CN216217529U

CN216217529U - Conversion circuit with audio frequency high level changes low level output

Info

Publication number: CN216217529U
Application number: CN202122377905.9U
Authority: CN
Inventors: 沈生猛; 张平; 张军波
Original assignee: Dongguan Huaze Electronic Technology Co ltd
Current assignee: Dongguan Huaze Electronic Technology Co ltd
Priority date: 2021-09-29
Filing date: 2021-09-29
Publication date: 2022-04-05
Anticipated expiration: 2031-09-29

Abstract

The utility model discloses a conversion circuit with audio high-level to low-level output, which comprises a vehicle-mounted audio signal input end, a left channel coupling attenuation circuit, a right channel coupling attenuation circuit, a left channel amplitude limiting circuit, a right channel amplitude limiting circuit, a left channel subtraction circuit, a right channel subtraction circuit, a left channel operational amplification following output circuit, a right channel operational amplification following output circuit, a power supply circuit and an audio signal output end, wherein one end of the left channel coupling attenuation circuit and one end of the right channel coupling attenuation circuit are connected with the vehicle-mounted audio signal input end, and the other end of the left channel coupling attenuation circuit and the other end of the right channel coupling attenuation circuit are respectively connected with the left channel amplitude limiting circuit and the right channel amplitude limiting circuit. The vehicle-mounted audio signal input end of the conversion circuit introduces an audio signal, performs attenuation processing, outputs the audio signal with standard rated sensitivity through the following conversion of the operational amplifier, outputs the audio signal with the standard rated sensitivity, and outputs the audio signal with the output sensitivity of 0dB, wherein the standard audio signal can be directly input into high-power HIFI audio amplification equipment of a user.

Description

Conversion circuit with audio frequency high level changes low level output

Technical Field

The utility model relates to the technical field of vehicle-mounted entertainment systems, in particular to a conversion circuit for converting audio high level into low level for output.

Background

In a common vehicle-mounted entertainment system, a vehicle owner cannot conveniently transmit an audio signal in the vehicle-mounted entertainment system to a high-power HIFI audio amplification device which is afterloaded and preferred by a user, such as an afterloaded vehicle-mounted subwoofer, a high-power HIFI vehicle-mounted sound box and the like. The existing desirable audio output signals of the original vehicle-mounted system only have horn power output signals, and the power signals output by the horn are high-voltage and high-current audio signals, so that the audio output signals cannot be directly connected with a user peripheral device for use. Therefore, the applicant designs a conversion circuit with audio high-level to low-level output, which can transmit the audio signals in the vehicle entertainment system to a user-preferred after-loading high-power HIFI audio amplification device for use.

SUMMERY OF THE UTILITY MODEL

The utility model aims to provide a conversion circuit with audio high-level to low-level output, which has the advantages that an audio signal is introduced into a vehicle-mounted audio signal input end of the circuit, attenuation processing is carried out, the output is converted into an audio signal output with standard rated sensitivity through an operational amplifier, the output sensitivity is 0dB (0.775mV), and the standard audio signal can be directly input into high-power HIFI audio amplification equipment of a user, so that the problems provided by the technical background are solved.

In order to achieve the purpose, the utility model provides the following technical scheme: a conversion circuit with audio high level to low level output comprises a vehicle-mounted audio signal input end, a left channel coupling attenuation circuit, a right channel coupling attenuation circuit, a left channel amplitude limiting circuit, a right channel amplitude limiting circuit, a left channel subtraction circuit, a right channel subtraction circuit, a left channel operational amplification following output circuit, a right channel operational amplification following output circuit, a power supply circuit and an audio signal output end, wherein one end of the left channel coupling attenuation circuit and one end of the right channel coupling attenuation circuit are connected with the vehicle-mounted audio signal input end, the other end of the left channel coupling attenuation circuit and the other end of the right channel coupling attenuation circuit are respectively connected with the left channel amplitude limiting circuit and the right channel amplitude limiting circuit, one end of the left channel subtraction circuit and one end of the right channel subtraction circuit are respectively connected with the left channel amplitude limiting circuit and the right channel amplitude limiting circuit, and the other end of the left channel operational amplification following output circuit and the right channel operational amplification following output circuit are respectively connected with the left channel amplitude limiting circuit and the right channel amplitude limiting circuit, the power supply circuit is respectively connected with the left sound channel subtraction circuit, the right sound channel subtraction circuit, the left sound channel operational amplification following output circuit and the right sound channel operational amplification following output circuit, and provides electric energy for the left sound channel subtraction circuit, the right sound channel subtraction circuit, the left sound channel operational amplification following output circuit and the right sound channel operational amplification following output circuit.

Preferably, the left channel coupling attenuation circuit is composed of a bidirectional transient suppression diode D13, a bidirectional transient suppression diode D14, a capacitor C3, a capacitor C15, a resistor R2, a resistor R3 and a resistor R5, wherein the bidirectional transient suppression diode D13 and the bidirectional transient suppression diode D14 are connected in parallel, one ends of the bidirectional transient suppression diode D13 and the bidirectional transient suppression diode D14 are grounded, the other ends of the bidirectional transient suppression diode D13 and the bidirectional transient suppression diode D14 are connected with a pin 1 and a pin 2 of the vehicle audio signal input terminal respectively, one ends of the capacitor C3 and the capacitor C15 are connected with the pin 1 and the pin 2 of the vehicle audio signal input terminal, the other ends of the capacitor C3 and the capacitor C15 are connected with a resistor R2 and a resistor R5 respectively, and two ends of the resistor R3 are connected with a resistor R2 and a resistor R5 respectively.

Preferably, the right channel coupling attenuation circuit is composed of a bidirectional transient suppression diode D11, a bidirectional transient suppression diode D12, a capacitor C5, a capacitor C8, a resistor R7, a resistor R10 and a resistor R11, wherein the bidirectional transient suppression diode D11 and the bidirectional transient suppression diode D12 are connected in parallel, one ends of the bidirectional transient suppression diode D11 and the bidirectional transient suppression diode D12 are grounded, the other ends of the bidirectional transient suppression diode D11 and the bidirectional transient suppression diode D12 are connected with a pin 3 and a pin 4 of the vehicle audio signal input terminal respectively, one ends of the capacitor C5 and the capacitor C8 are connected with the pin 3 and the pin 4 of the vehicle audio signal input terminal, the other ends of the capacitor C5 and the capacitor C8 are connected with a resistor R7 and a resistor R11 respectively, and two ends of the resistor R10 are connected with a resistor R7 and a resistor R11 respectively.

Preferably, the left channel limiter circuit limits the left channel audio signal output by the vehicle audio signal input terminal to within 12Vp-p, and includes a capacitor C2, a capacitor C6, a diode D1, a diode D2, a diode D3, and a diode D4, where the diode D1, the diode D2, the diode D3, and the diode D4 are all limiter diodes, one end of the diode D1 is connected to the supply terminal VCC1, the other end is connected to the capacitor C2 and the diode D3, one end of the diode D2 is connected to the supply terminal VCC1, the other end is connected to the capacitor C6 and the diode D4, and ends of the diode D3 and the diode D4, which are far from the diode D1 and the diode D2, are grounded.

Preferably, the right channel limiter circuit limits the right channel audio signal output by the vehicle audio signal input terminal to within 12Vp-p, and includes a capacitor C17, a capacitor C19, a diode D6, a diode D7, a diode D8, and a diode D9, where the diode D6, the diode D7, the diode D8, and the diode D9 are all limiter diodes, one end of the diode D6 is connected to the supply terminal VCC2, the other end is connected to the capacitor C17 and the diode D8, one end of the diode D7 is connected to the supply terminal VCC2, the other end is connected to the capacitor C19 and the diode D9, and ends of the diode D8 and the diode D9, which are far from the diode D6 and the diode D7, are grounded.

Preferably, the left channel subtraction circuit comprises a capacitor C1, a capacitor C4, a capacitor C9, a resistor R1, a resistor R6 and an operational amplifier U1A, the capacitor C9 and the resistor R6 are connected in parallel, one end of the capacitor C9 and one end of the resistor R6 are connected to the power supply circuit, the other end of the capacitor C9 and one end of the resistor R6 are connected to the non-inverting input terminals of the capacitor C4 and the operational amplifier U1A, the capacitor C1 and the resistor R1 are connected in parallel, one end of the capacitor C1 and one end of the resistor R1 are connected to the output terminal of the operational amplifier U1A, and the other end of the capacitor C4 and the inverting input terminal of the operational amplifier U1A are connected to the inverting input terminal of the operational amplifier U1A.

Preferably, the right channel subtraction circuit comprises a capacitor C16, a capacitor C18, a capacitor C24, a resistor R13, a resistor R17 and an operational amplifier U2A, the capacitor C24 and the resistor R17 are connected in parallel, one end of the capacitor C24 and one end of the resistor R17 are connected with the power supply circuit (10), the other end of the capacitor C24 and the other end of the resistor R17 are respectively connected with the non-inverting input ends of the capacitor C18 and the operational amplifier U2A, the capacitor C16 and the resistor R13 are connected in parallel, one end of the capacitor C16 and one end of the resistor R13 are connected with the output end of the operational amplifier U2A, and the other end of the capacitor C18 and the inverting input end of the operational amplifier U2A are respectively connected with.

Preferably, the left channel operational amplification following output circuit is composed of a capacitor C7, a capacitor C25, a capacitor C27, a capacitor C28, a capacitor C30, a resistor R4, a resistor R18, a resistor R21, a resistor R22, a resistor R23 and an operational amplifier U1B, wherein one end of the capacitor C7 is connected with the output end of the operational amplifier U1A, the other end is connected with the resistor R4, the capacitor C25 is connected with the resistor R18 in parallel, one end of a capacitor C25 and one end of a resistor R18 are connected with the output end of the operational amplifier U1B and the capacitor C27, the other end of the capacitor C25 and the other end of the resistor R18 are respectively connected with the resistor R4, the capacitor C28 and the inverting input end of the operational amplifier U1B, the capacitor C30 and the resistor R23 are connected in parallel, and one end of the capacitor C30 and one end of the resistor R23 are connected with the power supply circuit (10), the other ends of the capacitor C30 and the resistor R23 are respectively connected with the capacitor C28 and the equidirectional input end of the operational amplifier U1B, one end of the capacitor C27, which is far away from the operational amplifier U1B, is respectively connected with the resistor R21 and the resistor R22, and one end of the resistor R21, which is far away from the capacitor C27, is connected with a left channel interface of an audio signal output end.

Preferably, the right channel operational amplification following output circuit is composed of a capacitor C23, a capacitor C31, a capacitor C34, a capacitor C35, a capacitor C36, a resistor R15, a resistor R24, a resistor R27, a resistor R28, a resistor R29 and an operational amplifier U2B, wherein one end of the capacitor C23 is connected with the output end of the operational amplifier U2A, the other end is connected with the resistor R15, the capacitor C31 is connected with the resistor R24 in parallel, one end of a capacitor C31 and one end of a resistor R24 are connected with the output end of the operational amplifier U2B and the capacitor C34, the other end of the capacitor C31 and the other end of the resistor R24 are respectively connected with the resistor R15, the capacitor C35 and the inverting input end of the operational amplifier U2B, the capacitor C36 and the resistor R29 are connected in parallel, one end of the capacitor C36 and one end of the resistor R29 are connected with the power supply circuit, the other ends of the capacitor C36 and the resistor R29 are respectively connected with the capacitor C35 and the equidirectional input end of the operational amplifier U2B, one end of the capacitor C34, which is far away from the operational amplifier U2B, is respectively connected with the resistor R27 and the resistor R28, and one end of the resistor R27, which is far away from the capacitor C34, is connected with a right channel interface of the audio signal output end.

Preferably, the power supply circuit comprises a bidirectional transient suppression diode D10, a diode D5, a resistor R8, a resistor R9, a resistor R12, a resistor R14, a resistor R16, a capacitor C10, a capacitor C11, a capacitor C12, a capacitor C13, a capacitor C14, a capacitor C20, a capacitor C21, a capacitor C22, a capacitor C26, a capacitor C29, an operational amplifier U1C, an operational amplifier U2C, an inductor L1, an inductor L2 and a transient voltage suppression diode Z1, wherein one end of the diode D5 is connected with the bidirectional transient suppression diode D10 and the 12V vehicle battery voltage of the pin 6 of the vehicle audio signal input terminal, the other end of the diode is connected with the resistor R9, the capacitor C13, the capacitor C14, the capacitor C26 and the capacitor C29 are connected in parallel, and one ends of the capacitor C13, the capacitor C14, the capacitor C26 and the capacitor C29 are grounded. The other end of the resistor is connected with a resistor R9, an inductor L1, an inductor L2 and a transient voltage suppression diode Z1 respectively, a capacitor C10, a capacitor C11, a capacitor C12, a resistor R12 and an operational amplifier U1C are connected in parallel, a resistor R8 is located between the resistor R12 and the operational amplifier U1C, a capacitor C20, a capacitor C21, a capacitor C22, a resistor R16 and an operational amplifier U2C are connected in parallel, and a resistor R14 is located between the resistor R16 and the operational amplifier U2C.

Compared with the prior art, the utility model has the following beneficial effects:

1. the utility model provides a conversion circuit with audio high-level to low-level output, wherein an audio signal with the amplitude exceeding 5V is introduced into a vehicle-mounted audio signal input end of the conversion circuit, attenuation processing is carried out, the audio signal is output as an audio signal with standard rated sensitivity after being subjected to follow-up conversion by an operational amplifier, the output sensitivity is 0dB (0.775mV), and the input sensitivity requirements of a general rear-mounted vehicle-mounted subwoofer and HiFi sound are met.

Drawings

FIG. 1 is a schematic block diagram of the present invention;

FIG. 2 is a schematic diagram of a portion of the circuit of the present invention;

FIG. 3 is a schematic circuit diagram of a left channel operational amplifier follower output circuit according to the present invention;

FIG. 4 is a schematic circuit diagram of the right channel operational amplification follower output circuit of the present invention;

FIG. 5 is a circuit schematic of the power supply circuit of the present invention;

fig. 6 is a circuit diagram of an audio signal output terminal according to the present invention.

The reference numerals and names in the figures are as follows:

1. a vehicle audio signal input end; 2. a left channel coupling attenuation circuit; 3. a right channel coupling attenuation circuit; 4. a left channel clipping circuit; 5. a right channel clipping circuit; 6. a left channel subtraction circuit; 7. a right channel subtraction circuit; 8. a left sound channel operational amplification following output circuit; 9. the right sound channel operation amplification follows the output circuit; 10. a power supply circuit; 11. and an audio signal output terminal.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, an embodiment of the present invention: a conversion circuit with audio high level to low level output comprises a vehicle audio signal input end 1, a left channel coupling attenuation circuit 2, a right channel coupling attenuation circuit 3, a left channel amplitude limiting circuit 4, a right channel amplitude limiting circuit 5, a left channel subtraction circuit 6, a right channel subtraction circuit 7, a left channel operational amplification following output circuit 8, a right channel operational amplification following output circuit 9, a power supply circuit 10 and an audio signal output end 11, wherein one end of the left channel coupling attenuation circuit 2 and one end of the right channel coupling attenuation circuit 3 are connected with the vehicle audio signal input end 1, the other end of the left channel coupling attenuation circuit 2 and the other end of the right channel coupling attenuation circuit 3 are respectively connected with the left channel amplitude limiting circuit 4 and the right channel amplitude limiting circuit 5, one end of the left channel subtraction circuit 6 and one end of the right channel subtraction circuit 7 are respectively connected with the left channel amplitude limiting circuit 4 and the right channel amplitude limiting circuit 5, the other end of the left channel coupling attenuation circuit is respectively connected with the left channel operational amplification following output circuit 8 and the right channel operational amplification following output circuit 9, the left channel operational amplification following output circuit 8 and the right channel operational amplification following output circuit 9 are connected with an audio signal output end 11 at the ends far away from the left channel subtraction circuit 6 and the right channel subtraction circuit 7, and the power supply circuit 10 is respectively connected with the left channel subtraction circuit 6, the right channel subtraction circuit 7, the left channel operational amplification following output circuit 8 and the right channel operational amplification following output circuit 9 and provides electric energy for the left channel subtraction circuit 6, the right channel subtraction circuit 7, the left channel operational amplification following output circuit 8 and the right channel operational amplification following output circuit 9.

Referring to fig. 2, the left channel coupling attenuation circuit 2 is composed of a bidirectional transient suppression diode D13, a bidirectional transient suppression diode D14, a capacitor C3, a capacitor C15, a resistor R2, a resistor R3, and a resistor R5, wherein the bidirectional transient suppression diode D13 and the bidirectional transient suppression diode D14 are connected in parallel, one ends of the bidirectional transient suppression diode D13 and the bidirectional transient suppression diode D14 are grounded, the other ends of the bidirectional transient suppression diode D15 are connected to the pin 1 and the pin 2 of the vehicle audio signal input terminal 1, one ends of the capacitor C3 and the capacitor C15 are connected to the pin 1 and the pin 2 of the vehicle audio signal input terminal 1, the other ends of the capacitor C3 and the resistor R5 are connected to the resistor R2 and the resistor R5, and two ends of the resistor R3 are connected to the resistor R2 and the resistor R5, respectively.

Referring to fig. 2 again, the right channel coupling attenuation circuit 3 is composed of a bidirectional transient suppression diode D11, a bidirectional transient suppression diode D12, a capacitor C5, a capacitor C8, a resistor R7, a resistor R10, and a resistor R11, wherein the bidirectional transient suppression diode D11 and the bidirectional transient suppression diode D12 are connected in parallel, one ends of the bidirectional transient suppression diode D11 and the bidirectional transient suppression diode D12 are grounded, the other ends of the bidirectional transient suppression diode D8 are connected to the No. 3 pin and the No. 4 pin of the vehicle audio signal input terminal 1, one ends of the capacitor C5 and the capacitor C8 are connected to the No. 3 pin and the No. 4 pin of the vehicle audio signal input terminal 1, the other ends of the capacitor C5 and the capacitor C8 are connected to the resistor R7 and the resistor R11, and two ends of the resistor R10 are connected to the resistor R7 and the resistor R11, respectively.

Referring to fig. 2 again, the left channel limiter circuit 4 limits the left channel audio signal output by the vehicle audio signal input terminal 1 within 12Vp-p, and includes a capacitor C2, a capacitor C6, a diode D1, a diode D2, a diode D3, and a diode D4, wherein the diode D1, the diode D2, the diode D3, and the diode D4 are all limiter diodes, one end of the diode D1 is connected to the power supply terminal VCC1, the other end of the diode D1 is connected to the capacitor C2 and the diode D3, one end of the diode D2 is connected to the power supply terminal VCC1, the other end of the diode D2 is connected to the capacitor C6 and the diode D4, and ends of the diode D3 and the diode D4, which are far away from the diode D1 and the diode D2, are grounded.

Referring to fig. 2 again, the right channel limiter circuit 5 limits the right channel audio signal output by the vehicle audio signal input terminal 1 within 12Vp-p, and includes a capacitor C17, a capacitor C19, a diode D6, a diode D7, a diode D8, and a diode D9, wherein the diode D6, the diode D7, the diode D8, and the diode D9 are all limiter diodes, one end of the diode D6 is connected to the power supply terminal VCC2, the other end of the diode D6 is connected to the capacitor C17 and the diode D8, one end of the diode D7 is connected to the power supply terminal VCC2, the other end of the diode D7 is connected to the capacitor C19 and the diode D9, and ends of the diode D8 and the diode D9, which are far away from the diode D6 and the diode D7, are grounded.

Referring to fig. 2 again, the left channel subtraction circuit 6 includes a capacitor C1, a capacitor C4, a capacitor C9, a resistor R1, a resistor R6 and an operational amplifier U1A, the capacitor C9 and the resistor R6 are connected in parallel, one end of the capacitor C9 and one end of the resistor R6 are connected to the power supply circuit 10, the other end of the capacitor C9 and the other end of the resistor R6 are connected to the non-inverting input terminals of the capacitor C4 and the operational amplifier U1A, the capacitor C1 and the resistor R1 are connected in parallel, one end of the capacitor C1 and one end of the resistor R1 are connected to the output terminal of the operational amplifier U1A, and the other end of the capacitor C4 and the inverting input terminal of the operational amplifier U1A are connected to the inverting input terminal of the capacitor C4 and the operational amplifier U1.

Referring to fig. 2 for the last time, the right channel subtraction circuit 7 includes a capacitor C16, a capacitor C18, a capacitor C24, a resistor R13, a resistor R17, and an operational amplifier U2A, wherein the capacitor C24 and the resistor R17 are connected in parallel, one end of the capacitor C24 and one end of the resistor R17 are connected to the power supply circuit 10, the other end of the capacitor C18 are connected to the non-inverting input terminal of the operational amplifier U2A, the capacitor C16 is connected to the resistor R13, one end of the capacitor C16 and one end of the resistor R13 are connected to the output terminal of the operational amplifier U2A, and the other end of the capacitor C18 and the inverting input terminal of the operational amplifier U2A are connected to the inverting input terminal of the operational amplifier U2.

Referring to fig. 3 and 6, the left channel operational amplification follower output circuit 8 is composed of a capacitor C7, a capacitor C25, a capacitor C27, a capacitor C28, a capacitor C30, a resistor R4, a resistor R18, a resistor R21, a resistor R22, a resistor R23 and an operational amplifier U1B, wherein one end of the capacitor C7 is connected with the output end of the operational amplifier U1A, the other end is connected with the resistor R4, the capacitor C25 is connected with the resistor R18 in parallel, one end of a capacitor C25 and one end of a resistor R18 are connected with the output end of the operational amplifier U1B and the capacitor C27, the other end of the capacitor C25 and the other end of the resistor R18 are respectively connected with the resistor R4, the capacitor C28 and the inverting input end of the operational amplifier U1B, the capacitor C30 and the resistor R23 are connected in parallel, one end of the capacitor C30 and one end of the resistor R23 are connected to the power supply circuit 10, the other ends of the capacitor C30 and the resistor R23 are respectively connected to the capacitor C28 and the equidirectional input end of the operational amplifier U1B, one end of the capacitor C27, which is far away from the operational amplifier U1B, is respectively connected to the resistor R21 and the resistor R22, and one end of the resistor R21, which is far away from the capacitor C27, is connected to the left channel interface of the audio signal output terminal 11.

Referring to fig. 4 and 6, the right channel operational amplification follower output circuit 9 is composed of a capacitor C23, a capacitor C31, a capacitor C34, a capacitor C35, a capacitor C36, a resistor R15, a resistor R24, a resistor R27, a resistor R28, a resistor R29 and an operational amplifier U2B, wherein one end of the capacitor C23 is connected with the output end of the operational amplifier U2A, the other end is connected with the resistor R15, the capacitor C31 is connected with the resistor R24 in parallel, one end of a capacitor C31 and one end of a resistor R24 are connected with the output end of the operational amplifier U2B and the capacitor C34, the other end of the capacitor C31 and the other end of the resistor R24 are respectively connected with the resistor R15, the capacitor C35 and the inverting input end of the operational amplifier U2B, the capacitor C36 and the resistor R29 are connected in parallel, one end of the capacitor C36 and one end of the resistor R29 are connected to the power supply circuit 10, the other ends of the capacitor C36 and the resistor R29 are respectively connected to the capacitor C35 and the equidirectional input end of the operational amplifier U2B, one end of the capacitor C34, which is far away from the operational amplifier U2B, is respectively connected to the resistor R27 and the resistor R28, and one end of the resistor R27, which is far away from the capacitor C34, is connected to the right channel interface of the audio signal output terminal 11.

Referring to fig. 5, the power supply circuit 10 includes a bidirectional transient suppression diode D10, a diode D5, a resistor R8, a resistor R9, a resistor R12, a resistor R14, a resistor R16, a capacitor C10, a capacitor C11, a capacitor C12, a capacitor C13, a capacitor C14, a capacitor C20, a capacitor C21, a capacitor C22, a capacitor C26, a capacitor C29, an operational amplifier U1C, an operational amplifier U2C, an inductor L1, an inductor L2, and a transient voltage suppression diode Z1, wherein one end of the diode D5 is connected to the bidirectional transient suppression diode D10 and the 12V vehicle battery voltage of pin No. 6 of the vehicle audio signal input terminal 1, the other end is connected to the resistor R9, the capacitor C13, the capacitor C14, the capacitor C26, and the capacitor C29 are connected in parallel, and one end of the capacitor C13, the capacitor C14, the capacitor C26, and one end of the capacitor C29 are grounded. The other end of the resistor is connected with a resistor R9, an inductor L1, an inductor L2 and a transient voltage suppression diode Z1 respectively, a capacitor C10, a capacitor C11, a capacitor C12, a resistor R12 and an operational amplifier U1C are connected in parallel, a resistor R8 is located between the resistor R12 and the operational amplifier U1C, a capacitor C20, a capacitor C21, a capacitor C22, a resistor R16 and an operational amplifier U2C are connected in parallel, and a resistor R14 is located between the resistor R16 and the operational amplifier U2C.

In summary, the utility model provides a conversion circuit with audio high-level to low-level output, an audio signal with amplitude exceeding 5V is introduced into a vehicle-mounted audio signal input end of the conversion circuit, attenuation processing is carried out, the audio signal is converted into an audio signal with standard rated sensitivity through an operational amplifier, the output sensitivity is 0dB, namely 0.775mV, and the requirement of input sensitivity of a general rear-mounted subwoofer and a HiFi sound box is met.

It will be evident to those skilled in the art that the utility model is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the utility model being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Claims

1. A switching circuit having an audio high to low output, comprising: comprises a vehicle-mounted audio signal input end (1), a left channel coupling attenuation circuit (2), a right channel coupling attenuation circuit (3), a left channel amplitude limiting circuit (4), a right channel amplitude limiting circuit (5), a left channel subtraction circuit (6), a right channel subtraction circuit (7), a left channel operational amplification following output circuit (8), a right channel operational amplification following output circuit (9), a power supply circuit (10) and an audio signal output end (11), wherein one end of the left channel coupling attenuation circuit (2) and one end of the right channel coupling attenuation circuit (3) are connected with the vehicle-mounted audio signal input end (1), the other end of the left channel coupling attenuation circuit (2) and the other end of the right channel coupling attenuation circuit (3) are respectively connected with the left channel amplitude limiting circuit (4) and the right channel amplitude limiting circuit (5), one end of the left channel subtraction circuit (6) and one end of the right channel subtraction circuit (7) are connected with the left channel amplitude limiting circuit (4) and the right channel amplitude limiting circuit (5), the other end of the power supply circuit (10) is connected with a left channel operational amplification following output circuit (8), a right channel operational amplification following output circuit (9), an audio signal output end (11), and an electric energy is provided for the left channel subtraction circuit (6), the right channel subtraction circuit (7), the left channel operational amplification following output circuit (8) and the right channel operational amplification following output circuit (9).

2. The conversion circuit of claim 1 having an audio high to low output, wherein: the left channel coupling attenuation circuit (2) is composed of a bidirectional transient suppression diode D13, a bidirectional transient suppression diode D14, a capacitor C3, a capacitor C15, a resistor R2, a resistor R3 and a resistor R5, wherein the bidirectional transient suppression diode D13 and the bidirectional transient suppression diode D14 are connected in parallel, one ends of a bidirectional transient suppression diode D13 and one end of the bidirectional transient suppression diode D14 are grounded, the other ends of the bidirectional transient suppression diode D15 are connected with a pin 1 and a pin 2 of the vehicle audio signal input end (1), one ends of the capacitor C3 and one end of the capacitor C15 are connected with the pin 1 and the pin 2 of the vehicle audio signal input end (1), the other ends of the capacitor C3 and the capacitor C15 are connected with a resistor R2 and a resistor R5, and two ends of the resistor R3 are connected with a resistor R2 and a resistor R5.

3. The conversion circuit of claim 1 having an audio high to low output, wherein: the right channel coupling attenuation circuit (3) is composed of a bidirectional transient suppression diode D11, a bidirectional transient suppression diode D12, a capacitor C5, a capacitor C8, a resistor R7, a resistor R10 and a resistor R11, wherein the bidirectional transient suppression diode D11 and the bidirectional transient suppression diode D12 are connected in parallel, one ends of a bidirectional transient suppression diode D11 and one end of the bidirectional transient suppression diode D12 are grounded, the other ends of the bidirectional transient suppression diode D8 are connected with a No. 3 pin and a No. 4 pin of the vehicle audio signal input end (1), one ends of a capacitor C5 and one end of a capacitor C8 are connected with the No. 3 pin and the No. 4 pin of the vehicle audio signal input end (1), the other ends of the capacitor C5 and the capacitor C8 are connected with a resistor R7 and a resistor R11, and two ends of the resistor R10 are connected with a resistor R7 and a resistor R11.

4. The conversion circuit of claim 1 having an audio high to low output, wherein: the left channel amplitude limiting circuit (4) limits the left channel audio signal output by the vehicle-mounted audio signal input end (1) within 12Vp-p, and comprises a capacitor C2, a capacitor C6, a diode D1, a diode D2, a diode D3 and a diode D4, wherein the diode D1, the diode D2, the diode D3 and the diode D4 are amplitude limiting diodes, one end of the diode D1 is connected with a power supply terminal VCC1, the other end of the diode D1 is respectively connected with the capacitor C2 and the diode D3, one end of the diode D2 is connected with the power supply terminal VCC1, the other end of the diode D2 is respectively connected with the capacitor C6 and the diode D4, and one ends of the diode D3 and the diode D4, which are far away from the diode D1 and the diode D2, are grounded.

5. The conversion circuit of claim 1 having an audio high to low output, wherein: the right channel amplitude limiting circuit (5) limits the right channel audio signal output by the vehicle-mounted audio signal input end (1) within 12Vp-p, and comprises a capacitor C17, a capacitor C19, a diode D6, a diode D7, a diode D8 and a diode D9, wherein the diode D6, the diode D7, the diode D8 and the diode D9 are amplitude limiting diodes, one end of the diode D6 is connected with a power supply terminal VCC2, the other end of the diode D6 is respectively connected with the capacitor C17 and the diode D8, one end of the diode D7 is connected with the power supply terminal VCC2, the other end of the diode D7 is respectively connected with the capacitor C19 and the diode D9, and one ends of the diode D8 and the diode D9, which are far away from the diode D6 and the diode D7, are grounded.

6. The conversion circuit of claim 1 having an audio high to low output, wherein: the left channel subtraction circuit (6) comprises a capacitor C1, a capacitor C4, a capacitor C9, a resistor R1, a resistor R6 and an operational amplifier U1A, wherein the capacitor C9 is connected with the resistor R6 in parallel, one ends of the capacitor C9 and one end of the resistor R6 are connected with the power supply circuit (10), the other ends of the capacitor C9 and the resistor R6 are respectively connected with the non-inverting input ends of the capacitor C4 and the operational amplifier U1A, the capacitor C1 is connected with the resistor R1 in parallel, one ends of the capacitor C1 and the resistor R1 are connected with the output end of the operational amplifier U1A, and the other ends of the capacitor C4 and the inverting input end of the operational amplifier U1A are respectively connected with the inverting input ends of the capacitor C4 and the operational amplifier U1A.

7. The conversion circuit of claim 1 having an audio high to low output, wherein: the right channel subtraction circuit (7) comprises a capacitor C16, a capacitor C18, a capacitor C24, a resistor R13, a resistor R17 and an operational amplifier U2A, wherein the capacitor C24 is connected with the resistor R17 in parallel, one ends of the capacitor C24 and one end of the resistor R17 are connected with the power supply circuit (10), the other ends of the capacitor C24 and the resistor R17 are connected with the non-inverting input ends of the capacitor C18 and the operational amplifier U2A respectively, the capacitor C16 is connected with the resistor R13 in parallel, one ends of the capacitor C16 and the resistor R13 are connected with the output end of the operational amplifier U2A, and the other ends of the capacitor C18 and the inverting input end of the operational amplifier U2A are connected with the inverting input ends of the capacitor C18 and the operational amplifier U2A respectively.

8. The conversion circuit of claim 1 having an audio high to low output, wherein: the left channel operational amplification following output circuit (8) is composed of a capacitor C7, a capacitor C25, a capacitor C27, a capacitor C28, a capacitor C30, a resistor R4, a resistor R18, a resistor R21, a resistor R22, a resistor R23 and an operational amplifier U1B, wherein one end of the capacitor C7 is connected with the output end of the operational amplifier U1A, the other end is connected with the resistor R4, the capacitor C25 is connected with the resistor R18 in parallel, one end of a capacitor C25 and one end of a resistor R18 are connected with the output end of the operational amplifier U1B and the capacitor C27, the other end of the capacitor C25 and the other end of the resistor R18 are respectively connected with the resistor R4, the capacitor C28 and the inverting input end of the operational amplifier U1B, the capacitor C30 and the resistor R23 are connected in parallel, one end of the capacitor C30 and one end of the resistor R23 are connected with the power supply circuit (10), the other ends of the capacitor C30 and the resistor R23 are respectively connected with the capacitor C28 and the equidirectional input end of the operational amplifier U1B, one end of the capacitor C27, far away from the operational amplifier U1B, is respectively connected with the resistor R21 and the resistor R22, and one end of the resistor R21, far away from the capacitor C27, is connected with a left sound channel interface of the audio signal output end (11).

9. The conversion circuit of claim 1 having an audio high to low output, wherein: the right channel operational amplification following output circuit (9) is composed of a capacitor C23, a capacitor C31, a capacitor C34, a capacitor C35, a capacitor C36, a resistor R15, a resistor R24, a resistor R27, a resistor R28, a resistor R29 and an operational amplifier U2B, wherein one end of the capacitor C23 is connected with the output end of the operational amplifier U2A, the other end is connected with the resistor R15, the capacitor C31 is connected with the resistor R24 in parallel, one end of a capacitor C31 and one end of a resistor R24 are connected with the output end of the operational amplifier U2B and the capacitor C34, the other end of the capacitor C31 and the other end of the resistor R24 are respectively connected with the resistor R15, the capacitor C35 and the inverting input end of the operational amplifier U2B, the capacitor C36 and the resistor R29 are connected in parallel, one end of the capacitor C36 and one end of the resistor R29 are connected with the power supply circuit (10), the other ends of the capacitor C36 and the resistor R29 are respectively connected with the capacitor C35 and the equidirectional input end of the operational amplifier U2B, one end of the capacitor C34, far away from the operational amplifier U2B, is respectively connected with the resistor R27 and the resistor R28, and one end of the resistor R27, far away from the capacitor C34, is connected with a right channel interface of the audio signal output end (11).

10. The conversion circuit of claim 1 having an audio high to low output, wherein: the power supply circuit (10) comprises a bidirectional transient suppression diode D10, a diode D5, a resistor R8, a resistor R9, a resistor R12, a resistor R14, a resistor R16, a capacitor C10, a capacitor C11, a capacitor C12, a capacitor C13, a capacitor C14, a capacitor C20, a capacitor C21, a capacitor C22, a capacitor C26, a capacitor C29, an operational amplifier U1C, an operational amplifier U2C, an inductor L1, an inductor L2 and a transient voltage suppression diode Z1, wherein one end of the diode D1 is connected with the 12V vehicle battery voltage of the No. 6 pin of the bidirectional transient suppression diode D1 and the vehicle audio signal input end (1), the other end of the diode D1 is connected with the resistor R1, the capacitor C1 and the capacitor C1, the other end of the capacitor C1 is connected with the transient suppression diode D1, the capacitor C1, the inductor L1, the capacitor C1 and the capacitor C1, and the capacitor C1 are connected with the transient voltage suppression diode R1, the capacitor C1, the capacitor Z1, the capacitor C1, and the capacitor C1, and the capacitor C1 are connected with the transient voltage suppression capacitor C1, the capacitor Z1, the transient voltage suppression capacitor C1, the capacitor Z1, the capacitor C1, and the capacitor C1, the transient voltage suppressor, and the capacitor C1, the capacitor C1, The capacitor C12, the resistor R12 and the operational amplifier U1C are connected in parallel, the resistor R8 is located between the resistor R12 and the operational amplifier U1C, the capacitor C20, the capacitor C21, the capacitor C22, the resistor R16 and the operational amplifier U2C are connected in parallel, and the resistor R14 is located between the resistor R16 and the operational amplifier U2C.