CN102630069A - Volume adjustment circuit for audio system - Google Patents
Volume adjustment circuit for audio system Download PDFInfo
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- CN102630069A CN102630069A CN2012100035798A CN201210003579A CN102630069A CN 102630069 A CN102630069 A CN 102630069A CN 2012100035798 A CN2012100035798 A CN 2012100035798A CN 201210003579 A CN201210003579 A CN 201210003579A CN 102630069 A CN102630069 A CN 102630069A
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Abstract
The invention discloses a volume adjusting circuit for a sound system, which comprises: the signal preceding-stage circuit and the first potentiometer are connected in sequence; a post-stage drive circuit connected to a tap of the first potentiometer; and the second potentiometer is used for adjusting the input impedance of the rear-stage driving circuit to enable the resistance value of the first potentiometer to be multiple times of the input impedance of the rear-stage driving circuit or trimming the minimum volume output by the volume adjusting circuit and is connected between a tap of the first potentiometer and the rear-stage driving circuit. The invention makes the sound system obtain the logarithmic volume adjusting effect by adjusting the input impedance of the post-stage driving circuit or correcting the output volume of the tap of the linear potentiometer R1 at the position of 0 (corresponding to the minimum volume when Ra = 0), and has the advantages of simple circuit structure, low realization cost and the like.
Description
Technical field
The present invention relates to the acoustics volume regulating circuit, especially relate to the volume control circuit of realizing through the expensive true logarithmic potentiometer of simulation in a kind of sound system.
Background technology
Existing sound system volume output circuit sketch map as shown in Figure 1.In sound system, the voice signal that transmits from the signal front stage circuits at the signal of exporting to drive circuits such as loud speaker U1 or earphone, utilizes in addition dividing potential drop of potentiometer R1, and obtains to regulate the effect of volume.
Because people's ear is relatively sensitiveer to the induction of small volume, then more blunt to the reaction of big volume, its sense of hearing is logarithm (logarithmic) to the induction curve of sound press, shown in curve A among Fig. 2 (abscissa is represented volume, and ordinate is represented the sense of hearing).So when doing volume control, must do compensation, make the position ability of volume knob or slide bar consistent with operator's the sense of hearing to the response curve of human auditory system.So the curve of compensation should be the inverse function of logarithm, the exponential curve shown in curve B among Fig. 3 (abscissa is represented the position of volume knob or slide bar, and ordinate is represented volume).Potentiometer as control volume dividing potential drop; Its resistance is to the position (anglec of rotation; Or push rod position) curve also should be index variation (exponential); Shown in curve C among Fig. 4 (abscissa is represented the tap position of potentiometer, and ordinate is represented the resistance of potentiometer), this is the logarithmic potentiometer.
Because true logarithmic potentiometer is made difficulty; Deployment cost is high; So the logarithmic potentiometer as common volume control all is the resistance simulation logarithm that adopts two sections straight lines; Like two sections curve D 1 among Fig. 5 and D2 (abscissa is represented the tap position of potentiometer, and ordinate is represented the resistance of potentiometer).Such as 1 representative of, curve D from the position 0 to 60%, change in resistance from 0 to about 15%; Curve D 2 representative is from the position 60 to 100%, and change in resistance is from 15 to 100% (this breakover point is determined by manufacturer) approximately, so constitutes approximate logarithmic potentiometer.
Though the realization cost of this potentiometer is far below true logarithmic potentiometer, because it is when using in the acoustics volume regulating circuit, the variation slope of output volume is not a smooth change; In addition, because the particularity on making, the user selects potentiometer also to compare difficulty on purchase and numerical value.
Summary of the invention
The present invention proposes to pass through the volume control circuit that the expensive true logarithmic potentiometer of simulation is realized in a kind of sound system, utilizes two potentiometers to make sound system obtain the volume regulating effect of logarithm (index) type.
The present invention adopts following technical scheme to realize: a kind of volume control circuit that is used for sound system comprises: the signal front stage circuits and first potentiometer that connect successively; The post-stage drive circuit that is connected with the tap of first potentiometer; Be used to adjust the input impedance of post-stage drive circuit; The resistance that makes first potentiometer is the input impedance of several times post-stage drive circuit; Or second potentiometer of the minimal volume of finishing volume control circuit output, it is connected between the tap and post-stage drive circuit of first potentiometer.
Wherein, the post-stage drive circuit resistor R 3 that is connected in parallel.
Wherein, second potentiometer is serially connected between the tap and post-stage drive circuit of first potentiometer.Second potentiometer and first potentiometer oppositely link, and when the input resistance of first potentiometer was minimum value, the input resistance of second potentiometer was a maximum.
Compared with prior art, the present invention has following beneficial effect:
Input impedance or the tap of revising linear potentiometer R1 of the present invention through the adjustment post-stage drive circuit be the output volume of (during Ra=0, corresponding minimal volume) in 0 position, makes sound system obtain the volume regulating effect of logarithmic.The present invention has plurality of advantages such as circuit structure is simple, the realization cost is low.
Description of drawings
Fig. 1 is existing sound system volume output circuit sketch map;
Fig. 2 is the induction curve sketch map of human auditory system to sound press;
Fig. 3 is the curve synoptic diagram that sound system need carry out compensation of hearing to people's ear;
Fig. 4 is to the curve synoptic diagram of change between resistance and the tap position of potentiometer;
Fig. 5 is the curve synoptic diagram that adopts between resistance and the tap position of potentiometer of two sections straight line resistances simulations change;
Fig. 6 is the sound system volume output circuit sketch map that the present invention the 1st embodiment proposes;
Fig. 7 is the tap position of the potentiometer R1 after the circuit finishing shown in Figure 6 and the curve synoptic diagram of output volume corresponding relation;
Fig. 8 is the sound system volume output circuit sketch map that the present invention the 2nd embodiment proposes.
Embodiment
As shown in Figure 6; In the sound system volume output circuit that the present invention proposes, between the tap of the first potentiometer R1 and post-stage drive circuit, be connected in series the second potentiometer R2, and the first potentiometer R1 and the second potentiometer R2 link in the other direction (like the stain sign); When Rb was 0, R2 had maximum.Wherein, the first potentiometer R1 is divided into the resistance R a and the Rb of serial connection by tap, i.e. R1=Ra+Rb, and Rb is the tap of the first potentiometer R1 and the resistance between the ground.
In conjunction with shown in Figure 7; Curve C is the curve synoptic diagram of corresponding relation between tap position and the output volume (output voltage) of the first potentiometer R1 under the perfect condition; The curve synoptic diagram of corresponding relation between the tap position of the first potentiometer R1 and the output volume (output voltage) when curve D is illustrated in R1=R2=3*Ri, curve E then for this reason the total impedance RT of circuit to the percentage change of potentiometer R1.Can find out that the total impedance RT of (minimal volume) is the same with potentiometer R1 when position 0, and the total impedance RT of (max volume) is 1/4th of a potentiometer R1 resistance when position 100.
Therefore, (corresponding output minimal volume, the Ra=0) smoothness of output volume made sound system obtain the volume regulating effect of logarithm (index) type when foregoing circuit can be revised the tap position 0 of the first potentiometer R1.
In addition, because the input impedance Ri of post-stage drive circuit is parallelly connected with the first potentiometer R1, therefore, the resistance of the first potentiometer R1 will influence the dividing potential drop effect.As Ri during much larger than R1, the input signal Vi of post-stage drive circuit is by Ra and the decision of Rb dividing potential drop.Therefore; Corresponding relation will distribute the same with the resistance of the first potentiometer R1 between the resistance of the input signal Vi and the first potentiometer R1; If the resistance of the first potentiometer R1 is linear potentiometer, input signal Vi also is a straight line to the function of the tap position of the first potentiometer R1; Otherwise, if the first potentiometer R1 is approaching or more greater than input impedance Ri, then input signal Vi just loses linearity more to the tap position relation of the first potentiometer R1.
As shown in Figure 8, in further improved the 2nd embodiment of the 1st embodiment, the resistance that makes the linear first potentiometer R1 is the several times of input impedance Ri.Generally speaking, the input impedance Ri of post-stage drive circuit is generally tens of to hundreds of kilohms (K Ω); Therefore; If the input impedance Ri of post-stage drive circuit is very high; Then can use the input impedance of a parallel resistor device R3 adjustment post-stage drive circuit, adjusted input impedance is the parallelly connected total impedance of R3 and Ri, i.e. R3//Ri; Making the resistance of the first potentiometer R1 with this is the several times of adjusted input impedance R3//Ri, in the sound system volume control circuit, to realize obtaining the volume regulating effect of logarithmic.
The above is merely preferred embodiment of the present invention, not in order to restriction the present invention, all any modifications of within spirit of the present invention and principle, being done, is equal to and replaces and improvement etc., all should be included within protection scope of the present invention.
Claims (4)
1. a volume control circuit that is used for sound system comprises: the signal front stage circuits and first potentiometer that connect successively; The post-stage drive circuit that is connected with the tap of first potentiometer; It is characterized in that; Also comprise: be used to adjust the input impedance of post-stage drive circuit; The resistance that makes first potentiometer is the input impedance of several times post-stage drive circuit; Or second potentiometer of the minimal volume of finishing volume control circuit output, it is connected between the tap and post-stage drive circuit of first potentiometer.
2. according to the said volume control circuit that is used for sound system of claim 1, it is characterized in that second potentiometer is serially connected between the tap and post-stage drive circuit of first potentiometer.
3. according to the said volume control circuit that is used for sound system of claim 1, it is characterized in that, also comprise a resistor R 3 that is connected in parallel with post-stage drive circuit.
4. according to claim 1 or the 2 or 3 said volume control circuits that are used for sound system, it is characterized in that second potentiometer and first potentiometer oppositely link, when the input resistance of first potentiometer was minimum value, the input resistance of second potentiometer was a maximum.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2012100035798A CN102630069A (en) | 2012-01-09 | 2012-01-09 | Volume adjustment circuit for audio system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2012100035798A CN102630069A (en) | 2012-01-09 | 2012-01-09 | Volume adjustment circuit for audio system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN102630069A true CN102630069A (en) | 2012-08-08 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2012100035798A Pending CN102630069A (en) | 2012-01-09 | 2012-01-09 | Volume adjustment circuit for audio system |
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| CN (1) | CN102630069A (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH05203687A (en) * | 1992-01-28 | 1993-08-10 | Shimadzu Corp | Resistance/voltage converter |
| CN1159115A (en) * | 1996-03-01 | 1997-09-10 | 固昌有限公司 | Hands-free telephone conversion device |
| CN1320442C (en) * | 2004-03-19 | 2007-06-06 | 威盛电子股份有限公司 | Audio processing circuit and related method |
| CN202406283U (en) * | 2012-01-09 | 2012-08-29 | 赖德龙 | Volume adjusting circuit for sound system |
-
2012
- 2012-01-09 CN CN2012100035798A patent/CN102630069A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH05203687A (en) * | 1992-01-28 | 1993-08-10 | Shimadzu Corp | Resistance/voltage converter |
| CN1159115A (en) * | 1996-03-01 | 1997-09-10 | 固昌有限公司 | Hands-free telephone conversion device |
| CN1320442C (en) * | 2004-03-19 | 2007-06-06 | 威盛电子股份有限公司 | Audio processing circuit and related method |
| CN202406283U (en) * | 2012-01-09 | 2012-08-29 | 赖德龙 | Volume adjusting circuit for sound system |
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Application publication date: 20120808 |