Protection circuit capable of automatically reducing volume when power amplifier of automobile is overheated

Abstract

The utility model discloses a protection circuit for automatically reducing volume when an automobile power amplifier is overheated. The protection circuit comprises a transmission end, a pre-amplification / tone circuit, a power amplification circuit, a temperature detection control circuit and sound equipment, when the temperature of a radiator of sound equipment is below 70 DEG C, the transmission end inputs audio signal voltage to the circuit, the pre-stage amplification / tone circuit receives the audio signal voltage and then amplifies the audio signal voltage, and then the processed audio signal voltage is transmitted to the power amplification circuit. The power amplification circuit carries out amplification again so as to achieve an ideal vehicle-mounted effect; when the temperature of a radiator of the sound equipment is above 75 DEG C, the temperature detection control circuit can attenuate the audio signal voltage passing through the pre-stage amplification / tone circuit, so that the audio signal voltage reaching the power amplification circuit is reduced, the signal output volume of the power amplification circuit is reduced, and the temperature rise of the sound equipment is controlled; the utility model has the characteristics of improving the driving safety, prolonging the service life of the sound equipment and the like.

Description

Technical Field

[0001] The utility model relates to the field of circuits, in particular to a circuit for automatically reducing the volume of an automobile amplifier when it is overheated. Background Art

[0002] Overheating of car amplifiers can have a significant impact on car driving, such as reduced sound quality, shortened equipment life, and other faults. Excessive amplifier temperature can damage the electronic components of audio equipment, affecting the electrical characteristics of the components, thus deteriorating the sound quality; in the case of excessive temperature, electronic components may age or deform, thus affecting the performance and life of the audio equipment; excessive temperature may cause electronic components to expand, reduce the spacing between components, and further affect the electrical parameters of the components, ultimately leading to reduced performance of the equipment. In addition, excessive amplifier temperature may also cause circuit damage and may even cause serious consequences such as fire.

[0003] Therefore, car amplifier overheating is a problem that needs attention. Car owners should regularly check the heat dissipation of the amplifier equipment to ensure that it operates within the normal operating temperature range to ensure the sound effect and equipment safety. If the amplifier is found to be overheating, timely measures should be taken to solve it, such as adding heat dissipation equipment, adjusting the power settings of the audio system, etc.

[0004] At present, all car amplifiers have traditional overheat protection function, which is designed to prevent users from using them in harsh environments with high temperatures and poor heat dissipation conditions or improper operation and overload to protect the amplifier products from overheating and damage. With traditional overheat protection function, when the radiator temperature reaches about 80℃, the amplifier will stop working. In addition to being unable to continue listening to music, for some models, the navigation sound / front and rear radar prompt sound and other original car prompt sounds will not be broadcast to remind, affecting driving safety.

[0005] How to promptly remind the car owner when the car amplifier is overheated and improve driving safety is a technical problem that technicians in this field urgently need to solve. Utility Model Content

[0006] The utility model aims to provide a circuit for automatically reducing the volume of an automobile amplifier when it is overheated, so as to solve the problems raised in the above-mentioned background technology.

[0007] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0008] Provided is a circuit for automatically reducing the volume of an automobile power amplifier overheating protection, characterized in that it includes a transmission end, a preamplifier / tone circuit, a power amplifier circuit, a temperature detection control circuit, an audio device and a switch tube;

[0009] The transmission end inputs the audio signal voltage to the circuit, and the pre-amplification / tone circuit amplifies the power after receiving the audio signal voltage, selects and pre-processes the audio signal voltage, and performs power amplification, and then transmits the processed audio signal voltage to the power amplifier circuit, and the power amplifier circuit amplifies it again to achieve the ideal vehicle-mounted effect, and then the power amplifier circuit drives the audio equipment to make sound;

[0010] A voltage dividing point is provided at the connection between the pre-amplifier / tone circuit and the power amplifier circuit, the switch tube is connected to the voltage dividing point and grounded, the temperature detection control circuit is connected to the switch tube, and the temperature detection control circuit outputs high and low levels to the switch tube by detecting the temperature change of the power amplifier circuit to control whether the switch tube is turned on.

[0011] Furthermore, the temperature detection control circuit is provided with a voltage comparator, and two lines are provided from the power supply to the positive and negative electrodes of the voltage comparator respectively, the output end of the voltage comparator is connected to the base of the switching tube, and the collector of the switching tube is connected to the voltage dividing point.

[0012] Furthermore, the temperature detection control circuit includes a third resistor and a thermistor, and the two lines connecting the power supply and the voltage comparator are provided with a positive pole and a negative pole, and the third resistor and the thermistor are respectively connected to the positive pole and the negative pole and grounded.

[0013] Furthermore, when the temperature of the power amplifier circuit is below a limit value, the resistance of the thermistor is not less than the resistance of the third resistor.

[0014] Furthermore, when the temperature of the power amplifier circuit is at a limited value, the resistance of the thermistor is less than the resistance of the third resistor.

[0015] Furthermore, when the temperature of the power amplifier circuit is below a limit value, the voltage comparator outputs a low level and the switch tube is in a cut-off state.

[0016] Furthermore, when the temperature of the power amplifier circuit is within the limit value, the output of the voltage comparator is high, the switch tube is turned on, and part of the current output from the pre-amplifier / tone circuit is diverted from the switch tube, thereby reducing the audio signal voltage reaching the power amplifier circuit.

[0017] Furthermore, the temperature detection control circuit includes a first resistor and a second resistor, one end of the first resistor is connected to a power supply, and the other end is connected to a third resistor and a positive electrode of a voltage comparator, and one end of the second resistor is connected to a power supply and the other end is connected to a thermistor and a negative electrode of a voltage comparator.

[0018] Furthermore, the temperature detection control circuit includes a fourth resistor, one end of the fourth resistor is connected to the output end of the voltage comparator, and the other end is connected to the base of the switch tube.

[0019] Furthermore, it includes an eighth resistor, a fifth resistor, a sixth resistor and a seventh resistor, and a capacitor. One end of the eighth resistor is connected to the first resistor, and the other end is connected to the first resistor. One end of the fifth resistor is connected to the fourth resistor and is connected in parallel with the switch tube. The other end of the fifth resistor is grounded. The current output by the pre-amplifier / tone circuit flows partly to the seventh resistor through the sixth resistor, and partly flows to the capacitor. The seventh resistor is connected in parallel with the capacitor. The other end of the seventh resistor is connected to the switch tube, and the other end of the capacitor is connected to the power amplifier circuit.

[0020] Compared with the prior art, the beneficial effects of the utility model are:

[0021] The utility model provides a circuit for automatically reducing the volume of an automobile power amplifier when it is overheated. The utility model uses a voltage comparator and a temperature sensor to form a temperature monitoring control circuit and adds it to the power amplifier circuit, which can coexist with the traditional overheat protection function. When the temperature of the power amplifier radiator rises to the upper limit of the set maximum temperature of about 75°C, the temperature detection control circuit pulls down and attenuates the audio signal of the input power amplifier circuit, reduces its volume by about 50%, and reduces the output power, thereby controlling the temperature of the power amplifier radiator to continue to rise; when the temperature of the power amplifier radiator drops to the lower limit of the set recovery temperature of about 70°C, the temperature detection control circuit stops pulling down and attenuating the audio signal of the input power amplifier circuit, and the power amplifier returns to the normal volume level. Compared with the current automobile power amplifier, the advantage of the utility model power amplifier will not stop working due to overheating, but use the method of reducing the volume to limit the temperature of the power amplifier to continue to rise, which greatly reduces the problems of the power amplifier being unable to continue to listen to music due to overheating protection and being unable to broadcast the original car safety prompt sound normally, and the circuit can be applied to all power amplifier products. The utility model has the characteristics of improving driving safety and extending the service life of audio equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A circuit diagram of an automobile power amplifier overheating and automatic volume reduction protection circuit according to an embodiment of the utility model is shown;

[0023] The components in the accompanying drawings are marked as follows: 1 pre-amplifier / tone circuit; 2 power amplifier circuit; 3 temperature detection control circuit; 4 audio equipment; 5 transmission end; 6 voltage dividing point; 7 output end; 8 negative pole; 9 positive pole; R1 first resistor; R2 second resistor; R3 third resistor; R4 fourth resistor; R5 fifth resistor; R6 sixth resistor; R7 seventh resistor; R8 eighth resistor; IC1 voltage comparator; TH1 thermistor; Q1 switch tube; PE grounding point. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0025] See also Figure 1 , a car power amplifier overheating automatic volume reduction protection circuit, comprising a transmission end 5, a pre-amplification / tone circuit 1, a power amplifier circuit 2, a temperature detection control circuit 3 and an audio device 4;

[0026] When the temperature of the power amplifier radiator rises to a set value, the temperature control detection circuit pulls down and attenuates the audio signal input to the power amplifier circuit. When the temperature of the power amplifier radiator drops to a set value, the temperature control detection circuit stops pulling down and attenuating the audio signal input to the power amplifier circuit.

[0027] Specifically, when the temperature of the power amplifier circuit 2 is below 70°C, the transmission end 5 inputs an audio signal voltage to the circuit, and the pre-amplifier / tone circuit 1 amplifies the power after receiving the audio signal voltage, selects and pre-processes the audio signal voltage, and performs power amplification, and then transmits the processed audio signal voltage to the power amplifier circuit 2, and the power amplifier circuit 2 amplifies it again to achieve an ideal vehicle-mounted effect, and then the power amplifier circuit 2 drives the audio equipment to make a sound;

[0028] A voltage dividing point 6 is provided at the connection between the pre-amplifier / tone circuit 1 and the power amplifier circuit 2. The switch tube Q1 is connected to the voltage dividing point 6 and grounded. The other end of the switch tube Q1 is connected to the temperature detection control circuit 3. The temperature detection control circuit 3 outputs high and low levels to control whether the switch tube Q1 is turned on by detecting the temperature change of the power amplifier circuit 2. When the temperature of the power amplifier circuit 2 is above 75°C, the temperature detection control circuit 3 can attenuate the audio signal voltage passing through the pre-amplifier / tone circuit 1, so that the audio signal voltage reaching the power amplifier circuit 2 is reduced, thereby reducing the signal output volume of the power amplifier circuit 2 and controlling the temperature increase of the power amplifier circuit 2.

[0029] Specifically, the temperature detection control circuit 3 is provided with a voltage comparator IC1 and a switch tube Q1. Two lines are provided from the power supply and are respectively connected to the positive and negative electrodes of the voltage comparator IC1. The output terminal 7 of the voltage comparator IC1 is connected to the base of the switch tube Q1, and the collector of the switch tube Q1 is connected to the pre-stage amplifier / tone circuit 1.

[0030] The temperature detection control circuit 3 includes a third resistor R3 and a thermistor TH1. The two lines connecting the power supply and the voltage comparator IC1 are provided with a positive pole 9 and a negative pole 8. The third resistor R3 and the thermistor TH1 are respectively connected to the positive pole 9 and the negative pole 8 and grounded.

[0031] When the temperature of the power amplifier circuit 2 is below 70° C., the resistance of the thermistor TH1 is greater than the resistance of the third resistor R3 .

[0032] When the temperature of the power amplifier circuit 2 is 75° C., the resistance of the thermistor TH1 is smaller than the resistance of the third resistor R3 .

[0033] When the temperature of the power amplifier circuit 2 is below 70° C., the negative voltage of the voltage comparator IC1 is higher than the reference voltage set by the positive electrode of the voltage comparator IC1, and the output is a low level, and the switch tube Q1 is in the cut-off state.

[0034] When the temperature of the power amplifier circuit 2 is 75°C, the negative voltage of the voltage comparator IC1 is lower than the reference voltage set by the positive electrode of the voltage comparator IC1, and a high level is output. The switch tube Q1 is turned on, and part of the current output from the pre-amplifier / tone circuit 1 is diverted from the switch tube Q1, reducing the audio signal voltage reaching the power amplifier circuit 2.

[0035] The transmission end 5, the third resistor R3, the thermistor TH1, the fifth resistor R5, the emitter of the switch tube Q1 and the audio device 4 are all provided with grounding points, which are grounded and conductive.

[0036] Specifically, it includes a first resistor R1 and a second resistor R2, one end of the first resistor R1 is connected to the power supply, and the other end is connected to the third resistor R3 and the positive electrode of the voltage comparator IC1, and one end of the second resistor R2 is connected to the power supply and the other end is connected to the thermistor TH1 and the negative electrode of the voltage comparator IC1. It includes a fourth resistor R4, one end of the fourth resistor R4 is connected to the output end of the voltage comparator IC1, and the other end is connected to the base of the switch tube Q1. It includes an eighth resistor R8, a fifth resistor R5, a sixth resistor R6 and a seventh resistor R7, a capacitor, one end of the eighth resistor R8 is connected to the first resistor R1, and the other end is connected to the first resistor R1, one end of the fifth resistor R5 is connected to the fourth resistor R4 and connected in parallel with the switch tube, and the other end of the fifth resistor R5 is grounded, and the current output by the pre-amplifier / tone circuit 1 flows partly to the seventh resistor R7 through the sixth resistor R6, and partly to the capacitor, the seventh resistor R7 is connected in parallel with the capacitor, the other end of the seventh resistor R7 is connected to the switch tube Q1, and the other end of the capacitor is connected to the power amplifier circuit 2,

[0037] Preferably, the first resistor R1 has a resistance of 10kΩ, the second resistor R2 has a resistance of 13kΩ, the third resistor R3 has a resistance of 10kΩ, the fourth resistor R4 has a resistance of 4.7kΩ, the fifth resistor R5 has a resistance of 10kΩ, the sixth resistor R6 has a resistance of 2kΩ, the seventh resistor R7 has a resistance of 2kΩ, the eighth resistor R8 has a resistance of 100kΩ, the thermistor TH1 is preferably a negative temperature coefficient NTC thermistor 100K, and the model of the voltage comparator IC1 is preferably TJM4558D.

[0038] Working principle of temperature detection control circuit 3: When the working temperature is within the normal range, the voltage at pin 2 of voltage comparator IC1 is higher than the reference voltage set at pin 3 of voltage comparator IC1. According to the working characteristics of voltage comparator IC1, pin 1 of voltage comparator IC1 outputs a low level, which passes through the fourth resistor R4 to the base of switch tube Q1. At this time, the low level of the base of switch tube Q1 does not meet the turn-on voltage, and switch tube Q1 is in the cut-off state. The audio signal voltage passing through the sixth resistor R6 will not be pulled down and attenuated. When the working temperature of the power amplifier continues to rise and reaches the upper limit of the maximum working temperature, the resistance value of thermistor TH1 decreases as the temperature rises, and the voltage of pin 2 of voltage comparator IC1 decreases at the same time, until the voltage of pin 2 of voltage comparator IC1 is lower than the reference voltage set at pin 3 of voltage comparator IC1. According to the working characteristics of voltage comparator IC1, pin 1 of voltage comparator IC1 outputs a high level, which is divided by the fourth resistor R4 and the fifth resistor R5 to the base of switch tube Q1. At this time, the base and emitter of switch tube Q1 are forward biased, switch tube Q1 is turned on, and the collector of switch tube Q1 is at a low level. The audio signal voltage passing through the sixth resistor R6 is forcibly attenuated by the seventh resistor R7, so that the audio signal voltage reaching power amplifier circuit 2 is reduced, thereby reducing the power amplifier circuit 2. The signal output volume controls the temperature rise of the power amplifier circuit 2. As the output power decreases, the temperature of the power amplifier circuit 2 will gradually decrease. The resistance value of the thermistor TH1 increases as the temperature decreases. At the same time, the voltage of the 2nd pin of the voltage comparator IC1 increases until the voltage of the 2nd pin of the voltage comparator IC1 is higher than the reference voltage set at the 3rd pin of the voltage comparator IC1. According to the working characteristics of the voltage comparator IC1, the 1st pin of the voltage comparator IC1 outputs a low level, which passes through the fourth resistor R4 to the base of the switch tube Q1. The low level of the base of the switch tube Q1 does not meet the conduction voltage, and the switch tube Q1 is turned off. The collector of the switch tube Q1 is in a high-impedance state. The audio signal voltage passing through the sixth resistor R6 will not be pulled down and attenuated by the seventh resistor R7. At this time, the volume level is restored to a normal level. The eighth resistor R8 is a positive feedback resistor, which is used to set the temperature when the normal volume is restored.

[0039] The utility model provides a circuit for automatically reducing the volume of an automobile power amplifier when it is overheated. The utility model uses a voltage comparator IC1 and a thermistor TH1 to form a temperature detection control circuit 3 and adds it to the power amplifier circuit, which can coexist with the traditional overheat protection function. When the temperature of the power amplifier circuit 2 rises to the upper limit of the set maximum temperature of about 75°C, the temperature detection control circuit 3 pulls down and attenuates the audio signal input to the power amplifier circuit 2, reduces its volume by about 50%, and reduces the output power, thereby controlling the temperature of the power amplifier circuit 2 to continue to rise; when the temperature of the power amplifier circuit 2 drops to the lower limit of the set recovery temperature of about 70°C, the temperature detection control circuit 3 stops pulling down and attenuating the audio signal input to the power amplifier circuit 2, and the power amplifier returns to a normal volume level. Compared with the current automobile power amplifier, the advantage of the utility model power amplifier will not stop working due to overheating, but use the method of reducing the volume to limit the temperature of the power amplifier to continue to rise, which greatly reduces the problems of the power amplifier being unable to continue to listen to music due to overheating protection and being unable to broadcast the original car safety prompt sound normally, and the circuit can be applied to all power amplifier products. The utility model has the characteristics of improving driving safety and extending the service life of audio equipment.

[0040] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes within the technical scope disclosed by the present invention according to the technical scheme and the utility model concept of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A car amplifier overheating automatic volume reduction protection circuit, characterized in that: It includes a transmission end (5), a pre-amplification / tone circuit (1), a power amplifier circuit (2), a temperature detection control circuit (3), an audio device (4) and a switch tube (Q1); The transmission end (5) inputs an audio signal voltage to the circuit, and the pre-amplification / tone circuit (1) amplifies the power after receiving the audio signal voltage, selects and pre-processes the audio signal voltage, and performs power amplification, and then transmits the processed audio signal voltage to the power amplifier circuit (2), and the power amplifier circuit (2) amplifies it again to achieve an ideal vehicle-mounted effect, and then the power amplifier circuit (2) drives the audio equipment to emit sound; A voltage dividing point (6) is provided at the connection point between the pre-amplification / tone circuit (1) and the power amplifier circuit (2); the switch tube (Q1) is connected to the voltage dividing point (6) and is grounded; the temperature detection control circuit (3) is connected to the switch tube (Q1); the temperature detection control circuit (3) outputs high and low levels to the switch tube (Q1) by detecting the temperature change of the power amplifier circuit (2), thereby controlling whether the switch tube (Q1) is turned on.

2. The automobile power amplifier overheating automatic volume reduction protection circuit according to claim 1 is characterized in that: The temperature detection control circuit (3) is provided with a voltage comparator (IC1), and two lines are provided from the power supply and are respectively connected to the positive and negative electrodes of the voltage comparator (IC1), the output end (7) of the voltage comparator (IC1) is connected to the base of the switch tube (Q1), and the collector of the switch tube (Q1) is connected to the voltage dividing point (6).

3. The automobile power amplifier overheating automatic volume reduction protection circuit according to claim 2 is characterized in that: The temperature detection control circuit (3) comprises a third resistor (R3) and a thermistor (TH1); a positive pole (9) and a negative pole (8) are provided on two lines connecting the power supply and the voltage comparator (IC1); the third resistor (R3) and the thermistor (TH1) are respectively connected to the positive pole (9) and the negative pole (8) and are grounded.

4. The automobile power amplifier overheating automatic volume reduction protection circuit according to claim 3 is characterized in that: When the temperature of the power amplifier circuit (2) is below a limit value, the resistance value of the thermistor (TH1) is not less than the resistance value of the third resistor (R3).

5. The automobile power amplifier overheating automatic volume reduction protection circuit according to claim 3 is characterized in that: When the temperature of the power amplifier circuit (2) is at a limited value, the resistance of the thermistor (TH1) is smaller than the resistance of the third resistor (R3).

6. The automobile power amplifier overheating automatic volume reduction protection circuit according to claim 4 is characterized in that: When the temperature of the power amplifier circuit (2) is below a limit value, the voltage comparator (IC1) outputs a low level and the switch tube (Q1) is in a cut-off state.

7. The automobile amplifier overheating automatic volume reduction protection circuit according to claim 5 is characterized in that: When the temperature of the power amplifier circuit (2) is within the limit value, the output of the voltage comparator (IC1) is high level, the switch tube (Q1) is turned on, and a part of the current output from the pre-amplifier / tone circuit (1) is diverted from the switch tube (Q1), so that the voltage of the audio signal reaching the power amplifier circuit (2) is reduced.

8. The automobile power amplifier overheating automatic volume reduction protection circuit according to claim 3 is characterized in that: The temperature detection control circuit (3) comprises a first resistor (R1) and a second resistor (R2); one end of the first resistor (R1) is connected to a power supply, and the other end is connected to a third resistor (R3) and a positive electrode of a voltage comparator (IC1); one end of the second resistor (R2) is connected to a power supply, and the other end is connected to a thermistor (TH1) and a negative electrode of a voltage comparator (IC1).

9. The automobile amplifier overheating automatic volume reduction protection circuit according to claim 8 is characterized in that: The temperature detection control circuit (3) comprises a fourth resistor (R4), one end of the fourth resistor (R4) is connected to the output end of the voltage comparator (IC1), and the other end is connected to the base of the switch tube (Q1).

10. The automobile amplifier overheating automatic volume reduction protection circuit according to claim 9 is characterized in that: The invention comprises an eighth resistor (R8), a fifth resistor (R5), a sixth resistor (R6) and a seventh resistor (R7), and a capacitor. One end of the eighth resistor (R8) is connected to the first resistor (R1), and the other end is connected to the first resistor (R1). One end of the fifth resistor (R5) is connected to the fourth resistor (R4) and connected in parallel with the switch tube. The other end of the fifth resistor (R5) is grounded. A part of the current output by the pre-amplifier / tone circuit (1) flows to the seventh resistor (R7) through the sixth resistor (R6), and another part flows to the capacitor. The seventh resistor (R7) is connected in parallel with the capacitor. The other end of the seventh resistor (R7) is connected to the switch tube (Q1), and the other end of the capacitor is connected to the power amplifier circuit (2).

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