CN111432321B

CN111432321B - Audio equipment test circuit and test method

Info

Publication number: CN111432321B
Application number: CN202010151160.1A
Authority: CN
Inventors: 刘炳晖; 刘海刚
Original assignee: Wuyi University
Current assignee: Wuyi University
Priority date: 2020-03-06
Filing date: 2020-03-06
Publication date: 2022-04-08
Anticipated expiration: 2040-03-06
Also published as: CN111432321A

Abstract

The invention discloses a test circuit and a test method of audio equipment, wherein a test channel selection module is respectively connected with an ear amplifier output module, a balance input module, a main control module and an unbalanced input module, the ear amplifier output module is connected with an output volume attenuation module, an unbalanced output module and an earphone output control module, a monitoring audio input module is connected with the output volume attenuation module, the monitoring left and right output selection module and the main control module, the monitoring left and right output selection module is also connected with the monitoring left and right sound channel output module and the main control module, the earphone output control module is also connected with the main control module, and an LED display module and a rotary encoder module are respectively connected with the main control module, thereby effectively improving the test efficiency of the audio equipment.

Description

Audio equipment test circuit and test method

Technical Field

The invention relates to the technical field of audio test, in particular to a test circuit and a test method for audio equipment.

Background

At present, to the growth line of production audio equipment, can set up tone quality to audio equipment output sound usually and test, in prior art, to receiving audio equipment to putting outward usually, the sound that the test speaker sent through listening to putting outward to judge whether audio equipment output sound's tone quality has the problem, if go to test different audio equipment through the equipment of putting outward simultaneously, then can mutual interference in same environment, thereby influence the test effect. In addition, many audio equipment all have independent left and right channel output, if the sound quality that the pilot will test different sound channels alone, then need switch the audio line of plug different sound channels when being connected to the external device to reduce the efficiency of test.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a test circuit and a test method for audio equipment, which can effectively improve the test efficiency of the audio equipment.

The embodiment of the first aspect of the invention provides an audio device test circuit, which comprises a balanced input module, an unbalanced input module, an output volume attenuation module, an ear amplifier output module, an unbalanced output module, a test channel selection module, a left and right channel monitoring output module, a left and right output monitoring selection module, an audio input monitoring module, a main control module, an earphone output control module, an LED display module and a rotary encoder module, wherein the test channel selection module is respectively connected with the ear amplifier output module, the balanced input module, the main control module and the unbalanced input module, the ear amplifier output module is connected with the output volume attenuation module, the unbalanced output module and the earphone output control module, and the audio input monitoring module is connected with the output volume attenuation module, the left and right output monitoring selection module, the audio output volume attenuation module, the left and right output monitoring selection module, the audio output volume attenuation module, the earphone output control module, the audio output module, the audio module, The main control module is connected, the left and right monitoring output selection module is further connected with the left and right monitoring sound channel output module and the main control module, the earphone output control module is further connected with the main control module, and the LED display module and the rotary encoder module are respectively connected with the main control module.

The audio equipment test circuit according to the embodiment of the invention has at least the following beneficial effects: according to the embodiment of the invention, the balanced input module and the unbalanced input module are arranged, so that a balanced audio signal and an unbalanced audio signal can be selected for input, and multiple functions are realized; the input audio signals are input to the test channel selection module to select audio frequencies coming from different channels, for example, balanced signals of left and right sound channels are input simultaneously, the audio signals can be output to an external amplifier or an earphone by selecting the left sound channel or the right sound channel, and a sound tester does not need to plug and pull a sound channel line manually, so that the sound testing efficiency is improved; the embodiment of the invention is provided with the unbalanced output module which is used for outputting the unbalanced audio signal to the external playing device, and the audio signal is output to the earphone by arranging the earphone output control module, so that a sound tester can select to test the sound through the external playing device or the earphone according to the requirements of the field environment when testing the sound, and the influence of the environment can be reduced when selecting the earphone to test the sound; in addition, the embodiment of the invention also comprises a monitoring audio input module which can be accessed to monitor audio signals, and then the monitoring audio signals are output to the monitoring equipment through a monitoring left-right output selection module and a monitoring left-right sound channel output module; the embodiment of the invention also comprises a volume attenuation module and a rotary encoder module which can be used for adjusting the volume when the audio is output, so that the output volume can adapt to the requirements of a test speaker; the LED display module can visually enable the test tone staff to know the currently used channel or the corresponding functions. So, through the connection cooperation setting of above-mentioned circuit module, can effectively promote audio equipment's efficiency of software testing.

According to some embodiments of the present invention, the mobile terminal further comprises a peak detection module and a buzzer alarm module, wherein the peak detection module is respectively connected to the ear amplifier output module and the main control module, and the buzzer alarm is connected to the main control module.

According to some embodiments of the present invention, the balanced input module comprises a first socket J1000, a first operational amplifier U1000 and a second operational amplifier U1006, the T terminal of the first socket J1000 is connected to the first non-inverting input terminal of the second operational amplifier U1006, the BAL-port of the first socket J1000 is connected to the first non-inverting input terminal of the first operational amplifier U1000, the BAL + port of the first socket J1000 is connected to the second non-inverting input terminal of the first operational amplifier U1000, the first output terminal of the first operational amplifier U1000 is connected to the second non-inverting input terminal of the second operational amplifier U1006, the second output terminal of the first operational amplifier U1000 is connected to the second inverting input terminal of the second operational amplifier U1006, the first output terminal of the second operational amplifier U1006 is connected to the second inverting input terminal of the second operational amplifier U1006, a second output of the second operational amplifier U1006 is connected to the test channel selection module.

According to some embodiments of the present invention, the ear-play output module includes a third operational amplifier U1002, a fourth operational amplifier U1009, a first transistor Q5000, a second transistor Q5002, a third transistor Q1001 and a fourth transistor Q1002, a first inverting input of the third operational amplifier U1002 is connected to the test channel selection module, a first output of the third operational amplifier U1002 is connected to the output volume attenuation module and the peak detection module, respectively, a second non-inverting input of the third operational amplifier U1002 is connected to a power source VREF, a second output of the third operational amplifier U1002 is connected to the unbalanced output module, a first inverting input of the fourth operational amplifier U1009 and the earphone output control module, respectively, a first inverting input of the fourth operational amplifier U1009 is further connected to the output volume attenuation module, the output end of the third operational amplifier U1002 is connected to the bases of the first triode Q5000 and the second triode Q5002, the fourth operational amplifier U1009 is connected to the bases of the third triode Q1001 and the fourth triode Q1002, the emitter of the first triode Q5000 is connected to the emitter of the second triode Q5002 and to the earphone output control module, and the emitter of the third triode Q1001 is connected to the emitter of the fourth triode Q1002 and to the earphone output control module.

According to some embodiments of the present invention, the peak detecting module includes a fifth operational amplifier U1003, a first chip IC1001A, a second chip IC1001B, a third chip IC1001C and a fourth chip U1001, a first non-inverting input terminal of the fifth operational amplifier U1003 is connected to the ear-play output module, a first output terminal of the fifth operational amplifier U1003 is connected to an inverting input terminal of the first chip IC1001A and a non-inverting input terminal of the second chip IC1001B, respectively, a non-inverting input terminal of the first chip IC1001A is connected to the third chip IC1001C and the fourth chip U1001, respectively, an output terminal of the first chip IC1001A is connected to the main control module, an output terminal of the second chip IC1001B is connected to the main control module, and the fourth chip U1001 is connected to the main control module.

According to some embodiments of the present invention, the unbalanced input module comprises a second socket J1006, a sixth operational amplifier U1012, an input terminal of the second socket J1006 is connected to a first non-inverting input terminal of the sixth operational amplifier U1012, and a first output terminal of the sixth operational amplifier U1012 is connected to the test channel selection module.

According to some embodiments of the present invention, the listening audio input module includes a third socket MUSIC _ IN, a seventh operational amplifier U1015 and an eighth operational amplifier U1009, the input terminal of the third socket MUSIC _ IN is connected to the first inverting input terminal of the seventh operational amplifier U1015, a second inverting input terminal of the seventh operational amplifier U1015 is connected to the output volume attenuating module, a first output terminal of the seventh operational amplifier U1015 is connected to the output volume attenuating module, a second output terminal of the seventh operational amplifier U1015 is respectively connected to a first inverting input terminal, a first non-inverting input terminal, and a second inverting input terminal of the eighth operational amplifier U1009, a first output end of the eighth operational amplifier U1009 is connected to the left and right listening output selection module, and a second output end of the eighth operational amplifier U1009 is connected to the left and right monitoring output selection module.

According to some embodiments of the present invention, the power supply module further includes a power supply module, where the power supply module includes a dc power interface J1002, a fifth chip U2024, and a sixth chip, an input end of the dc power interface J1002 is connected to an input end of the fifth chip U2024 and an input end of the sixth chip, an output end of the fifth chip U2024 is connected to a power VCC interface, and an output end of the fifth chip U2024 is connected to a power MCU _3.3V interface.

The embodiment of the second aspect of the invention provides an audio device testing method, which comprises the following steps:

the audio signal is accessed from the balanced input module or the unbalanced input module, and the input channel is selected through the test channel selection module;

the ear amplifier output module amplifies the audio signal output by the test channel selection module and outputs the amplified audio signal to the external amplifier through the unbalanced output module or outputs the amplified audio signal to an earphone through the earphone output control module;

alternatively, the first and second electrodes may be,

the audio signal is accessed through the monitoring audio input module, and the input signal is divided into two paths of signals of left and right sound channels through the monitoring left and right output selection module;

and outputting the two paths of signals of the left and right sound channels to the earphone through different output interfaces respectively.

The audio equipment testing method provided by the embodiment of the invention at least has the following beneficial effects: by accessing the audio signals from the balanced input module or the unbalanced input module and selecting the input channel through the test channel selection module, the switching of the output of the sound channel can be realized without manually plugging and unplugging the sound channel wire by a sound tester, and the efficiency of testing the audio equipment is improved; the audio signal that output module was selected the module output with the test channel to the ear is put output module and is enlargied audio signal and export the equipment of putting outward through unbalanced output module, perhaps in export the earphone through earphone output control module, and the pilot can use the equipment of putting outward or the earphone is tried on the sound according to the demand on-the-spot, when using the earphone to try on the sound, can reduce the influence of surrounding environment. In addition, the audio input module can be monitored to access audio signals, the left output selection module and the right output selection module are monitored to divide the input signals into two paths of signals of left and right sound channels, the two paths of signals of the left and right sound channels are output to the earphone through different output interfaces respectively, the earphone can be ear return equipment, therefore, the test of various kinds of equipment can be completed on one large circuit module, switching to a new test circuit device is not needed, and the test efficiency of the audio equipment is improved.

According to some embodiments of the invention, further comprising: and inputting the audio signal of the ear amplifier output module into the peak value detection module, and controlling the buzzing alarm module to give out alarm sound if the detected audio signal exceeds a preset range value.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a schematic diagram of an overall structure of an audio device testing circuit according to an embodiment of the present invention;

FIG. 2 is a circuit diagram of a master control module of the audio device test circuit;

FIG. 3 is a circuit diagram of a balanced input module of the audio device test circuit;

FIG. 4 is a circuit diagram of a peak detect module of the audio device test circuit;

FIG. 5 is a circuit diagram of an ear-amp output module of the audio device test circuit;

FIG. 6 is a circuit diagram of an unbalanced input module of the audio device test circuit;

FIG. 7 is a circuit diagram of a test channel selection module of the audio device test circuit;

FIG. 8 is a circuit diagram of a rotary encoder module for the audio device test circuit;

FIG. 9 is a circuit diagram of an earphone output control module of the audio device test circuit;

FIG. 10 is a circuit diagram of a listening audio input module of the audio device test circuit;

FIG. 11 is a circuit diagram of an output volume attenuation module of the audio device test circuit;

FIG. 12 is a circuit diagram of a left and right output select module for listening of the audio device test circuit;

FIG. 13 is a circuit diagram of a left and right channel output monitoring module of the audio device test circuit;

FIG. 14 is a power block circuit diagram of an audio device test circuit;

FIG. 15 is a circuit diagram of an unbalanced output module of the audio device test circuit;

FIG. 16 is a buzzer alert circuit diagram of an audio device test circuit;

fig. 17 is a circuit diagram of an LED display module of the audio device test circuit.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

In the description of the present invention, it should be understood that the orientation or positional relationship referred to in the description of the orientation, such as the upper, lower, front, rear, left, right, etc., is based on the orientation or positional relationship shown in the drawings, and is only for convenience of description and simplification of description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.

In the description of the present invention, the meaning of a plurality of means is one or more, the meaning of a plurality of means is two or more, and larger, smaller, larger, etc. are understood as excluding the number, and larger, smaller, inner, etc. are understood as including the number. If the first and second are described for the purpose of distinguishing technical features, they are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.

In the description of the present invention, unless otherwise explicitly limited, terms such as arrangement, installation, connection and the like should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific contents of the technical solutions.

Referring to fig. 1, 2, 9, 12, 13, and 15, a first aspect of an embodiment of the present invention provides an audio device testing circuit, including: balanced input module, unbalanced input module, output volume attenuation module, ear put output module, unbalanced output module, test channel selection module, monitor left and right sound channel output module, monitor left and right output selection module, monitor audio input module, host system, earphone output control module, LED display module, rotary encoder module, test channel selection module respectively with the ear put output module balanced input module the host system, unbalanced input module connects, the ear put output module with output volume attenuation module, unbalanced output module, earphone output control module connects, monitor audio input module with output volume attenuation module, output selection module about monitoring about, host system connects, output selection module about monitoring still with sound channel output module about monitoring, The main control module is connected, the earphone output control module is further connected with the main control module, and the LED display module and the rotary encoder module are respectively connected with the main control module.

In some specific embodiments of the present invention, the mobile terminal further includes a peak detection module and a buzzer alarm module, the peak detection module is respectively connected to the ear amplifier output module and the main control module, and the buzzer alarm is connected to the main control module. The peak detection module can be arranged in the circuit, and when the input audio frequency exceeds a preset range value, the buzzer alarm module gives an alarm so as to remind a sound tester. A plurality of range values can be set through the rotary encoder module, so that detection of audio equipment with different standards can be realized in a large circuit module, and the testing efficiency of the audio equipment is improved. It is understood that the peak detection module may be used for detecting POP sound, and may be an audio device with a microphone and a microphone receiver as input, in some cases, there may be a "bang" noise when turning on or off, and the size of the sound should have a standard, and in the embodiment of the present invention, several ranges may be preset, for example, 5mV, 10mV, 20mV, and 30mV, so as to implement the normalization of POP sound detection.

Referring to fig. 3, in some embodiments of the present invention, the balanced input module includes a first socket J1000, a first operational amplifier U1000 and a second operational amplifier U1006, a T terminal of the first socket J1000 is connected to a first non-inverting input terminal of the second operational amplifier U1006, a BAL-port of the first socket J1000 is connected to the first non-inverting input terminal of the first operational amplifier U1000, a BAL + port of the first socket J1000 is connected to a second non-inverting input terminal of the first operational amplifier U1000, a first output terminal of the first operational amplifier U1000 is connected to the second non-inverting input terminal of the second operational amplifier U1006, a second output terminal of the first operational amplifier U1000 is connected to the second inverting input terminal of the second operational amplifier U1006, a first output terminal of the second operational amplifier U1006 is connected to the second inverting input terminal of the second operational amplifier U1006, a second output of the second operational amplifier U1006 is connected to the test channel selection module.

It is understood that the transmission of audio can be broadly divided into two types, one being unbalanced transmission and the other being balanced transmission. The transmission of wired signal needs to rely on the wire rod, and what unbalanced signal needs is two-wire transmission, a signal line, a ground wire, as the name implies, the signal line has born corresponding audio signal, the ground wire is the reference of signal line, however in the in-process of transmission, ground wire itself also plays certain antenna action, can receive the noise that does not need in the environment along the way together, also because this received noise's reason, make unbalanced signal use at the short distance best, in the circuit then avoid placing with the power cord parallel. For efficient long distance transmission, the concept of balanced signals is introduced. The transmission of the equalized signal requires three lines. In addition to the same signal wire and the ground wire as unbalanced signals, a signal wire with a phase difference of pi with the signal wire is additionally arranged, the two signal wires can be marked as + and-, or called as anode and cathode, the phases of the two signal wires are exactly 180 degrees out of phase, when the two signals are transmitted, the same interference is received, after the two signals reach a target, the cathode signal is overturned and superposed with the anode, the two signals are superposed in phase, the noise is cancelled in opposite phase, and therefore the noise along the way can be well cancelled, and the sound under the same condition is larger than that of unbalance. This is "common mode rejection" which rejects common noise.

The circuit principle is as follows: the audio signal balanced and input by the card-nong socket is respectively connected to the non-inverting input ends of the two operational amplifiers through capacitors after passing through the impedance matching and the anti-radio frequency interference network in front to carry out certain pre-amplification, the amplification factor is determined by a feedback resistor and an inverting end resistor, the audio signal is input into the same operational amplifier through the back coupling, the audio signal is respectively connected with the non-inverting input and the inverting input, and two signals with opposite phases after pre-amplification are output into a single-ended output signal through difference to be transmitted on a circuit board. It is understood that, in some embodiments, there are two balanced input modules, which are respectively used for inputting audio signals of left and right channels.

Referring to fig. 5, in some embodiments of the present invention, the ear-drop output module includes a third operational amplifier U1002, a fourth operational amplifier U1009, a first transistor Q5000, a second transistor Q5002, a third transistor Q1001, and a fourth transistor Q1002, a first inverting input terminal of the third operational amplifier U1002 is connected to the test channel selection module, a first output terminal of the third operational amplifier U1002 is connected to the output volume attenuation module and the peak detection module, respectively, a second non-inverting input terminal of the third operational amplifier U1002 is connected to a power source VREF, a second output terminal of the third operational amplifier U1002 is connected to the unbalanced output module, a first inverting input terminal of the fourth operational amplifier U1009 and the earphone output control module, respectively, a first inverting input terminal of the fourth operational amplifier U1009 is further connected to the output volume attenuation module, the output end of the third operational amplifier U1002 is connected to the bases of the first triode Q5000 and the second triode Q5002, the fourth operational amplifier U1009 is connected to the bases of the third triode Q1001 and the fourth triode Q1002, the emitter of the first triode Q5000 is connected to the emitter of the second triode Q5002 and to the earphone output control module, and the emitter of the third triode Q1001 is connected to the emitter of the fourth triode Q1002 and to the earphone output control module.

In some specific embodiments, the MIX _ R port is used to input data of the CH1 or CH2 port; the MIX _ L port is used for inputting CH3 or CH4, and the matching is the input of channel 4-to-1; the AUX _ OUT port is used for isolating the audio signal after volume control from the operational amplifier and then is used for a test sound external amplifier input source; the HPR port is used for the output of the ear speaker for the 3.5mm jack left channel; the HPL is used for the output of the earphone amplifier and is used for a left sound channel of a 3.5mm socket; EARPHONEI is used as the input end of volume control after channel 4 selects 1; the earphoseo port is used for volume control and then output to the ear discharge circuit.

Referring to fig. 4, in some embodiments of the present invention, the peak detecting module includes a fifth operational amplifier U1003, a first chip IC1001A, a second chip IC1001B, a third chip IC1001C and a fourth chip U1001, a first non-inverting input terminal of the fifth operational amplifier U1003 is connected to the ear-amplifying output module, a first output terminal of the fifth operational amplifier U1003 is connected to an inverting input terminal of the first chip IC1001A and a non-inverting input terminal of the second chip IC1001B, a non-inverting input terminal of the first chip IC1001A is connected to the third chip IC1001C and the fourth chip U1001, an output terminal of the first chip IC1001A is connected to the main control module, an output terminal of the second chip IC1001B is connected to the main control module, and the fourth chip U1001 is connected to the main control module.

When the signal to be detected exceeds the set window limit, the comparator outputs a low level to the MCU, and the MCU makes a peak value exceeding prompt after acquiring the signal.

LM393 is a chip of a double-voltage comparator, and one important parameter for measuring the comparator is input offset voltage, the parameter refers to the response range of the comparator relative to reference voltage, and the comparator can obtain a result after the difference value of the voltage to be measured and the reference voltage exceeds the offset voltage. The offset voltage of LM393 is typically 2mV and 5mV at maximum, but usually the input signal to be measured is only a few mV, so it is difficult to obtain the offset voltage, therefore, before inputting the offset voltage into the comparator, the signal is amplified, so the comparator can compare the output well. The requirement on window voltage is adjustable, a TL431 controllable precise voltage stabilizing source is continuously adopted, the output voltage can be changed only by changing the size of an input resistor, a common potentiometer is difficult to accurately master the resistance value, a variable digital potentiometer is used, DS3904 is a linear digital potential with three 20K omega and 128 taps, and the resistance setting of different channels through IIC communication is realized.

The SIG _ DET + port is used for detecting the peak upper limit, and if the peak upper limit is exceeded, a high level is output to inform the processor; SIG _ DET-is used for detecting the peak lower limit, and if the peak lower limit is exceeded, a high level is output to inform the processor.

Referring to fig. 6, in some embodiments of the present invention, the unbalanced input module includes a second socket J1006 and a sixth operational amplifier U1012, an input terminal of the second socket J1006 is connected to a first non-inverting input terminal of the sixth operational amplifier U1012, and a first output terminal of the sixth operational amplifier U1012 is connected to the test channel selection module. The processing mode of the unbalanced audio input relative to the balanced input is that the audio input is directly coupled to a subsequent circuit after passing through the magnetic bead and the impedance matching circuit and only needing certain pre-amplification.

Referring to fig. 10, IN some embodiments of the present invention, the listening audio input module includes a third socket MUSIC _ IN, a seventh operational amplifier U1015 and an eighth operational amplifier U1009, the input terminal of the third socket MUSIC _ IN is connected to the first inverting input terminal of the seventh operational amplifier U1015, a second inverting input terminal of the seventh operational amplifier U1015 is connected to the output volume attenuating module, a first output terminal of the seventh operational amplifier U1015 is connected to the output volume attenuating module, a second output terminal of the seventh operational amplifier U1015 is respectively connected to a first inverting input terminal, a first non-inverting input terminal, and a second inverting input terminal of the eighth operational amplifier U1009, a first output end of the eighth operational amplifier U1009 is connected to the left and right listening output selection module, and a second output end of the eighth operational amplifier U1009 is connected to the left and right monitoring output selection module.

Wherein, the INS _ DET port is used for inserting a 3.5mm earphone interface into the detection end; the MUSICI port is used for combining left and right sound channels input by a 3.5mm earphone interface and then used as the input of volume adjustment; the BAL _ OUT + port is used for outputting a positive phase end of a balanced signal through balanced processing of the audio frequency after low-power amplification; the BAL _ OUT-port is used for outputting a negative phase end of a balanced signal through balance processing of the audio frequency after low-power amplification; the MUSICO port is used for outputting after volume adjustment and then carrying out low-power amplification.

Referring to fig. 14, in some embodiments of the present invention, the present invention further includes a power supply module, where the power supply module includes a dc power interface J1002, a fifth chip U2024, and a sixth chip, an input end of the dc power interface J1002 is connected to an input end of the fifth chip U2024 and an input end of the sixth chip, an output end of the fifth chip U2024 is connected to a VCC interface, and an output end of the fifth chip U2024 is connected to the MCU _3.3V interface.

Referring to fig. 11, since the input signal is basically pre-amplified by a certain amount in the circuit of the previous stage, it becomes larger after passing through the base of the subsequent stage according to the output amplitude, and there is a possibility of occurrence of clipping distortion, so that there is a volume control for not only maintaining the integrity of the signal but also for the pilot to adjust the proper volume by himself. In order to control the volume, a digital adjustable volume attenuator is used for controlling the signals output by a test channel and the signals input by monitoring, and the NJU72341 is a dual-channel electronic volume controller, can perform gain on the input signals in a step length of 0dB to 9dB and 3dB, and can also perform volume reduction of 0dB to-95 dB in a step length of 1 dB.

Referring to fig. 7, SGM4806 originally was a solution for low-distortion high-quality audio POP sound, where channel muting is performed before POP sound generated by on/off POP sound, playback pause, and song switching is generated, and then the channel muting is turned on after that, so that the user can listen to the POP sound more comfortably without this bothering. But since the inside is similar to a double-pole double-throw switch, the switch can be used for channel switching and muting. In the design, the scheme of SGM4806 is adopted for testing channel selection, monitoring left and right output selection and 3.5mm earphone output control. According to the pin function in the data manual, the control is relatively simple, EN is an enabling end, a device is enabled at a high level, and all channels are closed at a low level; the MUTECHx port is a low-level effective mute control pin, and a corresponding channel is muted when the MUTECHx port is pulled down; CHSEL sets up the control foot for the channel, the channel 1 is connected when the low level, the channel 2 is connected when the high level; other peripheral circuits comprise charge pump flying capacitors and filter capacitors for power input and output, and the number of required devices is small. Since the left and right output control of the channel is synchronized, it is not possible to input 4 channels and select one output in one SGM4806, so two SGMs 4806 are used for testing channel selection. The left and right sound channels of the monitoring circuit are balanced and output by two paths, and the four paths are output by two paths, so that the purpose of outputting two balanced signals is achieved, and the earphone output control part plays a role of switching.

Referring to fig. 8, in addition to the normal tap key operation, for inputs requiring continuous operations, such as volume up-down control and shift up-down control, a rotary encoder is used for the input. In general, a rotary encoder has three pins, one of which is a common ground and the other two of which are phase (+) and phase (-) a, B, respectively. The AB phases are pulled up, when the knob is rotated, the AB phases output square waves, the phases of the square waves are 90 degrees different, the generated square waves are input into the single chip microcomputer by utilizing the characteristic, the program is processed, whether the square waves are positively rotated or negatively rotated can be distinguished, and corresponding addition and subtraction are carried out. Besides, some rotary encoders have key functions, and the encoder used in the design has the key functions, so that key input can be performed at the same time, and a hardware circuit can be directly connected with a singlechip for input except that a pull-up resistor is required to be added.

In the embodiment of the invention, three rotary encoders are arranged, wherein an HP _ SW port is used for a key detection end of the rotary encoder for trial sound output volume adjustment, and the key detection end is restored to a default volume value after detecting that the key is pressed down; the HP _ VOL + port is used for judging a phase A output end which rotates forward and backward by a rotary encoder for adjusting the sound testing output volume; the HP _ VOL-port is used for judging a B-phase output end which is rotated forward and backward by a rotary encoder for adjusting the sound testing output volume; the BAL _ SW port is used for monitoring a key detection end of a rotary encoder for adjusting the balanced output volume, and the BAL _ SW port is restored to a default volume value after detecting that the BAL _ SW port is pressed down; CAL _ SW is used for detecting a key detection end of a rotary encoder for switching gears by POP sound, enters gear switching when the key detection end detects that the key is pressed for the first time, then selects four gears by rotation, and exits and stores the gears when the key is pressed for the second time.

Referring to fig. 17, the LED display circuit is shown in fig. 17, and 74HC595 is used to drive the LED display, although five control lines are provided, namely (EN) -low level enable 595, (REST) -low level reset output, DATA serial DATA transmission line, CLK DATA clock line, and LATCH _ CLK receiving DATA LATCH control line, where (REST) -can be directly connected to high level, can be cleared by inputting 8-bit all 0 DATA, and (EN) -can be directly connected to low level if software is not needed to control the brightness. Therefore, in practical use, only three control wires are needed to control 8 LED lamps. SQh are used for multiple 74HC595 connections, which are not used here and therefore are left in the air.

Referring to fig. 16, for convenience of control, a 3.3V active buzzer is used, which can be beeped when energized, 2N7002 is an N-channel MOS transistor, which acts as a switch, and the buzzer can be switched by using the characteristic that DS is completely turned on when UGS > 2.5V.

An embodiment of a second aspect of the invention provides an audio device testing method, which includes the following steps:

step S100: the audio signal is accessed from the balanced input module or the unbalanced input module, and the input channel is selected through the test channel selection module;

step S200: the ear amplifier output module amplifies the audio signal output by the test channel selection module, and outputs the amplified audio signal to the external amplifier through the unbalanced output module, or outputs the amplified audio signal to an earphone through the earphone output control module.

In some specific embodiments, the method comprises the following steps:

step S300: the audio signal is accessed through the monitoring audio input module, and the input signal is divided into two paths of signals of left and right sound channels through the monitoring left and right output selection module;

step S400: and outputting the two paths of signals of the left and right sound channels to the earphone through different output interfaces respectively.

In some embodiments, the method further comprises: and inputting the audio signal of the ear amplifier output module into the peak value detection module, and controlling the buzzing alarm module to give out alarm sound if the detected audio signal exceeds a preset range value.

By accessing the audio signals from the balanced input module or the unbalanced input module and selecting the input channel through the test channel selection module, the switching of the output of the sound channel can be realized without manually plugging and unplugging the sound channel wire by a sound tester, and the efficiency of testing the audio equipment is improved; the audio signal that output module was selected the module output with the test channel to the ear is put output module and is enlargied audio signal and export the equipment of putting outward through unbalanced output module, perhaps in export the earphone through earphone output control module, and the pilot can use the equipment of putting outward or the earphone is tried on the sound according to the demand on-the-spot, when using the earphone to try on the sound, can reduce the influence of surrounding environment. In addition, the audio input module can be monitored to access audio signals, the left output selection module and the right output selection module are monitored to divide the input signals into two paths of signals of left and right sound channels, the two paths of signals of the left and right sound channels are output to the earphone through different output interfaces respectively, the earphone can be ear return equipment, therefore, the test of various kinds of equipment can be completed on one large circuit module, switching to a new test circuit device is not needed, and the test efficiency of the audio equipment is improved.

In addition, the audio signal of the ear amplifier output module is input to the peak value detection module, if the detected audio signal exceeds the preset range value, the buzzing alarm module is controlled to give out an alarm, whether the POP sound of the audio equipment reaches the required range can be tested, different tests on the audio equipment can be realized in one large circuit module, switching to other special test devices or circuits is not needed, and the effect of improving the test efficiency is achieved.

The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention.

Claims

1. An audio device test circuit, characterized by: including balanced input module, unbalanced input module, output volume attenuation module, ear put output module, unbalanced output module, test channel selection module, about monitoring sound channel output module, about monitoring output selection module, monitor audio input module, host system, earphone output control module, LED display module, rotary encoder module, test channel selection module respectively with the ear put output module balanced input module the host system, unbalanced input module connects, the ear put output module with output volume attenuation module, unbalanced output module, earphone output control module connects, monitor audio input module with output volume attenuation module about monitoring output selection module the host system connects, output selection module about monitoring still with about monitoring sound channel output module, The main control module is connected with the earphone output control module, the LED display module and the rotary encoder module are respectively connected with the main control module; the power supply module comprises a direct current interface J1002, a fifth chip U2024 and a sixth chip, wherein the input end of the direct current interface J1002 is connected with the input end of the fifth chip U2024 and the input end of the sixth chip, the output end of the fifth chip U2024 is connected with a power supply VCC interface, and the output end of the fifth chip U2024 is connected with a power supply MCU _3.3V interface;

the device also comprises a peak value detection module and a buzzing alarm module, wherein the peak value detection module is respectively connected with the ear amplifier output module and the main control module, and the buzzing alarm is connected with the main control module; the balanced input module includes a first socket J1000, a first operational amplifier U1000 and a second operational amplifier U1006, the T terminal of the first socket J1000 is connected to the first non-inverting input terminal of the second operational amplifier U1006, the BAL-port of the first socket J1000 is connected to a first non-inverting input of the first operational amplifier U1000, the BAL + port of the first socket J1000 is connected to the second non-inverting input of the first operational amplifier U1000, a first output terminal of the first operational amplifier U1000 is connected to a second non-inverting input terminal of the second operational amplifier U1006, a second output terminal of the first operational amplifier U1000 is connected to a second inverting input terminal of the second operational amplifier U1006, a first output of the second operational amplifier U1006 is connected to a second inverting input of the second operational amplifier U1006, a second output of the second operational amplifier U1006 is connected to the test channel selection module.

2. The audio device test circuit of claim 1, wherein: the ear amplifying output module comprises a third operational amplifier U1002, a fourth operational amplifier U1009, a first triode Q5000, a second triode Q5002, a third triode Q1001 and a fourth triode Q1002, a first inverting input terminal of the third operational amplifier U1002 is connected with the test channel selection module, a first output terminal of the third operational amplifier U1002 is connected with the output volume attenuation module and the peak detection module, respectively, a second non-inverting input terminal of the third operational amplifier U1002 is connected with a power source VREF, a second output terminal of the third operational amplifier U1002 is connected with the unbalanced output module, a first inverting input terminal of the fourth operational amplifier U1009 and the earphone output control module, a first inverting input terminal of the fourth operational amplifier U1009 is further connected with the output volume attenuation module, and an output terminal of the third operational amplifier U1002 is connected with the first triode Q5000, the second triode Q5002, the third triode Q1001 and the fourth triode Q1002 The base of the second triode Q5002 is connected, the fourth operational amplifier U1009 is connected to the bases of the third triode Q1001 and the fourth triode Q1002, the emitter of the first triode Q5000 is connected to the emitter of the second triode Q5002 and to the earphone output control module, and the emitter of the third triode Q1001 is connected to the emitter of the fourth triode Q1002 and to the earphone output control module.

3. The audio device test circuit of claim 1, wherein: the peak detection module includes a fifth operational amplifier U1003, a first chip IC1001A, a second chip IC1001B, a third chip IC1001C and a fourth chip U1001, a first positive phase input terminal of the fifth operational amplifier U1003 is connected to the ear-to-ear output module, a first output terminal of the fifth operational amplifier U1003 is connected to a negative phase input terminal of the first chip IC1001A and a positive phase input terminal of the second chip IC1001B, a positive phase input terminal of the first chip IC1001A is connected to the third chip IC1001C and the fourth chip U1001, an output terminal of the first chip IC1001A is connected to the master control module, an output terminal of the second chip IC1001B is connected to the master control module, and the fourth chip U1001 is connected to the master control module.

4. The audio device test circuit of claim 1, wherein: the unbalanced input module comprises a second socket J1006 and a sixth operational amplifier U1012, wherein the input end of the second socket J1006 is connected with the first non-inverting input end of the sixth operational amplifier U1012, and the first output end of the sixth operational amplifier U1012 is connected with the test channel selection module.

5. The audio device test circuit of claim 1, wherein: the audio monitoring input module comprises a third socket MUSIC _ IN, a seventh operational amplifier U1015 and an eighth operational amplifier U1009, an input end of the third socket MUSIC _ IN is connected with a first inverting input end of the seventh operational amplifier U1015, a second inverting input end of the seventh operational amplifier U1015 is connected with the output volume attenuation module, a first output end of the seventh operational amplifier U1015 is connected with the output volume attenuation module, a second output end of the seventh operational amplifier U1015 is respectively connected with a first inverting input end, a first non-inverting input end and a second inverting input end of the eighth operational amplifier U1009, a first output end of the eighth operational amplifier U1009 is connected with the left and right monitoring output selection module, and a second output end of the eighth operational amplifier U1009 is connected with the left and right monitoring output selection module.

6. An audio device testing method applied to the audio device testing circuit according to any one of claims 1 to 5, comprising the steps of:

alternatively, the first and second electrodes may be,

7. The audio device testing method of claim 6, further comprising:

and inputting the audio signal of the ear amplifier output module into the peak value detection module, and controlling the buzzing alarm module to give out alarm sound if the detected audio signal exceeds a preset range value.