CN202268848U - Broadcast power amplifier circuit - Google Patents
Broadcast power amplifier circuit Download PDFInfo
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- CN202268848U CN202268848U CN2011204047070U CN201120404707U CN202268848U CN 202268848 U CN202268848 U CN 202268848U CN 2011204047070 U CN2011204047070 U CN 2011204047070U CN 201120404707 U CN201120404707 U CN 201120404707U CN 202268848 U CN202268848 U CN 202268848U
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Abstract
The utility model discloses a broadcast power amplifier circuit, and aims to provide a broadcast power amplifier circuit without an audio-frequency transformer. The broadcast power amplifier circuit comprises an automatic switching circuit, a basic amplifying circuit, a control and display circuit and a horn, wherein the automatic switching circuit is respectively connected with the basic amplifying circuit and the control and display circuit; the basic amplifying circuit is respectively connected with the control and display circuit and the horn, and the basic amplifying circuit comprises a power amplifier chip; a first end of the horn is connected with the output end of the power amplifier chip, a second end of the horn is grounded through a sampling circuit, and the second end of the horn is also connected with the reverse input end of the power amplifier chip through a sampling resistor; and one part of voice frequency current output by the basic amplifying circuit is fed back to the reverse input end of the power amplifier chip through the horn, thereby forming a feedback current; the output end of the basic amplifying circuit is of a current type, the audio-frequency transformer at a power amplifier output end is omitted, the cost and the volume are reduced, and the security is improved. The power amplifier circuit provided by the utility model is suitable for all broadcast circuits.
Description
Technical field
The utility model relates to a kind of power amplification circuit, especially relates to a kind of broadcasting power amplifier of current mode.
Background technology
Along with the progress in epoch, the propagation of sound and record get into datumization processing epoch, DAB already; Program controlled telephone; Mobile communication has been widely known, and the progress of modern science and technology makes the design of family expenses power amplifier and professional power amplifier more become ripe, and circuit is more perfect; Especially the design of voicefrequency circuit, test have complete standards system and guarantee that this brings great convenience to the user and satisfies!
And the master-plan of traditional broadcasting power amplifier, rest on 20 years basically before, circuit construction variations is little; Especially voicefrequency circuit design aspect; Frequency characteristic is relatively poor, can't adapt to the digital audio broadcasting of high-fidelity, like sources of sound such as CD, DVD, MP3; And still do not have relevant standards system at present and examine, caused with the versatility of auxiliary device relatively poor with compatibility.
The output of traditional broadcast power amplifier all is connected to an audio frequency output transformer, and its effect is that transmission voltage is raise, thereby the electric current that flows through transmission line is reduced, to reach the purpose that reduces transmission line loss.Consequently: must increase by one with the power transformer audio frequency transformer of equivalent weight, volume, cost almost, and because the introducing of this transformer has caused following ubiquitous 5 main phenomenons:
(1) volume, weight cost increase: the power amplifier complete machine of same power grade, the volume of broadcasting power amplifier be obviously greater than common power amplifier, and give the broadcasting power amplifier of designing high-power (more than the single channel 500W) because of the restriction of volume weight and increased difficulty;
(2) access of audio frequency transformer degenerates the frequency characteristic of power amplifier output: the frequency characteristic of general broadcast power amplifier is 60Hz-18KHz; And with-3dB test condition as frequency range; Can't realize the high-fidelity (1dB test condition) and the long-distance transmissions (limited by frequency characteristic) of digital tone source; Transient response not good (effect of transformer inductance L) has also been introduced distortion sources;
(3) introduced dangerous characteristic: causing output because of the boosting of audio frequency transformer is " high voltage " state; Like 70V, 100V etc.; And " arcing " phenomenon that causes because of the reliability of this interface; Limit the use under some particular surroundings, as be laid in the suction top loudspeaker in the ceiling, and wet environment, mine, underground work etc.;
(4) output is the constant-pressure type way of output, is called for short " voltage-type power amplifier ", and its physical expressions is: Po=Vo * Vo/RL, and RL ≠ 0
In the formula, Po is the rated power of power amplifier, and Vo is the output voltage of power amplifier; RL is the load (loudspeaker impedances) of power amplifier, and according to this physical characteristic, the output of power amplifier is equipped with complete protective circuit; During with proof load RL=0, power amplifier is not burnt, and consequently the intervention of protective circuit makes power amplifier complicated; And protective circuit exists certain uncertainty, has increased difficulty for design, test;
(5) big electric current " arcing " phenomenon that moment produced of load short circuits can't be eliminated.
Summary of the invention
The utility model mainly is to solve the technical problem that existing in prior technology needs audio frequency transformer, and a kind of broadcasting power amplifier that need not audio frequency transformer of new structure is provided.
The utility model mainly is able to solve through following technical proposals to above-mentioned technical problem: a kind of broadcasting power amplifier; Comprise automatic switch-over circuit, basic amplifier circuit, control and display circuit and loudspeaker; Said automatic switch-over circuit is connected with said control and display circuit with said basic amplifier circuit respectively; Said basic amplifier circuit is connected with said loudspeaker with said control and display circuit respectively, and said basic amplifier circuit comprises a power amplifier chip; First end of said loudspeaker connects the output of said power amplifier chip, and second end is through sample circuit ground connection, and said second section is also passed through the reverse input end that sample resistance connects the power amplifier chip.
A part of tone currents of basic amplifier circuit output feeds back to the reverse input end of power amplifier chip through loudspeaker, forms feedback current, and making output is the current mode way of output, is called for short " current mode power amplifier ".Therefore, cancelled the audio frequency transformer of power amplifier output.The physical expressions of its power is:
Po=I * I * RL, and load RL can be 0,
When this means the load short circuits when power amplifier output, the feedback current of the loudspeaker of flowing through is 0 by short circuit also, and power amplifier will lose amplification, and output is in self-shield " closed condition ", and does not have " arcing " phenomenon.
According to physical expressions, Po is constant when rated power, and the increase of load impedance RL will cause reducing of power amplifier output current Io, and this characteristic has just in time adapted to the characteristics of broadcasting power amplifier " high resistant transmission ", and it is defined as:
Po=Io×Io×(RL+Rr）
In the formula, Rr is a transmission line loss resistance;
Then load total impedance is RL+Rr, it is generally acknowledged, when the impedance RL of loudspeaker much larger than transmission line loss resistance R r (more than 10 times), then the loss resistance Rr of transmission line can be left in the basket, and promptly suitably improves the impedance RL of loudspeaker, can reduce the loss of transmission line.The cancellation of audio frequency transformer, its advantage of bringing is:
(1) reduced cost significantly;
(2) dwindled the volume of complete machine significantly, alleviated weight, made the structural design miniaturization of complete machine, lightness simultaneously, also provides with reference to foundation for the broadcasting power amplifier of designing high-power (more than the single channel 500W);
(3) cancel traditional protective circuit, brought convenience for design, technology and use;
(4) output of power amplifier need not any impedance inverter circuit and booster circuit, and the short circuit of power amplifier output can not produce the phenomenon of " spark " or " arcing ";
The output interface of the broadcasting power amplifier of the utility model where necessary still can be through audio frequency transformer output; And during the short circuit of audio frequency transformer output; Still effectively (annotate: the short circuit at high pressure place " arcing " will exist the self-shield state of circuit; But amplitude is lowered), make the output interface have good compatibility.When the accessing to audio transformer was exported, the high-end of audio frequency can well extend to 20KHz (1dB parameter);
(5) electrical performance indexes is greatly improved, for the long-distance transmissions of high-fidelity source of sound provides guarantee.
As preferably, said sample circuit be one less than 1 ohm resistance.
As preferably, said automatic switch-over circuit comprises:
Amplifier circuit for sound frequency signal;
Be used to select the broadcast singal input gating circuit of telephone signal or microphone signal;
Be used to select the connection of broadcast singal or background signal to turn-off logical circuit;
Said broadcast singal input gating circuit turn-offs logical circuit with said amplifier circuit for sound frequency signal and said connection respectively and is connected.
Automatic switch-over circuit has been realized the automatic gating (it is first gating that this circuit is set microphone signal) of 2 kinds of broadcast signal source inputs; And can this mould shape be extended to the broadcast signal source input on n road; But no matter the sort of signal is imported; Can both make commutation circuit accomplish shutoff, and the structure of circuit is very simple to background signal.
Audio amplifier circuit can insert the audio output signal that comes from program controlled telephone, has realized the Remote connection broadcasting of global any program controlled telephone to the utility model, also can carry out the wireless remote remote control to this machine through a mobile phone and connect broadcasting.
As preferably, said control and display circuit comprise:
The circuit amplifying circuit;
Control section circuit with switching on and shutting down time-delay noise elimination, no signal automatic silencing function;
The display circuit of performance power amplifier work state;
Said control section circuit is connected with said display circuit respectively at said circuit amplifying circuit.
The power output stage static state of broadcasting power amplifier is AB class operating state in the prior art, be in the lightly conducting state to guarantee the final stage power tube, and " quiescent current " of lightly conducting is the main cause of complete machine quiescent dissipation.
The utility model is through the connection of the noise elimination port (MUTE) of IC amplifier, RC components and parts and transistor AND gate IC power amplifier; Can be after 10 minutes in no signal; Automatically close the quiescent current of power amplifier; In case the restoring signal input, complete machine can get into normal operating conditions automatically, has reached the purpose of stand-by energy-saving.
As preferably, said control section circuit comprises a temperature switch of being close to power discharging radiator.When the temperature of broadcasting power amplifier when rising to design temperature, the self-protection function also will work and close the operating current of power amplifier, play the effect of safeguard protection.
As preferably, said display circuit comprises a red blue dichromatic LED.Can show the different conditions of equipment through the different luminous combination of two red blue dichromatic LEDs.When the utility model was in no signal condition, red blue dichromatic LED was shown in red; When signal was imported, red blue dichromatic LED was shown as blueness; When this machine was in the overtemperature protection state, red blue dichromatic LED was shown as aubergine or rose-colored (red+blue).
The beneficial effect that the utility model brings is, saved audio frequency transformer, reduced cost, simplifies the structure, and improved fail safe, and signal can automatically switch apace, has temperature protection function, can show different state.
Description of drawings
Fig. 1 is a kind of module diagram of the utility model;
Fig. 2 is a kind of circuit theory diagrams of the basic amplifier circuit of the utility model;
Fig. 3 is a kind of circuit theory diagrams of the automatic switch-over circuit of the utility model;
Fig. 4 is the control of the utility model and a kind of circuit theory diagrams of display circuit;
Among the figure: 1, loudspeaker, 2, basic amplifier circuit, 3, automatic switch-over circuit, 4, control and display circuit.
Embodiment
Pass through embodiment below, and combine accompanying drawing, do further bright specifically the technical scheme of the utility model.
Embodiment: a kind of broadcasting power amplifier of present embodiment; As shown in Figure 1; Comprise automatic switch-over circuit 3, basic amplifier circuit 2, control and display circuit 4 and loudspeaker 5; Automatic switch-over circuit 3 is connected 4 with basic amplifier circuit 2 with control and display circuit respectively, and basic amplifier circuit 2 also is connected with loudspeaker 5 with control and display circuit 4 respectively.
As shown in Figure 2, basic amplifier circuit 2 has used power discharging IC chip TDA7294; One end of loudspeaker 5 is through sample circuit R037 (less than 1 Ω resistance) " suspension " ground connection! And the connection place one biasing resistor R031 of loudspeaker 5 and sample circuit connects the reverse input end of power amplifier chip, and the input in the same way of power amplifier chip is through a resistance R 048 ground connection; The unlimited increase of the access restriction loudspeaker impedances of R036, circuit is stable when having guaranteed load open circuit simultaneously.
As shown in Figure 3, constituted broadcast singal input gating circuit by Q03 and R044.1/2 part (N03b) by double operational N03 has constituted connection/shutoff logical circuit each other with transistor Q04, Q05, Q06, Schottky diode (1N5817) D004, D005 and related elements, has accomplished turning on and off broadcast singal and background signal.C022 and R046 have confirmed the off time of circuit upset.
1/2 part (N03a) by double operational N03 has constituted the circuit amplifying circuit with R038, R039, R040, R041 and C020, C021, sets sensitivity and is about 100mV, to adapt to the needs of various audio signal inputs.Input socket TEL uses three core sockets of M6.35 standard, and the formation of circuit is common to the input of balance or unbalanced signal.
As shown in Figure 4, constituted the circuit amplifying circuit of control section by 1/2 part (N02a) of double operational N02 and R016, R008, R010, C006, C007; Constituted the control section circuit of switching on and shutting down time-delay noise elimination, no signal automatic silencing (stand-by energy-saving) by 1/2 part (N02b) of double operational N02 and R017, R018, R019, R020, R021, R022, R032, R033, R034, C008, C011, C012 and transistor Q05, Q06, D002, D003, DW.Temperature switch Kto (67F090) is close to the radiator of power amplifier and installs, and has constituted the overtemperature protection control circuit with said elements.Constituted the luminous display circuit of 3 kinds of colors by R023, R024 and double-colored (red/indigo plant) light-emitting diode and said elements.
Constitute reverse circuit by half N03b of double operational integrated circuit N03 by/conducting; The match selection that cooperates input resistance; Constituted the automatic switchover of three road perfect input signals, switching noise and switching failure have also been avoided in the inconvenience of having avoided signal selecting switch to bring because of manual switching; Complete machine only needs a power switch key, can accomplish the automatic switchover of the opening of whole circuit, signal input; The start-up time delay of circuit is set at about 1s, has avoided the impulsive sound of start loudspeaker, makes this complete machine become real " key is logical ", to satisfy the requirement of " emergency broadcast system ".
It is first preferential that input signal ordering is set with microphone MIC, and sensitivity is: 3mV.
It is second preferential that phone input signal TEL ordering is set at, and opens threshold sensitivity and be:＜30mV is enough to guarantee the audio signal input range of program controlled telephone: 60mV-100mV.
Power amplifier has partly used the TDA7294 power discharging IC chip of " meaning method " company; And improved " typical circuit " in the past parameter that this IC chip manufacturer is provided; Make complete machine accomplish low noise, broadband, the high-fidelity requirement of low distortion; To satisfy the special requirement that long Distance Transmission line uses the weak electric signal transmission, reduced the input of equipment.
Circuit input AUX uses as the input of quality signal source (background music), like CD, and DVD, program source such as MP3.
Specific embodiment described herein only is that the utility model spirit is illustrated.The utility model person of ordinary skill in the field can make various modifications or replenishes or adopt similar mode to substitute described specific embodiment, but can't depart from the spirit of the utility model or surmount the defined scope of appended claims.
Although this paper has used terms such as power amplifier, loudspeaker, background music morely, do not get rid of the possibility of using other term.Using these terms only is in order to describe and explain the essence of the utility model more easily; It all is contrary with the utility model spirit being construed to any additional restriction to them.
Claims (6)
1. broadcast power amplifier for one kind; Comprise automatic switch-over circuit, basic amplifier circuit, control and display circuit and loudspeaker; It is characterized in that; Said automatic switch-over circuit is connected with said control and display circuit with said basic amplifier circuit respectively, and said basic amplifier circuit is connected with said loudspeaker with said control and display circuit respectively, and said basic amplifier circuit comprises a power amplifier chip; First end of said loudspeaker connects the output of said power amplifier chip, and second end is through sample circuit ground connection, and said second section is also passed through the reverse input end that sample resistance connects the power amplifier chip.
2. broadcasting power amplifier according to claim 1 is characterized in that, said sample circuit be one less than 1 ohm resistance.
3. broadcasting power amplifier according to claim 1 and 2 is characterized in that, said automatic switch-over circuit comprises:
Amplifier circuit for sound frequency signal;
Be used to select the broadcast singal input gating circuit of telephone signal or microphone signal;
Be used to select the connection of broadcast singal or background signal to turn-off logical circuit;
Said broadcast singal input gating circuit turn-offs logical circuit with said amplifier circuit for sound frequency signal and said connection respectively and is connected.
4. broadcasting power amplifier according to claim 1 and 2 is characterized in that, said control and display circuit comprise:
The circuit amplifying circuit;
Control section circuit with switching on and shutting down time-delay noise elimination, no signal automatic silencing function;
The display circuit of performance power amplifier work state;
Said control section circuit is connected with said display circuit respectively at said circuit amplifying circuit.
5. broadcasting power amplifier according to claim 4 is characterized in that, said control section circuit comprises a temperature switch of being close to power discharging radiator.
6. broadcasting power amplifier according to claim 4 is characterized in that, said display circuit comprises a red blue dichromatic LED.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011204047070U CN202268848U (en) | 2011-10-22 | 2011-10-22 | Broadcast power amplifier circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011204047070U CN202268848U (en) | 2011-10-22 | 2011-10-22 | Broadcast power amplifier circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN202268848U true CN202268848U (en) | 2012-06-06 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2011204047070U Expired - Lifetime CN202268848U (en) | 2011-10-22 | 2011-10-22 | Broadcast power amplifier circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN202268848U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106792372A (en) * | 2017-02-23 | 2017-05-31 | 广州海格通信集团股份有限公司 | Marine public address system |
-
2011
- 2011-10-22 CN CN2011204047070U patent/CN202268848U/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106792372A (en) * | 2017-02-23 | 2017-05-31 | 广州海格通信集团股份有限公司 | Marine public address system |
| CN106792372B (en) * | 2017-02-23 | 2020-03-17 | 广州海格通信集团股份有限公司 | Marine broadcasting equipment |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CX01 | Expiry of patent term | ||
| CX01 | Expiry of patent term |
Granted publication date: 20120606 |