CN202068499U - Audio signal output circuit - Google Patents
Audio signal output circuit Download PDFInfo
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- CN202068499U CN202068499U CN2011200785954U CN201120078595U CN202068499U CN 202068499 U CN202068499 U CN 202068499U CN 2011200785954 U CN2011200785954 U CN 2011200785954U CN 201120078595 U CN201120078595 U CN 201120078595U CN 202068499 U CN202068499 U CN 202068499U
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Abstract
The utility model discloses an audio signal output circuit suitable for transmitting an audio signal from a main core board of a television to an SCART (Syndicatdes Constructeursd Appareils Radiorecepteurset Televiseurs) audio interface. The audio signal output circuit includes a left channel input circuit connected to the main core board and used to transmit left channel audio signals; a right channel input circuit connected to the main core board and used to transmit right channel audio signal; a left emitter follower circuit connecting with an output terminal of the left channel input circuit and used to buffer the output of the left channel audio signals as well as make the output impedance to be adjustable; a right emitter follower circuit connecting with an output terminal of the right channel input circuit and used to buffer the output of the right channel audio signals as well as make the output impedance to be adjustable; a power source circuit used to supply power to the left emitter follower circuit and the right emitter follower circuit; a left channel output circuit connecting with an output terminal of the left emitter follower circuit and used to transmit the left channel audio signals to the SCART audio interface; and a right channel output circuit connecting with an output terminal of the right emitter follower circuit and used to transmit the right channel audio signals to the SCART audio interface.
Description
Technical field
The utility model relates to the audio signal output circuit, relates more specifically to a kind of audio signal output circuit of the SCART of being applicable to interface.
Background technology
SCART(Syndicatdes Constructeursd'Appareils Radior é cepteursetT é l é viseurs) interface is a kind of audio interface of special use, it is the audio-visual equipment interconnection industrial standard by the Peritel of French company exploitation, also is that European mandatory requirement is used for the interconnection and interflow interface on satellite television, receiver, television set, video tape recorder and other audio frequency apparatus.The SCART interface of standard is 21 needle connectors, and external form is at right angles trapezoidal, is commonly called as " broom head ".Define audio frequency and audio signal in this 21 pin, can be used to transmit audio signals such as CVBS and interlacing rgb signal, also can transmit stereo audio signal.21 pins transmit 21 signals simultaneously, and it is several that these 21 signals can be divided into audio signal, audio signal, control signal, ground wire and data wire.The SCART interface has the input and output function, be connected to video disc player, satellite television receiver or the game machine of SCART input interface specially, the output equipment ability usefulness that must possess the SCART output interface if do not have, can be used with the transducer of this interface commentaries on classics AV.The SCART interface is supported three kinds of audio signal forms, i.e. CVBS (compound composite video signal), YC (component audio signal) and RGB(color standard signal).The signal format of input can pass through the MCU(single-chip microcomputer) if level of the FB pin of detection SCART interface less than 1 volt then be RGB, otherwise is CVBS/YC.In addition, SCART interface or transmitted in both directions realize so-called " LOOP " circulatory function.The set-top box of for example two SCART interfaces is what to use less than the process chip of set-top box when using VCR, some simulated television can't be separated some coded signals, these signals can be imported by TV SCART interface from the SCART interface of some simulated televisions, output to VCR by VCR SCART interface, carry out being exported by VCR SCART after some deciphering wait processing, TV SCART interface outputs to televises again.The loop function of Here it is two SCART interfaces.
SCART interface on the market generally is built on the main central layer of television set, is used for the electronic device (being external load) of external display and so on.In order to meet the unified outputting standard in the industry, for example the magnitude of voltage that exports the audio signal of external load to the SCART interface is certain, but different chips has different output impedance values, if audio signal directly exports external load from the main central layer of television set to by the SCART interface, because the output impedance of main central layer and the resistance value of external load might not mate, the audio signal effect of its output is bad, does not meet industry standard.
Therefore, demand audio signal output circuit a kind of and external load realization impedance matching urgently, overcome above-mentioned defective.
The utility model content
The purpose of this utility model is to provide a kind of audio signal output circuit, be applicable to audio signal is transferred to audio interface from the main central layer of television set, the impedance matching of the electronic device that realization is connected with the SCART audio interface, thus make that the audio signal of output is stable, and applicability is wide.
To achieve these goals, the utility model provides a kind of audio signal output circuit, be applicable to audio signal is transferred to the SCART audio interface from the main central layer of television set, comprise L channel input circuit, R channel input circuit, left emitter follower circuit, right emitter follower circuit, power circuit, L channel output circuit and R channel output circuit, described L channel input circuit is connected in described main central layer, is used to transmit left channel audio signal; Described R channel input circuit is connected in described main central layer, is used to transmit right channel audio signal; Described left emitter follower circuit is connected with the output of described L channel input circuit, is used to cushion the output of left channel audio signal and makes output impedance adjustable; Described right emitter follower circuit is connected with the output of described R channel input circuit, is used to cushion the output of right channel audio signal and makes output impedance adjustable; Described power circuit is used for to described left emitter follower circuit and described right emitter follower circuit power supply; Described L channel output circuit is connected with the output of described left emitter follower circuit, is used for left channel audio signal is transferred to the SCART audio interface; Described R channel output circuit is connected with the output of described right emitter follower circuit, is used for right channel audio signal is transferred to the SCART audio interface.
Preferably, described left emitter follower circuit comprises first triode and first resistance, the base stage of described first triode connects the output of described L channel input circuit, collector electrode is connected with described power circuit, emitter is connected with an end of described first resistance, the other end ground connection of described first resistance, and described L channel output circuit is connected between the emitter and first resistance of described first triode.
Preferably, described right emitter follower circuit comprises second triode and second resistance, the base stage of described second triode connects the output of described R channel input circuit, collector electrode is connected with described power circuit, emitter is connected with an end of described second resistance, the other end ground connection of described second resistance, and described R channel output circuit is connected between the emitter and second resistance of described second triode.
Preferably, the described filter circuit that also comprises is connected between described power circuit and described left emitter follower circuit, the right emitter follower circuit.
Preferably, described filter circuit is a low-pass filter circuit.
Preferably, described filter circuit comprises filter resistance and filter capacitor, one end of described filter resistance connects described power circuit, the other end connects an end of described filter capacitor, the other end ground connection of described filter capacitor, and described left emitter follower circuit, right emitter follower circuit all are connected between described filter resistance and the filter capacitor.
Preferably, described filter circuit comprises the filter capacitor of two parallel connections, and an end of two described filter capacitors all is connected in described filter resistance, the equal ground connection of the other end.
Preferably, described first resistance is less than 1K ohm.
Preferably, described second resistance is less than 1K ohm.
Compared with prior art, the L channel input circuit of the utility model audio signal and R channel input circuit cushion the output of left and right sound channels audio signal and make output impedance adjustable by left emitter follower circuit and right emitter follower circuit respectively, by the resistance value of left emitter follower circuit and right emitter follower circuit is set, realize the output impedance of SCART audio interface and the resistance value coupling of external load, generally make output impedance less than 1K ohm, thereby the audio signal of output is effective, meets industry standard.
By following description also in conjunction with the accompanying drawings, it is more clear that the utility model will become, and these accompanying drawings are used to explain embodiment of the present utility model.
Description of drawings
In order to be illustrated more clearly in the technical scheme of the utility model embodiment, to do to introduce simply to the accompanying drawing of required use among the embodiment below, apparently, accompanying drawing in describing below only is embodiment more of the present utility model, for those of ordinary skills, under the prerequisite of not paying creative work, can also obtain other accompanying drawing according to these accompanying drawings.
Fig. 1 is the circuit theory diagrams of the utility model audio signal output circuit first embodiment.
Fig. 2 is the circuit theory diagrams of the utility model audio signal output circuit second embodiment.
Embodiment
Below in conjunction with the accompanying drawing among the utility model embodiment, the technical scheme among the embodiment is clearly and completely described, obviously, described embodiment only is the utility model part embodiment, rather than whole embodiment.With reference now to accompanying drawing, describe embodiment of the present utility model, the similar elements label is represented similar elements in the accompanying drawing.The utility model provides a kind of audio signal output circuit, be applicable to audio signal is transferred to audio interface from the main central layer of television set, the impedance matching of the electronic device that realization is connected with the SCART audio interface, thus make that the audio signal of output is steady and audible, and applicability is wide.
Figure 1 shows that the circuit theory diagrams of the utility model audio signal output circuit first embodiment.The utility model audio signal output circuit is applicable to audio signal is transferred to the SCART audio interface from the main central layer of television set, it comprises L channel input circuit 10, R channel input circuit 20, left emitter follower circuit 30, right emitter follower circuit 40, power circuit 50, L channel output circuit 60 and R channel output circuit 70, described L channel input circuit 10 is connected in described main central layer, is used to transmit left channel audio signal; Described R channel input circuit 20 is connected in described main central layer, is used to transmit right channel audio signal; Described left emitter follower circuit 30 is connected with the output of described L channel input circuit 10, is used to cushion the output of left channel audio signal and makes output impedance adjustable; Described power circuit 50 is used for to described left emitter follower circuit 30 and 40 power supplies of described right emitter follower circuit; Described L channel output circuit 60 is connected with the output of described left emitter follower circuit 30, is used for left channel audio signal is transferred to the SCART audio interface; Described R channel output circuit 70 is connected with the output of described right emitter follower circuit 40, is used for right channel audio signal is transferred to the SCART audio interface.
With reference to figure 1, the utility model first embodiment audio signal output circuit 100 is arranged on the circuit board (figure does not show) of television set, main central layer is installed on the television set, be mainly used in demodulation and audio signal, and the L channel after will handling, right channel audio signal transfers to L channel, R channel input circuit 10,20 input, then respectively by left emitter follower circuit 30 and right emitter follower circuit 40 buffering L channels, the output of right channel audio signal and make output impedance coupling after, the audio signal after will handling by L channel output circuit 60 and R channel output circuit 70 respectively transfers to load by audio interface.It should be noted that in the utility model that this audio interface is the SCART interface.
Particularly, described left emitter follower circuit 30 comprises the first triode Q1 and first resistance R 1, the base stage of the described first triode Q1 connects the output of described L channel input circuit 10, collector electrode is connected with described power circuit 50, emitter is connected with an end of described first resistance R 1, the other end ground connection of described first resistance R 1, and described L channel output circuit 60 is connected between the emitter and first resistance R 1 of the described first triode Q1.Described right emitter follower circuit 40 comprises the second triode Q2 and second resistance R 2, the base stage of the described second triode Q2 connects the output of described R channel input circuit 20, collector electrode is connected with described power circuit 50, emitter is connected with an end of described second resistance R 2, the other end ground connection of described second resistance R 2, and described R channel output circuit 70 is connected between the emitter and second resistance R 2 of the described second triode Q2.
The first triode Q1 and the second triode Q2 all have the effect of emitter following, this makes audio signal pass through the base stage input of the first triode Q1 and the second triode Q2, after the emitter output, the voltage of this audio signal is constant, and can follow the linear change of the audio signal of input in a big way.Being provided with of the first triode Q1 and the second triode Q2 improved audio signal output circuit 100 load-carrying abilities and as cushioning effect.
Like this, first resistance R 1 by adjusting left emitter follower circuit 30 and right emitter follower circuit 40 and the resistance value of described second resistance R 2, make first resistance R 1 and described second resistance R 2 all less than 1K ohm, thereby realize the output impedance of SCART audio interface and the resistance value coupling of external load, make the audio signal of output effective, meet industry standard.
Fig. 2 is second embodiment of the utility model audio signal output circuit.With reference to figure 2, the utility model audio signal output circuit has increased filter circuit 80 on the basis of first embodiment, and except filter circuit 80, other circuit structure is identical with first embodiment.In the present embodiment, filter circuit 80 is the RC filter circuit, and this filter circuit 80 is low-pass filter circuits.Filter circuit 80 is connected between described power circuit 50 and described left emitter follower circuit 30, the right emitter follower circuit 40.Described filter circuit 80 comprises filter resistance R3 and filter capacitor C1 and C2, the end of described filter resistance R3 connects described power circuit 50, an end is connected with the other end of described filter resistance R3 after described filter capacitor C1 and the C2 parallel connection, other end ground connection, and described left emitter follower circuit, right emitter follower circuit all are connected between described filter resistance and the filter capacitor.The setting of filter circuit 80 is for the contained high-frequency interferencing signal of elimination DC power supply, makes that the voltage of supply audio frequency signal output apparatus 200 is purer, thereby reaches better output audio signal.
Abovely the utility model is described, but the utility model is not limited to the embodiment of above announcement, and should contains various modification, equivalent combinations of carrying out according to essence of the present utility model in conjunction with most preferred embodiment.
Claims (9)
1. audio signal output circuit is applicable to audio signal is transferred to the SCART audio interface from the main central layer of television set, it is characterized in that comprising:
The L channel input circuit is connected in described main central layer, is used to transmit left channel audio signal;
The R channel input circuit is connected in described main central layer, is used to transmit right channel audio signal;
Left side emitter follower circuit is connected with the output of described L channel input circuit, is used to cushion the output of left channel audio signal and makes output impedance adjustable;
Right emitter follower circuit is connected with the output of described R channel input circuit, is used to cushion the output of right channel audio signal and makes output impedance adjustable;
Power circuit is used for to described left emitter follower circuit and described right emitter follower circuit power supply;
The L channel output circuit is connected with the output of described left emitter follower circuit, is used for left channel audio signal is transferred to the SCART audio interface;
The R channel output circuit is connected with the output of described right emitter follower circuit, is used for right channel audio signal is transferred to the SCART audio interface.
2. audio signal output circuit as claimed in claim 1, it is characterized in that, described left emitter follower circuit comprises first triode and first resistance, the base stage of described first triode connects the output of described L channel input circuit, collector electrode is connected with described power circuit, emitter is connected with an end of described first resistance, the other end ground connection of described first resistance, and described L channel output circuit is connected between the emitter and first resistance of described first triode.
3. audio signal output circuit as claimed in claim 1, it is characterized in that, described right emitter follower circuit comprises second triode and second resistance, the base stage of described second triode connects the output of described R channel input circuit, collector electrode is connected with described power circuit, emitter is connected with an end of described second resistance, the other end ground connection of described second resistance, and described R channel output circuit is connected between the emitter and second resistance of described second triode.
4. as each described audio signal output circuit in the claim 1 ~ 3, it is characterized in that the described filter circuit that also comprises is connected between described power circuit and described left emitter follower circuit, the right emitter follower circuit.
5. audio signal output circuit as claimed in claim 4 is characterized in that, described filter circuit is a low-pass filter circuit.
6. audio signal output circuit as claimed in claim 5, it is characterized in that, described filter circuit comprises filter resistance and filter capacitor, one end of described filter resistance connects described power circuit, the other end connects an end of described filter capacitor, the other end ground connection of described filter capacitor, and described left emitter follower circuit, right emitter follower circuit all are connected between described filter resistance and the filter capacitor.
7. audio signal output circuit as claimed in claim 6 is characterized in that described filter circuit comprises the filter capacitor of two parallel connections, and an end of two described filter capacitors all is connected in described filter resistance, the equal ground connection of the other end.
8. audio signal output circuit as claimed in claim 2 is characterized in that, described first resistance is less than 1K ohm.
9. audio signal output circuit as claimed in claim 3 is characterized in that, described second resistance is less than 1K ohm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011200785954U CN202068499U (en) | 2011-03-23 | 2011-03-23 | Audio signal output circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011200785954U CN202068499U (en) | 2011-03-23 | 2011-03-23 | Audio signal output circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN202068499U true CN202068499U (en) | 2011-12-07 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2011200785954U Expired - Lifetime CN202068499U (en) | 2011-03-23 | 2011-03-23 | Audio signal output circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN202068499U (en) |
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2011
- 2011-03-23 CN CN2011200785954U patent/CN202068499U/en not_active Expired - Lifetime
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C56 | Change in the name or address of the patentee |
Owner name: GUANGZHOU SHIYUAN ELECTRONIC TECHNOLOGY CO., LTD. Free format text: FORMER NAME: GUANGZHOU SHIYUAN ELECTRONICS TECHNOLOGY CO., LTD. |
|
| CP01 | Change in the name or title of a patent holder |
Address after: 510663 Guangdong city of Guangzhou province Guangzhou Science City Kezhu Road No. 192 Patentee after: Guangzhou Shiyuan Electronic Technology Company Limited Address before: 510663 Guangdong city of Guangzhou province Guangzhou Science City Kezhu Road No. 192 Patentee before: Guangzhou Shiyuan Electronic Technology Co.,Ltd. |
|
| CX01 | Expiry of patent term |
Granted publication date: 20111207 |
|
| CX01 | Expiry of patent term |