[SOLVED] Pulse meter circuit design

[patan.gova]

Hello,

I am working with the extraction of Pulse signals using the intensity of LED(Infrared) converted to current using Photo detector (VBP104SR ) and the small current of photo detector is being converted to voltage using the Trans impedance amplifier stage(OPA380).
The designed circuit is this **broken link removed**

The output of the transimpedance is
output1:**broken link removed**
output2 : **broken link removed**
output3 : **broken link removed**

sorry for the low quality and bad signal.
The real pulse signal willl be like Actual pulse signal **broken link removed**

Sometimes the output of the transimpedance stage is showing like the actual pulse signal with some noise but mostky it is very noisy and will be very difficult for the post processing of ADC read.

Cansome someone help me with the suggestions or corrections needed by the circuit designing of filtering or if anything is needed.

Thanks in Advance.

 

[tpetar]

This works like charm:

Introducing Easy Pulse: A DIY photoplethysmographic sensor for measuring heart rate
https://embedded-lab.com/blog/?p=5508

Easy Pulse (Version 1.1) Sensor Overview (Part 2)
https://embedded-lab.com/blog/?p=7400

This is my very small pulse meter, which is powered from phone Li-Po 3,7V :



Best regards,
Peter

 

[patan.gova]

Hello tpetar !!
Thanks a lot.Pretty good and more information to build a self easy pulse meter from the scratch.
I'm planning to build the reflective pulse meter using the Infrared LED and Photodiode but not with the phototransistor.

Can I use this filtering stages of Passive HPF and Active LPF by feeding the Output of photodiode signal directly to the Vsensor(as shown in the figure of Easypulse).will this give any better result or a signal that can be read out by the ADC.

Any suggestions or corrections of the circuit will be greatly appreciated.
Thanks in Advacne.

 

[tpetar]

I didnt try this with photo diode, I replace TCRT1000 with L-53P3C 5mm phototransistor and MCP6004 with LM324D, for TX led I use red 5mm high bright 15000mcd, and all works fine. You can try with photo diode and post results. Phototransistor is more sensistive then photodiode.



Best regards,
Peter