CN1032092A - The speech circuit of phone - Google Patents
The speech circuit of phone Download PDFInfo
- Publication number
- CN1032092A CN1032092A CN88106466A CN88106466A CN1032092A CN 1032092 A CN1032092 A CN 1032092A CN 88106466 A CN88106466 A CN 88106466A CN 88106466 A CN88106466 A CN 88106466A CN 1032092 A CN1032092 A CN 1032092A
- Authority
- CN
- China
- Prior art keywords
- circuit
- amplifier
- effect transistor
- field
- loud speaker
- Prior art date
- 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.)
- Pending
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Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G3/00—Gain control in amplifiers or frequency changers
- H03G3/20—Automatic control
- H03G3/30—Automatic control in amplifiers having semiconductor devices
- H03G3/3005—Automatic control in amplifiers having semiconductor devices in amplifiers suitable for low-frequencies, e.g. audio amplifiers
- H03G3/301—Automatic control in amplifiers having semiconductor devices in amplifiers suitable for low-frequencies, e.g. audio amplifiers the gain being continuously variable
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M1/00—Substation equipment, e.g. for use by subscribers
- H04M1/60—Substation equipment, e.g. for use by subscribers including speech amplifiers
- H04M1/6033—Substation equipment, e.g. for use by subscribers including speech amplifiers for providing handsfree use or a loudspeaker mode in telephone sets
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- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Amplifiers (AREA)
Abstract
The speech circuit of phone is used for receiving from the signal of switchboard circuit and with the signal that receives and amplifies the loud speaker that is sent to phone again, also is used to control the output signal level that is sent to loud speaker.This speech circuit comprises that dual-stage amplifier is used for amplifying signal.A field-effect transistor is connected across on the input lead leg of the amplifier first order, makes it to change input signal with the variation of the feedback signal of coming self-feedback ciucuit.Feedback circuit comprises a transistor that can switch on and off, its logical still disconnected electric current that depends on that the partial power supply lead leg of amplifier absorbs.
Description
The present invention relates to a kind of telephone set that comprises loud speaker, particularly the present invention relates to a kind of speech circuit that is used for loud speaker.
The telephone set that has loud speaker is well-known, and loud speaker is used for making the people need not pick up a receiver just can hear the people's who is positioned at another phone sound.But there are some problems in such telephone set, if the voice signal level height that telephone set received, then the output of its loud speaker will proportionally be increased.This is a kind of shortcoming clearly, and at first, the output of loud speaker can be up to the uncomfortable degree of listener that makes.And work as this telephone set and be contained under the environment of public office, the sound of output can be heard by the whole office chamber, cause very important interference.
Therefore, for the output of loud speaker is controlled in certain acceptable limit, just need a kind of speech circuit.Also need a kind of phone that sort circuit is housed.
The object of the present invention is to provide a kind of such words sound circuit and telephone set.
According to the present invention, provide a kind of speech circuit that is used for the telephone set loud speaker.This circuit contains an amplifier that an a pair of input and an output are arranged, output links to each other with loud speaker, input is used to receive the input signal from switchboard circuit or extension circuit, being connected across on the amplifier in is the field-effect transistor of a variableimpedance, and the impedance response amplifier output level of this field-effect transistor is in order to change the level of input signal.Preferably this field-effect transistor is exactly a variable resistor field-effect transistor.
A kind of feedback circuit that links to each other with amplifier with the base stage of field-effect transistor preferably is provided, makes the impedance of this field-effect transistor change along with the variation of the output level of amplifier.In one embodiment of the invention, the drain electrode of field-effect transistor and source electrode are connected across on the amplifier input terminal.Current-limiting resistance preferably is connected in series with field-effect transistor.
In another embodiment of the present invention, feedback circuit comprises a transistor, and its collector and emitter is connected across between the base stage of power supply and field-effect transistor.The base stage of feedback transistor links to each other with current-limiting resistor.This current-limiting resistor is between power supply and amplifier power supply lead leg.The emitter of feedback transistor links to each other with power supply.Current-limiting resistor is connected between the emitter and base stage of feedback transistor.
In addition, the invention provides a kind of telephone circuit of forming by loud speaker and the speech circuit that is connected with this loud speaker.
The present invention has a lot of advantages, and wherein topmost advantage is to the invention provides a kind of loud speaker that can keep to export basicly stable speech circuit, and no matter the received incoming signal level of this speech circuit is much.In many cases, the incoming level of voice signal all changes, such as, extension circuit that is connected with speech circuit or the impedance in the switchboard circuit just can cause the variation of incoming level.For example when extension circuit or switchboard circuit were longer, the input signal that is transported to speech circuit will produce decay.Otherwise if extension circuit or switchboard circuit are all more in short-term, impedance is just relatively littler, thereby the input signal that causes being transported to speech circuit strengthens.At this moment adopt the variable resistor field-effect transistor can make this signal produce needed decay and but do not produce any distorted signals.It is exactly by adopting variable resistor field-effect transistor and feedback circuit, the circuit that cost is lower and be easy to assemble can being provided that the present invention also has an advantage.
In an embodiment of the present invention, telephone set also comprises a ringing signal generator that is connected with loud speaker, and wherein speech circuit all passes through a switching circuit with the ringing signal generator circuit and links to each other with loud speaker.
Can clearerly understand the present invention below by introduction to a preferred embodiment.Introduction only provides by way of example, and with reference to accompanying drawing, it shows about a kind of telephone set network of the present invention.
Referring to accompanying drawing, telephone set network comprise one by shown in the reference number 101 about speech circuit of the present invention, it passes the signal to telephone set (not shown) loud speaker 102.In this certain embodiments of the present invention, ring back tone also is sent to loud speaker 102.Ringing signal generator 103 by transformer TR1 coupling links to each other with loud speaker 102 through switching circuit 104, and this also will introduce below.As seen, speech circuit 101 also links to each other with loud speaker 102 through switching circuit 104 from accompanying drawing.
Variable resistor field-effect transistor T1 is a n channel metal oxide semiconductor field effect transistor at this, is connected across between the first order amplifier IC1a input lead leg 3 and 4 to allow the variation of incoming signal level.The drain electrode of field-effect transistor T1 links to each other through the input lead leg 4 of 100 ohm the 1st grade of IC1a of current-limiting resistor R1 and amplifier, and the source electrode of field-effect transistor T1 then links to each other with ground 115.10 kilohms bias resistor R2 is connected between input 105 and 106.
The feedback circuit 107 of amplifier second level IC1b changes the impedance of field-effect transistor T1.Feedback circuit 107 links to each other with the grid of field effect transistor through the low pass filter that the capacitor C1 of 330 kilohms resistor R 4 and 100 millimicrofarads forms.Vent discharge vessel C1 when the resistor R 3 of 10 megohms descends at the signal of feedback circuit 107.Feedback circuit 107 comprises a PNP transistor T2, and its emitter links to each other with power supply V; This moment, power supply was+5 volts.Collector electrode links to each other through the base stage of resistor R 4 with field-effect transistor T1.5 volts supply voltage is also given power supply lead leg 8 power supplies of amplifier second level IC1b through 33 ohm current-limiting resistor R5.Resistor R 5 links to each other with the base stage of transistor T 2 through 10 kilohms resistor R 6.The base stage of 100 kilohms bias resistor R7 bias transistor T2.The decoupling capacitor C10 of 470 microfarads is used for the second level IC1b of amplifier.So when the level of output on the lead leg 7 of amplifier second level IC1b increases, also increase through the electric current that draws of lead leg 8.On resistor R 5, produce voltage drop like this, thereby the base voltage of transistor T 2 is reduced.So just produced the electric current of the transistor T 2 of flowing through and the voltage on the field-effect transistor T1 grid raise.This just makes the input lead leg 4 and ground conducting of field-effect transistor T1 with amplifier first order IC1b, thereby with the incoming signal level decay on the amplifier first order IC1a input lead leg 3 and 4, this has reduced the output signal on first order IC1a the 6th lead leg again, and then the input signal of second section amplifier IC1b is reduced, the output of its 7th lead leg is reduced.The impedance of field-effect transistor T1 is inversely proportional to its base voltage.So the electric current that amplifier second level IC1b lead leg 8 is pulled out is big more, the base voltage of transistor T 1 is high more, thereby its impedance is more little, the attenuated input signal of amplifier first order IC1a big more.
Direct current signal between blocking capacitor C2, C3, C4 isolated amplifier first order IC1a and the second level IC1b.Capacitor C2 is 330 millimicrofarads, and capacitor C3 and C4 are 4.7 millimicrofarads.Resistor R 15(15 kilohm) DC level among capacitor C2 and the C3 is remained on the earth potential.The output lead leg 6 that 180 ohm the resistor R 8 and the capacitor C5 of 220 millimicrofarads are used for amplifier first order IC1a plays low pass filter, and other circuit (not shown) links to each other with this speech circuit with 109 places in 108.Because itself and the present invention have nothing to do, so will not discuss.But capacitor C2 and C3 will cut off any direct current signal from these circuit.10 kilohms compensating resistor R9 and R10 are provided between capacitor C2 and C3.Transistor T 3 is complementary the first order of amplifier and the electrical impedance between the second level.Damping resistance device R11 and R12 are respectively 10 kilohms and 3.3 kilohms, make this signal attenuation.The emitter of resistor R 13 bias transistor T3.The collector electrode of transistor T 3 links to each other with 5 volts of power supplys.2.7 the base stage of the resistor R 14 bias transistor T3 of megohm.
The output lead leg 7 of amplifier second level IC1b links to each other with loud speaker 102 through the blocking capacitor C6 of 68 microfarads.Another terminal of loud speaker 102 links to each other with the ground 115 of speech circuit with T5 through a pair of field-effect transistor T4 of switching circuit 104.The grid of transistor T 4 and T5 is controlled through the resistor R 16 and the diode D1 of 1 megohm.Signal controlling field effect transistor T4 and T5 on the terminal 110.When needs are kept apart loud speaker and speech circuit, just will place on the terminal 110 from the signal of control circuit (not shown), so just turn-offed field-effect transistor T4 and T5.When the bell signal from ring generator 103 was added on the loud speaker, loud speaker 102 was just kept apart by transistor T 4 and T5 and speech circuit.Capacitor C8 is connected across between the grid of field-effect transistor T4 and T5 and transistor T 4 drain electrodes to guarantee that control signal one disappearance transistor T 4 and T5 on terminal 110 will be transformed into on-state.
Field-effect transistor T6 and T7 will be connected to loud speaker 102 from the bell signal of generator 103.The signal of generator 103 is sent to loud speaker 102 through field-effect transistor T6 and T7 more successively by transformer TR1 coupling.Signal on the terminal 111 is from control circuit, and it connects transistor T 6 and T7 (not shown).10 kilohms resistor R 17 is linked the earth with one of them terminal of loud speaker 102.
4.7 the electrolytic capacitor C9 of microfarad storage reserve electric charge is to keep the power supply of speech circuit during any short-term power interruptions.
Make idle circuit 112 to the power interruptions of speech circuit 101 time, be used to turn-off speech circuit 101.This situation may take place under the occasion of dialing or when telephone set is not in the loud speaker mode occurring.Turn-off speech circuit and just avoided the loss of power of loud speaker and speech circuit.Circuit 112 comprises field-effect transistor T8, and this transistor T 8 is linked the earth with the ground of speech circuit 101.The base stage of field-effect transistor T8 is subjected to be added in from the control circuit (not shown) control of the signal on the terminal 113.Terminal 113 is connected transistor T 9 during for high level, thereby makes the grid of field-effect transistor T8 become low level and transistor T 8 shutoffs.100 kilohms resistor R 18 is connected across between the collector electrode of 5 volts of power supplys and transistor T 9.Thereby when transistor T 9 conductings, a low level is added on the grid of field-effect transistor T8.
In actual applications, be added on 105 and 106 terminals of speech circuit 101 such as voice signal from switchboard circuit and extension circuit (not shown).This voice signal amplifies in the first order IC1a of dual-stage amplifier, and the output of the first order is amplified in the IC1b of the second level again.The signal of second level IC1b is sent to loud speaker 102 when field-effect transistor T4 and T5 conducting and field-effect transistor T6 and not conducting of T7.The electric current that draws of second level amplifier IC1b surpasses certain limit if resistor R 5 is assaied, the transistor T 2 of feedback circuit 107 is with regard to conducting, make the level that is added on the field-effect transistor T1 uprise, cause field-effect transistor T1 conducting, thus the input of the signal of the amplifier first order IC1a that decayed.The impedance of field-effect transistor T1 is reduced to by feedback circuit 107 and can makes the attenuated input signal of first order IC1a of amplifier to the degree that can be provided acceptable output by amplifier second level IC1b.
When the power supply to speech circuit 101 disconnects, for example, during dialing, make the field-effect transistor T8 connection of idle circuit 112 make the ground of speech circuit 101 link to each other with the earth.
When bell signal will be sent to loud speaker 102, add an appropriate signals by control circuit to terminal 110 and turn-off field-effect transistor T4 and T5.And add an appropriate signals by control circuit to terminal 110 and come turn-on field effect transistor T6 and T7.
Here only introduced a kind of special circuit between the amplifier first order and the second level, but also may provide any suitable circuit that does not exceed category of the present invention, here only introduced two-stage amplifier, also can be the one-level amplifier or in fact can also be casacade multi-amplifier in some cases.Certainly, the speech circuit that is provided can not have switching circuit 112 and control circuit 104.In fact, also be used for simultaneously the place of bell signal at loud speaker, any other the suitable circuit outside the dividing circuit 104 can both be in order to switch loud speaker 102 between ring generator 103 and speech circuit 101.
Here only introduced a kind of special circuit as feedback circuit, any other suitable feedback circuit can use in the lump with field-effect transistor T1.Take out in can be from any speech circuit suitable point of feedback signal.Can estimate that field-effect transistor T1 can be the variable resistor of any other type or the field-effect transistor of variableimpedance.
Claims (10)
1, a kind of speech circuit of telelecture, this circuit is by an amplifier (IC1a, IC1b) form, this amplifier has two inputs (3,4) and an output (7), output (7) links to each other with loud speaker (102), input (3,4) be used to receive input signal from switchboard circuit or extension circuit, it is characterized in that: variableimpedance field-effect transistor (T1) is connected across amplifier, and (IC1a is in input IC1b) (3,4), (IC1a, IC1b) output level changes in order to change the level of input signal with amplifier in the impedance of field-effect transistor (T1).
2, speech circuit as claimed in claim 1 is characterized in that: field-effect transistor (T1) is a kind of variable resistor field-effect transistor (T1).
3, speech circuit as claimed in claim 1 or 2, it is characterized in that, from the amplifier to the field-effect transistor feedback circuit of the grid of (T1) (107) with so that the resistance of field-effect transistor (T1) with amplifier (IC1a, IC1b) variation of output level and changing, the drain electrode of field-effect transistor (T1) and source electrode are connected across between the amplifier input (3,4).
4, as the described speech circuit of any claim in the above-mentioned claim, it is characterized in that, have between the grid of field-effect transistor (T1) and the source electrode low pass filter (R4, C1).
5, as claim 3 or 4 described speech circuits, it is characterized in that, feedback circuit (107) comprises a transistor (T2), its emitter links to each other with power supply (V), collector electrode links to each other with the grid of field-effect transistor (T1), (IC1a, voltage lead leg (8) IC1b) links to each other, and is connected to a current-limiting resistor (R5) between the power supply lead leg (8) of power supply (V) and amplifier for the base stage of feedback transistor (T2) and amplifier.
6, the speech circuit described in any one claim of claim 3 to 5, it is characterized in that amplifier is a two-stage amplifier (IC1a, IC1b), field-effect transistor (T1) is connected across the input (3 of the amplifier first order (IC1a), 4) on, feedback circuit is connected on the amplifier second level (IC1b).
7,, it is characterized in that second field-effect transistor (T8) of ground (115) through making idle circuit (112) of speech circuit (101) links to each other with zero potential as the described speech circuit of any one claim in the above-mentioned claim.
8, a kind of telephone circuit comprises loud speaker (102) and as the described speech circuit (101) of linking loud speaker (102) of any one claim in the claim 1 to 7.
9, telephone circuit as claimed in claim 8, it is characterized in that, phone also comprises the ringing signal generator (103) that is connected with loud speaker (102), and wherein speech circuit (101) links to each other with loud speaker (102) through a switching circuit (104) with ringing signal generator (103).
10, telephone circuit as claimed in claim 9, it is characterized in that, switching circuit is by two couples of field-effect transistor (T4～T7) form, one is docked between the ground wire (115) of loud speaker (102) and speech circuit (101), and another is docked between the output of loud speaker (102) and ringing signal generator (103).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IE872384A IE872384L (en) | 1987-09-07 | 1987-09-07 | Speech circuit for telephone |
| IE2384/87 | 1987-09-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1032092A true CN1032092A (en) | 1989-03-29 |
Family
ID=11034497
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN88106466A Pending CN1032092A (en) | 1987-09-07 | 1988-09-06 | The speech circuit of phone |
Country Status (7)
| Country | Link |
|---|---|
| CN (1) | CN1032092A (en) |
| AU (1) | AU2191088A (en) |
| GB (1) | GB2209646B (en) |
| IE (1) | IE872384L (en) |
| NL (1) | NL8702310A (en) |
| SE (1) | SE8704927L (en) |
| ZA (1) | ZA876822B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU622524B2 (en) * | 1989-03-16 | 1992-04-09 | Alcatel Australia Limited | Receiver mute circuit |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1263850B (en) * | 1965-11-10 | 1968-03-21 | Telefunken Patent | Electrically adjustable voltage divider with low non-linear distortion |
| GB1207339A (en) * | 1967-12-07 | 1970-09-30 | Standard Telephones Cables Ltd | Loud speaking telephone circuits |
| SE320599B (en) * | 1968-03-26 | 1970-02-09 | Bofors Ab | |
| US3533006A (en) * | 1968-11-04 | 1970-10-06 | Collins Radio Co | Infinite range electronics gain control circuit |
| JPS5549451B2 (en) * | 1972-08-30 | 1980-12-12 | ||
| FR2522451B1 (en) * | 1982-03-01 | 1988-10-14 | Audibel | IMPROVEMENT IN THE AUTOMATIC GAIN CONTROL CIRCUIT OF A TRANSISTOR AMPLIFICATION SYSTEM AND HEARING CORRECTION APPARATUS PROVIDED WITH SUCH A CIRCUIT |
-
1987
- 1987-09-07 IE IE872384A patent/IE872384L/en unknown
- 1987-09-11 GB GB8721477A patent/GB2209646B/en not_active Expired - Fee Related
- 1987-09-11 ZA ZA876822A patent/ZA876822B/en unknown
- 1987-09-28 NL NL8702310A patent/NL8702310A/en not_active Application Discontinuation
- 1987-12-10 SE SE8704927A patent/SE8704927L/en not_active Application Discontinuation
-
1988
- 1988-09-06 AU AU21910/88A patent/AU2191088A/en not_active Abandoned
- 1988-09-06 CN CN88106466A patent/CN1032092A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| NL8702310A (en) | 1989-04-03 |
| AU2191088A (en) | 1989-03-09 |
| GB2209646B (en) | 1991-06-12 |
| GB2209646A (en) | 1989-05-17 |
| GB8721477D0 (en) | 1987-10-21 |
| IE872384L (en) | 1989-03-07 |
| SE8704927D0 (en) | 1987-12-10 |
| ZA876822B (en) | 1988-05-25 |
| SE8704927L (en) | 1989-03-08 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C01 | Deemed withdrawal of patent application (patent law 1993) | ||
| WD01 | Invention patent application deemed withdrawn after publication |