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Electronic Stethoscope


t_ang4
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I'm finished working the ELECTRONIC STEThoSCOPE 2 project and its working just fine. now all i need to do now is to put or connect a 7 Segment LED  heart beat Counter circuit display to count in heart beats. but can i put or connect a 7 Segment LED Counter circuit to the ELECTRONIC STEThoSCOPE 2 even without changing the original circuit config. of the ELECTRONIC STEThoSCOPE 2? and is there a 7 Segment LED heart beat Counter circuit display project posted in the forums?

Please help!

any replies regarding to this topic will be highly appriciated! Thank you!

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  • 3 years later...

hi i m new here i want breif discription n working of each component of electronic stethoscope using 741 i ran that ckt 1st i got oscillation at d U1 when i tried 2nd tym it gave me sinewave so also i want 2 know what should output at U1 U2 U3 U4 & U5

Many years ago the project was defective with many errors and did not work. It used five 741 opamps.
I corrected the errors and removed the third opamp which did nothing.
The preamp and lowpass filter opamps are now a low noise dual opamp (TL072), the fourth opamp that blinks the LEDs is a 741 opamp and the 5th amplifier is an LM386 power amplifier.

Here is the corrected circuit:

post-1706-14279144316595_thumb.png

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I cannot understand what you say because you do not talk in English words.
The jack at the output is for over-the-ears headphones. "Open" earphones or a speaker will be heard by the microphone and will cause acoustical feedback howling.

Look at the new project in the Projects section on this site.

post-1706-1427914431685_thumb.png

post-1706-14279144316906_thumb.png

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thank you so much but its not enough for me. I have external oral so i don't know what will they ask on this project so please i want the whole description & also function of each component & also i want to ask you if you're my teacher & taking my oral then what will you ask me on this project? it will me help me for preparation 

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Since you don't know the function of each component in this very simple amplifier circuit then you don't know the basics of electronics.

Your teacher will probably cut the circuit apart:
1) The mic is an electret type that you can read about in Google. It must be powered from a filtered supply. Which components power it and which components are the filter?
2) Opamp IC1a is a very simple preamp that has only 2 resistors. What is the function of the resistors?
3) Opamp IC1b is a Sallen and Key second-order Butterworth Lowpass filter that you can read about in Google. Why is the gain of the opamp set to 1.59, why do R5 and R6 have the same value and why do C3 and C4 have the same value?
4) What is the function of R10 and R12?
5) Read about the components with the LM386 power amp in its datasheet.

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