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: