Audio automatic selection circuit

Abstract

The utility model discloses an audio automatic selection circuit, which relates to the field of electronic information and comprises a 3.3 V step-down circuit used for converting direct current into 3.3 V direct current and supplying the 3.3 V direct current to an audio comparison circuit; the audio biasing circuit is used for superposing 2V direct-current voltage bias on audio signals of a wired microphone or a wireless microphone or emergency broadcast in order to prevent noise interference of input audio, and outputting the biased audio signals to the audio comparison circuit; compared with the prior art, the beneficial effects of the utility model are that after one of the three microphone interfaces is connected, the audio bias circuit outputs a corresponding audio signal to the audio comparison circuit, and the audio comparison circuit outputs a corresponding identification signal and feeds back the identification signal to the CPU, thereby completing automatic audio selection; by arranging the audio biasing circuit, noise interference of input audio is prevented, an audio signal is superposed with 2V direct-current voltage bias, and the anti-interference capability of the system is enhanced.

Description

Technical Field

[0001] This utility model relates to the field of electronic information, specifically to an automatic audio selection circuit. Background Technology

[0002] The power amplifier unit is a key component of the intelligent broadcaster. It receives audio signals from the main control board of the intelligent broadcaster. The effective value of the audio signal is 2V. After amplification, the signal is output as a constant 100V output, with an output power of 300W to drive all the vehicle's speakers for broadcasting. The power amplifier unit has a dual-unit hot standby function, enabling automatic and manual switching between the two units.

[0003] According to the on-site functional requirements, the broadcaster has three microphone interfaces, which means there are three audio inputs. A microphone should be able to be used normally when randomly inserted into any microphone interface. However, the existing technology is difficult to achieve automatic audio selection, which needs to be improved. Utility Model Content

[0004] The purpose of this invention is to provide an automatic audio selection circuit to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, this utility model provides the following technical solution:

[0006] An automatic audio selection circuit includes:

[0007] The 3.3V step-down circuit is used to convert DC power into 3.3V DC power to supply the audio comparator circuit.

[0008] The audio bias circuit is used to bias the audio signal from a wired microphone, wireless microphone, or emergency broadcast by superimposing a 2V DC voltage to prevent noise interference from the input audio, and then outputs the biased audio signal to the audio comparator circuit.

[0009] The audio comparison circuit receives the biased audio signal and feeds back the voltage change to the CPU. Based on the interface that recognizes the voltage change, the CPU automatically identifies whether the audio input is a wired microphone interface, a wireless microphone interface, or an emergency broadcast interface, thus achieving automatic audio selection.

[0010] The audio bias circuit is connected to the audio comparator circuit, and the 3.3V step-down circuit is also connected to the audio comparator circuit.

[0011] As a further embodiment of this utility model: the 3.3V step-down circuit includes chip U2, model number MP2147GD. 5V voltage is introduced to pin 8 of chip U2. Pins 1 and 9 of chip U2 are connected to one end of inductor L1. The other end of inductor L1 is connected to pin 2 of chip U2, one end of capacitor C10, one end of resistor R2, one end of capacitor C7, one end of capacitor C8, and one end of capacitor C9. The other end of capacitor C10 is connected to pin 4 of chip U2. The other end of resistor R2 is connected to one end of resistor R5 and pin 3 of chip U2. The other end of resistor R5 is grounded, and the other ends of capacitors C7, C8, and C9 are grounded.

[0012] As a further improvement of this utility model: the audio bias circuit includes three audio bias units, which are respectively connected to a wired microphone interface, a wireless microphone interface, and an emergency broadcast interface. Each audio bias unit includes a resistor R204, a resistor R199, a capacitor C175, a capacitor C172, and an amplifier N7A. One end of the capacitor C175 is connected to an audio signal, and the other end of the capacitor C175 is connected to one end of the resistor R199, one end of the capacitor C172, one end of the resistor R204, and the non-inverting input of the amplifier N7A. The other end of the resistor R199 is connected to a 5V voltage, and the other end of the resistor R204 is grounded. The other end of the capacitor C172 is connected to the inverting input of the amplifier N7A, the output terminal of the amplifier N7A, and the audio comparator circuit.

[0013] As a further improvement of this utility model, the amplifier N7A is model number LM358.

[0014] As a further improvement of this utility model: the audio comparison circuit includes three audio comparison units, which are respectively connected to three audio bias units. Each audio comparison unit includes a chip U10, model AP331AWG-7. Pin 1 of chip U10 is connected to the sliding end of potentiometer R33. One end of potentiometer R33 is connected to 5V voltage, and the other end of potentiometer R33 is grounded. Pin 2 of chip U10 is grounded. Pin 3 of chip U10 is connected to the corresponding audio bias unit. Pin 5 of chip U10 is connected to 5V voltage. Pin 4 of chip U10 is connected to one end of resistor R31. The other end of resistor R31 is connected to one end of resistor R29. The other end of resistor R29 is connected to 3.3V voltage.

[0015] Compared with the prior art, the beneficial effects of this utility model are as follows: After one of the three microphone interfaces is connected, the corresponding audio signal is output to the audio comparison circuit through the audio bias circuit. The audio comparison circuit outputs the corresponding recognition signal and feeds it back to the CPU to complete the automatic audio selection. By setting the audio bias circuit, noise interference of the input audio is prevented, and the audio signal is biased by superimposing a 2V DC voltage, which enhances the anti-interference capability of the system. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of an automatic audio selection circuit.

[0017] Figure 2 This is the circuit diagram for a 3.3V step-down circuit.

[0018] Figure 3 This is a circuit diagram of the audio bias circuit.

[0019] Figure 4 This is a circuit diagram of an audio comparator circuit. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the protection scope of the present utility model.

[0021] Please see Figure 1 An automatic audio selection circuit includes:

[0022] The 3.3V step-down circuit is used to convert DC power into 3.3V DC power to supply the audio comparator circuit.

[0023] The audio bias circuit is used to bias the audio signal from a wired microphone, wireless microphone, or emergency broadcast by superimposing a 2V DC voltage to prevent noise interference from the input audio, and then outputs the biased audio signal to the audio comparator circuit.

[0024] The audio comparison circuit receives the biased audio signal and feeds back the voltage change to the CPU. Based on the interface that recognizes the voltage change, the CPU automatically identifies whether the audio input is a wired microphone interface, a wireless microphone interface, or an emergency broadcast interface, thus achieving automatic audio selection.

[0025] The audio bias circuit is connected to the audio comparator circuit, and the 3.3V step-down circuit is also connected to the audio comparator circuit.

[0026] In this embodiment: Please refer to Figure 2The 3.3V step-down circuit includes chip U2, model MP2147GD. Pin 8 of chip U2 introduces 5V voltage. Pins 1 and 9 of chip U2 are connected to one end of inductor L1. The other end of inductor L1 is connected to pin 2 of chip U2, one end of capacitor C10, one end of resistor R2, one end of capacitor C7, one end of capacitor C8, and one end of capacitor C9. The other end of capacitor C10 is connected to pin 4 of chip U2. The other end of resistor R2 is connected to one end of resistor R5 and pin 3 of chip U2. The other end of resistor R5 is grounded. The other end of capacitor C7, capacitor C8, and capacitor C9 are all grounded.

[0027] The 5V voltage is converted into a stable 3.3V voltage by the MP2147GD voltage conversion chip, which then supplies the audio comparator circuit.

[0028] In this embodiment: Please refer to Figure 3 The audio bias circuit includes three audio bias units, which are respectively connected to the wired microphone interface, the wireless microphone interface, and the emergency broadcast interface. Each audio bias unit includes resistor R204, resistor R199, capacitor C175, capacitor C172, and amplifier N7A. One end of capacitor C175 is connected to the audio signal, and the other end of capacitor C175 is connected to one end of resistor R199, one end of capacitor C172, one end of resistor R204, and the non-inverting input of amplifier N7A. The other end of resistor R199 is connected to a 5V voltage, and the other end of resistor R204 is grounded. The other end of capacitor C172 is connected to the inverting input of amplifier N7A, the output of amplifier N7A, and the audio comparator circuit.

[0029] The audio signal is biased by superimposing a 2V DC voltage through a 5V voltage, resistors R199 and R204 (the resistance ratio of resistors R199 and R204 is 3:2). After the audio signal is input, the biased audio signal is fed back to the audio comparator circuit.

[0030] In this embodiment: Please refer to Figure 3 The amplifier N7A is model number LM358.

[0031] Other amplifier models can also be selected.

[0032] In this embodiment: Please refer to Figure 4The audio comparison circuit includes three audio comparison units, which are respectively connected to three audio bias units. Each audio comparison unit includes a chip U10, model AP331AWG-7. Pin 1 of chip U10 is connected to the sliding end of potentiometer R33. One end of potentiometer R33 is connected to 5V, and the other end of potentiometer R33 is grounded. Pin 2 of chip U10 is grounded. Pin 3 of chip U10 is connected to the corresponding audio bias unit. Pin 5 of chip U10 is connected to 5V. Pin 4 of chip U10 is connected to one end of resistor R31. The other end of resistor R31 is connected to one end of resistor R29, and the other end of resistor R29 is connected to 3.3V.

[0033] The broadcast receiver has three microphone interfaces (wired microphone interface, wireless microphone interface, and emergency broadcast interface), providing three audio inputs. A microphone should function correctly when randomly plugged into any of these interfaces. For example, when a microphone is plugged into the wired microphone interface, the corresponding audio bias unit outputs a biased audio signal. The audio bias units for the wireless and emergency broadcast interfaces, based on the absence of audio input, output a fixed 2V signal. The audio comparator units for the wireless and emergency broadcast interfaces feed a high level back to the CPU. For the wired microphone interface, pin 1 of chip U10 has a fixed voltage, while pin 3 of chip U10 receives the biased audio signal. This causes pin 4 of chip U10 to feed a low level back to the CPU. The CPU, by inputting a low level to a specific pin, determines that the microphone is plugged into the wired microphone interface and automatically selects the wired microphone as the audio input (the CPU performs different content control based on the input high and low levels, a common CPU function).

[0034] The working principle of this invention is as follows: a 3.3V step-down circuit converts DC power into 3.3V DC power to supply the audio comparison circuit; an audio bias circuit, in order to prevent noise interference from the input audio, superimposes a 2V DC voltage onto the audio signal from a wired microphone, wireless microphone, or emergency broadcast, and outputs the biased audio signal to the audio comparison circuit; the audio comparison circuit detects which of the three output ports outputs a voltage signal, i.e., determines whether the audio input is a wired microphone interface, a wireless microphone interface, or an emergency broadcast interface; and based on the output voltage signal, automatic audio selection is achieved.

[0035] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects.

[0036] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An automatic audio selection circuit, characterized in that, The automatic audio selection circuit includes: The 3.3V step-down circuit is used to convert DC power into 3.3V DC power to supply the audio comparator circuit. The audio bias circuit is used to bias the audio signal from a wired microphone, wireless microphone, or emergency broadcast by superimposing a 2V DC voltage to prevent noise interference from the input audio, and then outputs the biased audio signal to the audio comparator circuit. The audio comparison circuit receives the biased audio signal and feeds back the voltage change to the CPU. Based on the interface that recognizes the voltage change, the CPU automatically identifies whether the audio input is a wired microphone interface, a wireless microphone interface, or an emergency broadcast interface, thus achieving automatic audio selection. The audio bias circuit is connected to the audio comparator circuit, and the 3.3V step-down circuit is also connected to the audio comparator circuit.

2. The automatic audio selection circuit according to claim 1, characterized in that, The 3.3V step-down circuit includes chip U2, model MP2147GD. Pin 8 of chip U2 introduces 5V voltage. Pins 1 and 9 of chip U2 are connected to one end of inductor L1. The other end of inductor L1 is connected to pin 2 of chip U2, one end of capacitor C10, one end of resistor R2, one end of capacitor C7, one end of capacitor C8, and one end of capacitor C9. The other end of capacitor C10 is connected to pin 4 of chip U2. The other end of resistor R2 is connected to one end of resistor R5 and pin 3 of chip U2. The other end of resistor R5 is grounded. The other ends of capacitors C7, C8, and C9 are grounded.

3. The automatic audio selection circuit according to claim 1, characterized in that, The audio bias circuit includes three audio bias units, which are respectively connected to the wired microphone interface, the wireless microphone interface, and the emergency broadcast interface. Each audio bias unit includes resistor R204, resistor R199, capacitor C175, capacitor C172, and amplifier N7A. One end of capacitor C175 is connected to the audio signal, and the other end of capacitor C175 is connected to one end of resistor R199, one end of capacitor C172, one end of resistor R204, and the non-inverting input of amplifier N7A. The other end of resistor R199 is connected to a 5V voltage, and the other end of resistor R204 is grounded. The other end of capacitor C172 is connected to the inverting input of amplifier N7A, the output of amplifier N7A, and the audio comparator circuit.

4. The automatic audio selection circuit according to claim 3, characterized in that, The amplifier N7A is model number LM358.

5. The automatic audio selection circuit according to claim 1, characterized in that, The audio comparator circuit includes three audio comparator units, which are respectively connected to three audio bias units. Each audio comparator unit includes a chip U10, model AP331AWG-7. Pin 1 of chip U10 is connected to the sliding end of potentiometer R33. One end of potentiometer R33 is connected to 5V, and the other end is grounded. Pin 2 of chip U10 is grounded. Pin 3 of chip U10 is connected to the corresponding audio bias unit. Pin 5 of chip U10 is connected to 5V. Pin 4 of chip U10 is connected to one end of resistor R31. The other end of resistor R31 is connected to one end of resistor R29, and the other end of resistor R29 is connected to 3.3V.

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