CN2259029Y - Device for avoiding fraudulent use of telephone line - Google Patents

Abstract

The utility model relates to an anti-theft device for telephone lines. The utility model is provided with an alarm threshold voltage as high as 40V, so that a line thief indeed fails on the attempt at using telephones by stealing. The device does not consume line current or need other cells, and helps users know whether someone is on the ear when the users use the telephone. The device with simple circuit and high performance/price ratio is composed of bidirectional power source, a photoelectric switch, an alarm locking, a personal telephone controlling, a reset switch and other circuits.

Description

The telephone line antitheft device

The utility model is a kind of telephone line antitheft device.

Along with popularizing of phone, telephone line is increased gradually by the phenomenon of steal, is indiscoverable if do not adopt an effective measure.The utility model is exactly in order to take precautions against a kind of device that telephone line is designed by steal.

Subtract so, the product category of " burglar alarm " that sell in current market and so on is various, and relevant utility model invention is quite a few, as: CN2187861Y, CN2192990Y, CN2194052Y disclose the design details of oneself.But, no matter be product or relevant design, all there are one great " mistaken ideas ", promptly the line voltage distribution under the conventional off hook state, (about 8～12V) alarming threshold magnitudes of voltage as " burglar alarm ".In fact, even also being may not be certain to take precautions against circuit effectively at more than 20 volts, this voltage design usurped by other people.I once was equipped with on the telephone line of " alarm " product " telephoning illegally " at several, inferior successfully! In addition, above-cited utility model also has 2 common defects: be furnished with external power; More or less to consume the circuit energy always.

The purpose of the utility model just is to overcome above-mentioned weak point of the prior art, and a kind of telephone line antitheft device is provided, and the height (about 40V) that its alarming threshold voltage is enough can prevent that fruitfully circuit is stolen; And, can not consume line current (momentary charge is only arranged) when keeping machine when access device; Do not need the user to join external connection battery in addition yet.

Technical solution of the present utility model is: a kind of telephone line antitheft device is controlled each circuit by bi-directional power, optoelectronic switch, warning locking, reset switch, private telephone and is formed.

The bi-directional power circuit is to be made of R8, D1, C2.Electricity group R8 one end connects the positive pole of diode D1, and the D1 negative pole can connect by capacitor C 2 one ends with all, another termination of C2 " " the o point, resistance R 8 another terminations are to the A point.

Photoswitch circuit by photoelectric coupled device DK, R6, R7, C1, constitute.Infrarede emitting diode negative pole among the DK is connected to the A point mutually with the phototriode collector electrode; Infrarede emitting diode is anodal to join with resistance R 7 one ends, and the R7 other end is coupled on the interface B of D1, C2; Resistance R 6, capacitor C 1 is in parallel, an end in parallel connects with the phototriode emitter among the DK, another termination " " point 0.

The warning lock-in circuit by R3, R4, R5, LED2, MUS, HDT, SCR, constitute.The anodal formation of resistance R 3 one ends and red light emitting diodes LED2 coupled in series, the R3 other end and LED2 negative pole and resistance R 4 two ends, sound equipment sheet power supply two ends are connected in parallel jointly, and piezoelectric patches HDT is the sounding component of sound equipment sheet; Parallel circuits one is terminated at the A point, and the other end connects with the anode of controllable silicon SCR, the SCR negative electrode connect " " the O point, control the utmost point connect with resistance R 5 one ends, the R5 other end connects with the phototriode emitter.

The private telephone control circuit is made of R1, R2, LED1, R9, R10, BG.Anodal and the resistance R 2 one end coupled in series of LED1 green LED, in parallel again with " sample resistance " R1 two ends then, a termination of parallel circuits " " the o point, the other end also connects with resistance R 10 1 ends then as an exit L4 of the present utility model; The R10 other end and BG base stage link, triode BG emitter connect " ", collector electrode and resistance R 9 one ends link, the crosslinking points B of the R9 other end and storage capacitor C2, diode D1 negative pole, R7 one end joins.

Reset switch K cross-over connection also promptly is connected to L1, L2 lead-out wire two ends in A, O point-to-point transmission.

Embodiment: accompanying drawing shows circuit full figure of the present utility model, and the telephone set DH in the frame of broken lines does not belong to this device.The operation principle of circuit is as follows:

1. the utility model connects with the correct of external equipment: this device lead-out wire L1, L2 connect with outside line L01, L02. must divide positive and negative.FX is former junction box among the figure.Two lead-in wires of other two lead-out wire L3, L4 and private telephone set L03, L04 connect, and can divide positive and negative.Because general electronic telephone has " polar switching ", and old-fashioned dial phone needn't divide positive and negative polarity.When connection is correct, picks up phone LED1 meeting green light, otherwise should exchange L1, L2 with connecting of outside line.

2. keep the machine state: online correct after, positive polarity outside line L02 is through A point, R8, D1, B point, C2 to common point " " 0 get back to L01 and finish the charging process of outside line the energy storage capacitor C2 in the bi-directional power, this process is very fast.C2 is charged near the about 48V of the voltage of outside line; R8 is a charging current limiter resistance, and D1 is for isolating diode.

3. private telephone: electric current the flow through load and the sample resistance R1 of phone DH inside are promptly arranged behind the off-hook, and on R1, cause a pressure drop.This voltage is added to the BG base stage through R10, and BG is conducting at once, and the electric charge on the C2 provides the energy for the BG conducting.

Should be noted that during private telephone, outside line voltage (or A, O point-to-point transmission voltage) also can reduce, but since the BG conducting preceding, make most electric charge of having released on the C2, and do not cause optoelectronic switch DK to devote oneself to work.During incoming call, ringing current can produce pressure drop equally on R1, and it is the same to work behind the off-hook.The R2 in parallel with sample resistance R1, LED1 are in order to show that personal phone works, and the change of its brightness simultaneously can reflect the variation of the electric current of the telephone set DH that flows through significantly, and the height of outside line this moment voltage.If when you just use phone; The unexpected deepening of LED1 illustrates that having the people is eavesdropping.

4. the work when stealing the line phone is arranged: as being connected to surreptitiously line phone in the outside line, owner does not use phone, and this moment, R1 went up no pressure drop, and BG ends.Steal the line phone and make voltage die between A, O, the infrarede emitting diode of optoelectronic switch DK is in positively biased, and D1 is in partially anti-, and the electric charge in the C2 storage is only to the DK discharge, and electric current is that L02 gets back to i.e. 0 point of L01 through R7, infrarede emitting diode to the A point.Be subjected to the coupling of infrared light, phototriode is conducting at once, produces a voltage on R6, thereby provides a control voltage for the conducting of SCR.Because the conducting of SCR, so sound equipment sheet MUS (comprising HDT), R4, R3, LED2 are through SCR and receive that outside line L01, L02 get on to send sound, light is reported to the police.Since R4, R5, LED2 is Low ESR, makes outer line drop to very low, furthermore adds sound interference, steals the line person and can't dial, and the attempt of telephoning illegally falls through.Though optoelectronic switch is the moment conducting, SCR has the lock function of keeping, and removes robber's line phone even steal the line person, and the acousto-optic of warning still can be kept, and reminds the vigilant line person's of stealing of owner attempt.Only remain after owner clicks reset switch K, it is unimpeded that circuit just recovers.

The utlity model has following advantage as can be seen in conjunction with above embodiment:

1. alarm threshold voltage height: outside line voltage 48V reduces to 40V and reports to the police at once later on;

2. the back latch voltage of reporting to the police is low: still can report to the police the outside line of energy effective blockade in 3～1V scope;

3. keep and do not consume outer circuit electric current under the machine state, the user does not need other distribution source yet;

4. during private telephone, can discover others and whether eavesdrop;

5. circuit is very simple, and the ratio of performance to price is higher, production easy to implement.

Claims (4)

1, a kind of telephone line antitheft device is characterized in that: this kind telephone line antitheft device is controlled each circuit by bi-directional power, optoelectronic switch, warning locking, reset switch, private telephone and is formed;

The bi-directional power circuit is to be made of R8, D1, C2.Electricity group R8 one end connects the positive pole of diode D1, and the D1 negative pole connects with storage capacitor C2 one end, another termination of C2 " " the o point, resistance R 8 another terminations are to the A point;

Photoswitch circuit by photoelectric coupled device DK, R6, R7, C1, constitute.Infrarede emitting diode negative pole among the DK is connected to the A point mutually with the phototriode collector electrode; Infrarede emitting diode is anodal to join with resistance R 7 one ends, and the R7 other end is coupled on the interface B of D1, C2; Resistance R 6, capacitor C 1 is in parallel, an end in parallel connects with the phototriode emitter among the DK, another termination " " point 0;

The warning lock-in circuit by R3, R4, R5, LED2, MUS, HDT, SCR, constitute.The anodal formation of resistance R 3 one ends and red light emitting diodes LED2 coupled in series, the R3 other end and LED2 negative pole and resistance R 4 two ends, sound equipment sheet power supply two ends are connected in parallel jointly, and piezoelectric patches HDT is the sounding component of sound equipment sheet; Parallel circuits one is terminated at the A point, and the other end connects with the anode of controllable silicon SCR, the SCR negative electrode connect " " the o point, control the utmost point connect with resistance R 5 one ends, the R5 other end connects with the phototriode emitter;

The private telephone control circuit is made of R1, R2, LED1, R9, R10, BG.Anodal and the resistance R 2 one end coupled in series of LED1 green LED, in parallel again with " sample resistance " R1 two ends then, a termination of parallel circuits " " the o point, the other end also connects with resistance R 10 1 ends then as an exit L4 of the present utility model; The R10 other end and BG base stage link, triode BG emitter connect " ", collector electrode and resistance R 9 one ends link, the crosslinking points B of the R9 other end and storage capacitor C2, diode D1 negative pole, R7 one end joins:

Reset switch K cross-over connection also promptly is connected to L1, L2 lead-out wire two ends in A, O point-to-point transmission.

2, according to claim 1, described telephone line antitheft device is characterized in that: described bi-directional power is to be composed in series by capacitor, diode, resistance.

3, according to claim 1, described telephone line antitheft device is characterized in that: described optoelectronic switch is that electric capacity constitutes jointly by the load resistance on infrarede emitting diode, current-limiting resistance and phototriode and the emitter thereof.

4, according to claim 1, described telephone line antitheft device is characterized in that: described warning lock-in circuit is by one-way SCR and goes up the load of connecting: resistance, light-emitting diode and series resistance, the resistance that the sound equipment sheet is parallel with one another and SCR control is extremely gone up constitute jointly.