A power amplifier output current indicating circuit

Abstract

The utility model relates to a kind of power amplifier output current indicating circuit, including the current sampling circuit, current comparison circuit and current indicating circuit connected in turn, the current sampling circuit includes a current mutual inductance circuit, the current mutual inductance circuit is used to convert the high-intensity current of power amplifier output into low-intensity current, after multi-stage threshold comparison by current comparison circuit, the intensity of the output current of the power amplifier is directly displayed by current indicating circuit.This utility model realizes the high-precision, real-time, safety monitoring of power amplifier output current, solves the problem of slow response, low precision and no isolation of traditional scheme, and is especially suitable for professional sound, vehicle-mounted power amplifier and other scenes that require strict protection of playback equipment.

Description

Technical Field

[0001] This utility model relates to the field of current indication, and in particular to a power amplifier output current indication circuit. Background Technology

[0002] An audio power amplifier (APA) is the core component of an audio system. Its main function is to amplify the weak audio signals output from audio source devices (such as CD players and mobile phones) by increasing voltage and current, so as to drive the playback device to reproduce sound with sufficient loudness and fidelity. In professional audio, home theater, and car audio systems, the performance of the APA directly affects the dynamic range, distortion, and overall listening experience of the sound.

[0003] However, abnormal power amplifier output current may cause playback devices to burn out or be damaged. Therefore, real-time monitoring of output current is crucial, but current generally cannot be directly measured. For this reason, there is an urgent need to propose a circuit that can represent the magnitude of power amplifier output current. Utility Model Content

[0004] Based on this, the purpose of this utility model is to overcome the defects or deficiencies of the prior art and provide a power amplifier output current indication circuit.

[0005] A power amplifier output current indication circuit includes a current sampling circuit, a current comparison circuit, and a current indication circuit connected in sequence. The current sampling circuit includes a current transformer circuit, which converts the high-intensity current output by the power amplifier into a low-intensity current. After the current comparison circuit performs multi-level threshold comparisons, the current indication circuit visually displays the intensity of the output current of the power amplifier.

[0006] Compared to existing technologies, the power amplifier output current indicator circuit of this invention keeps the output current within the allowable range, thereby protecting the power amplifier and playback devices such as speakers and enclosures connected to the power amplifier, and preventing damage to the equipment from using excessive current when the current magnitude is unknown.

[0007] In one embodiment, the current sampling circuit includes a current transformer circuit and a precision rectifier circuit connected in sequence. The high-intensity alternating current is first converted into low-intensity alternating current by the current transformer circuit in proportion, and then converted into low-intensity direct current by the precision rectifier circuit.

[0008] The current transformer circuit includes a current transformer T1, a resistor R2, a resistor R3, and a capacitor C1. Pin 2 of the current transformer T1 is connected to the power amplifier, pin 1 is connected to the playback device, pin 3 is grounded, and pin 4 is connected to one end of resistor R2. The other end of resistor R2 is connected to the subsequent precision rectifier circuit and resistor R3, and the other end of resistor R3 is grounded. The capacitor C1 is connected in parallel with resistor R3.

[0009] The precision rectifier circuit includes a resistor R4, an operational amplifier U1A, diodes D1 and D2, a resistor R5, and a capacitor C2. One end of resistor R4 is connected to the output of the preceding stage, and the other end of resistor R4 is connected to the inverting input of operational amplifier U1A. The non-inverting input of operational amplifier U1A is grounded. The two power supply terminals of operational amplifier U1A are connected to a positive power supply voltage and a negative power supply voltage, respectively. The anode of diode D1 is connected to the inverting input of operational amplifier U1A, and its cathode is connected to the anode of diode D2. The anode of diode D2 is also connected to the output of operational amplifier U1A, and the cathode of diode D2 is connected to the current comparator circuit in the following stage. One end of resistor R5 is connected to the inverting input of operational amplifier U1A, and the other end is connected to the cathode of diode D2. One end of capacitor C2 is connected to the cathode of diode D2, and the other end is grounded.

[0010] In one embodiment, the current comparison circuit includes comparator U2A, comparator U2B, comparator U2C, comparator U2D, and a voltage divider circuit; the voltage divider circuit includes resistors R9, R10, R11, R12, and R13 connected in series, and a positive power supply voltage connected to the other end of resistor R13; the other end of resistor R9 is grounded; the connection between resistors R9 and R10 is designated as a first connection point, the connection between resistors R10 and R11 is designated as a second connection point, the connection between resistors R11 and R12 is designated as a third connection point, and the connection between resistors R12 and R13 is designated as a fourth connection point;

[0011] The two power supply terminals of comparators U2A, U2B, U2C, and U2D are each connected to a positive power supply voltage and a negative power supply voltage, respectively; the positive input terminals of comparators U2A, U2B, U2C, and U2D are all connected to the negative terminal of diode D2 in the precision rectifier circuit; the output terminals of comparators U2A, U2B, U2C, and U2D are all connected to the current indication circuit in the subsequent stage.

[0012] The inverting input of comparator U2A is connected to the first connection point between resistors R9 and R10; the inverting input of comparator U2B is connected to the second connection point between resistors R10 and R11; the inverting input of comparator U2C is connected to the third connection point between resistors R11 and R12; and the inverting input of comparator U2D is connected to the fourth connection point between resistors R12 and R13.

[0013] In one embodiment, the voltage divider circuit further includes resistors R14, R15, R16, and R17 connected in series between resistor R13 and the power supply voltage, wherein the connection between resistors R13 and R14 is designated as the fifth connection point, the connection between resistors R14 and R15 is designated as the sixth connection point, the connection between resistors R15 and R16 is designated as the seventh connection point, and the connection between resistors R16 and R17 is designated as the eighth connection point.

[0014] Accordingly, the current comparison circuit further includes comparators U3A, U3B, U3C, and U3D. The connection method of the two power supply terminals of comparators U3A, U3B, U3C, and U3D is the same as that of comparator U2A. The output terminals of each operational amplifier are connected to the current indication circuit in the subsequent stage, and the positive input terminals of each operational amplifier are connected to the negative terminal of diode D2 in the precision rectifier circuit. The difference lies in the connection method of the inverting input terminals of each operational amplifier: the inverting input terminal of comparator U3A is connected to the fifth connection point between resistors R13 and R14; the inverting input terminal of comparator U3B is connected to the sixth connection point between resistors R14 and R15; the inverting input terminal of comparator U3C is connected to the seventh connection point between resistors R15 and R16; and the inverting input terminal of comparator U3D is connected to the eighth connection point between resistors R16 and R17.

[0015] In one embodiment, the current indicating circuit includes a series circuit of a PNP transistor Q3, resistors R6, R7, and R8, diodes D4 and D5, and a light-emitting diode.

[0016] The emitter of the PNP transistor Q3 is connected to the positive power supply voltage, and a resistor R6 is connected in series between the emitter and the positive power supply voltage; the base of the PNP transistor Q3 is connected to a resistor R7, the other end of the resistor R7 is connected to a resistor R8, the other end of the resistor R8 is grounded, and the collector of the PNP transistor Q3 is connected in series with the light-emitting diode; the positive power supply voltage is also connected to the anode of the diode D4, the cathode of the diode D4 is connected to the anode of the diode D5, and the cathode of the diode D5 is connected between the resistors R7 and R8;

[0017] The LED series circuit includes LED1, LED2, LED3, and LED4, a negative power supply voltage, and capacitor C3. The positive terminal of LED1 is connected to capacitor C3, the positive terminal of LED2 is connected to the negative terminal of LED1, the positive terminal of LED3 is connected to the negative terminal of LED2, the positive terminal of LED4 is connected to the negative terminal of LED3, and the negative terminal of LED4 is connected to the negative power supply voltage. The other end of capacitor C3 is grounded.

[0018] The collector of the PNP transistor Q3 is connected to the positive terminal of the LED1, and the output of the comparator U2A is also connected to the positive terminal of the LED1; the output of the comparator U2B is connected to the positive terminal of the LED2, the output of the comparator U2C is connected to the positive terminal of the LED3, and the output of the comparator U2D is connected to the positive terminal of the LED4.

[0019] In one embodiment, the current indicating circuit includes a series circuit of a PNP transistor Q3, resistors R6, R7, and R8, diodes D4 and D5, and a light-emitting diode.

[0020] The emitter of the PNP transistor Q3 is connected to the positive power supply voltage, and a resistor R6 is connected in series between the emitter and the positive power supply voltage; the base of the PNP transistor Q3 is connected to a resistor R7, the other end of the resistor R7 is connected to a resistor R8, the other end of the resistor R8 is grounded, and the collector of the PNP transistor Q3 is connected in series with the light-emitting diode; the positive power supply voltage is also connected to the anode of the diode D4, the cathode of the diode D4 is connected to the anode of the diode D5, and the cathode of the diode D5 is connected between the resistors R7 and R8;

[0021] The LED series circuit includes LED1, LED2, LED3, LED4, LED5, LED6, LED7, and LED8, a negative power supply voltage, and capacitor C3. The positive terminal of LED1 is connected to capacitor C3; the positive terminal of LED2 is connected to the negative terminal of LED1; the positive terminal of LED3 is connected to the negative terminal of LED2; the positive terminal of LED4 is connected to the negative terminal of LED3; the positive terminal of LED5 is connected to the negative terminal of LED4; the positive terminal of LED6 is connected to the negative terminal of LED5; the positive terminal of LED7 is connected to the negative terminal of LED6; the positive terminal of LED8 is connected to the negative terminal of LED7; and the negative terminal of LED8 is connected to the negative power supply voltage. The other end of capacitor C3 is grounded.

[0022] The collector of the PNP transistor Q3 is connected to the positive terminal of the LED1, and the output of the comparator U2A is also connected to the positive terminal of the LED1; the output of the comparator U2B is connected to the positive terminal of the LED2; the output of the comparator U2C is connected to the positive terminal of the LED3; the output of the comparator U2D is connected to the positive terminal of the LED4; the output of the comparator U3A is connected to the positive terminal of the LED5; the output of the comparator U3B is connected to the positive terminal of the LED6; the output of the comparator U3C is connected to the positive terminal of the LED7; and the output of the comparator U3D is connected to the positive terminal of the LED8.

[0023] In one embodiment, an LM339 chip is used to integrate comparator U2A, comparator U2B, comparator U2C and comparator U2D.

[0024] In one embodiment, an LM339 chip is used to integrate comparator U3A, comparator U3B, comparator U3C and comparator U3D.

[0025] In one embodiment, the operational amplifier U1A is model NJM4580; the diodes D1 and D2 are model 1N4148; the PNP transistor Q3 is model 2N5401; the diodes D4 and D5 are model D51N4148; and the LEDs LED1, LED2, LED3, LED4, LED5, LED6, LED7, and LED8 are model Ф3-white-green-fog-L26 / 28.

[0026] In one embodiment, the positive power supply voltage is 15V and the negative power supply voltage is -15V; the resistance values ​​of resistors R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12, R13, R14, R15, and R16 are 10KΩ, 1 ...

[0027] To better understand and implement this invention, the following detailed description is provided in conjunction with the accompanying drawings. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall circuit structure of this utility model;

[0029] Figure 2 This is a schematic diagram of the module structure of this utility model;

[0030] Figure 3 This is a schematic diagram of the module structure of the current sampling circuit of this utility model;

[0031] Figure 4 This is a schematic diagram of the current transformer circuit of this utility model;

[0032] Figure 5 This is a schematic diagram of the precision rectifier circuit of this utility model;

[0033] Figure 6 This is a schematic diagram of the current comparison circuit of this utility model;

[0034] Figure 7 This is a schematic diagram of the current indicating circuit of this utility model. Detailed Implementation

[0035] The present invention will now be described in detail with reference to the accompanying drawings.

[0036] like Figures 1 to 2As shown, the power amplifier output current indication circuit of this utility model includes a current sampling circuit 10, a current comparison circuit 20 connected to the current sampling circuit 10, and a current indication circuit 30 connected to the current comparison circuit 20. The current sampling circuit 10 acquires the high-intensity alternating current output by the power amplifier, converts it into low-intensity direct current, and then performs multi-level threshold comparisons through the current comparison circuit 20. Finally, the current indication circuit 30 visually displays the intensity of the power amplifier's output current.

[0037] like Figure 3 As shown, the current sampling circuit 10 includes a current transformer circuit 11 and a precision rectifier circuit 12 connected in sequence. The high-intensity alternating current is first converted into low-intensity alternating current by the current transformer circuit 11 in proportion, and then converted into low-intensity direct current by the precision rectifier circuit 12.

[0038] like Figure 4 As shown, the current transformer circuit 11 converts high-intensity alternating current into low-intensity alternating current proportionally, while also achieving electrical isolation between the high-voltage and low-voltage systems. The current transformer circuit 11 includes a current transformer T1, resistors R2 and R3; pin 2 of the current transformer T1 is connected to a power amplifier, pin 1 is connected to a playback device, pin 3 is grounded, and pin 4 is connected to one end of resistor R2; the other end of resistor R2 is connected to the subsequent precision rectifier circuit 12 and resistor R3, and the other end of resistor R3 is grounded.

[0039] Specifically, resistors R2 and R3 are voltage divider resistors. By adjusting the resistance values ​​of resistors R2 and R3, the signal output to the subsequent circuit can be changed. In this application, the resistance value of resistor R2 is 1KΩ and the resistance value of resistor R3 is 1KΩ.

[0040] Furthermore, in order to filter out high-frequency signals in the AC signal and enable the signal to be output to the subsequent circuit more stably, a capacitor C1 connected in parallel with resistor R3 is also included; in this application, the capacitance of capacitor C1 is 10nF.

[0041] Furthermore, it also includes a resistor R1 connected to pin 1 of the current transformer T1, with its other end grounded; it is a dummy load, which acts as a load and also serves as a discharge resistor, discharging residual electricity when the circuit is de-energized; in this application, the resistance value of the resistor R1 is 2.2KΩ.

[0042] like Figure 5As shown, the precision rectifier circuit 12 includes a resistor R4, an operational amplifier U1A, diodes D1 and D2, and a resistor R5. One end of resistor R4 is connected to the output of the preceding stage, and the other end of resistor R4 is connected to the inverting input of operational amplifier U1A. The non-inverting input of operational amplifier U1A is grounded. The two power supply terminals of operational amplifier U1A are connected to a positive power supply voltage and a negative power supply voltage, respectively. The anode of diode D1 is connected to the inverting input of operational amplifier U1A, and its cathode is connected to the anode of diode D2. The anode of diode D2 is also connected to the output of operational amplifier U1A, and the cathode of diode D2 is connected to the current comparator circuit 20 in the following stage. One end of resistor R5 is connected to the inverting input of operational amplifier U1A, and the other end is connected to the cathode of diode D2.

[0043] Specifically, the positive power supply voltage is 15V, and the negative power supply voltage is -15V.

[0044] Specifically, the output voltage of the precision rectifier circuit 12 can be changed by adjusting the ratio of resistors R4 and R5; in this application, the resistance of resistor R4 is 10KΩ and the resistance of resistor R5 is 6.34KΩ.

[0045] Specifically, the diodes D1 and D2 are of type 1N4148.

[0046] Furthermore, in order to filter out any AC signals that may exist after being processed by the precision rectifier circuit 12, a capacitor C2 is also included, one end of which is connected to the negative terminal of the diode D2, and the other end of which is grounded; in this application, the capacitance of the capacitor C2 is 10μF.

[0047] like Figure 6 As shown, the current comparison circuit 20 includes a comparator U2A and a voltage divider circuit. The voltage divider circuit includes resistors R9 and R10 connected in series, and a positive power supply voltage connected to the other end of resistor R10. The other end of resistor R9 is grounded. The voltage between resistors R9 and R10 is set as the first connection point, and its voltage can be set by adjusting the power supply voltage and the resistance values ​​of resistors R9 and R10. The positive input terminal of the comparator U2A is connected to the negative terminal of diode D2 in the precision rectifier circuit 12, and its reverse input terminal is connected to the first connection point between resistors R9 and R10. The two power supply terminals of the comparator U2A are connected to the positive power supply voltage and the negative power supply voltage, respectively. The output terminal of the comparator U2A is connected to the current indication circuit 30 in the subsequent stage.

[0048] When the voltage output from the negative terminal of diode D2 in the precision rectifier circuit 12 is greater than the voltage at the connection point between resistors R9 and R10, the output terminal of comparator U2A is left floating; when the voltage output from the negative terminal of diode D2 in the precision rectifier circuit 12 is less than the voltage at the first connection point between resistors R9 and R10, comparator U2A outputs a negative power supply voltage; in this process, the voltage output from the negative terminal of diode D2 in the precision rectifier circuit 12 can be compared with the voltage at the first connection point, and the output of comparator U2A is determined based on the comparison result.

[0049] Furthermore, in order to accurately represent the voltage output from the negative terminal of diode D2 in the precision rectifier circuit 12, the voltage divider circuit further includes resistors R11, R12, and R13 connected in series between resistor R10 and the power supply voltage. The connection between resistors R10 and R11 is designated as the second connection point, the connection between resistors R11 and R12 as the third connection point, and the connection between resistors R12 and R13 as the fourth connection point. The voltages at the first, second, third, and fourth connection points can be adjusted by regulating the power supply voltage and the resistance values ​​of resistors R9, R10, R11, R12, and R13.

[0050] Correspondingly, it also includes comparators U2B, U2C, and U2D. The connection method of the two power supply terminals of comparators U2B, U2C, and U2D is the same as that of comparator U2A, and the output terminal of each operational amplifier is connected to the current indicator circuit 30 in the subsequent stage. The positive input terminal of each operational amplifier is connected to the negative terminal of diode D2 in the precision rectifier circuit 12. The difference lies in the connection method of the inverting input terminals of each operational amplifier. Specifically, the inverting input terminal of comparator U2B is connected to the second connection point between resistors R10 and R11; the inverting input terminal of comparator U2C is connected to the third connection point between resistors R11 and R12; and the inverting input terminal of comparator U2D is connected to the fourth connection point between resistors R12 and R13.

[0051] Furthermore, in order to more accurately represent the voltage output from the negative terminal of diode D2 in the precision rectifier circuit 12, the voltage divider circuit further includes resistors R14, R15, R16, and R17 connected in series between resistor R13 and the power supply voltage. The connection between resistors R13 and R14 is designated as the fifth connection point, between resistors R14 and R15 as the sixth connection point, between resistors R15 and R16 as the seventh connection point, and between resistors R16 and R17 as the eighth connection point. By adjusting the power supply voltage and the resistance values ​​of resistors R9, R10, R11, R12, R13, R14, R15, R16, and R17, the voltages at the first, second, third, fourth, fifth, sixth, seventh, and eighth connection points can be adjusted.

[0052] Correspondingly, it also includes comparators U3A, U3B, U3C, and U3D. The connection method of the two power supply terminals of comparators U3A, U3B, U3C, and U3D is the same as that of comparator U2A. The output terminals of each operational amplifier are connected to the current indicator circuit 30 in the subsequent stage, and the positive input terminals of each operational amplifier are connected to the negative terminal of diode D2 in the precision rectifier circuit 12. The difference lies in the connection method of the inverting input terminals of each operational amplifier. Specifically, the inverting input terminal of comparator U3A is connected to the fifth connection point between resistors R13 and R14; the inverting input terminal of comparator U3B is connected to the sixth connection point between resistors R14 and R15; the inverting input terminal of comparator U3C is connected to the seventh connection point between resistors R15 and R16; and the inverting input terminal of comparator U3D is connected to the eighth connection point between resistors R16 and R17.

[0053] Specifically, in this application, an LM339 chip is used to integrate comparator U2A, comparator U2B, comparator U2C and comparator U2D; another LM339 chip is used to integrate comparator U3A, comparator U3B, comparator U3C and comparator U3D.

[0054] In this application, the resistance of resistor R9 is 120 ohms, the resistance of resistor R10 is 220 ohms, the resistance of resistor R11 is 300 ohms, the resistance of resistor R12 is 360 ohms, the resistance of resistor R13 is 360 ohms, the resistance of resistor R14 is 360 ohms, the resistance of resistor R15 is 620 ohms, and the resistance of resistor R16 is 630 ohms.

[0055] like Figure 7As shown, the current indicating circuit 30 includes a PNP transistor Q3, resistors R6, R7, and R8, diodes D4 and D5, and a series circuit of an LED. The emitter of the PNP transistor Q3 is connected to the positive power supply voltage, and resistor R6 is connected in series between the emitter and the positive power supply voltage; the base of the PNP transistor Q3 is connected to resistor R7, the other end of resistor R7 is connected to resistor R8, the other end of resistor R8 is grounded, and the collector of the PNP transistor Q3 is connected to the series circuit of the LED; the positive power supply voltage is also connected to the anode of diode D4, the cathode of diode D4 is connected to the anode of diode D5, and the cathode of diode D5 is connected between resistors R7 and R8.

[0056] Specifically, when the current comparison circuit 20 includes a comparator U2A, a series resistor R9, and a resistor R10, the LED series circuit includes an LED1, a negative power supply voltage connected to the negative terminal of the LED1, and a capacitor C3 connected to the positive terminal of the LED1. The other end of the capacitor C3 is grounded. The output terminal of the comparator U2A is connected to the positive terminal of the LED1, and the collector of the PNP transistor Q3 is also connected to the positive terminal of the LED1.

[0057] In this application, the resistance of resistor R6 is 150Ω, the resistance of resistor R7 is 510Ω, and the resistance of resistor R8 is 10KΩ.

[0058] Specifically, when the current comparison circuit 20 further includes comparators U2B, U2C, U2D, resistors R11, R12, and R13, the LED series circuit further includes LEDs LED2, LED3, and LED4 connected in series between LED1 and the negative power supply voltage. The positive terminal of LED2 is connected to the negative terminal of LED1, the positive terminal of LED3 is connected to the negative terminal of LED2, the positive terminal of LED4 is connected to the negative terminal of LED3, and the negative terminal of LED4 is connected to the negative power supply voltage. The output terminal of comparator U2B is connected to the positive terminal of LED2, the output terminal of comparator U2C is connected to the positive terminal of LED3, and the output terminal of comparator U2D is connected to the positive terminal of LED4.

[0059] Specifically, when the current comparison circuit 20 further includes comparators U3A, U3B, U3C, and U3D, resistors R14, R15, R16, and R17, the LED series circuit further includes LEDs LED5, LED6, LED7, and LED8 connected in series between LED4 and the negative power supply voltage. The positive terminal of LED5 is connected to the negative terminal of LED4, and the positive terminal of LED6 is connected to the negative terminal of LED4. LED5 is connected to the negative terminal; LED7 is connected to the negative terminal of LED6; LED8 is connected to the negative terminal of LED7; and the negative terminal of LED8 is connected to the negative power supply voltage. The output of comparator U3A is connected to the positive terminal of LED5; the output of comparator U3B is connected to the positive terminal of LED6; the output of comparator U3C is connected to the positive terminal of LED7; and the output of comparator U3D is connected to the positive terminal of LED8.

[0060] In this application, the PNP transistor Q3 is model number 2N5401.

[0061] In this application, the diodes D4 and D5 are model number D51N4148.

[0062] In this application, the capacitance of capacitor C3 is 10μF.

[0063] In this application, the LED1, LED2, LED3, LED4, LED5, LED6, LED7 and LED8 are of model number Ф3-white-green-fog-L26 / 28.

[0064] Compared with existing technologies, this utility model achieves high-precision, real-time, and safe monitoring of the power amplifier output current through end-to-end optimization of "sampling and processing - multi-level comparison - intuitive display". It solves the problems of slow response, low accuracy, and lack of isolation in traditional solutions, and is particularly suitable for scenarios such as professional audio equipment and car amplifiers that require strict protection of playback devices.

[0065] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of this application. The singular forms “a,” “the,” and “the” used in the embodiments and claims of this application are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that, unless otherwise stated, “a plurality” means two or more; the terms “first,” “second,” “third,” etc., are used only to distinguish and not to describe a particular order or sequence, nor should they be construed as indicating or implying relative importance. The term “and / or” as used herein refers to and includes any or all possible combinations of one or more associated listed items. When the above description relates to drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. In the description of this application, those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0066] The embodiments described above are merely examples of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these modifications and improvements all fall within the protection scope of this utility model.

Claims

1. A power amplifier output current indication circuit, comprising a current sampling circuit, a current comparison circuit, and a current indication circuit connected in sequence, characterized in that: The current sampling circuit includes a current transformer circuit, which converts the high-intensity current output by the power amplifier into a low-intensity current. After multi-level threshold comparison by the current comparison circuit, the intensity of the output current of the power amplifier is displayed visually by the current indication circuit.

2. The power amplifier output current indication circuit according to claim 1, characterized in that: The current sampling circuit also includes a precision rectifier circuit connected to the current transformer circuit. The high-intensity AC power output by the power amplifier is first converted into low-intensity AC power by the current transformer circuit in proportion, and then converted into low-intensity DC power by the precision rectifier circuit. The current transformer circuit includes a current transformer T1, a resistor R2, a resistor R3, and a capacitor C1. Pin 2 of the current transformer T1 is connected to a power amplifier, pin 1 is connected to a playback device, pin 3 is grounded, and pin 4 is connected to one end of resistor R2. The other end of resistor R2 is connected to the subsequent precision rectifier circuit and resistor R3, and the other end of resistor R3 is grounded. The capacitor C1 is connected in parallel with resistor R3. The precision rectifier circuit includes a resistor R4, an operational amplifier U1A, diodes D1 and D2, a resistor R5, and a capacitor C2. One end of resistor R4 is connected to the output of the preceding stage, and the other end of resistor R4 is connected to the inverting input of operational amplifier U1A. The non-inverting input of operational amplifier U1A is grounded. The two power supply terminals of operational amplifier U1A are connected to a positive power supply voltage and a negative power supply voltage, respectively. The anode of diode D1 is connected to the inverting input of operational amplifier U1A, and its cathode is connected to the anode of diode D2. The anode of diode D2 is also connected to the output of operational amplifier U1A, and the cathode of diode D2 is connected to the current comparator circuit in the following stage. One end of resistor R5 is connected to the inverting input of operational amplifier U1A, and the other end is connected to the cathode of diode D2. One end of capacitor C2 is connected to the cathode of diode D2, and the other end is grounded.

3. The power amplifier output current indication circuit according to claim 2, characterized in that: The current comparison circuit includes comparator U2A, comparator U2B, comparator U2C, comparator U2D, and a voltage divider circuit. The voltage divider circuit includes resistors R9, R10, R11, R12, and R13 connected in series, and a positive power supply voltage connected to the other end of resistor R13. The other end of resistor R9 is grounded. The connection between resistors R9 and R10 is designated as the first connection point, the connection between resistors R10 and R11 is designated as the second connection point, the connection between resistors R11 and R12 is designated as the third connection point, and the connection between resistors R12 and R13 is designated as the fourth connection point. The two power supply terminals of comparators U2A, U2B, U2C, and U2D are each connected to a positive power supply voltage and a negative power supply voltage, respectively; the positive input terminals of comparators U2A, U2B, U2C, and U2D are all connected to the negative terminal of diode D2 in the precision rectifier circuit; the output terminals of comparators U2A, U2B, U2C, and U2D are all connected to the current indication circuit in the subsequent stage. The inverting input of comparator U2A is connected to the first connection point between resistors R9 and R10; the inverting input of comparator U2B is connected to the second connection point between resistors R10 and R11; the inverting input of comparator U2C is connected to the third connection point between resistors R11 and R12; and the inverting input of comparator U2D is connected to the fourth connection point between resistors R12 and R13.

4. The power amplifier output current indication circuit according to claim 3, characterized in that: The voltage divider circuit further includes resistors R14, R15, R16, and R17 connected in series between resistor R13 and the power supply voltage. The connection between resistors R13 and R14 is designated as the fifth connection point, the connection between resistors R14 and R15 is designated as the sixth connection point, the connection between resistors R15 and R16 is designated as the seventh connection point, and the connection between resistors R16 and R17 is designated as the eighth connection point. Accordingly, the current comparison circuit further includes comparators U3A, U3B, U3C, and U3D. The connection method of the two power supply terminals of comparators U3A, U3B, U3C, and U3D is the same as that of comparator U2A. The output terminals of each operational amplifier are connected to the current indication circuit in the subsequent stage, and the positive input terminals of each operational amplifier are connected to the negative terminal of diode D2 in the precision rectifier circuit. The difference lies in the connection method of the inverting input terminals of each operational amplifier: the inverting input terminal of comparator U3A is connected to the fifth connection point between resistors R13 and R14; the inverting input terminal of comparator U3B is connected to the sixth connection point between resistors R14 and R15; the inverting input terminal of comparator U3C is connected to the seventh connection point between resistors R15 and R16; and the inverting input terminal of comparator U3D is connected to the eighth connection point between resistors R16 and R17.

5. The power amplifier output current indication circuit according to claim 3, characterized in that: The current indicating circuit includes a series circuit of PNP transistor Q3, resistors R6, R7, and R8, diodes D4 and D5, and a light-emitting diode. The emitter of the PNP transistor Q3 is connected to the positive power supply voltage, and a resistor R6 is connected in series between the emitter and the positive power supply voltage; the base of the PNP transistor Q3 is connected to a resistor R7, the other end of the resistor R7 is connected to a resistor R8, the other end of the resistor R8 is grounded, and the collector of the PNP transistor Q3 is connected in series with the light-emitting diode; the positive power supply voltage is also connected to the anode of the diode D4, the cathode of the diode D4 is connected to the anode of the diode D5, and the cathode of the diode D5 is connected between the resistors R7 and R8; The LED series circuit includes LED1, LED2, LED3, and LED4, a negative power supply voltage, and capacitor C3. The positive terminal of LED1 is connected to capacitor C3, the positive terminal of LED2 is connected to the negative terminal of LED1, the positive terminal of LED3 is connected to the negative terminal of LED2, the positive terminal of LED4 is connected to the negative terminal of LED3, and the negative terminal of LED4 is connected to the negative power supply voltage. The other end of capacitor C3 is grounded. The collector of the PNP transistor Q3 is connected to the positive terminal of the LED1, and the output of the comparator U2A is also connected to the positive terminal of the LED1; the output of the comparator U2B is connected to the positive terminal of the LED2, the output of the comparator U2C is connected to the positive terminal of the LED3, and the output of the comparator U2D is connected to the positive terminal of the LED4.

6. The power amplifier output current indication circuit according to claim 4, characterized in that: The current indicating circuit includes a series circuit of PNP transistor Q3, resistors R6, R7, and R8, diodes D4 and D5, and a light-emitting diode. The emitter of the PNP transistor Q3 is connected to the positive power supply voltage, and a resistor R6 is connected in series between the emitter and the positive power supply voltage; the base of the PNP transistor Q3 is connected to a resistor R7, the other end of the resistor R7 is connected to a resistor R8, the other end of the resistor R8 is grounded, and the collector of the PNP transistor Q3 is connected in series with the light-emitting diode; the positive power supply voltage is also connected to the anode of the diode D4, the cathode of the diode D4 is connected to the anode of the diode D5, and the cathode of the diode D5 is connected between the resistors R7 and R8; The LED series circuit includes LED1, LED2, LED3, LED4, LED5, LED6, LED7, and LED8, a negative power supply voltage, and capacitor C3. The positive terminal of LED1 is connected to capacitor C3; the positive terminal of LED2 is connected to the negative terminal of LED1; the positive terminal of LED3 is connected to the negative terminal of LED2; the positive terminal of LED4 is connected to the negative terminal of LED3; the positive terminal of LED5 is connected to the negative terminal of LED4; the positive terminal of LED6 is connected to the negative terminal of LED5; the positive terminal of LED7 is connected to the negative terminal of LED6; the positive terminal of LED8 is connected to the negative terminal of LED7; and the negative terminal of LED8 is connected to the negative power supply voltage. The other end of capacitor C3 is grounded. The collector of the PNP transistor Q3 is connected to the positive terminal of the LED1, and the output of the comparator U2A is also connected to the positive terminal of the LED1; the output of the comparator U2B is connected to the positive terminal of the LED2; the output of the comparator U2C is connected to the positive terminal of the LED3; the output of the comparator U2D is connected to the positive terminal of the LED4; the output of the comparator U3A is connected to the positive terminal of the LED5; the output of the comparator U3B is connected to the positive terminal of the LED6; the output of the comparator U3C is connected to the positive terminal of the LED7; and the output of the comparator U3D is connected to the positive terminal of the LED8.

7. The power amplifier output current indication circuit according to claim 5, characterized in that: Comparator U2A, comparator U2B, comparator U2C and comparator U2D are integrated using an LM339 chip.

8. The power amplifier output current indication circuit according to claim 6, characterized in that: The LM339 chip integrates comparator U3A, comparator U3B, comparator U3C and comparator U3D.

9. The power amplifier output current indication circuit according to claim 5 or 6, characterized in that: The diodes D1 and D2 are of type 1N4148; The PNP transistor Q3 is model 2N5401; The diodes D4 and D5 are of type D51N4148; The LED1, LED2, LED3, LED4, LED5, LED6, LED7, and LED8 are of model number Ф3-white-green-fog-L26 / 28.

10. The power amplifier output current indication circuit according to claim 5 or 6, characterized in that: The positive power supply voltage is 15V, and the negative power supply voltage is -15V; The resistance of resistor R2 is 1KΩ, the resistance of resistor R3 is 1KΩ, the resistance of resistor R4 is 10KΩ, the resistance of resistor R5 is 6.34KΩ, the resistance of resistor R6 is 150Ω, the resistance of resistor R7 is 510Ω, the resistance of resistor R8 is 10KΩ, the resistance of resistor R9 is 120Ω, the resistance of resistor R10 is 220Ω, the resistance of resistor R11 is 300Ω, the resistance of resistor R12 is 360Ω, the resistance of resistor R13 is 360Ω, the resistance of resistor R14 is 360Ω, the resistance of resistor R15 is 620Ω, and the resistance of resistor R16 is 630Ω. The capacitance of capacitor C1 is 10nF, the capacitance of capacitor C2 is 10μF, and the capacitance of capacitor C3 is 10μF.

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