DIY Heart rate monitor with a photoresistor and 2 op amps
- Published on Jan 23, 2015
- This project is a variation of the ECG Pulse Oximeter circuit from Scott Harden( ru-clip.net/video/bKAJsZJvMI0/video.html ) the main differences are that this one uses a
photoresistor instead of a photodiode and does not require a led, in fact it just needs ambient light, it even works pretty well in low light conditions.
For its realization you only need 2 general purpose op-amps, 3 if you don't want to use a dual voltage power supply.
I've used two old lm741 (lm324 would work as well).
In the right conditions of illumination you can even observe the systolic and diastolic blood pressure separated by the dicrotic notch, which coincides with the aortic valve closure.