I'm working on a project for a remote heart monitor based on a piezo contact mic and peak detection to identify heartbeats.
This is my circuit so far, I have the code written for counting the beats and my circuit works, however there is a sizeable background noise. Screenshot of oscilloscope:
Channel 1 (yellow) is output of peak detector, channel 2 (green) is output of amplifier
The peak detector capacitor is all over the place as well, I'm so close to having the system working just need to iron out these problems.
Here is a screenshot of the system in action, piezo pressed to my chest:
There is one spike for the first thump of each heart beat and another for the second thump, making up that "badump" rhythm of the heart
Here is the peak detector:
I'm thinking I'm missing a decoupling capacitor somewhere but I can't figure out where.
Could be the unrealistic gain I've expected from the OP-AMP but I'm unsure.
So to sum up I need help reducing noise and if possible I need a better Vref for the comparator, I currently have it set at just over 2.5v but obviously if I can make this dynamic to allow for quieter or louder heartbeats that would be perfect.
Any input is greatly appreciated!
This is my circuit so far, I have the code written for counting the beats and my circuit works, however there is a sizeable background noise. Screenshot of oscilloscope:
Channel 1 (yellow) is output of peak detector, channel 2 (green) is output of amplifier
The peak detector capacitor is all over the place as well, I'm so close to having the system working just need to iron out these problems.
Here is a screenshot of the system in action, piezo pressed to my chest:
There is one spike for the first thump of each heart beat and another for the second thump, making up that "badump" rhythm of the heart
Here is the peak detector:
I'm thinking I'm missing a decoupling capacitor somewhere but I can't figure out where.
Could be the unrealistic gain I've expected from the OP-AMP but I'm unsure.
So to sum up I need help reducing noise and if possible I need a better Vref for the comparator, I currently have it set at just over 2.5v but obviously if I can make this dynamic to allow for quieter or louder heartbeats that would be perfect.
Any input is greatly appreciated!
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