CN2247907Y

CN2247907Y - Shearing alarm device for telephone line

Info

Publication number: CN2247907Y
Application number: CN 95222285
Authority: CN
Inventors: 汤骐
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-09-23
Filing date: 1995-09-23
Publication date: 1997-02-19
Anticipated expiration: 2005-09-23

Abstract

The utility model relates to an anti-shearing alarm device for a telephone line, which is composed of a power circuit, a rectification circuit, a comparing identification circuit, a drive circuit and an alarm. The power circuit is changed from 220V alternating current into 12V alternating current via a transformer, and forms a DC regulated circuit through the rectification circuit to be connected to the comparing identification circuit, and DC regulated circuit is connected with the in-phase end of a comparing amplifier U2 through the DC voltage division points of resistors R4, R5. The voltage of the telephone line with indefinable positive-negative polarity is converted into the direct current with fixed polarity by the rectification circuit B2 to be output, and the direct current is connected with the reverse-phase end of the comparing amplifier through a voltage division sample circuit composed of resistors R2, R3; the comparing amplifier is connected with the drive circuit and the alarm.

Description

Be used for the anti-warning device of cutting of telephone wire

Along with the development of post and telecommunications cause, utilize the various warning devices of telephone line network transmission warning message to arise at the historic moment.This class device has long transmission distance, strong interference immunity, need not advantages such as special-purpose alarm circuit.Yet this type of device ubiquity is done nothing in case telephone wire is just cut off to the extremely strong dependence of telephone wire.

The purpose of this utility model is to design the anti-warning device of cutting of a kind of telephone wire, can effectively be reported to the police even telephone wire cuts also.

Technical scheme and the embodiment of taking with reference to description of drawings for achieving the above object:

The drawing explanation:

Fig. 1 is the utility model scheme block diagram

Fig. 2. be the utility model circuit theory diagrams

As shown in Figure 1 the utility model by power circuit 1, rectification circuit 2, relative discern circuit 3, Drive circuit 4 and alarm 5 five partly form. Power circuit by transformer TRANS with 220V Alternating current is transformed into the 12V alternating current, through bridge rectifier B1, by with the adjustable regulator block U1 of three ends The capacitor C 1, C2, C3, the C4 that connect, variable resistor W1 and resistance R 1 formation+12V direct current are steady Volt circuit output is connected to the relative discern circuit, through the dc partial voltage point A of resistance R 4, R5 with than In-phase end than amplifier U2 connects; Bridge rectifier B2 is with the uncertain phone of positive-negative polarity The line voltage transition becomes the fixing direct current output of polarity, through the pressure sampling circuit of resistance R 2, R3 formation The B point be connected to the comparison amplifier end of oppisite phase; Comparison amplifier output is connected to the driving three of drive circuit Utmost point pipe T is connected with alarm BELL.

Power circuit mainly provides+and the 12V dc source uses for whole warning device; Rectified current Road B2 is transformed into direct current with the uncertain telephone line voltages of positive-negative polarity, if telephone wire Do not cut off, then the DC voltage of rectification circuit output will still exist, otherwise then not have direct current output; Ratio Compare differentiation according to rectification circuit output situation just than identification circuit, from two kinds of Output rusults Can reflect that telephone wire is to connect or the access failure two states; Drive circuit is subjected to the relative discern circuit Control, if telephone wire is cut off, under the control of relative discern circuit, drive circuit will drive alarm Work makes it send chimes of doom, if telephone wire is normally connected, then alarm is not worked.

Circuit diagram can illustrate the scheme implementation example as shown in Figure 2:

The 220V alternating current is transformed into the 12V alternating current after bridge rectifier B1 is connected to the adjustable regulator block U1 of three ends from transformer TRANS, the desirable LM317 of its integrated circuit model, it and capacitor C 1, C2, C3, C4, variable resistor W1 and resistance formation+12V export direct current regulation circuit, supply with the entire circuit device and use.Bridge rectifier B2 is transformed into the fixing direct current output of polarity with the uncertain telephone line voltages of positive-negative polarity.According to different switches, its output can be 60V, 48V, 24V etc.R2, R3 are pressure sampling circuit and since R2, R3 value very the die sampling current less than 5 microamperes.This has just satisfied telephone set on-hook leakage current and has been not more than 5 microamperes national standard.The B point is that R2, R3 series circuit sampling voltage are promptly sent comparison amplifier U2 (model is got LM324) end of oppisite phase; It connects the LM324 in-phase end through R4, R5 dc partial voltage voltage and the A point is for+12V.Obviously, when telephone wire is in normal on-state, B point voltage (end of oppisite phase voltage) is higher than A point voltage (in-phase end voltage), and then comparison amplifier output low level (0V) makes driving triode BU406 be in cut-off state, and therefore alarm this moment (+12V DC operation) is not worked; And when telephone wire is cut or disconnected, obviously the B point voltage is 0V, less than the A point voltage, so LM324 comparison amplifier output high level (more than the 10V), this will make driving tube BU406 be in saturation condition, thereby make alarm have current supply circuit to make it send break alarm.

Advantage of the present utility model:

1. line unit is simple, and is with low cost.

2. overcome the dependence of prior art,, also can send warning even telephone wire is cut off to telephone wire.

Claims

1. be used for the anti-warning device of cutting of telephone wire, it is characterized in that forming by power circuit (1), rectification circuit (2), comparison identification circuit (3), drive circuit (4) and alarm (5), by transformer TRANS the 220V alternating current is transformed into the 12V alternating current in the power circuit, meet rectification circuit B1, through the adjustable regulator block U1 of three ends by connected capacitor C 1, C2, C3, C4, variable resistor W1 and the output of resistance R 1 formation+12V direct current regulation circuit are connected to the comparison identification circuit, are connected with the in-phase end of comparison amplifier U2 through the dc partial voltage point A of resistance R 4, R5; Rectification circuit B2 is transformed into the fixing direct current output of polarity with the uncertain telephone line voltages of positive-negative polarity, the B point of the pressure sampling circuit that constitutes through resistance R 2, R3 is connected to the end of oppisite phase of comparison amplifier, and comparison amplifier is exported the driving triode that is connected to drive circuit and is connected with alarm BELL.

2. the anti-warning device of cutting of electric hot line according to claim 1 is characterized in that it is the LM317 integrated circuit that the adjustable regulator block U1 of three ends gets model; Comparison amplifier U2 gets LM324; Drive triode T and get BU406.