CN211702374U - Audio amplification device and audio system - Google Patents
Audio amplification device and audio system Download PDFInfo
- Publication number
- CN211702374U CN211702374U CN201922194201.0U CN201922194201U CN211702374U CN 211702374 U CN211702374 U CN 211702374U CN 201922194201 U CN201922194201 U CN 201922194201U CN 211702374 U CN211702374 U CN 211702374U
- Authority
- CN
- China
- Prior art keywords
- amplifying
- audio
- unit
- gain
- resistor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Abstract
The utility model is suitable for an audio frequency amplification technology field provides an audio frequency amplification device and audio system, and audio frequency amplification device includes amplifying unit and two at least gain control units, and amplifying unit is connected to gain control unit's one end, and gain control unit is including the amplifying resistor unit and the switching device that establish ties and set up, and amplifying unit is perhaps connected to gain control unit's other end ground connection. When the gain needs to be adjusted, the corresponding gain adjusting unit is put into the control switch device, the resistance value of the equivalent resistor of the gain adjusting unit can be obtained through calculation of the resistance value of each put-in amplifying resistor unit, the specific multiple of the gain corresponding to the specific resistance value of the equivalent resistor can also be obtained through conversion, quantitative and accurate adjustment of the gain is achieved, and adjustment accuracy of the gain is improved. In addition, the audio amplifying device can realize accurate adjustment of gain through at least two gain adjusting units, and the circuit structure is simpler.
Description
Technical Field
The application belongs to the technical field of audio amplification, and particularly relates to an audio amplification device and an audio system.
Background
The gain controller is a main component in the audio amplification apparatus. The existing gain controller generally includes an input impedance controller, an input current controller, and an output impedance controller, so that the circuit structure of the gain controller is complicated. Also, the gain adjustment of the input impedance controller, the input current controller, and the output impedance controller is usually a coarse adjustment, making it difficult for the gain controller to make a fine adjustment of the gain.
SUMMERY OF THE UTILITY MODEL
In view of this, embodiments of the present application provide an audio amplifying device and an audio system to solve the problems that the circuit structure of the conventional audio amplifying device is complex and it is difficult to precisely adjust the gain.
A first aspect of an embodiment of the present application provides an audio amplifying apparatus, including:
an amplifying unit; and
at least two gain adjustment units;
one end of the gain adjusting unit is connected with the amplifying unit, the gain adjusting unit comprises an amplifying resistor unit and a switch device which are arranged in series, and the other end of the gain adjusting unit is grounded or connected with the amplifying unit.
In one embodiment, in each gain adjustment unit, one end of the amplification resistance unit is connected to the amplification unit, the other end of the amplification resistance unit is connected to the input end of the switching device, and the output end of the switching device is grounded.
In one embodiment, the switching device is an electronic switching device.
In one embodiment, the control terminal of the electronic switching device is provided with a current limiting resistor.
In one embodiment, in each of the gain adjusting units, the amplifying resistor unit includes one amplifying resistor or is formed by connecting at least two amplifying resistors in series/parallel.
In one embodiment, the resistance values of all the amplifying resistor units are the same.
In one embodiment, the amplifying unit includes a gain amplifying chip or an operational amplifying circuit.
In one embodiment, if the amplifying unit includes a gain amplifying chip, one end of the gain adjusting unit is connected to a gain adjusting pin of the amplifying unit; and if the amplifying unit comprises an operational amplifying circuit, one end of the gain adjusting unit is connected with an operational amplifier in the amplifying unit.
A second aspect of an embodiment of the present application provides an audio system, including:
an audio acquisition device;
a controller; and
an audio amplification device as provided in the first aspect of the embodiments of the present application described above;
the audio acquisition equipment is connected with the audio amplification device, and the audio amplification device is connected with the controller.
In one embodiment, the audio system further comprises a distance detection device for detecting a distance between a sound source and the audio acquisition device, the distance detection device being connected to the controller.
In one embodiment, the distance detection device comprises at least one of a laser range finder, a radar range finder and a camera.
By adopting the technical scheme, the switching-on or switching-off of the switching devices is controlled to realize the switching-on or the switching-off of the gain adjusting units, when different numbers of gain adjusting units are switched in, the equivalent resistances of the switched-in gain adjusting units are different, and the different equivalent resistances correspond to different multiples of gains. When the gain needs to be adjusted, the switch device is controlled to be put into the corresponding gain adjusting unit, and the resistance value of the equivalent resistor can be obtained through calculation of the resistance values of the put amplifying resistor units, so that the specific resistance value of the equivalent resistor can be accurately obtained by the audio amplifying device, the specific multiple of the gain corresponding to the specific resistance value of the equivalent resistor can be obtained through conversion, quantitative and accurate adjustment of the gain is achieved, and the adjustment accuracy of the gain is improved. In addition, the audio amplifying device can realize accurate adjustment of gain through at least two gain adjusting units, and the circuit structure is simpler.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without inventive labor.
Fig. 1 is a schematic circuit diagram of a first circuit structure of an audio amplifying device according to an embodiment of the present application;
fig. 2 is a schematic circuit diagram of a second circuit structure of an audio amplifying device according to an embodiment of the present application;
fig. 3 is a schematic diagram of a third circuit structure of an audio amplifying device according to an embodiment of the present application;
fig. 4 is a schematic diagram of a first overall structure of an audio system according to a second embodiment of the present application;
fig. 5 is a schematic diagram of a second overall structure of an audio system according to the second embodiment of the present application.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the present application. It will be apparent, however, to one skilled in the art that the present application may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.
It will be understood that the terms "comprises" and/or "comprising," when used in this specification and the appended claims, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It is also to be understood that the terminology used in the description of the present application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in the specification of the present application and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
In order to explain the technical means described in the present application, the following description will be given by way of specific embodiments.
Fig. 1 is a schematic diagram of a first circuit structure of an audio amplifying device according to an embodiment of the present application. For convenience of explanation, only portions related to the embodiments of the present application are shown.
As shown in fig. 1, the audio amplifying apparatus includes an amplifying unit 101 and at least two gain adjusting units 102.
The amplifying unit 101 is configured to amplify an audio signal, and the amplifying unit 101 includes an audio input end and an audio output end, where the audio input end is configured to input the audio signal, and the audio output end is configured to output the amplified audio signal.
The specific number of gain adjustment units 102 is determined by actual requirements, such as amplification requirements, and fig. 1 takes three as an example. One end of each gain adjustment section 102 is connected to amplification section 101. For any one of the gain adjustment units 102, an amplification resistance unit 1021 and a switching device 1022 are included, and the amplification resistance unit 1021 and the switching device 1022 are arranged in series.
Specifically, as shown in fig. 1, one end of an amplifying resistance unit 1021 is connected to the amplifying unit 101, and the other end of the amplifying resistance unit 1021 is connected to an input terminal of a switching device 1022. As another embodiment, the positions of the amplifying resistor unit 1021 and the switching device 1022 may be interchanged. The resistance of each amplifying resistor unit 1021 is determined by actual requirements, such as the gain adjustment range required actually, and the resistance of each amplifying resistor unit 1021 may be the same or different. The amplifying resistor unit 1021 includes one resistor or is constituted by at least two resistors connected in series/parallel, that is, the amplifying resistor unit 1021 may be constituted by only one resistor or at least two resistors connected in series/parallel, and each resistor is referred to as an amplifying resistor in order to correspond to a function.
The switching device 1022 may be an electronic switching device, such as a MOS transistor, or other type of electrically controlled switching device; or a manual switch, such as a conventional rocker switch, to realize manual switching. If the switching devices 1022 are electronic switching devices, a control terminal of each switching device 1022 is used to connect to a controller, and the controller controls each switching device 1022 to turn on or off.
Each gain adjustment unit 102 is connected to an audio amplification end, i.e., a gain adjustment end, of the amplification unit 101, where a specific type of the gain adjustment end is determined by a specific implementation manner of the amplification unit 101, the amplification unit 101 may include an audio amplification chip or an amplification circuit, and the amplification circuit may be an operational amplification circuit based on an operational amplifier (i.e., an operational amplifier), or may be another type of amplification circuit, such as an amplification circuit based on a triode. If the amplifying unit 101 is an audio amplifying chip, one end of each gain adjusting unit 102 is connected to a gain adjusting pin of the amplifying unit 101; if the amplifying unit 101 is an operational amplifier circuit, one end of each gain adjusting unit 102 is connected to an operational amplifier in the operational amplifier circuit.
The other end of each gain adjustment unit 102 may be grounded, or may be connected to the amplification unit 101, where the specific connection mode is determined by the specific implementation mode of the amplification unit 101, for example: if the amplifying unit 101 is an audio amplifying chip, it may be grounded; if the amplifying unit 101 is an operational amplifier circuit, it may be grounded, or an operational amplifier in the operational amplifier circuit may be connected, and the specific connection position to the operational amplifier is determined by the specific circuit structure of the operational amplifier circuit.
As for the connection mode of each gain adjustment unit 102, each gain adjustment unit 102 is provided in parallel, and for any gain adjustment unit 102, the switching device 1022 is turned on and the amplification resistance unit 1021 is put in; the switching device 1022 is turned off, and the amplification resistance unit 1021 exits. When different numbers of gain adjustment units 102 are put in, the equivalent resistances of the put-in gain adjustment units 102 are different, and different equivalent resistances correspond to different multiples of gain. Then, when the gain needs to be adjusted, the corresponding gain adjustment unit 102 is controlled to be put into operation according to the target gain, so that the specific resistance value of the corresponding equivalent resistor can be obtained, and the specific gain multiple can be obtained. Therefore, the audio amplification device can realize quantitative accurate adjustment of gain and improve the accuracy of gain adjustment. Moreover, the audio amplifying apparatus can realize accurate adjustment of the gain through at least two gain adjusting units 102, and the circuit structure is relatively simple.
Fig. 2 is a schematic diagram of a second circuit structure of an audio amplifying device according to an embodiment of the present application. For convenience of explanation, only portions related to the embodiments of the present application are shown.
The audio amplification apparatus includes an amplification unit 201 and at least two gain adjustment units.
The amplifying unit 201 is configured to amplify an audio signal, and the amplifying unit 201 is an audio amplifying chip, such as a programmable gain amplifier of the type PGA2311, and includes a gain adjustment pin, an audio input pin, and an audio output pin, where the audio input pin is configured to input the audio signal, and the audio output pin is configured to output the amplified audio signal.
The specific number of gain adjustment units is determined by actual requirements, such as amplification requirements, and fig. 2 takes four as an example. Each gain adjustment unit has the same structure, and as shown in fig. 2, any one gain adjustment unit includes an amplification resistor unit 202 and an electronic switching device 203, one end of the amplification resistor unit 202 is connected to a gain adjustment pin of the amplification unit 201, the other end of the amplification resistor unit 202 is connected to an input end of the electronic switching device 203, and an output end of the electronic switching device 203 is grounded. In this embodiment, in order to reduce the circuit complexity, each amplifying resistor unit 202 is an amplifying resistor, and the resistance values of the amplifying resistor units 202 are the same and are all 10k Ω. Each electronic switching device 203 is a MOS transistor.
In order to reduce the current received by the control end of the electronic switching device 203 and avoid burning out the electronic switching device 203, the control end of each electronic switching device 203 is provided with a current limiting resistor 204, and the resistance value of the current limiting resistor 204 is determined by actual conditions.
The control end of each electronic switching device 203 is used for connecting with a controller, and the controller controls the electronic switching devices 203 to be switched on or switched off.
Since one end of each gain adjusting unit is connected to the amplifying unit 201 and the other end is grounded, the gain adjusting units are arranged in parallel. For any gain adjustment unit, the electronic switching device 203 is turned on, and the amplification resistance unit 202 is turned on; the electronic switching device 203 is turned off and the amplifying resistor unit 202 is withdrawn. When different numbers of gain adjusting units are put in, the equivalent resistances of the put gain adjusting units are different, and since the resistance values of the amplifying resistor units 202 are the same and 10k Ω, when one amplifying resistor unit 202 is put in, the equivalent resistance is 10k Ω; when two amplifying resistance units 202 are put in, the equivalent resistance is 5k Ω; when three amplifying resistance units 202 are put in, the equivalent resistance is 3.333k Ω; when four amplifying resistance units 202 are put in, the equivalent resistance is 2.5k Ω. Different resistance values of the equivalent resistor correspond to different multiples of gain. Then, when the gain needs to be adjusted, the corresponding number of gain adjusting units are put into the target gain control, so that the required equivalent resistance can be obtained, and the accurate adjustment of the gain is realized. Therefore, the audio amplification device can realize quantitative accurate adjustment of the gain.
Fig. 3 is a schematic diagram of a third circuit structure of an audio amplifying device according to an embodiment of the present application. For convenience of explanation, only portions related to the embodiments of the present application are shown.
The audio amplification device comprises an amplification unit and at least two gain adjustment units. Wherein, the amplifying unit is an operational amplifying circuit. There are many operational amplifier circuits based on operational amplifiers, such as a proportional amplifier circuit, an in-phase amplifier circuit, an addition amplifier circuit, etc., and hereinafter, the most basic in-phase amplifier circuit is taken as an example, and any amplifier circuit is improved on the basis of the basic amplifier circuit.
The operational amplifier circuit comprises an operational amplifier 301, wherein the non-inverting input end of the operational amplifier 301 is an audio input end and is used for inputting an audio signal; the output end of the operational amplifier 301 is an audio output end for outputting the amplified audio signal.
One end of each gain adjustment unit is connected to the inverting input terminal of the operational amplifier 301, the other end is connected to the output terminal of the operational amplifier 301, and the inverting input terminal of the operational amplifier 301 is grounded through the resistor 304.
The specific number of gain adjustment units is determined by actual requirements, such as amplification requirements, and fig. 3 takes three as an example. The structures of the gain adjustment units are the same, and as shown in fig. 3, any one of the gain adjustment units includes an amplification resistance unit 302 and an electronic switching device 303, the amplification resistance unit 302 and the electronic switching device 303 are arranged in series, and the position between the amplification resistance unit 302 and the electronic switching device 303 is not unique. In this embodiment, each amplifying resistor unit 302 is an amplifying resistor, and the resistance values of the amplifying resistor units 302 are the same. Each electronic switching device 303 is a MOS transistor.
In order to reduce the current received by the control terminal of the electronic switching device 303 and avoid burning out of the electronic switching device 303, the control terminal of each electronic switching device 303 is provided with a current limiting resistor (not shown in fig. 3), and the resistance value of the current limiting resistor is determined by actual conditions.
The control end of each electronic switching device 303 is used for connecting with a controller, and the controller controls the electronic switching devices 303 to be turned on or off.
Since one end of each gain adjustment unit is connected to the inverting input terminal of the operational amplifier 301 and the other end is connected to the output terminal of the operational amplifier 301, each gain adjustment unit is arranged in parallel. For any gain adjustment unit, the electronic switching device 303 is turned on, and the amplification resistance unit 302 is turned on; the electronic switching device 303 is turned off and the amplifying resistor unit 302 exits.
If the equivalent resistance of all the input gain adjusting units is set to R1 and the resistance 304 is set to R2, the amplification factor of the operational amplifier circuit, i.e., the gain factor a, is:
then, different numbers of gain adjustment units are put into the circuit, the resistance of the equivalent resistor R1 will be different, and the gain multiple a will be different, so that the accurate adjustment of the gain can be realized by adjusting the put-in gain adjustment units according to the target gain.
In another embodiment, the positions of the gain adjusting units and the resistor 304 may be interchanged, that is, one end of each gain adjusting unit is connected to the inverting input terminal of the operational amplifier 301, the other end is grounded, one end of the resistor 304 is connected to the inverting input terminal of the operational amplifier 301, and the other end of the resistor 304 is connected to the output terminal of the operational amplifier 301. Then, the amplification factor of the operational amplifier circuit, i.e. the gain factor a, is:
wherein, R1 is the resistance of the equivalent resistor of all the input gain adjusting units, and R2 is the resistance of the resistor 304.
Then, different numbers of gain adjustment units are put into the circuit, the resistance of the equivalent resistor R1 will be different, and the gain multiple a will be different, so that the accurate adjustment of the gain can be realized by adjusting the put-in gain adjustment units according to the target gain.
The second embodiment of the present application provides a first audio system, as shown in fig. 4, including an audio acquisition device 401, an audio amplifying apparatus 402, and a controller 403. The audio acquisition device 401 is connected to an audio amplification device 402, the audio amplification device 402 is connected to the controller 403, and the amplified audio signal is output to the controller 403. If the switch device in the audio amplifying apparatus 402 is a manual switch, the controller 403 does not need to connect to each electronic switch device in the audio amplifying apparatus 402; if the switching device in the audio amplifier 402 is an electronic switching device, the controller 403 is also connected to each electronic switching device in the audio amplifier 402.
The audio capture device 401 may be a microphone; the controller 403 may be a control chip, such as a single chip, or a computing device such as a computer host. The audio amplifying apparatus 402 is described in detail in the above embodiments of the audio amplifying apparatus, and is not described in detail again.
It should be noted that the audio system is protected by a hardware structure, and is not limited to a software control strategy inside the audio system.
The second audio system provided in the second embodiment of the present application, as shown in fig. 5, includes an audio acquisition device 501, an audio amplification apparatus 502, a distance detection device 503, and a controller 504. The audio acquisition device 501 is connected with an audio amplification device 502, and the audio amplification device 502 and the distance detection device 503 are connected with a controller 504.
The audio capture device 501 may be a microphone. The distance detection device 503 is used to detect the distance between the sound source and the audio acquisition device 501, and the distance detection device 503 is of many kinds, such as a laser range finder, a radar range finder, and a camera, and then the distance detection device 503 may include at least one of a laser range finder, a radar range finder, and a camera. The camera identifies and obtains the distance between the sound source and the audio acquisition equipment 501 by acquiring images of the sound source and the audio acquisition equipment 501. In this embodiment, the distance detection device 503 is a camera, the arrangement of the camera is flexible, the camera can be placed at any position as long as the distance between the sound source and the audio acquisition device 501 can be obtained according to the acquired image, and when the position is changed, only the distance detection algorithm needs to be adjusted correspondingly. In the embodiment, a single-camera ranging method is adopted, and the distance between the sound source and the audio acquisition device 501 is calculated by measuring the focused distance by combining with the lens parameters of the camera, and the method is widely used and will not be described in more detail. Although the single-camera ranging method has the condition that the measurement result is not very accurate due to inaccurate lens parameter estimation, only the approximate distance needs to be known in the application. The controller 504 may be a control chip, such as a single chip, or a computer device such as a computer host. The audio amplifier 502 is described in detail in the above embodiments of the audio amplifier, and will not be described in detail.
It should be noted that the audio system protects the hardware structure, and is not limited to the software control strategy inside the audio system, such as: the distance detection device 503 detects the distance between the sound source and the audio acquisition device 501 in real time, and the controller 504 adjusts the gain of the audio amplification device 502 in real time according to the distance, so that when the distance between the sound source and the audio acquisition device 501 is increased, the gain of the audio amplification device 502 is increased, and reliable output of audio signals is ensured.
The above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may be modified or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present application and are intended to be included within the scope of the present application.
Claims (10)
1. An audio amplification apparatus, comprising:
an amplifying unit; and
at least two gain adjustment units;
one end of the gain adjusting unit is connected with the amplifying unit, the gain adjusting unit comprises an amplifying resistor unit and a switch device which are arranged in series, and the other end of the gain adjusting unit is grounded or connected with the amplifying unit.
2. The audio amplifying apparatus according to claim 1, wherein in each of the gain adjusting units, one end of the amplifying resistance unit is connected to the amplifying unit, the other end of the amplifying resistance unit is connected to an input terminal of the switching device, and an output terminal of the switching device is grounded.
3. The audio amplification apparatus of claim 1 or 2, wherein the switching device is an electronic switching device.
4. The audio amplifying device according to claim 3, wherein the control terminal of the electronic switching device is provided with a current limiting resistor.
5. The audio amplifying device according to claim 1 or 2, wherein the amplifying resistor unit comprises one amplifying resistor or is composed of at least two amplifying resistors connected in series/parallel.
6. The audio amplifying device according to claim 1 or 2, wherein the resistance values of all the amplifying resistor units are the same.
7. The audio amplifying device according to claim 1 or 2, wherein the amplifying unit includes a gain amplifying chip or an operational amplifier circuit.
8. The audio amplifier device of claim 7, wherein if the amplifying unit comprises a gain amplifying chip, one end of the gain adjusting unit is connected to a gain adjusting pin of the amplifying unit; and if the amplifying unit comprises an operational amplifying circuit, one end of the gain adjusting unit is connected with an operational amplifier in the amplifying unit.
9. An audio system, comprising:
an audio acquisition device;
a controller; and
the audio amplification apparatus of any one of claims 1-8;
the audio acquisition equipment is connected with the audio amplification device, and the audio amplification device is connected with the controller.
10. The audio system according to claim 9, further comprising a distance detection device for detecting a distance between a sound source and the audio capturing device, the distance detection device being connected to the controller.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201922194201.0U CN211702374U (en) | 2019-12-09 | 2019-12-09 | Audio amplification device and audio system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201922194201.0U CN211702374U (en) | 2019-12-09 | 2019-12-09 | Audio amplification device and audio system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN211702374U true CN211702374U (en) | 2020-10-16 |
Family
ID=72790332
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201922194201.0U Active CN211702374U (en) | 2019-12-09 | 2019-12-09 | Audio amplification device and audio system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN211702374U (en) |
-
2019
- 2019-12-09 CN CN201922194201.0U patent/CN211702374U/en active Active
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP4828542B2 (en) | Impedance detector | |
| TW201403078A (en) | Resistance testing apparatus | |
| US10955497B2 (en) | Phase compensation circuit, magnetic induction imaging device and phase compensation method | |
| US10834504B2 (en) | Temperature detecting and controlling integration device and the temperature controlling method applied for micro speaker | |
| CN107249165A (en) | Sensitivity of microphone adjusts system and method | |
| US10230336B2 (en) | RF power detector circuits | |
| CN211702374U (en) | Audio amplification device and audio system | |
| KR101559851B1 (en) | Apparatus for detecting a frequency of signal | |
| JP2003274491A (en) | Apparatus for detecting disconnection of loudspeaker | |
| CN111551864A (en) | High-precision bidirectional current detection circuit applied to battery charging and discharging and method thereof | |
| WO2019178740A1 (en) | Touch sensing circuit, touch panel, touch apparatus and touch method | |
| WO2020155068A1 (en) | Current measuring device, method, and apparatus | |
| US20210135697A1 (en) | Time-Sharing Detection Control Circuit, Wireless Transceiver System And Time-Sharing Detection And Control Method | |
| CN111262538A (en) | Audio signal gain adjustment method and device, terminal equipment and audio system | |
| US11262263B2 (en) | Sensing device, electronic system and sensing method | |
| CN110636411A (en) | Power balance method and device of loudspeaker system | |
| CN110572732B (en) | Earphone standard and impedance measuring device and method | |
| CN111432321A (en) | Audio equipment test circuit and test method | |
| US20170160312A1 (en) | Measuring device | |
| CN218866381U (en) | Voltage regulating circuit and voltage measuring circuit | |
| JP2006203796A (en) | Method of adjusting imaging apparatus | |
| TWI711827B (en) | Current measurement system | |
| CN211296932U (en) | But power balance's speaker | |
| KR20060025771A (en) | Programmable shunt calibration apparatus of strain gauge bridge | |
| CN210923868U (en) | Signal adjusting device for detecting performance of multilayer ceramic capacitor |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant |