Sound control circuit and sound amplification system

Abstract

The utility model relates to the field of sound amplification equipment, in particular to a sound control circuit and a sound amplification system, and the sound control circuit comprises a sound channel selection module, a resistor array, a sound output module, a main control module and an anti-interference module. The sound channel selection module is respectively connected with the main control module and the resistor array, and the resistor array is connected with the sound output module; the main control module is connected with the anti-interference module, the anti-interference module is connected with the sound output module, and the technical problem that sound interruption or mechanical noise is prone to occurring in an existing volume controller is solved.

Description

Technical Field

[0001] This utility model relates to the field of sound reinforcement equipment, and in particular to a sound control circuit and a sound reinforcement system. Background Technology

[0002] In the field of sound reinforcement equipment, traditional mechanical rotary toggle switch volume controllers are commonly used to control speaker volume. These controllers consist of a mechanical rotary switch and other auxiliary components. The main body of the mechanical rotary toggle switch typically includes a plastic or metal handle, terminals, a movable contact plate or spring, and other accessories. It offers relatively high resistance, and with increased usage frequency and environmental influences, poor contact or metal dust may occur between the terminals and movable contact plates, easily generating mechanical noise. This can lead to abnormal noise or sound interruption malfunctions in the sound reinforcement system's speakers, resulting in a poor user experience. Utility Model Content

[0003] This utility model discloses a sound control circuit and a sound reinforcement system to solve the technical problem that existing volume controllers are prone to sound dropouts or mechanical noise.

[0004] This utility model embodiment provides a sound control circuit, including: a channel selection module, a resistor array, a sound output module, a main control module, and an anti-interference module;

[0005] The channel selection module is connected to the main control module and the resistor array respectively, and the resistor array is connected to the sound output module;

[0006] The main control module is connected to the anti-interference module, and the anti-interference module is connected to the sound output module.

[0007] Optionally, the channel selection module includes at least one first electronic switch; each of the first electronic switches is connected to the main control module.

[0008] The first electronic switch is connected to the resistor array in a one-to-one correspondence.

[0009] Optionally, the sound output module includes at least one second electronic switch;

[0010] The second electronic switch is connected to the resistor array in a one-to-one correspondence.

[0011] Optionally, the resistor array includes: a plurality of resistors connected in series;

[0012] One end of each of the resistors is connected to the second electronic switch;

[0013] The resistors located at both ends of the resistor array are connected to the first electronic switch and ground, respectively.

[0014] Optionally, the first electronic switch is provided with a channel terminal, a channel selection terminal, a first disable terminal, an audio signal output terminal, and a power supply terminal;

[0015] The audio channel end is used to receive audio signals;

[0016] The channel selection terminal and the first prohibition terminal are respectively connected to the main control module;

[0017] The sound signal output terminal is connected to the first capacitor, and the first capacitor is connected to the first resistor;

[0018] The first resistor is connected to the resistor array;

[0019] The power supply terminal is connected to the power module.

[0020] Optionally, the second electronic switch is provided with a sound input terminal, a ground terminal, a power supply terminal, a sound output terminal, and an isolation signal input terminal;

[0021] The sound input terminal is connected to the resistor array;

[0022] The grounding terminal is connected to the ground;

[0023] The power supply terminal is connected to the power module;

[0024] The isolation signal input terminal is connected to the anti-interference module;

[0025] The sound output terminal is used to output sound signals.

[0026] Optionally, the anti-interference module includes: an optocoupler;

[0027] One end of the optocoupler is connected to the main control module, and the other end of the optocoupler is connected to the isolation signal input terminal.

[0028] Optionally, the optocoupler includes a second resistor, a light-emitting diode, a photosensitive element, and a third resistor;

[0029] One end of the second resistor is connected to the power module, the other end of the second resistor is connected to the anode of the light-emitting diode, and the cathode of the light-emitting diode is connected to the main control module;

[0030] The light-emitting diode is positioned opposite to the photosensitive element;

[0031] One end of the photosensitive element is connected to the third resistor, and the third resistor is connected to the power module and the isolation signal input terminal.

[0032] Optionally, the main control module is provided with a second disable terminal and a volume adjustment terminal;

[0033] The second blocking terminal and the volume adjustment terminal are respectively connected to the optocoupler one by one.

[0034] This utility model also provides a sound reinforcement system, including the sound control circuit as described in any of the preceding claims. As can be seen from the above technical solutions, the embodiments of this utility model have the following advantages:

[0035] This utility model embodiment provides a sound control circuit, including: a channel selection module, a resistor array, a sound output module, a main control module, and an anti-interference module; the channel selection module is connected to the main control module and the resistor array respectively, the resistor array is connected to the sound output module; the main control module is connected to the anti-interference module, and the anti-interference module is connected to the sound output module.

[0036] In the audio control circuit provided by this utility model, based on the connection relationship between the main control module and the channel selection module, it can be used to select the channel. The channel selection module is connected to a resistor array, so that the resistors in the resistor array divide the signal output by the channel selection module. Based on the connection relationship between the resistor array and the sound output module, and the connection relationship between the main control module, the anti-interference module, and the sound output module, the resistance values ​​of the resistors participating in the voltage division in the resistor array can be changed, and the divided signal can be output to adjust the sound volume. Furthermore, by setting up an anti-interference module, interference in signal transmission between the main control module and the sound output module is reduced, improving circuit performance. Therefore, the audio control circuit provided by this utility model eliminates the need for a mechanical knob toggle switch-type volume controller for volume adjustment, avoiding the problems of interrupted sound or mechanical noise that are prone to occur with mechanical knob toggle switch-type volume controllers, thus improving the user experience. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the structure of a sound control circuit provided in an embodiment of this utility model;

[0039] Figure 2 This is another structural schematic diagram of a voice control circuit provided in an embodiment of the present utility model. Detailed Implementation

[0040] This utility model provides a sound control circuit and a sound reinforcement system to solve the technical problems of existing volume controllers easily experiencing sound interruptions or mechanical noise. The technical solution of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the scope of protection of this utility model.

[0041] In the description of this utility model, it should be noted that the terms "front," "rear," "upper," "lower," "both ends," "center," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Relational terms such as "first," "second," etc., are only used to distinguish one entity from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities.

[0042] Unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," "fixing," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, a direct connection, or an indirect connection through an intermediate medium; or they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0043] Please see Figure 1 One embodiment of the sound control circuit provided in this utility model includes: a channel selection module 1, a resistor array 2, a sound output module 3, a main control module 4, and an anti-interference module 5;

[0044] The channel selection module 1 is connected to the main control module 4 and the resistor array 2 respectively, and the resistor array 2 is connected to the sound output module 3;

[0045] The main control module 4 is connected to the anti-interference module 5, and the anti-interference module 5 is connected to the sound output module 3.

[0046] It should be noted that the channel selection module 1 receives the audio signals from each audio channel. The main control module 4 is connected to the channel selection module 1 and can output a level signal to enable the channel selection module 1 to output the desired audio signal, thus achieving audio signal selection. The channel selection module 1 is connected to the resistor array 2 and outputs the audio signal to the resistor array 2. The resistor array 2 is used to divide the audio signal into voltages to achieve volume adjustment. Based on the connection between the resistor array 2 and the audio output module 3, each divided voltage signal can be input to the audio output module 3. The main control module 4 is connected to the audio output module 3 through the anti-interference module 5. In practical applications, the main control module 4 can output a level signal to change the resistors in the resistor array that are connected to the audio output module, thereby causing the audio output module 3 to output the required divided voltage signal and achieve volume adjustment.

[0047] Therefore, the volume control circuit provided in this embodiment does not require a mechanical knob toggle switch for volume adjustment, avoiding the problems of interrupted sound or mechanical noise that are common with mechanical knob toggle switch volume controllers, thus improving the user experience.

[0048] In one specific embodiment, the channel selection module 1 includes at least one first electronic switch; each of the first electronic switches is connected to the main control module 4.

[0049] The first electronic switch is connected to the resistor array 2 in a one-to-one correspondence.

[0050] It should be noted that the number of first electronic switches can be determined based on the channel scenario in which they are applied. For example, when applied to two channels, there are two first electronic switches, and when applied to multi-channel channels, such as 5.1 channels, there are six first electronic switches.

[0051] The number of resistor arrays 2 is the same as the number of first electronic switches, and each first electronic switch is connected to one resistor array 2. Each first electronic switch is connected to the main control module 4.

[0052] In one specific embodiment, the sound output module 3 includes at least one second electronic switch;

[0053] The second electronic switch is connected to the resistor array 2 in a one-to-one correspondence.

[0054] It should be noted that the number of second electronic switches is the same as the number of resistor arrays 2. Each second electronic switch is connected to one resistor array 2.

[0055] In one specific embodiment, the resistor array 2 includes: a plurality of resistors connected in series;

[0056] One end of each of the resistors is connected to the second electronic switch;

[0057] The resistors located at both ends of the resistor array 2 are connected to the first electronic switch and ground, respectively.

[0058] It should be noted that multiple resistors are set in resistor array 2, each resistor is connected in series, and each series connection is connected to the second electronic switch. The resistors located at both ends of resistor array 2 are connected to the first electronic switch and grounded. The resistor connected to the first electronic switch is also connected to the second electronic switch at the connection point between the resistor and the first electronic switch.

[0059] Based on the resistor array 2 provided in this embodiment, the sound output from the first electronic switch can be divided into voltages to different degrees, thereby changing the voltage level of the signal and achieving volume adjustment. Specifically, the volume can be changed by adjusting the number and resistance value of the resistors participating in the voltage division in the resistor array.

[0060] In one specific embodiment, the first electronic switch is provided with a channel terminal, a channel selection terminal, a first disable terminal, an audio signal output terminal, and a power supply terminal;

[0061] The audio channel end is used to receive audio signals;

[0062] The channel selection terminal and the first prohibition terminal are respectively connected to the main control module 4;

[0063] The sound signal output terminal is connected to the first capacitor, and the first capacitor is connected to the first resistor;

[0064] The first resistor is connected to the resistor array 2;

[0065] The power supply terminal is connected to the power module.

[0066] It should be noted that the first electronic switch has seven channel terminals, each used to receive the audio signal from one audio channel. It also has three channel selection terminals and a first disable terminal. These three selection terminals and the first disable terminal receive the level signals output from the main control module 4, which are used to activate the corresponding audio channel and audio output terminal, thereby causing the audio output terminal to output the corresponding audio signal. Therefore, based on the connection between the main control module 4 and the first electronic switch, audio signal selection can be achieved.

[0067] The first blocking terminal is used to stop and enable channel selection. The three channel selection terminals are used to select the channel to be activated.

[0068] In one specific embodiment, the second electronic switch is provided with a sound input terminal, a ground terminal, a power supply terminal, a sound output terminal, and an isolation signal input terminal;

[0069] The sound input terminal is connected to the resistor array 2;

[0070] The grounding terminal is connected to the ground;

[0071] The power supply terminal is connected to the power module;

[0072] The isolation signal input terminal is connected to the anti-interference module 5;

[0073] The sound output terminal is used to output sound signals.

[0074] It should be noted that the second electronic switch has multiple audio input terminals, each connected to a corresponding resistor array 2. The other end of the resistor in resistor array 2 connected to ground is connected to the audio output terminal of the second electronic switch, and one end of each of the remaining resistors in resistor array 2 is connected to an audio input terminal of the second electronic switch. There are four isolation signal input terminals, each connected to the anti-interference module 5. One isolation signal input terminal is used to turn the audio input and output terminals on or off, while the other three isolation signal input terminals are used to turn the audio input and output terminals on.

[0075] It is understandable that the structure of the second electronic switch is similar to that of the first electronic switch, and the isolation signal input terminal of the second electronic switch is similar in principle to the channel selection terminal and the first inhibit terminal of the first electronic switch. Furthermore, the working principle of the first and second electronic switches is similar to that of a single-pole multi-throw switch; that is, by setting corresponding level signals to switch the internal connection channels of the switch, one of the multiple input terminals can be connected to the output terminal.

[0076] Specifically, in the second electronic switch, the isolation signal input terminal is used to receive a level signal processed by the anti-interference module. This level signal is used to connect the sound input terminal and the sound output terminal. Therefore, different level signals can be input to the isolation signal input terminal to connect the corresponding sound input terminal and sound output terminal, thereby changing the number and resistance value of the resistors connected to the sound input terminal and the sound output terminal, thus changing the voltage division degree of the sound signal and realizing the volume adjustment of the sound signal.

[0077] In one specific embodiment, the anti-interference module 5 includes: an optocoupler;

[0078] One end of the optocoupler is connected to the main control module 4, and the other end of the optocoupler is connected to the isolation signal input terminal.

[0079] It should be noted that, due to the high power of the sound reinforcement system, it may cause unpredictable interference to the sound control circuit. The optocoupler used in this embodiment has a very low input impedance, while the impedance of the interference source is relatively high. Therefore, even if the amplitude of the interference voltage is large, the noise voltage fed to the input terminal of the optocoupler will be very small, and the resulting current will be very weak, insufficient to turn on the light-emitting diode inside the optocoupler. Thus, the interference source can be suppressed, reducing its impact on the circuit.

[0080] This embodiment uses an optocoupler for opto-isolation, which can effectively protect the signal transmitted between the main control module 4 and the second electronic switch.

[0081] In one specific embodiment, the optocoupler includes a second resistor, a light-emitting diode, a photosensitive element, and a third resistor;

[0082] One end of the second resistor is connected to the power module, and the other end of the second resistor is connected to the anode of the light-emitting diode. The cathode of the light-emitting diode is connected to the main control module 4.

[0083] The light-emitting diode is positioned opposite to the photosensitive element;

[0084] One end of the photosensitive element is connected to the third resistor, and the third resistor is connected to the power module and the isolation signal input terminal.

[0085] It should be noted that the photosensitive element can be a phototransistor. The working principle of the optocoupler in this embodiment is as follows: When the main control module 4 outputs an electrical signal to the input terminal of the optocoupler, the light-emitting diode in the optocoupler emits light due to the current flowing through it. The phototransistor generates current after being illuminated by the light-emitting diode, and the CE terminal of the phototransistor conducts, pulling down the voltage at the connection between the third resistor and the isolation signal input terminal. Therefore, the optocoupler outputs a low-level signal. When the main control module 4 stops outputting electrical signals, the light-emitting diode does not light up, the CE terminal of the phototransistor is cut off and does not conduct, and the voltage at the connection between the third resistor and the isolation signal input terminal is the power supply voltage. Therefore, the optocoupler outputs a high-level signal.

[0086] Therefore, when the input of the optocoupler is a high level "1", the photosensitive element is cut off and the output is a high level "1"; when the input of the optocoupler is a low level "0", the photosensitive element is saturated and turned on, and the output is a low level "0".

[0087] In one specific embodiment, the main control module 4 is provided with a second disable terminal and a volume adjustment terminal;

[0088] The second blocking terminal and the volume adjustment terminal are respectively connected to the optocoupler one by one.

[0089] It should be noted that the second disable terminal is used to output a level signal to start or stop volume adjustment.

[0090] The volume adjustment terminal is used to output a level signal to turn on the corresponding sound input and sound output terminals in the second electronic switch, change the resistors in the resistor array that are connected to the second electronic switch, and make the second electronic switch output the corresponding voltage divider signal to achieve volume adjustment.

[0091] In one application example, the audio control circuit provided by this utility model will be further explained using a two-channel application scenario as an example.

[0092] like Figure 2 As shown, the main control module uses a microcontroller U1. The microcontroller U1 also includes a crystal oscillator circuit, which consists of a crystal oscillator X and two capacitors C, as detailed below. Figure 2 As shown on the left side of U1.

[0093] The first electronic switch consists of two switches, U3 and U4. U3 is used to receive signals from each channel of the R channel, and U4 is used to receive signals from each channel of the L channel. Figure 2 As shown, U3 has seven channel terminals on its left side, RN0~RN6, and an output terminal X, a first disable terminal RINH, and three channel selection terminals (A, B, and C) on its right side. Output terminal X is connected to capacitor C and resistor R. The three channel selection terminals are RA, RB, and RC. Two power supply terminals are also provided, connected to power supply VCC and power supply VEE respectively. Terminals RINH, A, B, and C of U3 are connected to terminals P16 / ADC6MISO, P1.5 / ADC5MOS1, P0.3, and P1.4 ADC / SS of U1 via connecting wires RINH, RA, RB, and RC, respectively.

[0094] The left side of U4 has seven channel terminals, LN0~LN6, and the right side has an output terminal X, a first disable terminal LINH, and three channel selection terminals (A, B, and C). Output terminal X is connected to capacitor C and resistor L. The three channel selection terminals are LA, LB, and LC. Two power supply terminals are also provided, connected to power supply VCC and power supply VEE respectively. The INH, A, B, and C terminals of U4 are connected to the P13 / ADC3, P0.2, P1.2 / ADC2, and P1.1 / ADC1 terminals of U1 via connecting wires LINH, LA, LB, and LC respectively.

[0095] In this application example, there are two resistor arrays, connected to U3 and U4 respectively, and the two resistor arrays have identical structures. Figure 2 The diagram only shows the resistor array connected to U3. This application example will use this resistor array as an example for explanation.

[0096] This application example uses U3 to illustrate the connection relationship between the first electronic switch, the resistor array, and the second resistor switch. Figure 2 In the diagram, resistor R in U3 is connected to the resistor array via the VOLR connection line. The connection points of each resistor in the resistor array are connected to the second electronic switch U2 via VOL1~VOLN connection lines (only the connection of VOL1~VOL7 is shown as an example in the diagram). The other end of the resistor connected to ground is connected to the sound output terminal X of the second electronic switch U2 via the VOLOUT connection line. The INH, A, B, and C terminals (i.e., the isolated signal input terminals) of the second electronic switch U2 are connected to resistors R in optocouplers IC1, IC2, IC3, and IC4 via connection lines INH-D1, A-D1, B-D1, and C-D1, respectively. The LEDs of optocoupler IC1, optocoupler IC2, optocoupler IC3, and optocoupler IC4 are connected to P1.0 / ADC1, P2.7, P2.6, and P1.0 / ADC0 of microcontroller U2 via connecting lines INH, VOLA, VOLB, and VOLC, respectively.

[0097] The working principle of this application example is as follows: Figure 2 As shown, electronic switch U3 has three channel selection input terminals C, B, and A, and one disable terminal INH. It is equivalent to a single-pole 8-throw switch. Which switch is internally activated can be determined by setting the 3-bit address code A, B, and C. For example, it can be set so that when INH = "1" (i.e., INH = Vp), all channels are disconnected, disabling analog input; and when INH = "0" (i.e., INH = Vss), channels are enabled. Figure 2 As shown, for example, when the INH, RC, RB, and RA of the microcontroller U1 and electronic switch U3 are 0, channel RN0 is turned on; when the INH, RC, RB, and RA are 0, channel RN1 is turned on, and so on. The L channel works similarly. For example, when the INH, LC, LB, and LA of the microcontroller U1 and electronic switch U4 are 0, channel LN0 is turned on; when the INH, LC, LB, and LA are 1, channel LN1 is turned on.

[0098] The working principle of the second electronic switch U2 is similar to that of U3. For example, it can be set so that when the INH of the microcontroller U1 is 1, VOLC is 1, VOLB is 1, and VOLA is 0, the optocouplers IC1 to IC4 output 0, 0, 0, 1, that is, when the INH of the electronic switch U2 is 0, VOLC is 0, VOLB is 0, and VOLA is 1, channel VOL1 is turned on, and the signal received by channel VOL1 is output. When the INH of the microcontroller U1 is 1, VOLC is 1, VOLB is 0, and VOLA is 1, the optocouplers IC1 to IC4 output 0, 0, 1, 0, that is, when the INH of the electronic switch U2 is 0, VOLC is 0, VOLB is 1, and VOLA is 0, channel VOL2 is turned on, and the signal received by channel VOL2 is output, and so on, so as to flexibly realize volume adjustment.

[0099] Therefore, as can be seen from the above, by setting the on and off states of each pin of each electronic switch, the resistance value of the resistor array can be changed, the input signal can be divided, and the speaker volume can be changed.

[0100] It is understandable that the working principle of L-channel or multi-channel is the same as that of R-channel, so it will not be elaborated here.

[0101] This utility model also provides a sound reinforcement system, including the sound control circuit as described in any of the preceding claims.

[0102] This utility model provides a sound control circuit and sound reinforcement system that is less prone to mechanical noise or other malfunctions associated with rotary switch-type volume controllers. It offers superior moisture and dust resistance, resulting in better equipment reliability, stability, and ease of use, leading to a longer service life and a better user experience. In practical applications, it can be integrated into a single circuit board, enhancing circuit stability and simplifying circuit board wiring. Alternatively, it can be configured with discrete components, offering high flexibility. Appropriate components can be selected based on the power output to the speaker, providing versatility.

[0103] Therefore, this utility model can be used to solve the problems of sound dropout and mechanical noise that are common in existing volume controllers, improve sound quality synchronization, provide users with better sound quality performance, extend the service life of the device, enhance the stability of the device, greatly improve the user experience, and has the function of automatic memory when power is off.

[0104] The above provides a detailed description of the sound control circuit and sound reinforcement system provided by this utility model. For those skilled in the art, based on the ideas of the embodiments of this utility model, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this utility model.

Claims

1. A volume control circuit, characterized in that, include: Channel selection module, resistor array, audio output module, main control module, anti-interference module; The channel selection module is connected to the main control module and the resistor array respectively, and the resistor array is connected to the sound output module; The main control module is connected to the anti-interference module, and the anti-interference module is connected to the sound output module.

2. The circuit according to claim 1, characterized in that, The channel selection module includes at least one first electronic switch; each first electronic switch is connected to the main control module. The first electronic switch is connected to the resistor array in a one-to-one correspondence.

3. The circuit according to claim 2, characterized in that, The sound output module includes at least one second electronic switch; The second electronic switch is connected to the resistor array in a one-to-one correspondence.

4. The circuit according to claim 3, characterized in that, The resistor array includes: a plurality of resistors connected in series; One end of each of the resistors is connected to the second electronic switch; The resistors located at both ends of the resistor array are connected to the first electronic switch and ground, respectively.

5. The circuit according to claim 2, characterized in that, The first electronic switch is provided with a channel terminal, a channel selection terminal, a first disable terminal, an audio signal output terminal, and a power supply terminal; The audio channel end is used to receive audio signals; The channel selection terminal and the first prohibition terminal are respectively connected to the main control module; The sound signal output terminal is connected to the first capacitor, and the first capacitor is connected to the first resistor; The first resistor is connected to the resistor array; The power supply terminal is connected to the power module.

6. The circuit according to claim 3, characterized in that, The second electronic switch is provided with a sound input terminal, a ground terminal, a power supply terminal, a sound output terminal, and an isolation signal input terminal; The sound input terminal is connected to the resistor array; The grounding terminal is connected to the ground; The power supply terminal is connected to the power module; The isolation signal input terminal is connected to the anti-interference module; The sound output terminal is used to output sound signals.

7. The circuit according to claim 6, characterized in that, The anti-interference module includes: an optocoupler; One end of the optocoupler is connected to the main control module, and the other end of the optocoupler is connected to the isolation signal input terminal.

8. The circuit according to claim 7, characterized in that, The optocoupler includes a second resistor, a light-emitting diode, a photosensitive element, and a third resistor; One end of the second resistor is connected to the power module, the other end of the second resistor is connected to the anode of the light-emitting diode, and the cathode of the light-emitting diode is connected to the main control module; The light-emitting diode is positioned opposite to the photosensitive element; One end of the photosensitive element is connected to the third resistor, and the third resistor is connected to the power module and the isolation signal input terminal.

9. The circuit according to claim 8, characterized in that, The main control module is equipped with a second disable terminal and a volume adjustment terminal; The second blocking terminal and the volume adjustment terminal are respectively connected to the optocoupler one by one.

10. A sound reinforcement system, characterized in that, Includes the volume control circuit as described in any one of claims 1-9.

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