CN2195167Y

CN2195167Y - Telephone cipher filter

Info

Publication number: CN2195167Y
Application number: CN 93239579
Authority: CN
Inventors: 陈继文
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-11-22
Filing date: 1993-11-22
Publication date: 1995-04-19
Anticipated expiration: 2003-11-22

Abstract

The utility model is composed of a ringing current stop circuit 1, a simulated off-hook and time release circuit 2, a DTMF demoding and BDC decoding circuit 3, a discriminating counting and assurance circuit 4, a ringing control and ring generating circuit 5, a display circuit and voice prompt 6. Phone calls which input codes can directly enter by ringing, and other calls are stopped because ring of a phone is silent. Thus the trouble of phone disturbance can be avoided.

Description

Telephone cipher filter

The utility model is relevant with telephone communication, and especially the electronic circuit of design is relevant with exempting harassing call to call out.

For a long time, a lot of telephone subscribers suffer inessential hardship of making nuisance calls, and usually accept some unintelligible calls, during rest particularly late at night, a burst of telephone bell is waken up with a start the telephone subscriber, but the phone of answering often is the phone of misplaying, and what answer sometimes then is the harassing and wrecking of having a mind to.The existing treating method that makes phone have do-not-disturb functionality has:

1. allow telephone set only have call out function and refuse the incoming call of all phones;

2. close ringing telephone stations sound, make the phone of squeezing into enter recorder;

3. close ringing telephone stations sound, the phone ringing sound when squeezing into is shown by light emitting diode lamp.

The common defects of three kinds for the treatment of methods is can not discern useful or critical call under the interruption-free state.

The purpose of this utility model provides a kind of calling of importing password under the interruption-free state can directly enter user's (telephone bell is arranged), then is prevented from the telephone cipher filter of (the telephone set the tinkle of bells does not ring) except that all callings in addition.

The utility model is achieved in that

The telephone cipher filter stops circuit 1 by ringing-current, the simulation off-hook, and delay releasing circuit 2, the DTMF decoding, BDC decoding circuit 3 differentiates that counting is confirmed circuit 4, ring control, the tinkle of bells generation circuit 5, display circuit, voice warning circuit 6 are formed,

Telephone line is introduced terminals L1, L2 connects electric bridge D1-D4 input, D1-D4 output connects electric bridge D5-D8 input by K-3, D1-D4 one output is by functional switch K-3 connection circuit, electric bridge D5-D8 output is by functional switch K-1, the K-2 machine terminals L3 that answers the call, L4, VR1 is connected to L1, meets L4 between the L2 and by functional switch K-2.

Functional switch K-3 is leaded up to transformer B, DZ4, R14, R16, R17, VR3, LED2 ground connection, another road is by VR2 ground connection, and the base stage of T2 connects between R16 and the R17, emitter meets R14, and between the R16, collector electrode is leaded up to C11 ground connection, and another road is by DZ3 ground connection, the IC214 pin, 4 pin of IC3,16 pin of IC4,14 pin of IC5,16 pin of IC6 connect the positive pole of C11,7 pin of IC2,8 pin of IC3,8 pin of IC4,7 pin of IC5, the 8 pin ground connection of IC6.5 pin of IC2 are by R15, C9 ground connection, and the positive pole of C9 connects the base stage of T3, and D10 and R15 are connected between T3 base stage and the IC25 pin, and the collector electrode of T3 connects the base stage of T2 by R17, and the emitter of I3 passes through LED2 ground connection, and VR3 is connected between the collector and emitter of T3.

IC7 and transformer B lotus root are closed, and VDD is leaded up to C15 and connect the T6 base stage, and the collector electrode of T6 connects the base stage of T7 by R28, and D19 is connected between the base stage and emitter of T6, one tunnel ground connection, and one the tunnel connects the Vss end of IC7.

7 pin of IC3 are connected to 1 pin of IC1 by C10 one tunnel, and one the tunnel meets B, 2,1,14 of IC3,13 pin connect 10,13,12,11 pin of IC2, and 12 pin of IC3 connect 1 pin of IC6,9 pin of IC3 are parallel with XL and R18 between 10 pin, 3,4,6 pin of IC3 are leaded up to D13 and met C11, lead up to D11, D12 ground connection, another road is by DZ5 ground connection, 1,6 of IC4,7,4,9,5 pin connect the end of 49 bidirectional switch DK of series connection, another termination 42 of each DK and 1,5,8,12 pin of door integrated circuit (IC) 5.

3,4,10 of IC5,11 pin are connected to 9 pin of IC6 respectively by D14-17, another road is respectively by R10 and C12 ground connection, 2 of IC5,6,9,13 pin meet 7 of IC6,5,4,3 pin, 14 pin of IC6 and 6 pin are leaded up to R22 ground connection, and another road is by C13, C11 ground connection, 14 pin of IC5 connect 7 pin of IC6 by R19, another road leads to AK2, and R21 connects 5 pin of IC6, and 15 pin of IC6 connect 16 pin, 2 pin of IC6 connect the base stage of T5 by R23,10 pin of IC6 connect the base stage of T6 by R24, and the T5 base stage connects the C14 positive pole, ground connection after the C14 negative pole connects the collector electrode of T6 and meets R25, the emitter of T5 and the collector electrode of T6 are connected and are connected to by R27 the base stage of T4, the collector electrode of T5 is connected to the C11 positive pole by R26, and 10 pin of IC6 are by D18, and R11 meets AK1,14 pin of IC6,6 pin are by R22 ground connection.

10 pin of IC2 are by R6 ground connection, and 9 pin of IC2 connect the T1 base stage by R9, R10 ground connection by the C4 time-delay.

11 pin of IC2 are by C7 ground connection, and 3 pin are by C5 ground connection, and 2 pin are connected with 6 pin leads up to C8 ground connection, and R13, R12, C11 ground connection are passed through in another road.14 pin of IC2 are connected to R12, between the R13.4 pin of IC2 are connected with 14 pin, R5, R7, D5, C5 be series at and C11 between, 13 pin of IC2 are connected to R5, between the R7,8 pin and 12 pin are connected in D5, between the C5,8 pin are connected with 13 pin by R8.

Be connected to piezo-electric generator SP between 8 pin of IC1 and 5 pin, 4 pin connect 3 pin and connect the T1 collector electrode by C2 by R2, and 5 pin connect the T1 collector electrode, 6 pin connect 7 pin and connect the T1 collector electrode by C3 by R4, the grounded emitter of T1,2 pin of IC1 meet DZ2 and C1 by R3, the collector electrode of another termination of DZ2 and C1 T1.

Display circuit is by DZ1, R1, LED1 be serially connected with and K-3 between form.

Said IC1 is KA2410, and IC2 is LM556, and IC3 is MC145436, and IC4 is CD4028, and IC5 is CD4081, and IC6 is CD4015.

The utility model is setting code arbitrarily, and the call that knows the cipher directly ring enters, and in addition all are called out then and are not prevented from because of the telephone set the tinkle of bells does not ring, and have thoroughly exempted the hardship of making nuisance calls.The utility model also is provided with " common " " filtration " selector switch and state demonstration light-emitting diode, when need not reverting to the general function phone easily again during interruption-free, uses very convenient.The utility model is applicable to public switched telephone network and Private Branch Exchange PBX telephone subscriber, and it is very convenient to install, need not additional supply, and directly be connected between circuit and the telephone set and get final product, the machine class of answering the call is not limit.

Following is accompanying drawing of the present utility model:

Fig. 1 is a block diagram of the present utility model,

Fig. 2 is circuit theory diagrams of the present utility model,

Fig. 3 is appraisal counting, affirmation circuit theory diagrams,

Fig. 4 is integrated package function end structure figure,

Fig. 5 is the utility model outside drawing.

Fig. 6 is the rearview of Fig. 5.

Following is embodiment of the present utility model:

IC1 of the present utility model is KA2410(GF 8204) the phone ringing integrated circuit, IC2 is the LM556 dual time-base ic, IC3 is the MC14536DTMF decoding integrated circuit, IC4 is CD4028BCD one decimal system decoder ic, IC5 is CD4081 42 and door integrated circuit, IC6 is the CD4015 double shift register, and IC7 is a SR88 series speech IC.

The utility model uses audio telephone squeezing into directly input password of back only to the dtmf signal decoding as the other side; Use the Pulse Electric phone " P/T " switch of phone should be placed " T " can dial password again as the other side, or get final product facing to transmitter transmission password with the DTMF code sender at (behind the breadboardin off-hook) behind this machine of squeezing into.

The utility model setting code is four, and password can be any in the combination of kind surplus in the of 6000, and setting code is " 3721 " in this example, and then closed following line is to inductive switch:

A1－Q3，A2－Q7，A3－Q2，A4－Q1。

1 pin of IC1 of the present utility model connects positive source, and 2,3 pin are trigger control end, and 3,4 pin are low frequency time constant end, and 5 pin connect power cathode, and 6,7 pin are high frequency time constant end, and 8 pin are audio signal output end.

1 pin of IC2 is the D1 end, and 2 pin are the TH1 end, and 3 pin are the C01 end, and 4 pin are the R1 end, and 5 pin are the OUT1 end, 6 pin are the TR1 end, and 7 pin are the VSS end, and 8 pin are the TR2 end, and 9 pin are the OUT2 end, and 10 pin are the R2 end, 11 pin are the CO2 end, and 12 pin are the TH2 end, and 13 pin are the D2 end, and 14 pin are vdd terminal.

1 pin of IC3 is the D2 end, and 2 pin are the D1 end, and 3 pin are the EN end, and 4 pin are vdd terminal, and 5 pin are the GT end, 6 pin are the XEN end, and 7 pin are the AIN end, and 8 pin are the VSS end, and 9 pin are the OSC1 end, and 10 pin are the OSC2 end, 11 pin are the ATB end, and 12 pin are the DV end, and 13 pin are the D4 end, and 14 pin are the D3 end.D1, D2, D3, D4 is the binary-coded decimal output, OSC1, OSC2 are external clock source, and AIN is the dtmf signal input, GT is timing output, ATB is a CLK signal testing end, and XEN is a CLK signal controlling end, and EN is the decoding output control terminal, DV is input data live end, is connected as the counting of receiving the sign indicating number number of times with the CPB end of back level IC6 and triggers.

1 pin of IC4 is the Q4 end, and 2 pin are the Q2 end, and 3 pin are the Q0 end, and 4 pin are the Q7 end, and 5 pin are the Q9 end, and 6 pin are the Q5 end, 7 pin are the Q6 end, and 8 pin are the VSS end, and 9 pin are the Q8 end, and 10 pin are the A end, and 11 pin are the D end, 12 pin are the C end, and 13 pin are the B end, and 14 pin are the Q1 end, and 15 pin are the Q3 end, and 16 pin are vdd terminal.A, B, C, D end are the binary-coded decimal input, and Q is a signal output part, and the Q0 end need not in the utility model.

1 pin of IC5 is the A1 end, and 2 pin are the B1 end, and 3 pin y1 end, 4 pin are the y2 end, and 5 pin are A2, and 6 pin are B2, and 7 pin are the VSS end, and 8 pin are A3, and 9 pin are B3, and 10 pin are y3, and 11 pin are y4, and 12 pin are B4, and 13 pin are A4, and 14 pin are vdd terminal.

1 pin of IC6 is CPB, and 2 pin are QB4, and 3 pin are QA2, and 4 pin are QA2, and 5 pin are QA1, and 6 pin are RA, and 7 pin are DA, and 8 pin are the VSS end, and 9 pin are CPA, and 10 pin are QA4, and 11 pin are QB3, and 12 pin are QB2, and 13 pin are QB1, and 14 pin are RB, and 15 pin are DB, and 16 pin are vdd terminal.CPA, CPB are trigger end, and D is a data input pin, and R is zero clearing.QB1, QB2 in the utility model, QB3 need not.

VR1 of the present utility model, VR2 is anti-high voltage protective resistance; VR3 then when high pressure resistance descend significantly, T2 base circuit path is provided.

R1, R11, R14, R17, R19, R21, R23, R24, R26, R27, R28 are current-limiting resistance.

R2, C2, R3, R4, C3, SP and IC1 form the tone tone generator.

R9, R10, C4, T1 forms the tone generator switch.

DZ2, DZ3 are voltage-stabiliser tube, DZ1, and DZ4 is a votage control switch, close current when being lower than burning voltage.

AK1 is the working power switch of 1/2IC2 time-base circuit.

R5, R7, R8, D9, C5, R12, R13, C8 constitutes the oscillatory work periphery of IC2.

R6 gives IC2, and R2 provides an earth potential, makes 1/2IC2 be in " dormancy " state when leading at the AK1 end.

T3, T2 forms the primary path switch, and R16 is the pull-up resistor of T2, provides the ringing-current high pressure to VR3, guarantees the T2 reliable turn-off when no ringing-current.

C4, C6, C7, C9, C12, C14 are shunt capacitance, improve antijamming capability.T4, T3 constitutes control switch, and D10 provides discharge path for C9, D11, D12 is the clamping protection diode of IC3, C10 is the signal coupling capacitance.

XL is the clock source of IC3, and R18 is that the Q value is regulated resistance.D13 provides IC3 operating current path, is depressurized to 0.7V simultaneously.

C1, C11 are filtering, energy storage capacitor.

The promising IC5 output of D14-D17 OR function stops signal to be played a reversed role simultaneously.

R20 makes IC6's " CPA " 0 be " 0 " when Triggerless.

AK2 is that the DA of IC6 changes control.

C13, R22 are IC6 clear " 0 ".

T6, T7 are the trigger switch of IC7 sound circuit.C15 provides T5 the moment base current.D19, C15 constitute the discharge route.

B can be bonded to circuit with the voice lotus root, and can make the audio frequency chokes, improves DTMF and receives the sign indicating number reliability.

LED1 is that interruption-free is filtered indication

LED2 is the indication of simulation off-hook.

L1, L2 are line input, L3, the L4 machine of answering the call, and K(K-1, K-2 K-3) is filtration switch of the present utility model.

The utility model housing is 1, and LED 1 is 2, and " common ", " filtration " selector switch are 3.Password setting is 4.

The telephone cipher filter stops, simulates off-hook, time-delay release, DTMF decoding, BDC decoding, appraisal counting, affirmation, ring control, double-tone the tinkle of bells generation frequently and display circuit etc. by ringing-current and partly forms.

L1, L2 are that telephone line is introduced terminals, and L3, L4 are that telephone set terminals, K are functional switch (three groups of changeover contacts).When functional switch K places " common " state (showing state as Fig. 2), the telephone set link is by being that L3 → K-1(is quiet) → L1; L1 → K-2(is quiet) → L2, insert telephone line, K-3(is quiet simultaneously) disconnected and being connected of subsequent conditioning circuit, so this password filter is not worked, the incoming call of telephone set, exhalation are the same with the ordinary telephone set use.When functional switch K places " filtration " state, to exert an influence to the incoming call of phone, (exhalation to phone does not have influence, under this state, the secondary rectification that a rectification → D5～D8 that we's phone exhalation off-hook phone line signal is formed through D1～D4 forms is after L3, L4 enter telephone set, because telephone line signal and conversation signal are superimposed upon on the direct voltage, though so can big decay not arranged to the signal transmission through twice rectification of D1～D4, D5～D8, telephone set equally dialled and conversed with normal state this moment).

When the phone incoming call, 90V AC signalling signal from telephone line at first becomes the half-wave pulse signal that is superimposed upon on the DC component after D1～D4 rectification, faint jingle bell when these pulse signals still can make our telephone set produce first shaking, so must add the one-level rectification makes it the DC pulse composition and further decays, become comparatively level and smooth d. c. voltage signal when the 90V AC signalling signal that enters from circuit enters telephone set at last, and the ringing telephone stations response condition is the AC signalling signal of input greater than 30V, telephone set can not produce the tinkle of bells response in the case, thereby has played the effect that ringing-current stops.VR1 in the circuit, VR2 is the 270V piezo-resistance, shields when transient high voltage appears in circuit.

90V AC signalling signal is through moving at K-3(after D12～D4 rectification when the phone incoming call) and ground between formed the 90V direct voltage, this voltage is added on VR3, the LED2 through the transformer B coil of wire → DZ4 → R14 → R16 → R17, since VR3 is 82V piezo-resistance resistance under this voltage to descend greatly → T2 base potential decline → T2 just obtains a base current → T2 and begins conducting, C11 obtains charging after the T2 conducting, each integrated circuit just obtains operating voltage V+, and this moment is by dual time base circuit IC2's

4. 1. 2. 5. 6. 7. Square-wave oscillator circuit Deng pin and peripheral composition is started working, and (a dual time base circuit IC2 has been share in simulation off-hook and ring control, when basic at that time circuit constitutes oscillator, external R, C has determined frequency of oscillation, f=1/(t1+t2)=1.44/(R12+2R13) C8, pulse width t1(R12+R13 during output " 1 ") C8 C8ln2=0.693(R12+R13), interval t2=R13C8ln2=0.693R13C8 during output " 0 "), by 5. pin output " 1 " through current-limiting resistance R15, the T3 conducting is saturated after the C9 charging, the saturated back of T3 T2 base current increase and thereupon meal and, provide maximum operating currenbt to integrated circuits at different levels, so far DZ4 flows through, R14, T2, DZ3 and each integrated circuit VDD to the ground total current reach telephone exchange off-hook loop holding current (＞20mA), thereby constitute the simulation off-hook.R16 is that the pull-up resistor of T2 keeps T2 reliably to end when not receiving ring; Provide one to route to VR3 when receiving ring.R14, R17 are resistance flowing resistance, and DZ4 cuts off operating currents at different levels circuit at different levels are withdrawed from when our off-hook.The effect of D10 is that C9 discharge loop (C9 positive pole → D10 → IC2 is the pin → C9 negative pole of pin → IC2 inside → 7. 5.), LED2 are provided when circuit is not worked is the part of display circuit, is the indication of simulation off-hook when lighting.

IC7(sound circuit behind the simulation off-hook) vdd terminal has just had operating voltage, through C15 T6 conducting → T7 conducting → IC7 just is triggered, and voice output is sent to telephone line through the C11 coupling through D1～D4 through transformer B, and this moment, the caller phone user just obtained voice suggestion.R28 is a current-limiting resistance, provides the discharge route for C15 when D19 is static.

Whole subsequent conditioning circuit is in and waits for the reception dialing status after the sound circuit work, prescribe a time limit when time-delay discharges simultaneously, do not dial or dial incomplete as the calling subscriber, overtime in case (40 seconds), IC2 and the peripheral square-wave oscillator of forming said by the front reverse, and 5. pin becomes " 0 " by original " 1 ", the T3 base stage utmost point loses malleation and ends, then T2 ends, and is 0 by D1～D4 output plus terminal to the electric current on ground, and entire circuit promptly is forced to discharge (the caller phone user listens busy tone).

Receiving under the dialing status, the caller dialing, then DTMF reception, BCD decoding are started working, and form DTMF(dual-tone dialing signal by DTMF decoding integrated circuit IC3 peripheral D23, C10, XL, R18 and D11, D12, DE5) receiving circuit.Dtmf signal is introduced 7. pin → through the IC3 internal analysis at its output 2. 1. of IC3 through coupling capacitance C10 Pin is exported corresponding binary-coded decimal, the BCD decoding circuit that constitutes by BCD one decimal system decoder ic IC4 with the BCCD sign indicating number of IC3 output be translated into the nature decimal code its output 1. 6. 7. 4. 9. 5. pin export appraisal counting to and confirm circuit.The D13 effect is step-down, and D11, D12 are the clamper protection of IC2, and DZ5 guarantees the IC3 operating voltage, and XL is the reference clock source, and R18 is that the 3. pin that the Q value is regulated, IC4 is output as 0 end is not used.

Appraisal counting, affirmation circuit are made up of with a door integrated circuit (IC) 5, double shift register integrated circuit (IC) 6 and peripheral D14～D17, R19, R20, R21, C12, AK2, C13, R22, R23, R24, R25, R26, R27, C14, D18, T4, C9 etc. four 9 bidirectional switch DK, 42.Under initial condition (referring to Fig. 3), IC6 output Q is " 0 ", be B2, B3, B4 be " 0 " thus IC5 each with door in have only B1=" 1 " → 1# door to open, (V+ → R19 → B1), and " 1 " that IC4 translates have only and possess output Q end and A1 simultaneously and connects the DK position of the switch and just can be sent to IC6CPA end (9 pin) through D14 by the 1# door when consistent and it is triggered be shifted, and the every reception one-stage dialing of while IC3 is exported live end DV by its data

Pin is to the IC6CPB(1 pin) send a triggering signal, as the counting that receives the dialing number of times.Suppose that dialing is for the first time translated by IC4 and triggers IC6CPA by DK, IC51# door, the output Q of → IC6 is by " 0 " → " 1 " → IC52# door B2=" 1 ", the 2# door is opened while IC6Q1=" 1 " → AK2 triggering and conducting and maintenance → IC51# door B1=" 0 " closes the 1# door, the 2nd dialing in like manner possesses IC4 output Q end can connect the consistent condition in the DK position of the switch with A2, receive the 2nd dialing back IC6Q1 by " 1 " → " 0 ", B2=0, close the 2# door, IC6Q2=" 1 " → B3=" 1 " opens the IC53# door.Dialing back Q2 is by " 1 " → " 0 " for the third time, B3=" 0 ", close the 3# door, Q3=" 1 " → B4=" 1 " opens the IC54# door, the 4th dialing back is because IC6CPB obtains four triggerings → IC6QB4 by " 0 " → " 1 " → the make T5 conducting of delaying time, at T5 as yet not during conducting, circuit is judged signal results: 1. if four dialing all satisfy IC4 output Q end and each A of I5 hold to connect the DK switch bit consistent, IC6CPA promptly obtains four times and triggers QA4=" 1 " → T6 conducting, in 0.7V, this moment, the T5 conducting can not make the T4 conducting by clamper for T6 collector electrode and ground terminal potential; While IC6QA4(10 pin) " 1 " promptly starts working AK1 triggering and conducting and maintenance → ring control circuit by D18, R11.2. if IC6CPA is provided with and obtains four times and trigger (above-mentioned condition is not satisfied in one of them time dialing) QA4=" 0 ", V+ makes the T4 conducting by T5, R27 after T5 conducting this moment, T3 base potential=0 after the T4 conducting and ending.Then T2 ends → entire circuit release.DK is that password setting switch, each password can select 1～9, establish four passwords altogether, D14～D17, D18 play buffer action, R20 keeps IC6CPA end=" 0 " when D14～D17 no-output, C12 is anti-tampering shunt capacitance, R19, R21, R23, R24R26, R27 are current-limiting resistance, C13 and R22 when initial V+ forms, and make the IC6 clear terminal to V+ by C13

, 6. pin gets a direct impulse and IC6 zero clearing, C13 charging is subsequently finished, , 6. pin remains " 0 " by R22 ground connection, C14 and R23 constitute the T5 delay circuit, after the T5 conducting, V+ produces a positive voltage formation T2 turn-on condition on R25.

The ring control circuit does machine circuit with above-mentioned simulation and share a dual time base circuit IC2.It is by second half IC circuit 2

10.

8.

9. 3. 7. pin and peripheral R5, R7, D9, R8, C5, C6 etc. form square-wave oscillator circuit, its operation principle is identical with the square-wave oscillator circuit of above-mentioned second half formation, different is to add R7, D9, effect is to improve output waveform to make it more precipitous, because dual time base circuit is same power end and ground altogether, and the job initiation asynchronism(-nization), the work of ring control circuit is controlled by last output state of IC6 and T5, the result of T6 conducting, so after the work of simulation circuit for answering, the ring control circuit is not still worked, insert R6 and make it remain on " resting state ", the AK1 ring control circuit that is triggered when 10. the pin current potential is for " 1 " after the conducting is just started working." 1 " and " 0 " is intermittently exported by 3 pin in the work back." 1 " is 3 seconds, and " 0 " is 1 second, palpus R9 when being output as " 1 ", the R10 dividing potential drop makes the T1 conducting again after C4 time-delay, the tinkle of bells generation circuit obtains operating current and works after the T1 conducting, quits work when being output as " 0 ", R9 provides a down inclined to one side value for current limliting, R10 stream, and C4 is the faulty action preventing shunt capacitance.

The tinkle of bells generation circuit by the phone-specific double-tone take place frequently living acoustic-electric road IC1, and peripheral DZ2, R2, R3, R4, C1, C2, C3 and SP form; double-tone rings telephone sound frequently takes place by SP in IC1 work back; R3 is the starting of oscillation controlling resistance; R2, C2 are bass duration of oscillation constant; R4, C3 are the high audio time constant, and DZ2 provides IC1 burning voltage for voltage-stabilizing protection, the C1 of I2.SP is a piezo-electric generator.

DZ1, R1, LED constitutes status display circuit, when the password filter place " line voltage distribution is added in through DZ1, R1 that flicker light-emitting diodes LED1 goes up, the LED1 flicker is luminous notes with the prompting user when filtering state; DZ1 is the 24V voltage-stabiliser tube, terminal voltage was 48V(or 60V when circuit was in zero load); the DZ1 reverse breakdown is led, and R1 is a current-limiting resistance.

DZ3, C11 provide stable operating voltage for IC2～IC6.

Claims

1, telephone cipher filter is characterized in that stoping circuit (1) by ringing-current, simulation off-hook, delay releasing circuit (2), the DTMF decoding, BDC decoding circuit (3) differentiates that counting is confirmed circuit (4), ring control, the tinkle of bells generation circuit (5), display circuit, voice warning circuit (6) are formed

IC7 and transformer B lotus root are closed, and VDD is leaded up to C15 and connect the T6 base stage, and the collector electrode of T6 connects the base stage of T7 by R28, and D19 is connected between the base stage and emitter of T6, one tunnel ground connection, and one the tunnel meets the V of IC7 _SsEnd.