CN102158185B

CN102158185B - Cardiac sound amplifying circuit based on MAX 4465 amplifier chip and LM 386 amplifier chip

Info

Publication number: CN102158185B
Application number: CN 201110123760
Authority: CN
Inventors: 夏振宏; 袁赞; 曾艳芳
Original assignee: HUANAN MEDICAL ELECTRICAL TECH Co Ltd HENAN
Current assignee: HUANAN MEDICAL ELECTRICAL TECH Co Ltd HENAN
Priority date: 2011-05-13
Filing date: 2011-05-13
Publication date: 2012-09-26
Anticipated expiration: 2031-05-13
Also published as: CN102158185A

Abstract

The invention discloses a cardiac sound amplifying circuit based on an MAX 4465 amplifier chip and an LM 386 amplifier chip, comprising a prime amplifying circuit and a post amplifying and filtering circuit. An acquiring and amplifying circuit consists of the MAX 4465 amplifier chip and the LM 386 amplifier chip, with a direct-current power supply of 5V for providing voltage to the whole circuit. The cardiac sound amplifying circuit completes acquisition and amplification of a cardiac sound signal by necessary filtering, can be flexibly transplanted to various application circuits with a high degree of modularization, realizes a monitoring function to the cardiac sound and can meet the design requirements on the traditional portable medical products.

Description

Hear sounds amplifying circuit based on MAX4465 and LM386

Technical field

The present invention relates to a kind of amplifying circuit, be mainly used in medical instruments field, be used for the monitoring and the diagnostic system of the various physiology sign of human body parameter, be specifically related to a kind of hear sounds amplifying circuit based on MAX4465 and LM386.

Background technology

Along with developing rapidly of medical electronics industry, portable medical device also more and more receives people in the industry's attention and favor.So-called portable equipment is meant advantages of small volume, light, power-saving, moderate treatment usefulness or the sub-apparatus product of detection of complete machine deal.Portable medical electronic devices mainly is divided into portable medical treatment electronic equipment of family expenses and medical portable medical treatment electronic equipment, and the former comprises electrosphygmomanometer, electronics blood glucose meter, electronic hearing aid etc.; The latter comprises portable electrocardiograph, Portable, multiple parameter patient monitor, portable ultrasonic surveymeter etc.The parameter that Portable, multiple parameter patient monitor is in the market mainly guarded is parameters such as electrocardio, blood pressure, blood oxygen, breathing, body temperature, pulse frequency, and the multi-parameter monitor of monitoring hear sounds is seldom arranged.Much research and develop producer for the demand that adapts to market and all want to detect hear sounds to add in the multi-parameter monitor to go, this just needs the collection of relevant cardiechema signals and the monitoring that amplifying circuit is realized hear sounds.

Summary of the invention

In view of above background, the object of the present invention is to provide a kind of hear sounds amplifying circuit based on MAX4465 and LM386, can be applied in the multiple portable medical device, realize portability, miniaturization, the multifunction and integrated of Medical Devices.

The present invention adopts following technical scheme:

A kind of hear sounds amplifying circuit based on MAX4465 and LM386; Wherein, comprise preamplifying circuit and back level amplification filtering circuit, said preamplifying circuit comprises resistance R 1, R2, R3, R4, R8, R9; Capacitor C 1, C3, C7, C10, C11 and amplifier; One pin connecting resistance R3, R4 and the capacitor C 3 of amplifier, the end of C7, pin 2 ground connection, the end of pin 3 connecting resistance R8, R9 and C10; The other end of pin 4 connecting resistance R8, C10 and back level amplification filtering circuit, pin 5 connects the 5V power supply; Another termination capacitor C 11 of resistance R 9, the other end ground connection of C11; Another termination 5V power supply of resistance R 3; The other end ground connection of resistance R 4, the input and the resistance R 2 of another termination electrocardiosignal of capacitor C 3 and C7, the other end connecting resistance R1 of resistance R 2 and capacitor C 1; Another termination 5V power supply of resistance R 1, the other end ground connection of capacitor C 1; Said back level amplification filtering circuit comprises polar capacitor C4, adjustable rheostat W1, polarity free capacitor C2, C5, C6, C8, C9, resistance R 5, R6, R7, and amplifier; The pin 1 tape splicing resistance R 6 of amplifier and the end of R5, another termination capacitor C 9 of R5, the pin 8 of another termination amplifier of C9; Another termination C5 of R6, the pin 5 of another termination amplifier of C5, the pin 5 of amplifier has also connected capacitor C 6 and C2; Pin 4 ground connection of amplifier, pin 6 connects the 5V power supply; The pin 7 of amplifier connects capacitor C 8, the pin 2 of another termination amplifier of C8 and ground; Amplifier pin 3 connects the centre tap end of adjustable resistor W1, other two ends difference ground connection of W1 and the end of polar capacitor C4, another termination preamplifying circuit of C4; The other end connecting resistance R7 of capacitor C 6, the other end ground connection of R7, the other end of capacitor C 2 is the cardiechema signals of output.

Further, the amplifier of said preamplifying circuit is the MAX4465 chip.

Further, the amplifier of said back grade amplification filtering circuit is the LM386 chip.

Collection and amplifying circuit that this circuit is made up of MAX4465 amplifier chip and LM385 amplifier chip, the supply power voltage of entire circuit are the 5V DC power supply.Chip MAX4465 is a kind of low cost of MAXIM company research and development, the microphone and the full cut-off chip of little power consumption, and it is mainly used in the equipment such as loudspeaker amplification, hearing aids, portable phone, sound discriminator, DAB detection, earphone and portable computer.Its unique advantage is exactly that high cmrr and good power supply suppress, and amplifying this chip for the signal in the noisy environment is optimal selection, and this chip can lower the power consumption and the cost of whole instrument simultaneously.This chip has been accomplished the prime amplification and the part filter function of cardiechema signals in this circuit module, and we have adopted the filter circuit that electric capacity and resistance are formed at its input, and signal is carried out simple filtering.Feedback resistance through between the configuration input and output is regulated multiplication factor.The signal that this chip comes out is isolated the input of sending into the LM386 chip through electric capacity, carries out next step processing.

The LM386 that uses in this circuit is the low-voltage audio frequency amplifier of UTC company design research and development, and its internal gain is 20, but through the size of resistance between configuration pin 1 and the pin 8 its gain is changed between 20-200.The main feature of this chip is exactly the supply power voltage that can use powered battery, peripheral components few, wide, adjustable voltage gain etc.This circuit adopts this chip to amplify as the secondary of cardiechema signals, simultaneously capacitance-resistance filter is arranged also, and signal is carried out further filtering.This circuit has added adjustable resistance in the middle of the input of signal and this chip, can change the size of exporting signal through regulating this resistance.The coupling of amplifier chip He their peripheral components through above two special uses, cardiechema signals is finally seen the electrocardiosignal of relative clean off through filtering and amplification, supplies the designer of Medical Devices to use.

The invention has the beneficial effects as follows:

This circuit adopts special-purpose amplifier chip; The collection and the amplification of cardiechema signals have been accomplished through essential filtering; The degree of modularity can be transplanted in the various application circuits very by force neatly; Realize the monitoring function of hear sounds,, can satisfy the designing requirement of present portable medical product for the designer has saved the valuable research and development time.

This circuit is a modular circuit, can be applied in the design of various electrostethophones, can clearly hear the sound that human heart is beated through external earphone or loudspeaker, in addition through regulating the lungs sound that adjustable resistance also can human body.This circuit is easy to use and low-cost design principle in line with the designer; Adopt special audio frequency to amplify chip; Simultaneously also select the components and parts of low-voltage and little power consumption for use, and reduce the peripheral cell of device as far as possible, this circuit can simply be transplanted in the portable medical device; Make the with better function of portable medical device, integrated level is higher.

Description of drawings

Fig. 1 is circuit theory diagrams of the present invention.

Fig. 2 is an application block diagram of the present invention.

Embodiment

Below in conjunction with accompanying drawing and embodiment the present invention is further described:

As shown in Figure 1, the present invention mainly is made up of prime amplification filtering circuit 1 and back level amplification filtering circuit 2, and " IN " among the figure is the input of cardiechema signals source, and " OUT " is final output signal.

Preamplifying circuit 1 comprises resistance R 1, R2, R3, R4, R8, R9; Polarity free capacitor C1, C3, C7, C10, C11 also have an amplifier chip MAX4465, a pin connecting resistance R3, R4 and the capacitor C 3 of chip MAX4465, the end of C7; Pin 2 ground connection; The end of pin 3 connecting resistance R8, R9 and C10, the other end of pin 4 connecting resistance R8, C10 and back level amplification filtering circuit 2, pin 5 connects the 5V power supply.Another termination capacitor C 11 of resistance R 9, the other end ground connection of C11.Another termination 5V power supply of resistance R 3; The other end ground connection of resistance R 4, the input and the resistance R 2 of another termination electrocardiosignal of capacitor C 3 and C7, the other end connecting resistance R1 of resistance R 2 and capacitor C 1; Another termination 5V power supply of resistance R 1, the other end ground connection of capacitor C 1.

Back level amplification filtering circuit 2 comprises polar capacitor C4, adjustable rheostat W1, and polarity free capacitor C2, C5, C6, C8, C9 and resistance R 5, R6, R7 also have amplifier chip LM386.The pin 1 tape splicing resistance R 6 of amplifier chip and the end of R5, another termination capacitor C 9 of R5, the pin 8 of another termination amplifier chip LM386 of C9.Another termination C5 of R6, the pin 5 of another termination amplifier chip of C5, the pin 5 of amplifier chip has also connected capacitor C 6 and C2.Pin 4 ground connection of amplifier, pin 6 connects the 5V power supply.The pin 7 of amplifier connects capacitor C 8, the pin 2 of another termination amplifier chip of C8 and ground.Amplifier chip pin 3 connects the centre tap end of adjustable resistor W1, other two ends difference ground connection of W1 and the end of polar capacitor C4, another termination preamplifying circuit 1 of C4.The other end connecting resistance R7 of capacitor C 6, the other end ground connection of R7.The other end of capacitor C 2 is the cardiechema signals of output.

The supply power voltage that from Fig. 1, can find out entire circuit is 5V; Cardiechema signals gets into prime amplification filtering circuit 1, carries out the signal filtering and the amplification of one-level, gets into back level amplification filtering circuit 2 then; Signal is carried out secondary filtering and amplification, the clean effectively cardiechema signals of final output.Can change the strong and weak degree of exporting signal through regulating adjustable resistance W1.The yield value that the resistance R 5 among change Fig. 1 between LM386 pin of chip 1 and the pin 8 and the value of capacitor C 9 can change the LM386 chip is between 20 to 200.Value through disposing rational C5 and R6 can compensate the cardiechema signals intensity of output.

Fig. 2 is the concrete application of circuit of the present invention in reality.Obtaining of cardiechema signals among Fig. 2 can be passed through old-fashioned stethoscopic vibrating diaphragm head; On vibrating diaphragm ear handle, put 1 ~ 2 inch long rubber tube; The microminiature Electret condenser microphone of one 1/4 inch diameter is clamp-oned in the other end; Two leads of microphone are received IN and GND place in the circuit with shielded type cable, and the Electret condenser microphone place available heat draw is reinforced, in case produce unnecessary noise jamming.Handle through can signal being sent into microprocessor behind the amplifying circuit, externally connected with display screen can show the waveform of cardiechema signals, if but want to listen heartbeat sound lug machine.If wave-shape amplitude is less or the very low W1 that can regulate Fig. 1 of sound regulates, perhaps disposes C5 and C6 and carry out the weak signal compensation.

Explanation is at last; Above embodiment is only unrestricted in order to technical scheme of the present invention to be described; Other modifications that those of ordinary skills make technical scheme of the present invention perhaps are equal to replacement; Only otherwise break away from the spirit and the scope of technical scheme of the present invention, all should be encompassed in the middle of the claim scope of the present invention.

Claims

1. hear sounds amplifying circuit based on MAX4465 and LM386; It is characterized in that: comprise preamplifying circuit and back level amplification filtering circuit; The amplifier of said preamplifying circuit is the MAX4465 chip, and the amplifier of said back level amplification filtering circuit is the LM386 chip; Said preamplifying circuit comprises resistance R 1, R2, R3, R4, R8, R9; Capacitor C 1, C3, C7, C10, C11 and amplifier; Pin 1 connecting resistance R3, R4 and the capacitor C 3 of amplifier, the end of C7, pin 2 ground connection, the end of pin 3 connecting resistance R8, R9 and C10; The other end of pin 4 connecting resistance R8, C10 and back level amplification filtering circuit, pin 5 connects the 5V power supply; Another termination capacitor C 11 of resistance R 9, the other end ground connection of C11; Another termination 5V power supply of resistance R 3; The other end ground connection of resistance R 4, the input and the resistance R 2 of another termination electrocardiosignal of capacitor C 3 and C7, the other end connecting resistance R1 of resistance R 2 and capacitor C 1; Another termination 5V power supply of resistance R 1, the other end ground connection of capacitor C 1;

Said back level amplification filtering circuit comprises polar capacitor C4, adjustable rheostat W1, polarity free capacitor C2, C5, C6, C8, C9, resistance R 5, R6, R7, and amplifier; The pin 1 connecting resistance R6 of amplifier and the end of R5, another termination capacitor C 9 of R5, the pin 8 of another termination amplifier of C9; Another termination C5 of R6, the pin 5 of another termination amplifier of C5, the pin 5 of amplifier has also connected capacitor C 6 and C2; Pin 4 ground connection of amplifier, pin 6 connects the 5V power supply; The pin 7 of amplifier connects capacitor C 8, the pin 2 of another termination amplifier of C8 and ground; Amplifier pin 3 connects the centre tap end of adjustable resistor W1, other two ends difference ground connection of W1 and the end of polar capacitor C4, another termination preamplifying circuit of C4; The other end connecting resistance R7 of capacitor C 6, the other end ground connection of R7, the other end of capacitor C 2 is the cardiechema signals of output.