Record digital audio with amplifier and bandpass filter-> capture into raspberry pi 4

That looks very unsuitable, and you have a label saying "bandpass filter" with nothing much resembling a worthwhile one?.

If you want to record heartbeats etc. then you need a fairly good low pass filter, as you're looking for very low frequencies, and some kind of contact mike. Essentially an electronic stethoscope.

You'd be better off googling for Arduino examples, as there are masses of stuff out there, and you can easily use the circuits with other processors if required.

Nigel Goodwin said:

That looks very unsuitable, and you have a label saying "bandpass filter" with nothing much resembling a worthwhile one?.

If you want to record heartbeats etc. then you need a fairly good low pass filter, as you're looking for very low frequencies, and some kind of contact mike. Essentially an electronic stethoscope.

You'd be better off googling for Arduino examples, as there are masses of stuff out there, and you can easily use the circuits with other processors if required.

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could you please state some componets to experiment
Raspberry Pi 4 + MCP3008 + Dual MAX9814 Microphones + Preassembled LM358 Band-Pass Filter Modules
this from GenAI. not sure whether this works or not. please help me

Does the PI not already have A2D inputs?, you don't really need a 16 bit A2D, or the power of a PI - the MAX9814 is expensive, and has AGC (AGC could well be a bad thing), and a pre-assembled filter board rather depends on if it's the required frequency. The LM358 is also a VERY old antique and low specification device, far better modern devices are available.

My initial thought would be a simple (and cheap) electret insert, a correctly designed low-pass filter and amplifier (no real need for bandpass - although a simple capacitor on the input would block DC), feeding the in-built A2D on some kind of micro-controller.

Like I suggested before, look for Arduino examples, there's so much out there - rather than asking Artificial Stupidity

Your programing skills ? Can you do embedded C/C++ programing ?

You can implement IIR or FIR filters in code for low frequency stuff like this. Or
even FFT to extract rate (freq) info.

Single chip solutions like attached, but maybe a challenge for a student.

vishnu8888 said:

View attachment 150137
Hello all, i just build this with GenAI help. I am CSE student, and don't much about the ckt design. Any one please help me to do this. I want to record ~5–75 dB SPL sounds (non-vocal like Digestive, Heart, ...etc ) using two microphones.

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This thread may help. https://forums.raspberrypi.com/viewtopic.php?t=337579