Heart beat sensor

Heart beat sensing from fingertip using IR Led + photo diode.
Inspired from http://embedded-lab.com/blog/?p=1671

Category:

Science & Technology

Tags:

• heart beat
• ir
• electronics
• medical device

[jackjosephtz3]

- Year I can see the IR light through camera.

- I drive the IR LED with a 68Ohms + 500Ohms Potentiometer ( in series ).

- NO! Am using LM358 opamp

[goeb1]

@jackjosephtz3 I first tried with a LM358 but couldn't get it to work, I think you've to change a few values and/or capacitors, but I couldn't tell how to make it work, go get a MCP602 ;)

I also think that a 500 ohms pot is not enough with the TCRT5000, I had to use a 2k ohms one to achieve the best sensitivity, and it's set over 1k.

[jackjosephtz3]

Thanks for the heads up! BUT I have another problem,

1). I did the circuit but I cant get the RED LED to blink according to the heart beat. Am using a 470 Ohm resistor in series with the RED LED,

2) When I place my fingre on the sensor, the output stays still at 0.03V.

[goeb1]

@jackjosephtz3 can you verify with a camera that the IR Led is lit ?

How do you drive the IR Led (how much resistance) ?

Are you using a MCP602 opamp ?

[goeb1]

@jackjosephtz3 in fact I think I see what you want to do, and this doesn't even require VirtualWire library.

You only have to connect the opamp's output pin to your RF TX module data pin. Then connect the data pin of the RX module to an input pin on your mcu, then poll this pin state or trigger an interrupt when its signal rise.

[goeb1]

@jackjosephtz3 I use a 68 ohm resistor + 2k pot in series to drive the IR LED, the pot is for easy tuning.

315/435 MHz modules are easy to use at least on the Arduino or with an AVR w/ Arduino bootloader and the VirtualWire library.The drawback is they are not very reliable (lots of dropped packets)

[jackjosephtz3]

Thanks allot that really helps.. Just curious, what resistor value are you using for the sensor IR detector (am using the same sensor TCRT5000).

I like the Bluetooth Heart beat rate monitor project.

Do you think you can help me demonstrating the same project but using RF module (315/435Mhz). Am really struggling with the interface...

PLZ help......

Thanks.

[goeb1]

You can also see my other videos where I send the beat over bluetooth to an android phone.

[goeb1]

@jackjosephtz3 you can see it on an oscilloscope but this will be a conditioned / filtered signal, not an actual 4 phases heart signal waveform.

[jackjosephtz3]

Great work.... Am actually doing the same projet but incorporating wireless transmission of the heart rate. Plz tell me, can i actually see the final output signal on an OSCILLOSCOPE apart from the blinking LED result.

Thanks..

Plz reply ASAP if possible....