24-60V, and general voltage is reduced to 7-10V behind the off-hook.When telephone wire is stolen, steal line phone off-hook, line voltage distribution descends, and line current passes through from steal the line phone, current monitoring circuit is monitored less than electric current.As long as line voltage distribution descends and monitors less than electric current (no matter being parallel operation or trimming) simultaneously, logical circuit is promptly made the stolen judgement of circuit, and executive circuit sends the conversation of warning, starting recorder record appropriator at once or applies interference.

Entire circuit is a main devices with a slice CMOS integrated circuit 4069 only, and circuit is simple, and cost is low, and the operating current when not reporting to the police has only several microamperes.

The utlity model has that circuit is simple, cost is low, when on duty power consumption small, can distinguish normal off-hook and usurp off-hook, to need not the people on duty and can implement advantages such as multiple countermeasure, can be used for stolen warning of telephone wire and telephone wire break alarm, and in other alert devices.

Accompanying drawing 1 is the block diagram of the utility model embodiment.

Accompanying drawing 2 is the circuit diagram of the utility model embodiment.

See accompanying drawing 1, present embodiment is by electric voltage observation circuit (1), current monitoring circuit (2), and logic judging circuit (3), executive circuit (4) are formed.The electrode line of telephone line connects the input of electric voltage observation circuit (1) and arbitrary end of telephone set (TEL), the input of another termination current monitoring circuit (2) of telephone set (TEL), the input of the output termination logic judging circuit (3) of the output of electric voltage observation circuit (1) and current monitoring circuit (2), the input of the output termination executive circuit (4) of logic judging circuit (3).

See accompanying drawing 2, the utility model operation principle is as follows: electric voltage observation circuit (1) is made up of R4, Z1, R5 resistance series connection voltage-stabiliser tube pressure sampling circuit and C2, U1, and line voltage distribution is not higher when having off-hook, the U1 output low level, line voltage distribution reduced when off-hook was arranged, and U1 exports high level.Current monitoring circuit (2) is made up of R1, LED resistance led current sample circuit in parallel and R2, R3, C1, U2, and when telephone set (TEL) when not having off-hook, no current passes through, and U2 exports high level, when off-hook is arranged, and the U2 output low level.Logic judging circuit (3) is made up of D3, the positive AND of R6 resistance diode and U3.Stolen or when broken string when telephone wire, line voltage distribution reduces and detects less than electric current, and at this moment U1 and U2 export high level, and the output of inverter U3 is immediately by high step-down, order about relay J 1 closure through U4, Q2, the closure of this switch can make recorder start phone is recorded.The oscillator starting of oscillation that the low level of U3 also is made up of U5, U6, R7, C3 by the D2 instruction, the audio signal of generation send loudspeaker S1 to report to the police after Q1 amplifies.When K1 was changed to closure, chimes of doom can be sent in the telephone wire, and the conversation of appropriator is disturbed.

Claims

1, the stolen alarm of telephone wire, form electric voltage observation circuit (1) by a slice CMOS integrated circuit 4069 for main devices, current monitoring circuit (2), logic judging circuit (3) and executive circuit (4), it is characterized in that: telephone line connects the input of electric voltage observation circuit (1) and an end of telephone set (TEL), the input of another termination current monitoring circuit (2) of telephone set (TEL), the input of the output termination logic judging circuit (3) of the output of electric voltage observation circuit (1) and current monitoring circuit (2), the input of the output termination executive circuit (4) of logic judging circuit (3).

2, the stolen alarm of telephone wire as claimed in claim 1 is characterized in that: the resistance diode positive AND of the logical circuit in its logic judging circuit (3) for being made up of D3, R6.

3, the stolen alarm of telephone wire as claimed in claim 1 is characterized in that: the sample circuit in its current monitoring circuit (2) is the resistance led current sample circuit in parallel that LED, R1 form.

4, the stolen alarm of telephone wire as claimed in claim 1 is characterized in that: the resistance series connection voltage-stabiliser tube pressure sampling circuit that the sample circuit in its electric voltage observation circuit (1) is made up of R4, Z1, R5.