CN2282751Y - Telephone line protector - Google Patents
Telephone line protector Download PDFInfo
- Publication number
- CN2282751Y CN2282751Y CN 97203506 CN97203506U CN2282751Y CN 2282751 Y CN2282751 Y CN 2282751Y CN 97203506 CN97203506 CN 97203506 CN 97203506 U CN97203506 U CN 97203506U CN 2282751 Y CN2282751 Y CN 2282751Y
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- circuit
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- triode
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- link
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Abstract
The utility model relates to a telephone line protector which is composed of a voltage detecting circuit (1) for outside lines, a host recognition circuit (2), an audio interference and alarm display circuit (3) and a power switch circuit (4). When the outside lines are connected in parallel with a line stealing telephone, the utility model can send out audio interference signals toward the lines, thus effectively prevent the line stealing telephone from normally working and reach the purpose of protecting the lines.
Description
The utility model relates to a kind of protector, especially can discern the telephone line protector that phone and eavesdropping are usurped in outside line.
At present, many telephone line protectors do not possess warning function in the society, adopt the variation of line voltage distribution to judge whether circuit is stolen simultaneously, when usurping telephone set and insert outside line, circuit are caused swinging cross, make to usurp telephone set and can not pull out number.But post and telecommunications office's measuring chamber often detects local line, and method of measurement is that circuit is carried out charge and discharge process twice, judges whether automatically normally by computer.Because the change in voltage scope that discharges and recharges is bigger, makes line protector think that circuit is stolen by mistake, causes serious swinging cross of measurement result and line capacitance bigger, causes misjudgment, and has influenced the operate as normal of measuring chamber.
The purpose of this utility model is to have overcome above-mentioned the deficiencies in the prior art, provides that a kind of utilization is plucked, on-hook voltage difference and audio disturbances, judges whether stolen telephone line protector.
The purpose of this utility model is achieved in that it is made up of outside line voltage detecting circuit, main frame identification circuit, audio disturbances and alarm indication circuit, power switch circuit.When telephone set and off-hook are usurped in outside line; outside line voltage is reduced to about 10V by 50V; outside line this moment voltage detecting circuit detects voltage signal; trigger power switch circuit; audio disturbances and alarm indication circuit are got; and to sending audio disturbances signal and alarm indication on the circuit, usurp telephone set and can't converse with the other side thereby make, reach the purpose of route protection reliably.
The utility model telephone line protector has adopted special audio to disturb integrated circuit, and peripheral cell is few, welds errorlessly can reach designing requirement.
Owing to adopted such scheme, solved circuit swinging cross and the big problem of electric capacity that post and telecommunications office's measuring chamber false judgment causes.The utlity model has the advantage that volume is little, cost is low, reliability is high.
Below in conjunction with accompanying drawing the utility model is further specified.
Fig. 1 is the utility model circuit block diagram.
Fig. 2 is the utility model circuit theory diagrams.
In Fig. 1, outside line voltage detecting circuit (1) is made of resistance (R1, R2, R3, R4, R5), triode (T1, T3).Main frame identification circuit (2) is made of resistance (R7), triode (T2).Audio disturbances and alarm indication circuit (3) are made of luminous tube (D3), resistance (R8), electric capacity (C2), piezo (YD) and audio disturbances integrated circuit (IC1).Power switch circuit (4) is made of electric capacity (C1), voltage-stabiliser tube (D2), luminous tube (D3), resistance (R6), triode (T4).When phone and off-hook are usurped in outside line; by outside line voltage detecting circuit (1); detect voltage change signal; trigger power switch circuit (4); offer audio disturbances and alarm indication circuit (3) working power by power switch circuit (4); promptly send audio disturbances signal and alarm indication, make and usurp telephone set and can't converse, thereby reach the not stolen purpose of protection circuit reliably with the other side to circuit.
In Fig. 2, terminals (A) link to each other with the outside line positive terminal, terminals (B) link to each other with the outside line negative pole end, terminals (C, D) two ends link to each other with owner's telephone set, diode (D1) is anodal to link to each other with terminals (A), and resistance (R1, a R2) end links to each other with triode (T1) base stage, and the other end links to each other with diode (D1) negative pole and terminals (B) respectively, resistance (R3) links to each other with triode (T1, T2) collector electrode, and triode (T1, T2) emitter links to each other with terminals (B).When phone or hook state are not usurped in outside line, terminals (A, B) both end voltage is 50V, after resistance (R1, R2) dividing potential drop, triode (T1) base voltage is about 1.8V, make triode (T1) saturation conduction, because triode (T1) collector electrode links to each other with triode (T3) base stage, so triode (T3) ends, can not provide operating voltage for triode (T4) base stage, triode (T4) also ends, and special audio disturbs integrated circuit (IC1:CM3525) to can not get operating voltage and do not work.
When owner's telephone set off-hook, the ordinary telephone set working direct current is generally 30mA-45mA, then resistance (R7) both end voltage is about 1V, resistance (R7) end links to each other with triode (T2) base stage, and the other end links to each other with terminals (B), makes triode (T2) saturation conduction, triode (T3) ends, so triode (T4) also ends, special audio disturbs integrated circuit (IC1:CM3525) to can not get operating voltage and does not work, but then owner's telephone set normal dialing conversation.
After telephone set and off-hook are usurped in outside line; terminals (A, B) both end voltage is reduced to about 10V by 50V; after resistance (R1, R2) dividing potential drop; triode (T1) base voltage is reduced to 0.3V by 1.8V; triode (T1) is ended; triode (T3) conducting; trigger triode (T4) conducting; (IC1:CM3525) provides working power for the audio disturbances integrated circuit; and send audio disturbances signal and alarm indication to circuit immediately; make and usurp telephone set and can't converse, thereby reach the not stolen purpose of protection circuit reliably with the other side.
Claims (3)
1; a kind of telephone line protector; it is by the outside line voltage detecting circuit; the main frame identification circuit; audio disturbances and alarm indication circuit; power switch circuit is formed; it is characterized in that: terminals (A) link to each other with the outside line positive terminal; terminals (B) link to each other with the outside line negative pole end; terminals (C; D) link to each other with owner's telephone set; diode (D1) is anodal to link to each other with terminals (A); resistance (R1; R2) end links to each other with triode (T1) base stage; the other end respectively with diode (D1) negative pole; terminals (B) link to each other, triode (T1; T2) emitter links to each other with terminals (B).After phone and off-hook are usurped in outside line; terminals (A, B) both end voltage is reduced to about 10V by 50V; after resistance (R1, R2) dividing potential drop; triode (T1) base voltage is reduced to 0.3V by 1.8V; then triode (T1) ends; triode (T3) conducting; trigger triode (T4) conducting; (IC1:CM3525) provides working power for the audio disturbances integrated circuit; send audio disturbances signal and alarm indication to circuit immediately; make and usurp telephone set and can't converse, thereby reach the not stolen purpose of protection circuit reliably with the other side.
2, telephone line protector according to claim 1 is characterized in that: diode (D1) positive pole links to each other with terminals (A), negative pole links to each other with resistance (R1, R3, R4), voltage-stabiliser tube (D2) negative pole, audio disturbances integrated circuit (IC1:CM3525) the 1st pin.
3, telephone line protector according to claim 1 is characterized in that: adopt special audio to disturb integrated circuit (IC1:CM3525), resistance (R8) links to each other with the 2nd, 3 pin, and piezo (YD) links to each other with the 4th, 5 pin.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 97203506 CN2282751Y (en) | 1997-04-17 | 1997-04-17 | Telephone line protector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 97203506 CN2282751Y (en) | 1997-04-17 | 1997-04-17 | Telephone line protector |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN2282751Y true CN2282751Y (en) | 1998-05-27 |
Family
ID=33924349
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 97203506 Expired - Fee Related CN2282751Y (en) | 1997-04-17 | 1997-04-17 | Telephone line protector |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN2282751Y (en) |
-
1997
- 1997-04-17 CN CN 97203506 patent/CN2282751Y/en not_active Expired - Fee Related
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C19 | Lapse of patent right due to non-payment of the annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |