CN2266843Y - Multifunction antitheft device for telephone - Google Patents

Abstract

The utility model relates to a multifunction antitheft device for telephones preventing telephone making and wire tapping. The utility model is characterized in that a trimming resistor R11 is connected in parallel with the coil of a miniature relay XJ to form a wire tapping preventing loop, and voltage stabilizing diodes D7, D8, D10 and D 11 whose polarities are reversely connected are connected in series in the trigger circuit of double silicon D9 and D12 to form an extension set mutually confidential loop. Two totally symmetric phase inverter resistor R6, a triode Q4, a resistor R9 and a triode Q5 are crossed towards base coupling through coupling capacitors C3 and C4. The utility model has the advantage of low cost and has the functions of preventing telephone making and wire tapping for voice frequency telephones or pulse telephones.

Description

The multi-function telephones alarm

The utility model belongs to field of telephone communication, the multi-function telephones alarm of particularly a kind of anti-free call on sb. else's expense through illegal means, anti-eavesdrop.

Along with popularizing and phone stolen of phone, various forms of Device for anti-fraudulent use telephone line are also gone on the market in a large number.But at present the commercially available prod all has the following disadvantages respectively: one, can prevent free call on sb. else's expense through illegal means but can not anti-eavesdrop.Two, can prevent free call on sb. else's expense through illegal means but can only prevent dual tone phone dialing and can not prevent the pulse telephone dialing.Three, dc impedance and leakage current exceed standard, and insert an alarm and have been equivalent to increase the line loss more than five kilometers.Four, influence telecommunication bureau's 112 complaint desks inquiry fault.Five, some product also needs external accessory power supply etc.Just can only prevent free call on sb. else's expense through illegal means as Chinese utility model patent CN2177309Y described " the antitheft telltale of phone " and can not anti-eavesdrop, the external power supply of still needing particularly has polar requirement to telephone line, makes troubles for installing and using.

The purpose of this utility model be exactly overcome the deficiency of above-mentioned various products and provide a kind of cheaply, can prevent the multi-function telephones alarm of free call on sb. else's expense through illegal means, anti-eavesdrop.

The purpose of this utility model can realize by following scheme: it comprises input circuit, anti-eavesdrop loop, the mutual secret loop of extension set, electronic switch loop and warning circuit.Above-mentioned anti-eavesdrop loop is by semifixed resistor R11 and midget relay XJ coils from parallel connection of coils and constitute.Regulating semifixed resistor R11 can make this alarm all obtain good anti-eavesdrop effect under 0 kilometer, 10 kilometers line impedances.The mutual secret loop of extension set is in the circuits for triggering of two silicon D9, D12, seal in voltage stabilizing didoe D7, the D8 of error-polarity connection and D10, D11 and constitute, no matter it is positive and negative that its effect is a voltage direction, all trigger voltage makes two silicon conductings accurately, thereby avoids using the bridge heap to proofread and correct the drawback that polarity brings impedance to increase.Warning circuit then is that inverter resistance R 6, triode Q4 and resistance R 9, the triode Q5 of symmetry are coupled to base stage by coupling capacitance C3, C4 intersection fully by two, form positive feedback and vibrate, produce abundant high order harmonic, these harmonic waves both can be shut double-audio signal, can flood pulse signal again, thereby make usurp phone can not dual-tone dialing, can not pulse dialing.Prior art is adopted in input circuit of the present utility model and electronic switch loop.

Below in conjunction with accompanying drawing operation principle of the present utility model is described below:

Outside line provides the direct voltage of 48V-60V by the input of A, B point, and K2 enters electronic switching circuit by change over switch.Diode D1-D4 is a polarity correction circuit, and the C point voltage just is always to guarantee A, the positive anti-change of B point voltage.The above voltage of 46V when being in waiting state, phone is arranged between C, D.This circuit makes triode Q1 conducting through resistance R 2, R3 dividing potential drop, and Q2 ends, thereby triode Q3 ends, and the E point does not have.Be that electronic switch turn-offs, do not work with the warning circuit that the E point connects this moment, and buzzer RL is sounding alarm not.

When A, B point-to-point transmission are connected to when usurping the phone off-hook, then voltage falling is below 12V between C, D, and this moment, the F point voltage was extremely low, voltage-stabiliser tube D5 turn-offs, then triode Q1 end, the Q2 conducting, the Q3 conducting, E orders.It is the electronic switching circuit conducting.So back level warning circuit work.Its warning course of work is as follows: resistance R 6, triode Q4 and resistance R 9, triode Q5 form two identical inverters, cross one another by capacitor C 3, C4 and to connect the other side's base stage, form positive feedback and vibrate, oscillator signal drives buzzer RL sounding through resistance R 10 by triode Q6.Simultaneously its harmonic wave feeds back to A, B end, makes to usurp telephone set and can't carry out double-tone frequently and pulse dialing, can not eavesdrop.Realize thief-proof T/P compatibility.

If be connected on arbitrary the user's oneself at OUT1 or OUT2 place receiver off-book work, though voltage also will fall to below the 12V, but because midget relay XJ coil is by its normally opened contact closure of electric current about 30mA, thereby make triode Q2 base earth turn-off triode Q3, thereby warning circuit does not have electricity and sounding not.

The mutual secret circuit's principle of extension set be when first receiver off-book of user for example be OUT1, thereby one of them puncture of voltage stabilizing didoe D7, D8 at this moment triggers two silicon D9 conducting phone operate as normal, this moment, voltage falling was below 12V, another receiver off-book of OUT2 place is arranged again, voltage-stabiliser tube D10 or D11 all can not puncture two silicon D12 just can not conducting, and this phone is not worked.Vice versa, thereby this circuit has guaranteed that two phones can not work first off-hook person priority task simultaneously.Resistance R 12 and R13 are current-limiting resistance, prevent that the voltage-stabiliser tube overcurrent from burning.The consistency that has kept conducting voltage is used in the reversal connection series connection of voltage-stabiliser tube D7, D8, D10, D11, has also avoided the polarity of voltage in circuit at the corresponding levels to proofread and correct simultaneously.Thereby reduced dc impedance.

Anti-eavesdrop loop works principle is as follows: relay XJ has shut the electronic switch loop in the contact during work of subscriber phone off-hook, warning circuit is not worked, this moment is if there is the external phone of usurping, then 12V voltage further drops, cause the midget relay electric current to reduce and the contact disconnection, electronic switch is connected like this, warning circuit work, eavesdropping failure.Because the utility model operational environment differs, for example: different in size because of circuit, the phone impedance differs, so operating current differs greatly.Therefore in the anti-eavesdrop circuit, be provided with semifixed resistor R11, can guarantee that the electric current by relay is 30mA under concrete environment.

K1 is the self diagnosis button in the input circuit, can simulate the phone works situation of usurping, whether to check this device operate as normal.K2 is a change over switch, and shown position is antitheft anti-eavesdrop state.If conversion is left then cut off this device, so that telecommunication bureau's 112 complaint desks inquiry fault.

Compare with prior art, the utlity model has following distinguishing feature: free call on sb. else's expense through illegal means also can effectively prevent eavesdropping no matter a dual tone phone or pulse telephone all can prevent other people.Two, this device dc impedance and leakage current all meet national inner quality standard.Three, when free call on sb. else's expense through illegal means or eavesdropping state occurring, this machine gives the alarm automatically and disturbs, cuts off automatically main frame, and fault is eliminated this machine of back and automatically reset, and recovers operate as normal.Four, do not influence telecommunication bureau's 112 complaint desk operate as normal.

Fig. 1 is a schematic appearance of the present utility model.

Fig. 2 is an electrical schematic diagram of the present utility model.

Provide embodiment of the present utility model below in conjunction with accompanying drawing.

As shown in Figure 1,1 is shell, and by injection molded, 2 is change over switch, and 3 is the self diagnosis button, and 4 is the buzzer hole, and 5 is the alarm output wiring terminal, and 6 are words line input wires head.

As shown in Figure 2, the utility model comprises input circuit, anti-eavesdrop loop, the mutual secret loop of extension set, electronic switch loop and warning circuit.Input circuit is made up of self diagnosis button K1, change over switch K2 and resistance R 1.The anti-eavesdrop loop is with semifixed resistor R11 and midget relay XJ coils from parallel connection of coils and constitute.The mutual secure circuit of said extension set is to seal in voltage stabilizing didoe D7, D8 and constitute in the circuits for triggering of two silicon D9, D12, and wherein D7, D8 oppositely are connected in series the trigger end that the back connects D9, and D10 oppositely is connected in series the trigger end that the back is connected D12 with D11.The electronic switch loop comprises diode D1, D2, D3, D4, voltage-stabiliser tube D5, D6, triode Q1, Q2, Q3 and resistance R 2, R3, R4, R5.Described warning circuit is that resistance R 6 is connected with triode Q4 collector electrode, resistance R 9 connects with triode Q5 collector electrode, and be connected with the base stage of triode Q5, Q4 respectively by coupling capacitance C3, C4, form positive feedback, drive buzzer RL sounding by triode Q6.This circuit also comprises resistance R 7, R8, R10.

Claims (2)

1, a kind of anti-free call on sb. else's expense through illegal means, the multi-function telephones alarm of anti-eavesdrop, comprise input circuit, the anti-eavesdrop loop, the mutual secret loop of extension set, electronic switch loop and warning circuit, it is characterized in that constituting the anti-eavesdrop loop by semifixed resistor R11 and midget relay XJ coils from parallel connection of coils, at two silicon D9, seal in the voltage stabilizing didoe D7 of error-polarity connection in the circuits for triggering of D12, D8 and D10, D11 constitutes the mutual secret loop of extension set, by two symmetrical fully inverter resistance R 6, triode Q4 and resistance R 9, triode Q5 is by coupling capacitance C3, C4 intersects to base stage coupling formation warning circuit.

2, multi-function telephones alarm according to claim 1 is characterized in that voltage stabilizing didoe D7, D8 oppositely are connected in series the trigger end that the back connects two silicon D9 in the mutual secret loop of extension set, and voltage stabilizing didoe D10 oppositely is connected in series the trigger end that the back is connected two silicon D12 with D11.

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